Ship Handling 2019 - PDFCOFFEE.COM (2024)

Acknow le dge m e nt s l would first like to express my gratitud e to th e President of the

There have been numerous oth ers who helped me in my re­

French Federation of Marine Pilots, Fréd ér ic Moncany de Saint­

search, among whom l would like to thank in particular:

Aignan, who did me the honour of sponso ring this proj ect, and oget her with the community of marine pilots, gave his support

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or the writing of this book. My sincere thanks go also to Yves ichard, Secretary General of the Federation, marine pilot at the ort of Marseille-Fos, who gave his time generously throughout ~ e proj ect. e successful completion and the consistency of this book are - e result of close collaboration with a team of marine pilots hom l t hank most sincerely for their ded ication: -

Christine de Jouëtte, hydrodynamics engineer with Principia and her staff, for their well-informed, expert opinions on dig­ itisation tools for hydrodynamic flow; Erwan Jacquin, chief executive of the HydrOcean laboratory, specialis ing in the field of computational fluid mechanics, for allowing me to reproduce documents from their work. Hans Herderstrôrn; Managing Director of Csmart and Captain Muratore for thei r cooperation and their prec ious advises; Olaf Hohls, Becker-marine systems, fo r his expertise; Cees de Groot, sen ior lecturer at the Amste rdam University of

Eric Baron, ma rine pilot at the Port of Marseille-Fos and former

App lied sciences .

pro fessor at the Marseille merchant navy college; his perfec­

My Dutch publisher Klaas Van Dokkum for his support

ti onism , his vast experience and extraordinary ability to ex­ plain t he theory of ship manoeuvres in great detail, especia lly

Barry Roberts, Liverpool, United Kingdom

in th e f ield of hydrodynamics, have made him a valuable and dil igent contri but or throughout the writing of this book;

This book includes numerous illustrations and pho tos f rom ma­

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Pascal Ollier, marine pilot at the port of Le Havre, especially for

from manufacturers, especially Transas , Becker Marine Syste ms ,

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his c1 ear expia nations of towing ; Eric Vèche, marine pilot at Dunkerque, for his practical ap­

Rolls-Royce, Schottel , Voith Sch neider, Wartsila , ABB; fro m l a~;~ oratories including HVSA, One ra, Friendsh ip System s and DGf. 'J-;f

pro ach t o wha rfing manoeuvres; Benoît Sagot and David Toul lalan , marine pilots on the Seine ,

Towing tanks. My sincere thanks to ail of them .

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or th eir in sigh t into navigation in rivers and shallow waters;

The author should not fa il to mention Pierre Bertran , president

want to t hank ail t hose who responded to my requests and gave

of IFPM and forme r I nspect or General of maritime education and Commander Serge Bethoux, the Secretary-General , who, through their association, have fac ilitated the publication of th is work .

: eir ti me generously to share their knowledge, including: -

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rine compa nies Bourbon, CMA-CGM, La Mérid ionale and SNCM;

Patrick Payan, president of, and ail the marine pilots at, the Mars eille- Fos statio n, for their hosp itality at L'Est aque, Fos and

l must also thank the management of the Marsei lle centre of the

Frio ul st at ion s;

National Maritime College of France for their support and encour­

Franck Maleco, ship's husband for the harbour tugs from

agement, and my colleagues who have given me relevant advice

Bolud a to Marseille and his crews, for their enthusiasm in shari ng with me t heir fasc inating work.

on particular aspects of the work. Finally, l offer sincere thanks to my family and loved cnes. for their encouragement and support in t his work at the expense of valuable time that l could have spent with them .

Container ship, 13,880 TEU

FOREWORD Acting quickly, wi t hout looking ahead, often leads ta trouble . On

I n following this plan, t he book com plies with t he recommen­

the ot her han d, wi t h care ful attent ion and a will ingness t a learn ,

dations of STCW 2010 (Standards of Training, Certificatio n

we can gain valuable insigh ts t hat enhan ce ou r level of co m pe­ tenc e, Even if we st ill m ight make mi stakes. T his book aim s t a sha re Expe r ience wi t h seafarers w ho w ish ta beg in ta learn ship ha nd ling , or t a im prove t heir sk ill s : st ude nts in mar iti me t raining inst itu t ions, bridge wat eh officers, corn­ ma nders - whether just begin nin g or with long service - as weil as those sitting the marine pilot competitive ex am înations . I n other words , anyone w ishing ta acquire a t heoret ical ap proach t a t he general pr inciples of ship manoeu vring . Each cha pter attempts ta meet the var ious needs of the readers by starting with a basic section ex plaining the manoeuvring pr in­ clples, m oving on to a second part th at sets out fu rt he r conce pts in mo re deta il. Th is st aged learn ing pro cess is fecilitated by div id­ ing t he book int o three parts: - Part 1 focuses on describing t he elements of the ship that will allow t he ship handler to develop skills ; a sort of "t oolbox". - Part 2 pro vides an expia nation of the mechanisms t hat put the ship in motion . - Part 3 de scribes the specifi e manoeuvres for a particular envi­ ronment (saîli ng in confined wat ers, mooring, etc .) as weil as emergency ha ndling . The cha pter on "Dock side manoeuvri ng pract ice" provtdes an overview of th e principles set out in t his work wi t h concret e exa m ples of th e m ost co m m on m an oe u­ v res .

,.\-U

Gigantic ships

a nd Watchkeepi ng) reg ardi ng the manoe uvring ski Ils required

of deck off ice rs.

Ali of th ese principl es as desc r ibed in this book Treat ise on ma ­

no euv rin g are ex pla ine d on t he associat ed website

- www .t ra ite dem anoeuvre.fr - in online animations record ed

from the manoeuvring simu lator at t he Marse ille ENSM centre.

The author disclaims ail responsibility consequent on the incorrect use of information and data provided, and may not be held responsible for any errors or omissions or for the consequences of the incorrect use of information and diagrams contained in this work, particularly with regard to the simulator examples. Any comments readers m ay have can be sent by email to t he fol­ lowing address: contact@traitedema noeuvre.fr.

TABLE Of CONTENTS

Acknowledgements Foreword Preface Introduction to manoeuvring

Chapter 1: The ship

3

4

6

8

10

Part 1 Characteristics and definition of the ship

12

Part 2 Manoeuvring gear

20

Part 3 The helm

32

Part 4 The propeller

46

Part 5 Bow and stern thrusters

66

Part 6 Other methods of propulsion

74

Chapter 2: Ship underway Part 1 Vessel underway: Basic concepts

88

90

Part 2 Complementary concepts of ship hydrodynamics

116

Part 3 Wind effect on superstructure

144

Part 4 The influence of waves

152

Part 5 Turning

160

Chapter 3: Special manoeuvres

176

Part 1 Navigation in shallow water

178

Part 2 Navigating in rivers and in channels

188

Part 3 Mooring in open water

204

Part 4 Man overboard manoeuvres

220

Part 5 5hip stopping manoeuvres

228

Part 6 Towing

238

Part 7 Cooperation with pilots

260

Part 8 Oockside manoeuvring practice

268

Part 9 Manoeuvring training resources: simulation

284

Part 10 Regulations

290

Appendices Index Photo credits

297

304

307

PREFACE

Dear reade r,

After rea ding this book, 1 am prou d to have ag reed t o write the

Every single day, Fre nch ma ri ne pilots based in 32 pilo t statio ns

Manoeuvrin g a ship ls t eam work. Ali t hose involve d have to coor­

contro l the ma noe uvring ope ration s of shi ps ar riv ing at , and leav­

dinat e in orde r to bring the operation to a successf ul conclusion .

preface t o t his ed it ion.

ing , ports in France and Frenc h ove rseas terrrtortes. Around the

As the "co nductor" of t his orchestra, the pilot w ill st imul ate t he

whole of Fran ce's coastline, in ail the commerc ial ports, in ail

esse ntiel synergy amo ng the bridge crew, the capta in, t he t ug

weathe rs and throug hout the year, t he 350 marine pilots ens ure

boats and with ail the lin ks in t he port syst em in ge ne ral.

the safe and free Flow of maritime tra ffie by thelr prese nce on t he

T he work of t he t ug boat cr ews and t he pilot boats should be

bri dge of the ships . They are t he essentia l link in the protection of

highlighted at t his point, with t heir unhesitating bravery, no mat­

coastal and port zones an d more genera lly of t he ma rine enviro n­

t er what t he weather and the v ulnerability of t heir small craft

ment of th is beautif ul cou nt ry. They gua rd the liv ing environme nt of their fellow citizens resident on the French coast . Marine pllots have always ensured the success of this pub lic ser­ vice by giving t raini ng t he ve ry highest priority in thelr prof ès­ stone ! practlce . Its de livery has changed over ttme, as techno logy has advanced. As maritime traffi c grows, and the size of vessels has increased at a spectacular rate along wi th eve r greater de ­ man ds in terrns of environmental pressures, pilot stations have developed ever mo re va ried and effective training courses . One of t he maj or compo nents use d in de liver ing train ing nowadays is the use of sirnulato rs for prac tica l work. Th e I nternationa l Maritime Organization, in lts resolution A960 on t he t rain ing of ma r ine pilots, exp licit ly recommends th is meth od . One consta nt fact o r rema tns, however: the most expe rie nced pi­ lots are still dedicat ed to passing on their knowledge and experi ­ ence t o t hei r younger co lleag ues. This knowledge -transmissio n process is the keystone in the marine pilots' tra ining structure. Conttnu tnç th is lengthy trad it ion of transgeneratio nal inter­ change, Messrs . Eric Baron, Pascal all ier, Eric Vèche, Benoît Sagot and David Toullalan, m arine pilo ts at the ports of Marseill e­ Fos, Le Havre, Dunkirk and Seine respect ive ly, ta ke an active part in writing a Ship Handling book w ith Hervé Baudu, professor of marine education at the Marseille centre of ENSM. This close collaborative effort has led to the wo rk Vou have be ­ fore Vou, wh ich 1 am certain will become a reference work in the subject. It offers a complete expia nation of the subtleties of shlp behav­ leur; as wei l as the difficulty of ship manoeuvres. With generous illustrations, practical and educatio nal exa mp les, t his Ship Han d ling book will be favourably received by ail seafar­ ers who wish to improve their know ledge of sh ip manoeuvr ing .

com pa re d ta t he size of t he ships t hey serve. Th eir v ita l raie m ust

be saluted! Let us hope t hat reading this book on ma noeuvring

also contributes t a t he continued im provem ent in the esse nt ial

techni cal ski Ils of ail th ese professio na ls.

Ali seafa rers, from t he novice ta th e mos t experience d, un der­

stand that m anoeuv r ing a ship is not an exact science.

Don't they often speak of th e "a rt of m anoeuvr ing", or the "ship­

handler 's eye "? There is no one solution to handli ng a vessel in

con fined waters. Depend ing on circ ums tances, t he pilot has to

choose f ro m a variety of scen ar ios for wha rfing or casting off.

This can be a difficult cho ice, but it helps to make t he prof ession

of ha rbo ur pilot particul arly fascinating .

Th e manoeuvres desc r ibed here are theoret ical only, an d are not

to be t reat ed as sac rosa nct examples. In a pa rticular sit uation,

one manoeuvre very differe nt fro m t he recommendations of t his

work may be THE correc t operation .

Fina lly, betore 1 leave Vou to some enthralling read ing , 1 would

like to offer m y si ncè re thanks ta th e marine pilots involved in

writ ing t his wo rk - Eri c Baron, Pascal a llier, Eric Vèc he, Benoît

Sago t and David Toullalan - in close collaboration wlth Hervé

Bau du, professor of maritime education.

ln the current context of the dem and for zero ris k at sea, thi s

t reat ise indicates the com m itment of so ma ny marine pil ot s t a

ma ritime t raining bodies, and in particular ta the mercha nt navy

off icers.

Good re ad ing, an d good m anoeuvring ..

F. Moncany de Saint-A ignan Preside nt of the French Fed erati on of Marine Pilot s.

Dear reader,

The ' Guide' is informe d, up-to-date, precise , ins truct iv e and rel ­ evant - an in valuable source of infor mat ion for anyone ab out to

It is my privilege to be invit ed t o preface the first Engl ish t rans­

undertake shiphan dlin g res pon sibilities .

lat ion of t he book 'SHI P HANDLIN G', by Hervé Baudu fra m t he Nat ional Mari t im e College of France ( ENSM) . T his rece nt publica­

The ' Guide' st rikes a go od ba lance between t he theo ry and the

ti on was braug ht to my attent ion by my distinguished collea gue,

pra ct ice of ship handling: t he t heoretical aspects ar e ex plain ed in

Captatn Frederic Moncan y de Saint-A ign an, t he President of the

a ve ry easy - to- und erst and manner giv ing the reade r a greater

FFPM ( French Mariti me Pil ot s' Associ atio n) an d Vice Presi de nt of

insi g ht and a better und erst and ing of forces acting on the ship

I MPA (I nt ern at io nal Marit ime Pilo ts' Associat io n).

wh ile ma ne uve ring. Th e pract ical 'b ands -o n' approac h wit h nu ­

The IMPA brings to gethe r over 8000 of t he m ost expe rie nced

m er ou s iIIust rat ed exam ples is eq ually valuab le and edifying . This

marit ime shi ph andlers in t he world and 1 am pr oud to represe nt

uni que publ icatio n is requ ired readi ng fo r ail mariners, no m atte r

th em and t o promote t hel r in t erest s wo rJdwide .

wh ere t hey work : on riv ers, in ope n seas, in narrow passages or

1 have been honored to serve as Presid ent of IM PA since first

in li m ited draft conditions.

t>ei ng elected at our 2006 Cong ress in Havan a Cuba, an d now in

1 am sure vou will ail join with me in tha nking Her vé Baudu and

my second term after re -e lection in 201 0 . Today IM PA repr esents

t he members of t he FFPM fo r th eir de dication and for producing

over 60 nat ion s world -wide and plays an esse nt ial ra ie in the

t his valuable 'Guide' for bot h novi ce and ex perien ced ma rine rs .

adv ancem ent of pilots' prafessional qu alifications throu gh th e or­

It will be welco med by everyone in the ma rit ime commun ity who seek to tmp rove t heir shiphand li ng abil it ies .

ganizat ion of further education courses and profess iona l training wit h sim ulat ion and practice . That ls why as Pres ide nt of IM PA, 1 wo uld like to commend ail the Pilot St atio ns of the FFPM and the

Capt ain Mich ael Wat son,

indrvld ual pilots w ho have wo rk ed wit h Herv é BAUDU in develop ­

Presid ent

-ng t his Guide. ' SHI PHANDLI NG' ls t he fruit of t he ir cooperat ion .

Internatio na l Marit im e Pilots Assoc iatio n American Pilot s Associat ion

Th e ' Guide' meets t he lat est statuto ry STCW requirem ents on shiphandling . The topics described are also in li ne w ith IMO reso­ ott on A960 .

INTRODUCTION TO MANOEUVRING

Introduction to ma noeu v r ing .

The result ing speed and accele ratio n are

The re are in fa ct fa r too many in t eract ions

phys ica lly associated with the vess el's

bet ween th e shi p and th e port env iron ­

5h ips have always re ma ined f undamen­

mass, calcul ate d as several tens of t ho u­

m ent , in bot h water an d air.

tally uncha nged, subj ect as they are ta

san d to nnes. It is t he refore vital t o take

It is t heref ore very difficult to accu rately

t he same physical laws. However; t ech­

account of th e pr inciples of ine rtia, since

deco de ail th e f orces acti ng on t he vessel's

nologi cal advances allow t hem t a evolve

t hey de ma nd pr ecise cont ro l of spee d and

equilib riu m and t o understan d how it be­

continua lly . Especially in recent ye ars, t he

t raje cto ry when manoeuv ring .

exp los ive growth of in t ernat ional com ­

haves. Even t he most powerf ul com puters

struggle t o m od el ail phys ical ph eno mena

merce and t he ex pans ion of the cr uising

"The art of m anoeuv ring" thu s involves

individ ually,

market has led t a ships becom ing larger,

con tinua lly adap t ing t he cou rse and speed

with wate r and air f low aro und t he ship.

The latest sh ips ar e large r and pr opo rtion­

es pecially t hose assoc iated

fas ter and in ge neral, more powerful.

of th e vesse l wit h t he help of t hes e forces,

Grea te r awareness of the need for safe ty

whose scale varies and is often impossible

ately lighter t han thei r predecessors .

at sea and t he risks of pollution have also

t o measu re. Sailo rs have learned by expe­

This means t hey drift more eas ily.

led ta internationa l developme nts in regu ­

rience to assess their relat ive importance

It is t herefore difficult to contro l the ir t ra­

lat ions ta make ships safer, especiaJly in

according t o circu mstances . For t he most

jectories and t heir movement s.

coastal waters . Port s have also responded

experienced pilo ts, t his assessm ent is of­

The high ris k of accide nt mean s t hat im ­

t a this need for safety, by incorporating VTS inta the ir struct ures.

te n ins t ant and al most instinctive, since

pro v isation cannot be t olerat ed an d a pr o­

t he speed at wh ich t he proble ms arise dur­

fessional, rigoro us approach is necessary.

They are not always suitable, however, for t he huge size and bulk of ships. Sailing

ing a ma noeuvre leaves no ti me for calcu ­ ration an d lit t le tlrne, if any, for re flect ion .

t hrough na rrow straits, passing thro ugh

The various forces acting on the vesse l as

It is for mali sed by a close coo peration

betwee n t he ship's capta in and the pilot,

whose particular tra ining and abil ity to an­

tici pate are so va luab le .

lock s and channets, t hen manoeuvring in

it manoeuvres fa ll into two catego ries:

confined, sha llow bas ins that subject to

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Those whic h t he ship handler applies

t he wind and current, is a very co mplex

and which can then be modified as re­

The pilot has foll owed an init iat o ry course

exercise. Port manoeuvres are t hus mo re

quired . These are m ainly the t hru st of

comb ini ng seve ra l years' sailing experi­

tha n ever one of the ma jor challenges for

the propellers, the tu rn ing m om ent of

ence and th eo retical knowledge , leading

the movement of vessels .

t he ru dder, the t ension of hawsers and

to nationa l competitive exam inations and

They in volve fast decision-making, de ­

anchor chams, t he t raction applied by

a lengthy,

pendent upon rational kn owledge of the

the tugboats, and so on .

Cap ta ins and pilots jointly ta ke resp onsl­

sea, and intuition . Intuitive understan d ­

pee r~ l ed

pe riod of training .

The forces the shiphandler enco unte rs

bility for manoeuvr ing the vesse l, faveur­

but which can be used t o his advan­

ing an app roac h based on obse rvat ion ,

complement each other, the one temper­

tage : effects of wind, curre nt , hull and

pract ice and ex perience.

ing t he extremes of t he other.

swell resistance, turning effects of pro ­

"Fir st study t he scie nce, then pro ceed

Ship manoeuvring may be understood as

pe llers, etc.

t hrough pr acti ce bo rn of the science. "

ing an d reaso n, also known as sea sense,

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a physics problem. The process actually

This met hod, f irmly anchored in m ar it ime

conststs of a quantitative and conce ptual

I n order to enha nce t heo retical knowl­

analysis of forces, and the effects that act

edge, t he ship's interact ion w it h t he flu ­

be anti cipat ed an d "felt" t hro ugh em piri ­

upon the sh ip. There is a very large quan­

Ids aro und it m ay be better understood

cal knowledge of the forces app lie d to th e

underwat er hull or the to psides.

It in vokes t he sailor's "sensitivity" .

This intuit ive ap proach is ail the m or e

effective whe n it ls based on theoret ical

knowl edge, and uses t he ship-h and ler's

va ried experience . Nowadays, tt is also

suppo rte d by accu rate, hig h-pe rforma nce

digital positioning t ools .

It also t eaches hum ility and sea sense

in genera l, lead ing ultim at ely, after long

years of pra cti cal ex perie nce, to a tho r­

ough un der st and ing of how a ship m oves

w it hin lts environment, with th e associ ­

ated ex pertise in ship speed, ine rt ia and

hand ling qua lities, and w ith t he compe­

tence of t hel r crews.

tity of data to be cons idered .

through experiments carried out using

These data are associated with t he vesse:

hull models in tanks and in wind -tu nne ls .

and it s loading, as weil as the port envi­

Studies of the th rust of the ship's propel ­

ronment, the wind and t he sea .

ler, t he efficiency of t he rud der blade, th e

The significa nt number of parameters in­

effects of wlnd or ana lysis of t he t urn ing

vo lved, some unstable, with greater or

trajectorv provide information helpful in

lesser influence on the situation, make

un derst anding a vess el's react io ns .

each ma noeuvre unique and diffi cult to re­

They also hel p in developing mathematical

produce. Thus it is ve ry difficult to develop

models for perfectin g simulato rs

a prec ise theo ry abo ut these forces , with

rs useful

whic h the shiphand ler still has to be en­

This work

t irely familiar. The bas ic princ iples of dy­

im pr ove experience.

namics imply that such forces cause mov­

Analysis of the rea lity of hyd ro dy nami c

ing solids to accelerate.

as a basls on which to

and aerodynamic phe no mena that come in t o play during port manoeuvres is made difficult by t he very co m plex wa ter and air

Vessel Traffic Serv ice (V TS ) is a body lin ked to t he port authorities to man­ age shipp ing traffic at port approach­

es.

f lows involved. Nor is it realist ic t o ex pect to be ab le t o simulate by modelling ail possible real world situations that m ight be encountered.

t rad it ion, enab les the ship's react io ns to

Csptein and pilot in tandem "The art of m anoeuvri ng " im pro ves day ':Jy day. It takes yea rs t o learn , requit­ 1"Ig a sig nif icant pers onal com ml tme nt. is ach ieved th ro ugh t heo retica l t rain­

:t

-rq, naut ical knowledge and a gre at dea l :ç pract ice work on real shi ps, in orde r to çein solid expe r ience, ost m arine t rain ing schools, many ship owners and t he majority of pilot stations - ave t herefore supp lemen ted t he theo ­ ' et ical t raining t hey offe r w it h sim ulator exerctses to encourage t he shari ng of ex ­

Sophisticated toots ­ Bridge on a 360-metre container ship are needed in rela tio n to ail the different t raffi c situations associat ed wit h the port's operat ion, Ship manoeuvring is t herefore

In bad weathe r, the coura ge of the sailo rs and t hei r abi lit y to adapt is expressed by t he saying : "Start mov ing, t hen obse rve",

a d iscip line t hat requ ires th e mas t ery of cem m ands, responsiveness and "sea sense" .

I n a port environ m ent, which is both prot ecti ve and hazardou s for ships, t his watc hwo rd cou Id also app ly t o manoeu­ vrin g.

I t is c1 ear ly im possible to sum marise a vessel 's behav iou r in a few for mul ae t hat are mo re or less cons iste nt with each ot h­ er. The " pract ical" sailor m ay be te mpted to do t his, but lt is da mag ing if tt leaves no room for profess ional develo pment.

oertence . The ship handle r m ust build on experience

Safety does, of course, imp ose a lim it on this . Set t ing th is lim it , and t ak ing respon­ sibility fo r tt, ofte n requires great er cour­ age t han facin g stormy wea ther, because of t he very deman ding regu lat o ry and fi­ nanci al cons traints th at apply today. The zero-rtsk culture ls im posed on eve ­

"he ship handler must be certain of his or ~ e r decisions, as weil as cont inually q ues­ :KJning them in order to adjust quick ly to "ast -chang ing situatio ns.

by making a sensible assessm ent of each ma noeuv re. Hence the purp ose of t his work is not t e prov ide a fe w simp le recip es for ma noe uv ring, but rat her to give each

This underst and ing of t he process allows fo r t he tec hnica l difficult ies of ma noe u­

" ne human facto r in the managem ent of

person t he necessary t ools t o underst and how ships res pond, in or der t hat t he y con­ struct th eir own style of ship manoeuv rin g.

v rin g, t he serio usness of th e risks in­ volved, and the scale of t he environmenta l and commercial cha llenges .

Know ledge of a ship begins with a descrip ­ ti on of it s physical and tec hn ical proper­

We old hands have Jearned this, and we constantly remin d ourselves of the saying "The Tarpeian Rock is close to the Capit ol"

· "'e ship and it s crew is t herefore also in ­ - uoeo in teac hing , since stress - often corn out of ignorance - can have adverse -: ect s on safety when manoeuvring . hi le tec hnical skil ls are necessa ry for r roper underst anding of the relations hip cetween the vessel's movements and thetr causes, a successfu l manoeuvre requires -tanv ot her qualities. =-.rst of ail , "the r ight question s" have to asked, ana lys ing th e situation , it s Iikely : evelopment and the risk s involved. " ne cr ew mu st then be info rm ed c1 early of -:"le resources to be im plement ed. JE

" he vessel's reactions also need to be an­ xi pat ed, in order to engage in a coher­ -=: t scenario which allows for the vessel 's -e rtrcular feat ures and t hose of t he port -=: viro nm ent . Finally, rapid adj ustments

ti es. Hull resistan ce and t he various forces applied to the ship are t hen linked t o basic concep ts of hydrody nam ics, using ex per i­ me ntal data gathered from hull t ank tes ts, The ship's behav iour can t hen be under­ stood in com binat ion with t he chang ing effects of wind, sea, t he env iron me nt, t he t ugboat s and other for ces w hich act on it during ma noeuvring. Navigation alo ng r ivers and canals ls also described in deta il. Sorne exa m ples from pilots themse lves are also give n to bring theory and practice together, emphasising t he involvement needed fo r success in un­ favou rable sailing con ditions .

rvone, captain and pilot alike . Som et im es,

it's im porta nt t o kn ow when te give up .

(A rx tarpeia Capitoli proxim a) ; sim ply put, 'pr ide comes befo rea fa ll'. 50 day by day, sailors undertaking diff icult ship m anoeuv res prove their skill t hrou g h their courage and breverv, and t hrou gh their mast ery of t he art of compro mise .

Characteristics and

definition of the ship

Co n t e nt 1 2 3

4 5

Description of the ship Terms and descriptions of ship movements 5hapes of the vessel 3.1 Ratio of leng th / beam 3 .2 Draught Vessel i n e rti a - power/displacement ratio Propulsion 5.1 Diffe rent types of prop ulsion

1

Description of the ship

Any assessme nt of the manoeuvring qua lities of a ship begins with an appraisal of its overall appearance. It Is often impressive in its size and bulk, but its huit shape and waterline evoke purity and delicacy. Sailors often say that a good ship is also a beautiful shlp . Despite seeming subjecti ve, this aesthet ic quali ty act ually expresses how well-balanced are the vessel's shapes, and how weil suited it Is t o its marine environment. Greater specialisation in ship design has led to sign ificant differences in their shapes and the power of thei r eng ines . Nonetheless, the for ces of sea and wi nd const rain the ship's manoeuvrabi lity, or its safety in general, imposing rul es of balance and harmony on naval arc hit ects . In tern atio nal ru les and regulations on safety and manoeu vrab ilit y, governed by good sea sense, reinforce this approach by restricting t he free dom of shipbuilders. Above ail, a vessel must be enti rely suited to its envi ron­ ment. What is most striking as one becomes famili ar with ships is their commo n behav iour. Whatever therr type, size or powe r, t heir resistance to forw ard move ment through t he water and air comes from the same causes. The "shtp'' as an entity is t herefore a real­ it y waiting to be discovered. It is nonet he­ less unden iable that t hey each have a set of issues in manoeuvring specifie to their parti cular dimensions, loading, engines and appendages. It is therefore vit al to gaug e the ship's capacit v by observation . In th is way, it s reactions can be anti clpat­ ed, depending on circum stances , and the 3 manoeuv re undertaken with the minimum of energ y outlay (mi nimum action by en ­ Characteristics of a sbto gine, propel lers or tugs ). A "good" ma­ The following criteria characterise a sh ip noeuvre therefore is one in whic h the ship 1. Its hull : length, beam, draft, trim , block coeffi cient (Inertt a) also called coeffi cient of hand ler ts asstst eo by the forces exerted fineness, windwa rd surfa ces ( longitudinal and transverse), on the vessel by wind and sea, while de­ 2. Propulsio n: type of eng ine, powe r, propeller, mand ing a minim um of exte rnal act ions. 3. Rudde r : type, surface area, This simple approach helps t o improve 4. Special equipment: Transverse and azimuthal t hruste rs. safety since it always allows for a safety 5. Windward surface. margin .

2

Terms and descriptions of ship movements

A ship' s under wat er body consist of the part of the hull underwater. The topsides is the part above the water­ lin e. The hull can atso be called the 'q uickwork' because it ls th e major component in the smo oth runn ing of the ves­ sel. The ship ls actua lly surrounded by t wo fl uld s: water and air. The wate r is about eight hundred and Fifty t imes cens ­ er and a hundred ti mes more viscous than air, so it quickl v has a much more sign iFi cant effect on the ship's performance. The underworks aucw th e ship t o fl oat and displace wat er, but exp erience significant resi stance to forwa rd mo vement. The t opsides of th e ship present a significan t wind surface area leading to the appearance of aerod ynamic forces that interfere with th e ship's motion, and creat e drift. The six degrees of freedom are defined by the fol­ lowing terms : 1. Heave is a vertical displacement movement of the ship. 2. Sway ls a tra nsverse move ment. 3 . Surge is a longitudinal movement. 4 . Yaw is a rotation movement around th e ve rt ical axis. It y involves a change of heading . 5 . Pitch is a rot atio n movement ar ound t he transverse axis of the ship . It is normally a per iodic movement X around a med ian position (the trtm) caused by th e A ship's six degrees of freedom ship passing through a swell coming fro m the front or rear. 6. Roll ls an alternating rotation mo vement around the Inertia: Typ ical fineness coeffi cient Un der Keel Clearance: longitudinal axis of the shlp. Genera lly tt ts caused by of a ship's hull , whi ch also shows its an ex pression tha t has swell or sea taking the ship from the rear. I f the ship mass and inert ia; conce pt explained ente red into current ls angled t o one side only, it Is said to list . Some ships . in more deta il in the "Ship underw ay" speech that signifie s such as container vessels, can start pertcd!c, large chapt er. t aking a margin of safe­ amplit ude (pa rametric) rolling , caused by seas com­ ty during a manoeuvre ing from in front . This phenomenon occurs when the and by exte nsion in any rolling period is close to that of the waves , and t he roll actio n undertaken . and pit ch movement s begin to resonate .

z

3

Shapes of the vessel

The vesse l's ste rn shapes are des igned to improve prope ller and rudd er effic iency, and lim it eddies, in othe r words resi stance

The shapes of a ship, it s underside and t opsides, are arrived at th ro ugh man y to forw ard movem ent . The shape of t he com prom ises. The ship 's vol ume ls dete r­ . vessel's st ern panel is indi cative of t he huH mi ned by the t yp e, qua nt it y and packag ing of the goods t ransportee, whil e its shape 5 im posed by it s speed and st abili ty . e ship's manoeuvring char acteristics, of

os t interest ta us, depend on its sh a pe, ctsptacement (volume of water disp laced ), m e power of its engine and the efficiency

resist ance, especiall y w hen it is straight and sub merged and creates eddies (oll tan ker s) . Bow sha pes thrust t he wate r aside as th e ship mo ves forward, and their fineness reduces resistance ta forward movem ent . Addi ng a ram bow also re­

its manoeuvring equipment (rudder,

duces resistance caused by the fo rm ation of the waves that accompany the ship .

c-ansverse thrusters, and 50 on ) . These ocaunes are ail the more subtly con­

Nonetheless, the latter works pro perly fo r a trim and draft of a fully-1aden ship.

:ealed since they often conflict wlth ether seakeeping qua lit ies, sor inst ance, turn ing capabili t y whe n ma ­

The shapes of the shtp are thus det er­ m ined by m any scientific and em piric al

"'Oeuvring ( large rudd er blade, f iat stern) :onfl ict s wit h the need for course holding abili ty and the low resistance to forw ar d .,ovement at sea ( Iow d rag rudd er, nar ro w stern shapes) . Observing a ship t heretor e teaches many lessons about the behav­ r to expect when ma noe uvri ng (in ert ia, .... rn ing capac ity, sensitivitv to dr ift, cou rse -oldtn ç . etc.). - je forces t he sea exerts on a t urn ing hull =~e

concent rat ed mainly on t he bows and :'"":"le stern (slende r body t heory ) . Thes e are a-e part s of t he ship on whic h we need to :oncent rat e, theretore . Generally speak ­ -9, fai rly round and bluff- bowed shapes :... m better. Shapes t hat are ta pered in t he and stern have greater di rect ional 5 , this in­ dicates the ship is no longer positioned within it s draft lines. Its hydrodynamic qu alifie s may t hus be sharply degraded, reducing the perfor­ mance of the propulsio n unit and the rud­ der. Wit h a positive or negative trim, the qualities of the control surface are also se­ verely affected . In the forme r case, nor­ mally occu rring wi t h a sma ller load, the ship turns easily but te nds to drift as it turns . I n the second case, wlth a larger load, the ship dr ifts tess, but sways and has difficulty ma intaining its head ing. If the hull is close to the sea bed, this also affects the ship 's behaviour adversely. The flow and pressure of water around the hull are affected by confinement . This changes the balance of the ship. Resistance to for­ ward movement increases, and t he con­ trol surface becomes sensitive (the squat pbencmenonj>.

Manoeuvri ng a ship requires accurat e con­ t rol of it s m ovem ent s, and th us of its in­ ertta . Th e mass, or di splacement , of t he ship is thus also an essentia l feature, since it direc t ly influences it s inert ia. Strictly speakinq t he shape of the ship is also im ­ porta nt, because it det erm ines the mo­ ment of tn e r t ta ê. The disp lacement over drive power ( D/P) rat io is an im port ant fact or for assessing a ship's ma noeuvrability. Clearly, th e higher t his ratio, t he harder it is to ma noeuvre the ship. This is a very variable rat io; for in st ance, it is ten tonnes per horse power for a large crude carrier; a tonne and a half per horsepower f or a large container ship and one to nne per horsepower for a passenger liner. The "block coefficient or coefficient of Fi neness"4, equal t o the rat io of t he hull vo lume over the cuboid containing it

L x B x Te

the hull. I t varies from 0.5 for a fast ship (frigate -type naval vessels) t o 0.85 for a VLCC (very large crude carrier). The block coefficient for a given ship may vary with its draft. The hull fine ness also affects inertia of th e shlp (idea of added mass)s . The slimmer the hull, the easier it is to ac­ celerate and conversely the harder it is to slow dow n. Finall y, the efficiency of t he propulsion unit, espec ially its reve rsing power, affects the inert ia.

1 1

L..:,..-­

1

..s;,...- - _L_

Black coefficient Cb

--­ v

Th e manoeuvrabilit y of a ship de pends on th e perfo r mance of t he propu lsion unit and the rudde r. The latter nor mall y lies behind the propeller, for increased effi ­ cien cy, and its surface area is oft en lim ­ ited by the ship's draft. There are many di ff erent propulsion and cont rol systems . Thelr per formances vary treme ndous ly, and help to strengthen the particular na­ ture of each ship, as weil as it s suita bil ity for its function and use. The most common propulsion dev ice for ships is the propeller. It crea tes a propulsive force of abou t one to nne per 100 hp of the engine (0.6 t onne per 100 hp in reverse) . The rudder blade di vert s t he flow of water as it leaves t he pro peller. This crea tes a transverse force of about 30% ta 50% of t he prope ller's thrust, t o turn the ship . 5hips with a high bloc k coefficient nor ­ ma lly have lower propulsive performance, since the f low of wate r thro ugh the propel­ 1er are dls rupted by the solid stern shapes

1. A ship has a positive trim if its stern

allows displacement of a given ship to be calculated. It exp resses t he fullness of

B Te

Propulsion

that generate eddies.

V Cb =

5

--­

--­

-----­

is sunk down, and negat ive trim when the bows are down. 2. Th is subject is explained more tho r­ oughly in t he chapter on squat. 3. The mo ment of inert ia represents the resistance of a body subject t o rot a­ tion, or to angular acceleration, a concept exp lained in more det ail in the chap ter, "Vesse l underway, corn ­ plement ary concep ts of ship hyd rody­ nam ics".

4 . It is normally shown on the Whee lhouse Poster displayed on the br idge for a loaded ship. 5. The principle is expa nded in t he chap ­ ter "Vessel in motion, com plementary aspects on ship hyd rodynamics" .

5.1

Different types of propulsion

There are different types of engine, eech with its own ma noeuvring characteristics. The ter m used is propu lsion assembly since the type of dr ive used determines the type of pro peller and v ice versa . There is a difference therefore between driving engines with a âxed pit ch prope ller and those with gear units or reverse drive .

5.1 . 1 510w diesel engine / fixed pitch propeller Most cargo vesse ls over 20,000 dead ­ weight ton nes are equtpped with t his drive un it combination . It can be sta rted and st opped very quickly. It has the ad­ vanta ge of a powerful starter thrust . This

comblnatlcn gives t he best overall pr o­ pulsion performance. On t he other hand, t he minimu m "very slow" forward rnove­ me nt speed is ofte n high, arou nd 6 t o 7 knots. The switch to reve rse movement is unp red icta ble above a certai n speed (for­ ward dr ive of t he pr opeller caused by t he wake) . The num ber of cons ecutive starter operati ons is often limîted ta around te n, because of the compressed air capacity reserves needed for starting up . The latest motor s have an etectronic injector control unit wh ich reduces the m in imum rotation speed giving a lower "very slo w" fo rw ard speed.

mbust ion engine propulsion unit

: ectric propulsion unit

5 . 1.2 Med ium-speed diesel engine 1 clutch 1 gea r unit 1 variable pitch propell er This prop ulsion asse m bly is used on most cargo ships below 20,000 tonnes, such as ferries, ro- ro vessels, small passenger ships, etc . The engine is put in gear at the last moment to manoeu vre the ves ­ sel. Reverse motion is pr ovi ded by invert­ Inq the propeller pitch . Th is arrangement gives the greatest f1ex ibility, th us ensuring re liable re verse motion. Low speed cont rol Is possible. Ships with two rudders and two shafts are among the mast man oeu v rable . The const ant speed of the engine means it is possible t o coup le an alternato r to t he engine in order ta increase the useful elec­ t ri city pro duction output. Cant inuo us rot a­ t ion of the prope ller makes control dîff icult at neutra l pitch, and t here is a high r isk of tang ling with mooring ropes w hile m a­ noeuvring at the dockside. Compared to a slow diesel engine/fixed propeller pitch combination, t he starting thru st ÎS less ef­ fic ient and the propuls ion performan ce of­ ten lower, especiall y in re verse.

5.1.3 Medium (or high) speed diesel engine / gear unit / reversing drive / fixed pitch propeller For vessels of less t han 5000 deadw eight tonn es, a high-speed or med ium -speed diese l eng ine with a gear unit, fixed pitc h pro­ peller and rever sing drive is a reliable system . The reversing dri ve make s backward movement qulc k and unrestricted when manoeuvring . There is a powerfu l starter th rust and good pro­ pu lsion performance. However; the m inimum "very slow " forward movem ent speed is often high, around 5 t o 6 knots . Reverse mo­ ti on is unp red ictable at high speed . 5 . 1.4 High (or medium) speed diesel engine / gear unit / controllable propeller A norm ally streamlined propeller, mechan ically dri ven by a diese l eng ine, can turn t hroug h 360 0 to give equal power no matter what directi on it t akes. The additiona l cost of this t ype of propul­ sion un it means it is only used for snips that requ ire very good man oeuvrability (t ugs, fast ferries , liners, offshore ships, etc .) .

5.1.6 Diesel engine / alternator / variable speed con­ troller / synchronous motor / fixed pitch propel­ ler

Electric pro pulsion ls widely used on large liners, and is becom ­

ing mo re popula r fo r some ty pes of cargo ships in order to com­

ply with carbon-reduction ta rgets .

There ar e man y advantages to the se. They have very good pro ­

pulsion performance, especiall y with the coup ling of generators

used as required.

The installations are compact, with low noise and vibration, since

the diesel rnotors used are lower power. Manoeuvrab ility is lm ­

proved , with unlimited rever sing speed .

"Very slow" fo rwa rd speed is low, and acceleration is graduaI to

ensure good control at low speed.

The pod-mounted electric motor is steerab le, 50 the vessel's per­

formance ls especiall y good . There are noneth eless const ruct ion

costs associated wit h th is propul sion un it and com paratively high

operating costs compared to convent ion al unlt s, especiall y for

the pods .

5.1.5 Steam boiler / turbine-gear units / fixed pitch propellers This ty pe of propulsio n unit is still fitted t o some large ships (crude carr iers, aircraft carrie rs), and Iiquefied nat ural gas carri ­ ers. This system has the advantage of deliverin g very high power (45,000 hp). Forward "very slow " speed is indeed very slow, ensuring good control when man oeuvring. Power and operating time are howeve r Iimited in reverse motion . The starter thrust ls inefficient, since acceler at ion ti me is t oo slow . Finally, overall propul sion efficiency is moderate in comparison wrt h sta ndard propul sion syst ems. This type of prop ulsion unit, on met hane carriers, is grad ually disappear ing, in favour of a diesel- elect rlc unit fuelled partl y by the evaporated gases from the t anks of the vessel.

1. 2. 3. 4.

Clutc h t ransfo rmers synchro no us motors converters

Conven tional electric propulsion unit

r

Electric propulsion unit

2 Manoeuvring gear

Cont e nt 1

2

Anchorage gear - Anch ors 1.1 Forward mano euvring deck

1.2 Anchor

1.3 The chain

1.4 Equipme nt num ber

Mooring gear - Mooring Iines

2.1 The different types of moori ngs

2.2 Mooring wharfs

1

Anchorage gear - Ancho rs

Anchors are desi gned ta im mobilise ships in an outer an chor age. I n part icula r cases, as desc ribed below, they can also be ve ry useful in port manoeuv res. The consta nt ly -i ncreasing size of sh ips, togeth er with im prove­

ments in ship-building, espec ially develo pm ent of bow th rus ters and efficie nt rudders, red uce t he need for these practices w hich must nonetheless be part of t he ship-ha nd ler's range of sk iIls. In an emergency, t he anc hors may be the test resort for losi ng way or otherwlse im mobilising ships, in arder ta escape a danger­ DUS situation. Before entering th e port env iron ment, it is there ­ fo re essential t a pre pare and hold the ancho rs ready for moor ing. As an example, t he re is an acco unt of a 300 ,000 tonnes crude carrie r approach ing the port, which lost the use of ail it s contra is and propu lsion , but still managed to lose way and avo id a serious accident by using its anchors .

T he chain co mes out of t he chain locke r t hrough the sp url ing pipe

t o t he w ind lass gy psy ab ove. The chain

rs fed

fra m the cap stan/

w ind lass alon g t he fo'c'sle dec k t hr oug h a paw l/cha in stopp er and

dow n t hro ugh a hawse pi pe in the deck , ex iting at t he shi p's bow .

From here, the chain d rop s down ward s and ls connecte d to the

anchor using a shackle wh ose ha rde ned stee l pin passes t hroug h

a hole drill ed in the anchor cent ra l shank."

A band brake controls t he t rave l of th e anch or line an d blocks it

as necessary.

T he ave rage, regulat ion speed for wind ing or releasing an anchor

li ne is about 10 metres a minute, or one shac kle every 3 m in­

utes. On some windlasses, t here may be a warp ing end with the

winch to ha ul in the ro pes . A sprocket/w inch coupling and c1 utch

lev er also enab les t ran sfer between the anchoring and mooring

f unctions .

The stopper is the deviee whlch takes up t he effort of the anchor

1.1

Forw ard manoeuvring range

once lt is lowe red, t hus reliev ing th e force app lied to the win d­

Ships have two anchors and cables, one on each stde. Each side

lass. A solid hinged part loc ks into a Iin k.

has an anchor with multiple leng ths of cab le, usually joined by

The anchor is secured re ady for sea by a cable calied a lashing .

Kenter shackles.

For medium -tonnage ships, t he ancho r lin e te nsion can also been

The anchor cha in is stored in the cha in locker where its end is

taken up by a single cable or a qufck- release clip attac hed by a

secured to a f itting in the chain locker bulk head.

tu rn buck le called a Gué r igny stoppe r.

Th is is known as the anchor cha in's "bitter end" and must be capable of quick release (or should be of weake r construction

Finally, the hawse pipe is a cast meta l support piece whic h links

than the su rrounding matertals, which should then fail if the an ­

the deck and t he plating, as weil as t he housing for t he ancho r

chor cab le runs away, preventing damage to the shlp's struc­

once lt ls ho isted int o its storage pos ition . When anchoring, a

ture). Anchor chains are connected to t he wi ndlass, or if vertica lly

removable grille, t he hawse pipe cover, blocks t he ope ning to

mounted, to the capstan.

prevent person ne l from boa rding.

The capstan/windlass has a drive whee l calied a gypsy, wh ich is

A safety rail stops people passing across t he deck and fa lli ng into

notched to suit the forged steel chain links of the cable .

t he hawse pipe.

1.

Hawse pipe

2.

Chain sto pper

3.

Anchoring cha in

4.

Kenter shackle Gypsy wheel Brake Dr um War ping head

5. 6. 7. 8. Porwerd manoeuvring deck

1.

Hinged part

2.

To sprocket

3.

Anc horing lin e

4.

Turn buck le

1. 2

Anchor

inged stockless anchors are the m ost

com man . Hall type ancho rs are the usual ty pe foun d on merchant ships , but t here

are othe r va ria nts, Spek, Baldt, etc. "be anch or cons ists of a shank at the end w hîch the chain is atta ched . Th e flukes

e

o

inge at around 45 0 for better pen et ration

1. 2. 3. 4. 5.

ta t he seabed . The weight of t he anchor 5 det er m ined accordi ng ta t he equi pm ent

nurnber (see sect ion 1.3).

Anch orhead Arrn Hinged palm Shank Bill

ULCC anc ho rs m ay weig ht over 20 t onnes.

Weig h t i n kg

=3 x equipment number

e

An c h o r holdi ng capacities a re cov­ ered in t he chapter on "Anchoring" . Count 4 ta 10 t im es the we ight of t he ancher for good hold ing botto ms . Ultr a Large Cr ude Carrie r : crude carrier ove r 300,000 tonnes

45°

e

~ o

1. 3

T h e cha in

-"e anchar chain ts meas ured in lengths :& about 30 m etres , each length consist ­ -..g of links. Ali t he links have a stud in s-e mi ddle, so they do not d ist ort under extrerne ten sion, and are perpend fcu tar to each ot her as they arr ive at the notches th e sprocket, and fina ll y do not fo rm . nks. The chain diameter, gauge "d " ls :! 50 calculat ed according to the ship's equ iprnent number, and depends on the :.Jalit y of steel used in it s manufact ure ild, high -strengt h or very hi gh- st rength eel). For a high-st rengt h st eel : d = 1. 6 0. v 'eq u lp m e nt number. ~e weight in kg per linear met re of chain 'S given by t he fo llo wing for m ula: p

-

= 0. 0 2 1 8 .d 2 lengt hs are lin ked t ogeth er by a rem ov­

1.4 The anchor c1inch con sist s of removable lin ks, a swi vel so the anch or can t urn on itse lf, stud less links and a shackle assem­ bly. The removable link whlch joins the anchor ctinch and the chain length must be accessible from t he deck so the an­

The equipment number defined by class i­ fication companies is used t o calculat e the weig ht of the anchors and gauge of the cha in . It is often expressed with the formula : NA= tJ.2/3 + 2.0 x h x B + AllO

chor can be det ache d safely if necessary.

-

A ship carries betw een seve n and fifteen chain lengths. The port side anchor Hne is norma tty long er t han t hat on th e st ar­

-

boa rd side . Because of th e unfavourable prop wa lk in reverse motion for a ship wrt h a single shaft, having a fixed pltch r ight-hand prope ller, t he port anchor fine is th e most used , since the ship's sw ing ­ ing t a the right w hen moving in reverse prevents the anchor line from chafing on the ram bow.

Equ ipment number

ship 's displacem ent in tonnes at the summer load waterl ine. h = effective height above wat erttne,

Ô =

under summer load, of t he hig hest deckh ouse, not incl uding camber and -

sheer. B = ship's beam in metres. A = lateral surface area of the hull in squa re metres , superstructures, deck­ hou ses whose wi dt h is more than 1f4 B above load waterl ine under summer load , and between u pri ghts.

a le link called a Kente r shackl e. ~ the end of th e first leng th , w hich pass­ es t hrough a rin g called a couplinq, at t he cott om of t he chai n locke r, th e last Hnk ts artached t o a bitter end remote release -oc k, The positi on of t he rem ote release cont rol must be marked and known to a

the perso nne l co ncern ed, so t hat t he chor Hne can be quicklv released in an e-oerç encv. At th e other end , t he final link :!

'S

atta ched to t he anchor.

1. 2.

Removab le shackle Chain shackle

3. 4.

SwiveJ links

2 2.1

Mooring gear and - Iines The different types of moorings

2 . 1.1 The structure of mooring lines Moor ing lines are divided into two cat ego­ r ies, synthetic mooring lines and stee l wire lines. - Synth et ic mooring lines: These mooring lines are asse mbled in severa l bra ids, th em selves the n corn ­ bined int o several st ra nds, in arder ta ach ieve the properties req uired. The more t he line is braided and stra nded, the greater the lengthening, for one materîa l. The hawser section is propor­ tlona l ta the desired st rength. A section of 48mm is standard for moo r ing most cargo ships. Sorne mooring cable mate­ rials are very sens itive ta abrasion and ta ultrav iolet light. A braided sheath ­ ing is therefore needed ta protect the mooring line against such attacks . These sheaths can affect buoyancy.

ma inly for t ripping lin es and tcw- trnes ,

-

tion under st retch loading. They are very absor bent , an d do not f loat . These hawsers are used in mooring confi gura ­ t ions under significant strai n, on buovs. whe re there is sign ificant swell, or for ship-to-ship coup lings.

-

-

Sheated cable

Tow-lines: low cross-section rope at ­ tached to t he m oorin g line eye, so that the lat t er can be hauled more easily.

Steel cable

-

better, they also need to be sheathed for protection against ultraviolet light. They are preferred for use in towing

5ynth et ic cab les are most popular. New,

Synthetic mooring lines: - Polyethylene and propylene ropes ar e sensitive t o abrasion, and have low strain res ist ance. Th ese ropes are buoya nt and do not absorb much wa­ te r, are ligh t and fairly low-cost, used

H MPE ( Hig h M o d u l u s Po lyethylene)

ropes, are lighter t han aramid, with the same strength and elasticity character­ istics. Although they t olerat e abrasion

2.1.2 Mooring line materials

high -st rength mat er ial s are fast replacing steel wire for mooring unes.

Polyester ro pes are very strcnq, du ra ­ ble and resistant to abrasion. Although they do not float, and are relatively ex ­ pensive, they are used fo r demanding mooring operations, on crude carriers for instance, and also for towing, or on mooring posts. Ara m id fibre ropes, more co mmonly known as Kevlar, have very hig h trac­ t ion resista nce, and low elastlcttv. They do not f1 oat , are sens itive to ultravio ­ let lig ht and low resistance to friction and abrasion . For this reason, these ropes need to be sheathed . Despi te be­ ing expensive, they are preferable to po lyester ropes stnce they are twice as strong, but weigh the same . These are used on large crude carriers to replace steel cables for mooring posts. One (shackle) le ngt h ls equivalent t o

15 fathoms or 27.3 me tres.

Kink : a knot formed by the chain whe n

lt twists round on itse lf.

The weight of one shackle ls ap­

proximately equiva lent to arou nd half

the weight of the ancho r.

Braided cable

- Steel wires: Steel mooring cables are normally cern­ posed of twisted stee l wires with a steel core . They have hig her breaking strain and very low st retch. They are very dif­ ficult to handl e, becaus e of th eir com po­ sition. They are being generally rep laced by high- stre ngth , synthetic fibre cables.

though more rarely for hawsers. Poly am ide (nylon ) towing Iines are stro ng an d have a goo d elo nga ­

-

because of the ir buoyancy desp ite t he higher cost. They are easy to recognise as they are usually yellow . Steel cables: Although only having haIf the strength of high -performance syn t het ic ropes , steel cables are much cheaper. They are very resistant to abrasion and ult rav iolet light. Steel ca­ bles tw ist easily and quickly lose their tensile strength when used with very small radii of curvature. Spec ial care

mu st be taken whe n t hey are stored on w inches or attached t o a boll ard. They are m ainly used for mixe d moor­ ing lines on large ships (cru de carr ier s) , as m ooring Hnes, for mooring posts and buovs, or fo r tow ing .

2.1.3 Risks associated with use of mooring lines Many accidents, some very serious, are caused when handling m ooring lin es on manoeuvring decks . This is why these tasks m ust be car ried out by trained, qu alif ied personnel. The main hazards whe n handling moor ing lines are assoct­ ated with their elasticity, f1 exibilit y, weight an d degree of wear. The elasticity of moor­ ing unes which reach breaking point and snap cause them to wh ip round. This is an especially ser ious ris k with po lyester and po lyamide mooring lines. Synthetic ropes can gi ve way with no prier warn ing. Moor ing lines must not be put under ex­ cessive strain, and pe rsonnel must remain in safety zones wh ile di recti ng operations involving te nsion on the line.

1.

Shackle pin

2.

Nylon end

Shackle on mixed tow/ine

Shackle on mixed towline

Towing cable

Winch on crude carrier

Material

Tensile

Elongation

Resistan ce

Resistance

(comm ercial name)

streng th

(at 50 % of

ta abras ion

to UV

(kg/mm ')

break ing stra in)

Density*

Melting TO

Loss of strength

(with knots)

55 ta 6 0 %

Polyethyle ne

50

0.97

6%

paor

avera ge

150°C

Polypropylene

60

0 .91

7%

poor

poor

16 5°C

55 ta 65%

Polyam ide ( Ny lon)

90

1. 14

12 tc 30%

average

average

22 0°C

60 ta 6 5%

110

1.38

7 ta 11%

good

very good

26 0°C

50 ta 60%

Stee l

180

7.8

0 .5 %

exce llent

excelle nt

2000 0C

/

Aram id (Kevla r)

300

1.44

1. 5%

average

ave rag e

56 0°C

6 0 ta 65%

300

0.9 7

1.5%

good

average

150°C

30 ta 50 %

Polyester

( Dacron, Terylene)

HMPE Dyneema, Spect ra)

· Sho w n in bol d , buoyant moor ing lines

2.2

Mooring wharfs

Constructi on of wh arfs w here ships com e alongs ide varies accord îng ta th e place or ty pe of cargo ta be loade d or unloaded .

I n t he do ck ing st age, t he m ovement of t he wat er mass displaced by th e ship along t he wha rfside va ries depen ding o n w het he r

Most wharfs have a solid, closed construc­ t ion, built on fo undations. I n sorne envi­ ro nme nts, rive rs for inst anc e, t he w harf

t he wha rf is soli d or piled ( holl ow wh arf) . The verti cal wall s of the wharf, kn own as doc k faces, have t a have defe nce s ta ab­

may cons ist of a conc rete platform rest ing on pillars or pil es, gen era lly built aga inst t he rive r ba nk ta ab sor b ho r izont al t rac­ t ion fo rces . For j etties where ships cann at

sorb t he ship's residual kinet ic ene rgy du r­ ing bert hing phas es, and prevent wear on hulls caused by friction against the st one surface of t he w ha rf. These Fit t ings are de­

come directly alongside, suc h as t hose fo r ai l or gas loading, moo ring point s are sometimes prov ided by f irm , iso lated structures called do lphi ns.

Cylindrical defences

signed t o disto rt an d abso rb kinetic energy From the largest ships berthing at the ter­ mina is. Whe re mo re ru d ime nta ry de fen c­

es ar e st ill found in sorne places, such as tyres, t hese are gene ra lly of t wo klnds, ei­ t her f loatin g or solid cylin der s in synthetic ma te ria ls, or neoprene panel s.

Panel defences

The ship is held at th e wha rf using m oor ­ ing lines t ied ta bollards or sa ms on post, cast iron or steel fittings. Bolla rds, spaced ab out t went y m et res apart an d anchored into the w harfs found at ions, can t olerate tractio n forces of 50 to 300 tonnes . The forces f rom th e m oore d vessel are distributed among at least four t o six bol­

Solid wharf

lar ds. Several ropes are normally attached to one samson post . If these are lines fro m differe nt shi ps, t he latest arrivai makes its lin es fast by pass ­

Mooring !ines hitched to bollard

,..~

i:']'i!m~-'

ing the m t hro ugh t he eye of the rop es already attached . Thus t he first ship at the doc ksi de can no r ma lly depart witho ut havin g to cast off t he ot her moorin g lines. Bollards are set back slightly from the edge of t he dock fa ce, so that the counter of t he ship's hull do es not st rike aga inst them du ring docking operatio ns.

Bollard set back From dockside

On wharfs for gas, crude oil an d che m i­ cal tankers, t radit ional m oor ing posts are replaced by qufck release ho oks ( QRH) . These ma y inclu de a capsta n on t he top, to haul in the rope bef ore tying it off. On some new types of equip ment, a cen­ trai contro l dev ice is used to cast off m oor­ ing lines remotely. These hook s may have a st ra in gauge to cont rol how t he shi p is held at t he dockside . Automatic mooring syste ms are now ap ­ pearing in sorne te rmina is, in orde r t o re­ move the need for lengt hy and risk han­

Quick release books QRH

dling of ropes and minim ize t he use of coasting pilots. The most popul ar of these is the vacuum type. A hing ed plate which compensates for the sh ip's vertical move­ ment, is ap plied to t he fi at side of the hull . The vacu um created between su pport plate and wall holds the ship alongside t he wharf.

Dolphins

Vacuum-based mooring

2.3

2 .3.1 Man oeuvring decks

Mooring e q u i p m e nt

Mooring lines keep t he ship alo ngside t he w harf 50 tha t com­ m ercial operat ions can proceed in opt im al condit ions of safety. A good moo rin g mu st resist t he various force s ta be applied t a t he ship du rin g it s stopover. These forces are cause d ma inly by the eff ects of : - wind , - ti de and cur rent,

- variat ion s in t rim , dra ught and list cause d by com m ercia l op ­

er at ions, - edd ies caused by ot her shlps pass ing nearby, -

Most new ships have drums on wh ich ro pes are sto red. They are d riven by electric or hydraulic m at or, for w inding and unw ind­ Ing th e rope as requ ir ed. Th e dr um has a j aw - bra ke ta m ai nta in ten sion on the rope . Sorne dr ums have a te nsion ing devi ce ta maîntain constant traction on the rop e no matter how the t ide or free board changes. Each dr um ho lds one rope . The rope is fed outwa rds, pass ing through rouer fa ir leads. Drums are placed on th e manoeuvring deck in orde r t o lim it the radii of curvature of th e ropes, 50 as not t o affect their st reng th . Samson posts are arra nged on the decks fo r tying of f additional mooring and t ow ropes .

swel l and waves, ice .

In some circu mstances, moor ing lines are also used to assist in -nanoeuv nn ç when coming alongs ide or gettin g unde r way. This aartic ular ope ration is covered in the chapte r on practical ma­ nceuvrinq situations .

1.

Winch moto r

2.

Clearance cable drum

3.

End cable drum

4.

Fatrle ad

S.

Samson post / bollard

6.

End cabl e drum

7.

Win ch mot or

8.

Breast fine

Mooring plan

~D DQ DDQg=J'

~

Bow and stern fines

ç

1.

stern Hne

2. 3. 4.

5.

stern breast line waist line stern spring bow spr ing

6. 7. 8.

waist line forw ard breas t line head lin e

2 .3 .2 Arrangement of mooring li nes The moo ring plan ts desig ned to hold the ship alon gside the dock with ropes arra nged forward, across and ta the stern of the ship, each with t hetr own particular functian. - Bo w o r st ern s p ri ng s: These keep the shi p alongside the dock, reducing longitud inal move­ ments. They are dupllcat ed t o di stribut e fo rces. In order to reduce tens ion appli ed towards th e dock, caused by a crosswind for insta nce, t he second line ls held away by the fairlead . I f t here are not enough bollards at the bow end on t he wharf side, t he walst line is fed by a fairlea d to t he rear of t he manoeuvrin g deck the n carr ied towards the end of t he wharf. -

Br ea st lines: Arranged perpendicular to the dockslde, breast lines prevent the ship moving away from the wharf, especially wh en pushed by an offshore wind or strong backwash. If the ship has a high freeboard, breastlines will be pulled downwards and lose efficiency. This is also af­ fected by the short distance between bollard and mooring point which prevents the se ropes using their natural elasticity. There rs a risk of break ­ ing caused by too much tensio n. Ext ra head Iines are favoured in such configurations.

D D D

Breast fines

The breast line is no longer considered effective if t he angle to t he wharfside exceeds 30°. -

Springs: In addition to bow lines, bow and stern springs are fastened longitudinally as much as possible, in order to prevent the ship apprcach­ ing or retreating from the wharfside.

Typical coefficients of diffe rent ships are given in the chapters on "The ship in motion " and "Towing". They are used ta as­ sess these const raints .

Springs

Analysing the constraints im posed by the environment, along the ship 's vertical, longitudinal and transverse axes allows mooring plans to be drawn up and managed to balance forces on the vari­ ous mooring Iines during the stopover. Mooring lines do not te ter­ ate vertical forces, which are very pcwerful when t he ship rises with the tide or variations in its draught. The ir length therefore has to be adjusted regularly. A mooring line ls at its maximum efficiency when it is aligned that it directly counters the force tt has to overcome. Wind and current forces are approximately horizontal. It ls therefore important to take account of the angle to the horizontal made by the rope, and the direction of the fo rce applied when assessing its effectiveness. These forces may be very high (several hundred tonnes), especially t ransve rse forces in high winds . The sim plest mooring plan consists of cancellin g out long it ud inal forces with springs and head Iines, and transverse forces with bre ast lines.

50

This is t he preferr ed config uration at ail, gas and chemic al t anker terminais. If possible, t he fo llowing provisions must be respected whe n drawing up t he mooring plan: - the mooring plan must be as symmetrical as possible with respect ta the central perpendicular, - breast lines must be as far as possible from the central per­ pendicular, and be perpendicular to the ship's longitudinal axis. - springs must be as parallel as possible to the longitudinal axis of the ship (see next section), - t he angle of each moo ring lin e with the horizontal must be small, - moo rin g lines wit h the same tas k (spr ings, breast lines, etc.) must have srmuer characteristics (dtarne ter; lengt h, elasticl t v, etc .), 50 t hat stresses are eve nly distribut ed amo ng t hem, - the mooring plan must consider t he particular features of t he port (wind, current, depth, t raffl c, etc.) .

2. 3 .3 V ertica l d istribution of forces The mooring plan m ust be desig ned 50 th at the bre ak ing strain lim it s on the mooring unes are not exceeded . For a force F ap­ olied to the ship, te nsion on the mooring line Is calcula ted by div idi ng this fo rce by the cosine of angle a as follo ws:

2510n5

11­

F T= COSa

The angle a wit h the hor izonta l is therefore kept as low as

Force considered horizontal

Oblique force

posslble ( below 30° for loaded ships), since t he t ension T ap­

olied t o t he rope increases rapidly as this ang le lnc reases for

an unladen shi p. For a fo rce of 25 t on nes, t he force act uall y

app1îed ta t he rope Is :

- T = 28 .9 t onnes for a = 30°,

- T = 35 ,3 tonnes fo r a = 4 5° ,

- T = 50 tonnes for 0= 60° .

"he pr inciple is identi cal for the longitudina l plane . The spring

""as ta be as horizont al as possib le since the st rength of the

25 tons

Force considered horizontal

-cp e falls wit h the angle tt forms wit h the w harf side.

"hi s phenom enon becomes more noticeable as the ship 's load s lig ht ened. The pressure of an offshore wind on t he long it u­ anal surfa ce increases as the freeboa rd area increases. The angle a increases at t he same time and t he effective ness of :ne t ension applied to each ro pe falls. The same reaso ni ng ap­ cnes for a ship m oored to the wha rf aff ected by the rise and ~ II of t he t ide. During t hese cri tic al phases, specia l vi gilance

25 tons

Obli que force

s needed, adjust ing ropes and st rengt hening mooring fines if -cecessa ry. , e major cons traints on t he ship can be evaluated using t he :ata giv en in the chapt ers on the action of wi nd and current. , ese const rai nt s are expressed by longitudinal and tra nsverse =:)rces, and yaw moments that show how im port ant the breast "es are in compensating for the transverse forces and t he aw mo me nt s.

2.3 .4 Vari ous m ooring configurations , e most com monly used m ooring configuration is alon gside .;;e w harf, since lt is th e safest for commercial operations. -"'ere are plenty of other ways ta moor a ship, depending on :.,e ty pe of cargo, layout of the port, load ing site, rive r or open sea, such as moorin g to a buoy or post. The latter are ma inly

.sec for

oil or gas operations .

- Moor in g a longsi de a w h arf: The shi p is moored parallel ta the wharf. The whole length of th e dec k is accessib le for handling equ ipment. Mooring alongside dock

- Moor i n g al ongside a wharf and dolphi n : This ty pe of m oor ing rs used especiall y on a r iver, or for oil or gas loadi ng and discharge operations. The ship rs along­ side a f airly short solid or pile d dock, on which th e loadi ng arm s are inst all ed. Only t he springs are t ied to the bollards on the dockside, wi th t he othe r mo oring lines taken o ut to dol phins or t ied up on the land.

.,

large ships, subject to particularly strong forces fro m win d

= d cur rent

(very confined navigation in rlvers, for inst ance), -rcor tnq post" attachments of steel cable and chain are added ~ conv ent ional mooring s. Mooring to wharf and dolphin

• • •

"

'1

••

_

(.. I~;Z!'1!tJ o 810 20 13 20)

, )1 .

. ..:,' "

. 1 1

Mooring stern ta wharf -

Mooring stern te wharf: 5h ips ar e m oored perp endi cular ta t he w harf, with the bows held by a moo ring rope attached ta a post or m oored w it h one or t wo anchors, or Even t a a dolphin. This type of moo ring is kept for ships where there is reduced space avail ­ ab le on a wha rf, with onl y the end of t he wharf free ta attach th e mooring ro pe. 5hips wit h a st ern ram p, such as ra-ros , often use th is mooring method . Holding on th is position rs tri cky with a strong crosswind .

Yokohama type fenders -

Snio -to-snip mooring

Sh ip-to-ship mooring : In particu lar sit uat io ns, where t here Is insufficient space in a port , for com me rcia l load ing or d ischarging of bulk liq uids, two shi ps may have to be moored t ogether. This ma noeuv re ls norm ally used fo r crude car rier Iig ht ening operat ions , with bot h ships hove to or mov ing at low speed. The m ot her shi p has Yokoha m a type fend ers alo ng th e freebo ard t o protect t he hulls of both ships during the operation .

CALM buoy

SPM buoy

2. 3 .5 Mooring t o a b u oy Th is method is ma inl y used for taking on oi l or gas, w it h the refuell ing ship moored to a singl e- poi nt mooring (SPM) buoy. A f1oating , fle xibl e collect or ls then connect ed on board fr om th e buoy. The SPM buoy Leg Mooring) , or else atta ched to a rigid struct ure f ixed to t he bott om .

rs

anchored to the bottom, fo r a CALM (Catenary Anch or

2. 3 .6 Ele ctr o ni c m o ori n g aids The ship han d ler has t o be ab le to qu antify moveme nt cont inually. Heading and speed infor mati on norm ally com es fro m th e gy roco mpass an d t he log. I n some cases, t he accuracy of t his informa t ion rnav.be consid­ er ed inade q uate. The pilo t is helped in ma noeuvr ing by seve ral effective electronic aids. The most popula r and easily availab le rs a portable compute r connect ed

ta a DGPS (PPU, Porta ble Pilot Unit) . The pilot bri ngs me lapt op on boa rd, an d connects it t o a pair of DGPS ent erinas fi tted on the bridge w ing . The position ob­ tained using this met hod is accurate to a few tens of cent im et res, ± 0 .2 0 for heading and ± 0 .5 0 per minute , t urn ing rate. ~

specif ie map is prov ide d to show the ship within t he

JOrt plan, during th e va rious stages of the m anoeuvre. :f great er accuracy is needed , the reat-tr me kînemat­

c syst em ( RTK) comb ines the DGPS signaIs with real orne co rrect ions made by a refer en ce land station . It is m en accu rate to a few centimetres. Nonetheless, on an ordi nerv com put er screen, one pixel is the equivalent

:ç a few te ns of centimetres for a scale appr opr iate for a m ooring . - "'e laser sight measurement system is t he most accu ­ -ate at the moment; a few centimetres at 500 metres :-.am t he wharf. Sensors at t he ends of the Quay berth -t easure the dista nce from t he wh arf, as weil as t he acoroach speed in centimetres per second. Th is infor­ -atio n is displa yed at t he dockside . : - is pos sible on ly t o take a perpendicular measu rement ac he wharf in the une of sight, and the ship ha ndler -3S to assess long it ud inal speed . The sigh t can be ad­ est ee for poor v isibilit y.

:

/ / !

./

°

0,1

/ 0,2

F =V

0,4

O,B

0,8

1

1,2

1,4

,vs;.

1....

Order of magnitude of the Rw/R ratio as a function of the Fraude number (therefore of speed)

Conversely, ail the phenom ena associated with t he hull's restric­

t ion wlthin a channel or basin increase t he relat ive im port ance of

pressur e and wave resist ance effects .

Whe n manoeuvring, observing th e waves for med by the ship as it

prog resses allows the relat ive im portance of resist ances lin ked to

pressure and t hose linked t o v iscosity to be quantlfied.

8 . 2. 2 Reynolds similitude The same reasoning appües t o v iscous resist ances using ano the r dime nsionless nu mber as reference, the Reynolds number, Re. V.L

Re

= v

V: speed, L: length, v: kinematic viscos ity. The Reyno lds similitude w ill be used w henever visco us res istance is more useful, such as in the case of extreme ly turb ulent flow cond it ions . It is im possible to respect bot h t he Fro ude and the Reynolds similitudes in a tow test on a moder. A quick examination of t he formulae shows us that in orde r t o satisfy the Reynolds similitude, the mo del 's veloc ity mus t be in­ creased in equa l proportion to the rat io of scate (for a model at a scale of 1 :25, it has to travel25 t imes fast er t han the ship), while for the Reech-Froude similitude, the mode l's speed is reduced (ratio of speed 1/5 of t he examp le used). Port manoeuvres take place at low speed, and ex per ience shows that waves formed by t he ship are small and t heir effect on m a­ noeuvrability may be ignored, at least in com parison with t he pressure and eddy forces that crea te lift (res istance ta drift). In practice, it can be seen that with a Froude number of unde r 0.3, wave resistance does not have a determining influence on resistance to forward movement, and t hus on ma noeuvring. On the other hand, the Reynolds number has an effect on the forces applied to t he hull for wide drift angles, which are frequent w hen turning . Using a ship of 180 metres as an exemple. manoeuvring at speeds of less t han 8 knots (Froude number between 0.1 and 0.2) the graph in figu re 54 shows clea rly that in open water t he wave resistances Rw do not represent more than 20% of t he total hydrodynam lc resistance R.

Bow wave on a model For in st ance, especi ally when passing t hrough conf ined waters,

the ship crea t es large waves, showing th at pressure-re lated phe ­

nome na are dom inant (co nf inement) .

This info rm at io n ls used to antlclpate t he ship's perf or m ance

(si nkage, sens itive stee r ing, etc.), Another spec ifie examp le ls

t aken f rom t he ship as it turns.

In t urn ing, the ship pushes back the water ahead of the out er

side of the tu rn , smoothing t he wate r created by eddies to t he

rear of t he inner side of the t urn.

The size of waves forme d ahead expresses the value of t he lift

(w ate r pressure) and t he ship's cap acity to come t o a st andstilL

Astern, t he ship's capacity to smooth t he sea, form ing eddies,

shows t he extent of tu rning drift and phe nomena linked to vis­ cosity.

8.3 Extrapol ation of t e st resu lts In gene ral, t he results of the tow tank tests are extrapolated using sim ilit ude, as weil as the Fraude hypothesis, giving sorne prefere nce ta wav e resist ance and assurninq that t he hull resist ­ ance R is t he sum of the wa ve res ista nce .aw and the viscous

resist ance Rv. R = Rw

+ Rv

Viscous resista nce can be de comp osed into f rictio na l re sist ance

RF and sha pe resis t ance Rf (all ow ing for t he hull 's vo lu me as­

pect) : R

=Rw + RF + Rf

Frlction al resista nce is a funct ion of the Rey nold s number an d

t he roughness; on the othe r hand , shap e re sista nce is seen as

proportio nal ta fr iction al resista nce :

Rf = kRF

Digital simulation

8.4 This gives :

R

=Rw + (1 + k) x RF

( 1 + k) call ed t he coefficie nt of shape; it g reat ly depen ds on t he

shape of th e bows ( k = 0 . 1 ta 0.25) . The Froud e si m ilit ude is

th erefore use d to ext rapol at e the ex per ime nt al result s fr om the

mo del t o th e rea l shi p, 50 defining t he speed of the mod el as a

function of it s size and of t he speed of th e real ship to be stu die d.

Measuring R ( m odel) t herefore defin es t he non-dime nsion al co­

eff icient s of the real ship : Ch, Cw and CF'

Measur ing R ( model) t her efore defines the non-d im ensional co­

eff icie nts of t he real ship : Ch, Cw and Cf.

R (model) Ch (model)

= (lj2.p.S.V 2 (mode!)

and

Other types of tests

Red uced scale propeller t est s are norm ally carried o ut in hyd ro­ dy namic t unnels. This t im e t he Reynold s sim ilit ude is preferred ( based for instance

Ch ( m o d e l ) = Cw ( m o d e l ) + ( l + k ) C F (model)

on th e propeller diam et er ) since it is wate r v iscosity that deter­ m ines the quatltv of t he flow and propeller eff icie ncy. The size of t he propeller s on large ships, howe ver, me ans t hat this sim ilit ude is oft en tec hnically difficult to achi eve. Ot her sim ilit ude laws are also consi dered, in or der t o assess pro­ peller performan ce under it s no rma l condition s of use : cav it at ion, Fro ud e, wa ke and immersion laws. coef­ Non- dim ension al f icient s of t hru st exe rted by the prope ller torque, neede d for drive an d per ­ formance , are qu ant if ied at differ ent rot at ion speeds

Cw is the same fo r tests on t he mode l and calculations of t he

and ship speeds, as weil as in acceleratio n (V < a and N > 0 ) an d brakin g

ship's hull res istan ce, sin ce it in dicates t he effects of grav it y and t he fact t hat th e Fra ud e num ber is ret ained; however, th e coef­ fi cient CF, which ind icat es th e viscous effects and the refo re de­

(V > a and N < 0) phases. Scale model in tunnel Cav itation, vi brat ion and

inte rfe ren ce bet ween hull , propeller and appe ndages are st ud ied .

pend s on the Reynold s number of the Fl ow, is not retained. I n calculat ing th is coeffi cient CF, the formula given by the ITTCl )

57 is used : 0 ,0 75

Finall y the coeffi cient of sh ape ( 1 + k) may be calculated ex­ perim ent ally, (Pro haska , low speed method , met hod using geo­ m et r ically srmuer rnodels , etc. ) or else CFD ( Computational Fluid Dyna mics; ICARE software developed by OGA and CNRS for in­ st ance ; EOLE softwa re developed by Prtncl pial - J.

Study of cavitation on propellers in real world J

I nt ernat ional Tow ing Tank Conference.

2 Wave resista nce may also be celcutated using codes based on t he pot ent ial theo ry, bu t wit h un helpful hy pot heses : no vortex det achmen t (app endage drag ), Iim it s t o detac h­ ment modelling. Potentiel theorv applies to Flow of a ncn -rctatronet flutd (n o rot at ion of t he fluid parti cle) for which v iscosity effects (bou ndary layer ) may be ign ored.

The ship 's aerodynam ic resistance is m easured in th e w ind tunnel on rnod­ els, also using th e Reynolds simi litude. Dim ens ionless coefficients (Cx, CV, Cn, Ck) of long it udinal and transverse forces and yaw and heel m oments are assessed . The superst ructures often have sha rp edges , whose aerod ynamic coefficient is pract ically independent of the Rey nolds number. Reference may also be m ade t o another dim ension less coefficient, the de­ gree of win dage, in order to ext ra polat e win d effec ts on ships of the sam e t ype but differe nt sizes. y ( w i n d a g e surface) De g r e e of w indage

~( h u ll volum e )

Rudders are tested in t he tan k . Lift and drag coefficients measured in t his way al­ 10w the fo rces exe rted on t he helm that cause the ship to t urn , t o be measured for a given flo w ve locity and ang le of in­

How ever, usin g computer sim ulation to

perform expe rimental test s may lead to

the 1055 of an empirical app rcach to ex­

peri me ntation .

The question needs to be asked as to what

t he limitations of this int egrati on of exper­

iment int o t heoret ical practlce ar e.

It should t herefore be st ressed t hat ma ­

rine hydrodyn amics is sti ll, above ail, an

experimen t al scien ce t hat is doser to

physics than mathematics.

It is fou nded in experience in t he real

world, not on sophisticate d, iso lat ed t heo­

ries, eut off entirely from t rue life.

There is no denying t he usefulness of

t hese theories, since they can be used to

develop mathematical m ode ls that simu­

lat e rea lity. But a mod el and its simulation must always invo ke exper ience to obt ai n confirmation by fact s, t o validat e a neces­ sarily li mi t ed fie ld of appl icat io ns.

cidence. Calculating these fo rces still re ­ outres inte gratio n of a correct ive coeffi­ cient that is difficult to quantify, in arder to allo w for turbulent effects of wake and t he flow from th e prop eller on the perf or ­

I n th is sense, port man oeuvr ing Is a spe­ cial case. First of ail, because local port

mance of the rudd er.

ship mo t io n . Excessive ly t urbulent f low, often breaking away w hen t he shi p dr ifts, is also often dist urbed by t he fre quent changes in en ­

To conc lude, tank and wind tu nnel tests can quantify a large num ber of forces act ­ ing on a shi p's dynami c equi libriu m . The y ar e comp lex, lengthy and expe nsive , but unfortunately do not necessaril y all ow ail th e effec ts of a shi p' s turn ing during port ma noeu vres t o be quantified fully .

It is necessary to rem emb er that the ma in purpose of t hese tests is t o study resist ­ ance to forward m ovement, pro puls ion, manoe uvrab ility and seakeeping qualities of shi ps, and t hat it ls not ent irely reells t lc to com bine th e re sults fr om man y te st s in order to simulate a port manoeuvre .

8.5

Compulational tools

These tests will , in th e future , certainl y be repl aced by m uch faster trials in a vi rt ual ta nk O. Full scale sim ulat ion and m ode !­ ling of shi ps will ove rco me th e limitatio ns of t he laws of similitu de . The shi p coul d then be placed in a virtual port environ­ ment, where manoeu vres could be slm u­ lated step by step, calculating t he for ces exerted on it by water and air. Hist orically, it should be noted that t he t heory supported t he expe riment. Nowadays , as computing powe r increases, th e pr ocess seems reve rsed . European Virtue project Tank Utility in Europe.

- Virtual

features (t opography, currents, etc .) that are not take n into account in tank tests very ofte n have conside rable infl uence on

gine speed, by the proxim ity of the quay­ side and banks, or by t he quality of wate r whi ch may often be polluted by suspended silt . It is therefore d iffi cult t o accu rately ext rap olate tank tes ts or CFD calculations in order t o q uantify hul l resistance, pr opel­ 1er thrust and r udd er syste m effi ciency ac­ curat ely during the tricki est manoeu vres. Th eory and therefo re also com put er sim ­ ul ati on are not yet exa ct sciences in th is situation and 50 m ust be combi ned with emp irica l work .

It is very valuable, w hen studying ship be­ haviour in tra nsit, or some m aj or stages in manoeuvri ng, however, to use ma noeu­ v rabi lit y experiments performed in t he t an k. They pro vide a way of understand ing t he shi ps better in general. For inst ance, any trajecto ry of a ship while passing t hrough a port normally com bines drift and turning . As snow n in the pre vious sect ions, the ne w along either side of the hull is complex and asymmetri cal, and t he shi p "sli ps as it presses on the wate r" . The wat er flows aro und the hull and circu­ lates in different ways at unequal speeds (different colo urs on t he drawing) either side of t he hull.

Water flow along a hull in drift and turn Eddies appea r on one side, mainly t o front and ast ern . As a first approximation, th e Bern oulli equa tio n ( p + lh .p .V2 = Cte ) shows that t here is a difference in pre s­ sure because of the difference in velocity. The hu ll's confi neme nt wi t hin the sma ll vo lum e of t he port basin amplifies t hese effe cts . The difference in pressure ex­ pla in s t he appearan ce of resultants from resis t ance forces exerted by the water w hich ar e dire cted in such a way as t o counter t he ship's forward mo vement ( Ox) and dr ift (Oy). These for ces vary in scale acco rding ta the hull 's shape and surfa ce area, t he angle of drift and its capacity t o press on t he water, and to divert th e Flow, showin g a sign if icant difference in velo c­ ity either side of the ship, while limi t ing turbulent separa tio n . (st raight and ve rti ­ cal shape s enco urag e th is effect, and will cou nt er drift m ore th an rounded or f iat shapes, for inst ance) .

The transverse forces (Dy) and the yaw moment Cn must occup y ail the ship han­ dler' s attention . They express the ship's capacity to counter drift and turn , while creatin g a turning torque which tends to change its headîng . Lift and damping are therefo re very important in terms of ma­

Drift

F no

Cx

0.250

-0 .188

0.0

0.250

-0 . 183

0 .22

10°

0 .250

-0 .180

0 .048

15°

0 .250

-0 .180

0 .81

20°

0.250

-0 . 177

0.12

noe uvra buttv!'.

30°

0.171

-0 .069

0 .19

The linear t heory of t he aer ofo il was developed by a number of sei­ entists ( Prandtl, Joukovs ki, et c.) and is applied in concret e terms in ma ny specifie areas of ship design (rudder, stabiliser fins, pro petler s) . Hydro dy namic forces exerted on a hull moving obliquely also have vari ­ ous sources. As weil as viscous re­ sist ance and wave resistance, forces which are generally parallel to the axis of the ship, this hull may also be the source of a nat ural vort ex force , simi lar to the lift exerted on a win g. This ts, however, a very special kln d of wing with very Indifferent perfor­ mance, since it has a very sma ll span (ratio 2 x TE / L) dou ble its draft (TE) in length, around 1/7 at th e most . The free eddies t herefor e no longer escape from this wing ma inly alon g the traili ng edge (here t he stern), but along its end (the keel) .

Cv

Cn

F no.

Cx

0 .0

0.150

-0 .124

0 .0

0 .0

0 .0 12

0.150

-0 .11 7

0 .018

0 .013

0 .0 24

0.150

-0 .11 6

0.046

0 .023

0 .0 35

0.150

-0 .11 4

0 .080

0 .034

0 .047

0 .150

-0.105

0.119

0 .043

0 .065

0.102

-0 .038

0 .198

0 .063

Cn

Cv

50°

0.111

0 .044

0 .38

0.077

0.067

0 .065

0 .377

0 .077

70°

0.090

-0 .062

0.484

0 .049

0.054

-0 .027

0 .509

0 .045

90°

0.086

0 .596

0.0

0.051

0 .0

0 .586

0.004

Hydrodynam ic coefficients as a functio n of Cx, Cy and Cn of a crude carrier hull in pure drift.

These te sts show up several t rends. For inst ance, the y demonstrate that drift has little influence on Cx (drag), but a great influence on Cy ( lift). Converse ly, speed signlficantl y affe cts Cx and only slightl y affects CV. F is the Froude number (for a given mode l, an inc rease in the Fraude nu mber equ als an increase in speed ). The Cn yaw moment is at its maximum wh en th e angle of drift ls close ta 45 ° . Above this value, it fall s. Longit udinal and t ransverse forces are equal wh en the ang le of drift is araund 25 ° .

l./R : rat io of ship's lenght aver rad ius of t urn

L/R

F no

Cx

Cv

Cn

F no.

Cx

Cv

Cn

0.2

0.150

-0 .117

0.007

0 .008

0 .200

-0 .136

0.00 7

0.008

0.4

0 .150

-0 .109

0.0 11

0.0 13

0.200

-0 .129

0.0 10

0. 014

0.6

0.150

-0 .100

0.0 15

0 .0 19

0.200

-0 .121

0 .0 13

0 .020

0 .8

0 .150

-0 .088

0 .020

0.027

0.200

-0 .113

0 .0 16

0 .028

1

0 .150

-0.079

0 .0 29

0 .036

0.200

-0 .110

0 .0 22

0 .037

Hydrodynamic coefficients as a function of Cx, Cy and en of a crude carrier hull in pure turn.

While the traje ctory may be sim ilar t o a drifting mov ement, which ls fairl y sta nd­ ar d when a ship is approaching a berth drifting because of t he effect of wind, hull resistances may be examined by means of experiment in the te st ta nk on models re presenting different t yp es of ship (c rude carriers, cont ainer shtps, et c.) . The hydr odynamic stre sses are separat ed into long itudinal (Fl() and t ransverse ( Fy ) component s and int o a yaw moment (MN which expresses the turn ing effect of the hull resista nce. These concepts facili t ate t he analy sis of t he ship's behaviour. The t able (fi gure above) com pares t he hydrodynam ic coefficients represe nt ative of drag , lift and yaw mom ent forces on a cr ude car ri er hull in pure drift at various speeds. The lon gitudin al and transve rse st resses and the yaw moment are pr opor­ trona! t o the square of th e ship's speed, which is therefore th e ma in factor t o con­ sider. The coeffi cient s apply to the same refere nce surface (Lpp x Te) .

If th e trajectary is similar ta pur e turn (na drift), other tests on the same hull are used

t a analyse the ship's reacti ons.

Comparing the two tab les, it can be seen for inst ance that in arder t a redu ce th e ship's

speed, it Is better ta allo w it t a drift rather than turn lt (in practice, drift alane happens

aften, but turning without dr ift is rare ).

Similarly, if drift, caused by wind for example, is added ta the ship's turning (drift ta­

wards the autside of t he curve ), the ship slows and comes ta a sta ndstill (i t luff s up) ,

Canversely, if the dr ift caused by th e win d is subtracted fra m the tu rn ing drift (drift

tawards t he inside of t he turning cir cle), th e ship turns with grea ter diffic ult v, slaw ing

down less.

Distance (d = Cn 1 Cy x Lht ) is used ta assess the position of the tran sver se forces on

th e ship's long itud inal axis with respect ta the centre of gra vit y.

This distance , always greater t han Lht / 2 for turn ing , shows that in such sit uat ions,

the turni ng effect of t ransverse for ces places them exp er imenta lly ahead of t he baw. I n

drift exam ples used, th is dista nce fall s belaw about Lht 1 2 at around 10° of drift. lt then

tends tawa rds zero at very wide angles of drift.

1

The ta ble in th e f igure below shows ho w drag (Cx), lift ( Cy) and yaw m oment (Cn) coefficie nts change for a ve ry st rea m lined, cont ainer shi p subj ect t e Flow whose ang le of incidence varies From 0° ( into t he current ) t a 180 0 (curr ent From ast ern ) . These curv es pot ent ially describe t he beh av iour of a ship t hat drifts underway ahead and as tern . It high ­ lig ht s for ins ta nce that t he yaw m om ent is at its ma xim um for an angle of ar ound 50° and it is can­ celle d out for an an gle of 100 0 (n eutral posit ion ) . The diagram also shows t hat t he ship luffs in t a t he wind more sharply when maki ng headway and Falls

50

1,2

"'- l-n r:

\

----- Cy'..

/' ./

---

/

\ \

10 C

/

0,5

-:

60

80 90'

C,

Î'--..

/'

1/

/'

.;~--~--")_~ 200

- - lO O'l k>ad@d Car Carri. r -

-0,5 +--------'r~r--h'---

10 O'l lleht car Cam.,.

-1 +--------~'"""'--=---

.1,5 1.--

-

- - - --

-

-

-

-

-

-

-

Aerodynamic coefficient of a car carrier

1,5 - , - - - - - - - - - - - - - - - ­

l -tr-- -=--- - -- - -- - - -­ - - 10 en loaded tilnker 0,5 +---=:::>l,c..:"''

~ , 1,

,,

,,

8

,

4

~, , ,, ,

"rumtn q orameter

,,

5

12

,,

..,

,, ,

16

,

Tactical di amet re

at + 90°, t he t rans ition, w hich repr esent s t he lat ­

- -----

, Transfer

,, ,,

twee n t he in iti al course and its course -

-

o

-

~ ~udrl

Eng., '-"11~liInIl 100 316 , 100 314, -80 500, .80 536 s .80 784 ,

,

--'- ~

T Cbere cteristics of the turning curve

3

-8 1

35 -35 35 .35 0

2

3 4 5

-4

-

o

1

4

. 8

H,,,j_" Of'~.,..,"", 3.06 cbls 4.6cbls 3.05 cbls .4.56 cbls 4.8cbls 5.08 cbls 4.73cbls ·5.32 obis 15.64cbls 2.46cbls

Emergency manoeuvers in deep waters

.... -',....".;:----"'''"'''-,..-......

Each ship has it s own turn ing cu rves for d iff er ent angles of helm, both in deep an d sha l­ low water, They are no rm ally disp layed on poste rs in t he whee lhouse. It is im port ant to kn ow the turn ing capa bilit ies of th e ship, as a fu nct ion of th e helm ang le set. The diameter of turn is ofte n given as a number of sh ip's leng t hs. Norm ally it is between 3 an d 5 times t his length for a helm angle of 35°, wit h a con­ ventlo na! rudder. It m ay be equal t o 1 fo r a sop histicated rudder. The f igure shows the turn ing circle fo r a 32,000 to nne container ship mov ing at 12 knots, tu rn ing with 15° of helm t o st ar­ board . The diameter of t he curve is 1000 metres, or around 5 ship's lengths. Turning point

3 .1

The turning point

...

([,

,;

,

Turning circle

of container ship of 32,000 tonnes, 15° angle of helm.

-.

-

General information - - --

for the sh ip-handler who wants to assess t he trajecto ry in turning , since at th is po int sim ply looking forward shows the direction in which the ship is m ovin g . The position of the tu rn ing poi nt 9 depends upon the adj ust ment of speed and t he angle of helm , and thu s on t he tran sverse fo rces exerted on t he sh ip (lift fo rce from t he an­ gle of helm, hull re sist ances, centrifuga i force) . Dur ing turning , the effect of increasing the helm ang le is to increase moment MF/ G • The speed vector of t he ste rn is inclin ed t ow ards the outside of the bend , and the bow speed vector is inc lined to war ds t he in ­ side . The t urning point mo ve s back and the ship comes to a standstill. The m oment MR/ G then amplifies t he turn as the hu ll resist ance evolves. An inc rease in speed increases the flow rate of the wat er ov er t he rudder, increases the moment MF/ G , and also accelerates t he tu rn . The conce pt of t urning point shows that the assessment of the t urn, espec ially th e drift, depends on t he location of t he wheelho use.

~

-,

Vesse! type Container ship 1 (Di5 32025l)

Displac:ement 32025.01 Max spedd 19.4knl

""m >Sm

In the turn , not ail po ints on the ship move at t he same speed (se e 2 f igures below) . The bows slow dow n ins ide t he t urning clrcle. while the stern chases on th e outs ide . The ang le of drift "(5" is greater to th e stern of t he ship than towa rds the bows "a". There is a single point, the t urning point "g", whose spee d vector ~ is aliqned to th e lo ngit udi ­ nal ax is of th e sh ip . With th e turning phase esta blished, at t his point , wh ich is abo ut a quarter of t he way along t he ship from the bows, drift is zero. Th is is t he ideal position

.

~-~ -""-~~

aem 10_0rn

Hei!tlt of eye

22_9rn

3.2

Trajectory o f centre of gravity G

A simp le, but non ethe less useful approach ta man oe uvring a vessel , involves definin g a kinem ati c t rajectory t hat can be followed

wh en berthing or leavi ng t he docks ide . For an earth-based re fe ren ce mark, th e mo ti o n of t he cen t re of grav it y on a vessel undergoing an y mo vement breaks down in ta a longit udinal an d a t ra nsverse displa cement. At the sam e t ime, t he ves sel is al so rotating around this cent re. The iss ue of manoe uvr ing th eretore cornes down t a the skill of the vesse l handler in im posing a tra jeetory, t oge t her wl t h a rotation on the centre of gravity.

Traj ect ory of G

G

----

,

This is based on a mechanics theo­ rem, that the centre of gravity of a vessel moves as if ail the mass of the vessel were concentrated there, and ail the forces applied at that point were transported parallel to themselves at this point.

Breakdown of the vetocttv of the vessel's centre of gravity The ves sel hand ler uses t he hel m, t he

l n ord er to understand t he be haviour of a

Finall y, t he effect of exte rn al elem ent s

engine and an y othe r re sources ava ilab le

vessel, the next que stion ls t herefore :

(w ate r and air) is include d in t he assess­

(t ug boats, thrust ers, etc.) t o begin th ese

"How wi ll the ves sel resp ond to the actions

me nt to understand the vesse l's respo ns­

movements . The fi rst qu esti on the vessel

1 am implementing ?"

es bette r. T he effects of wate r on the hull

handl er has to an swer t herefore is:

These two question s provtde t he guide­

and wind on the topstdes are stu d ied ei ­

"Wh at mo vem ent s will be as a result of th e

Iines for this chapter; Fir st of ail, cons id­

ther empi rically, or by expe riment (t est ing

act ion s 1 am im plement ing?"

er t he effect of t he forces on t he vessel,

tank, wind tunnel ) . The hull re sista nce and force exercised by

It is also poss ible to imagine, intuitive ly,

which serve t o lnlt lat e lt s movements.

that t he water will oppose these t wo t rans ­

The eas iest way to asses s these forces is

t he wind are br oke n dow n in to longit udinal

lations and t his rotat ion by app lyin g hu ll

in fact to differentiate th e various t ra nsla­

an d t ra nsverse forces applied t o the cen ­

res ista nces t hat are me chanical action s, or

t ion an d rotat ion movements.

tre of gravity and co m bined with t he tu m ­ ing eff ects app lied t o t he vesset in order t o

more sim ply, fo rces .

rnaintaln t he same m ovem ent.

3 .3

The rate of turn

3.3 .1 Turning at a constant rate

In the turning phase, at constant spee d, t he shlp has a con stant

I n order to ens ure t urn ing on a specifie d t rajectory ( 1) , and

angular speed if it keeps the sam e hel m angle : thi s is the rate of

the refore maintain a constant radius R, th e rate of turn is kep t

t urn (ROT) , which is expresse d in degrees per minute ( o/ m in). It

st able by adj usting ve loc ity and he lm (figure 17 and 18 ) . I n prac­

ls zero whe n the man oeu vring phase begin s and tt is at its maxi ­

tice , in obli que steer ing, th e ship t ends to lose speed, so it ls

mum in th e turning phase . If during the t urn t he rud der returns

a lso necessary t o incr ease speed as soo n as the t urning rat e falls

to th e neu t ral position, it t ak es some t ime t o re cove r a zero rate

without gaining t oo mu ch velocit y as a re su lt .

of t urn : this is the t urning in ertie . Thi s tirn e can be red uced by

____ @

----------

CD

eutornat!c pilot ma y be set t o t urn with a defined t urn ing rat e . The turning rate ls proporti onal t o the an gle of he lm " 0" : ROT = k x o.

;

Expressed in degrees per m inute, it depends on verocit v V and

-

---

ROT

(O/ m in )

-----(6)

_

radiu s of turn R: ROT (O/min) =

EJf---'-----­ v

!

shifting t he helm t o t he opposite direction . At runni ng speed , t he

......

360 V

I------i 2" R 60

Indicator of rate of turn

rn

or in mo re practical terms

1 ROT ("/ m i, )

~

Curv e in tu rn ing For inst ance at an initial speed of 6 knots , an ROT of 20 o/ mi n ls need ed to ens ure a t urn followin g a ctrcre w it h a radius of 0 .3 miles. If during the turn the ship deviates from it s initial cours e because of externat fa ct or s (2 and 3) , comb ined action on th e

with V in knots and R in mil es.

engine and helm will correct th e cou rse whi le maintaining a con­ stant ROT.

4

Factors influencing t h e t urning curve

4.1

Influence of speed

The spee d at whlch t he tu rn begins has littl e influence on the di amet er of tu rn.

It does ho wever alter t he rat e of tu rn and thus the t im e needed ta com pl et e t he turn. For inst ance, at 16 knots, th e rate of t urn will

be pra ct ically t w ice t hat at 8 k no t s wlth a helm ang le of 15° .

Whatever t he speed at th e beg inn ing of the turn , lt Falls

.•.

gra duall y because of the drag components of t he force

ex ert ed on t he rudder and t he hul l resist ance. There is als o an increase in t he re sistant torque on t he ~

prope ller, wh ich is particularly notrceebre at full speed .

....

Depending on t he type of eng ine, th is increa sed load is detected differentl y. Th e die sel engi ne wo r ks at a con­ st ant torq ue and re duces t he rpm and thrust of th e pro­ pelle r. The electric m ot or operates at a constant r pm and increases t he load of t he th erm al drive m otor. The turbo -p rop ope rates at a co nst ant powe r and also re­ du ces t he numb er of tu rns of t he prope ller.

Turning arcte of a container ship at 8 and 16 knots with 15° helm angle At running speed, a shtp loses about a quarter of its ve locity after a heading variation of 60° . The speed then stabilises at about

60% of the initial speed , with a helm angle of 35°. The reduction in speed is even greater for ships with high -performance rud­ ders . Turni ng is the easiest and most effic ient way of arresting the ship 's forward moveme nt.

Conversely, a va riat ion in speed d ur ing t urn ing modifies the di am et er of t he t urn . An inc rease in speed has t he effect of redu cing th e ra ­ dius of th e curv e, and reduci ng th e spee d incre ases t he rad ius. In t he f irst case, the accelera ted wat er Fl ow over t he rud de r, which acts at the squ are of t helr speed, in ­ creases t he pair of m om ent s MF/ G an d M R/ ~ th e angl e of drive increases, t he turn ing point falls back , an d t he ship comes to a sta nds till. Conversely, redu cing speed m oves the t urn ing poin t forw ard an d increa ses t he ra­ dius of tu rn . The exa m ple be low shows an Il ,00 0 t on ne f erry, 145 metres long with an entry speed of 8 kn ots sta rting to t urn with a helm an gl e of 15°, An incr ease in spee d after a 90° cha nge of heading re­ duces t he rad ius of the turn.

15° he/m angle, full ahead engine speed increased after 90° change of

15° angle of tietm at 8 kno ts

heading Reducing radius of turn by increasing the speed of an 11,000 tonne ferry

4.1.1 The phenomenon of "skidding" Due t o the lift of the r udd er (tra nsverse compone nt of pr essure fo rce) and centrifuga i force, the ship d rifts and t he rear "skids" t o th e

outsi de of the bend , especi ally d uring the initial phase of t he turn . Th is is t he phe nomeno n of sk idd ing,

This effe ct m ust be controlled and ant icipated in co nfine d wat ers so t hat the ship fo ll ows the planned traject ory during the t urn , with ­

out comin g dangerously close to sha llow wate rs .

The turn can be stopped quickly and t he sh ip brou g ht back o nt o a stra ight cou rse by putting the he lm hard over (angle doub le t hat

used t o start t he turn ) and potentially tempora rily inc reasing eng ine speed as weil t o im prove t he effi cien cy of t he r udder and cancel

t he drift .

Drift ang le 6

=10"

Helm angle "0."

0"-- - - - - ----+:,-· 35' Drift angle whiJe turning as a function of helm angle

4.2

Influence of helm angle

Unli ke speed, th e effe ct of the hel m an gle on enter ing th e tum is a determi ning factor. Keeping the helm at a g iven angle of inci den ce

determ ine s the radiu s of t um, and thereto re t he rate of tu rn .

The smaller th e helm angle, the greater the diamete r of the tum will be. Pilot cards norma lly give a turn ing curve wit h 15° and 35°

of helm , valid for an y sea speed.

Whe n t urning at a given speed, changing the helm angle mod ifies th e rad ius of th e tu m . It Is reduced by increasi ng th e helm angle, which im proves t he lift of t he rud ­ der, and th us the moment MF/ G • This is theoretically less effec tive th an a qulck

increase in speed (th e rudder effi ciency varies with the squa re of the speed of the water f1ow).

In practi ce, increasing th e helm ang le is ofte n the qu icke st an d most effe ctive way of spee ding up the t urn . Reducing t he hel m angle produces t he opposi t e effect, with redu ced turnin g since the pair of mo­ me nts M F/ G an d M R/G is less significant. The rate of t he curve below show s how in­ effective t he helm is at sma ll ang les of in ­ clinatio n . The radiu s of t urnjlength of ship rat io falls rapid ly as the angle of the helm inc re ases. For ships with a sta ndard ru d­ der, thi s rat io genera lly t ends towards 2 .

...,..~.:

......:::~

.....

":~-/

magn itude of hull resist ances t hat are expressed as the square of the ship's speed. It ls ofte n seen that negative trim encou rages in­

-: V

stability. Heading inst abili t y is reve aled at shallow helm angles, by a steering response opposite to

V

-:

/

~ .--:V

)1

V

hip un ta ble

V

5 hip table

;,~o

o

V

18

9

y -> 36

27

45

54

72 Len gt h / speed (sec)

63

Accep table instability ioop (IMO reference)

Gener ally speaking, shlps' manoeuvra­ bility may be evaluat ed using th e zigzag test . When th e ship ls on a const ant ini t ia l heading, the helm ls moved to starboard at a given ang le (fo r inst ance, 10°, 20° or 30°) . The ship begins t o tu rn t o star board. At the mom ent the headin g changes re­ spectively f rom 10°, 20° or 30°, t he helm is moved t o 10° , 20°, or 30° to port, t hen to starboard again, and 50 on. The regu lato ry tests are the 10°/10° and 20°/20° tests . The ship dep ict s a zigzag pat h characterised by two parameter s: - The maxim um heading, or mo re pre­ cise ly the diffe ren t ""V S" betwee n thi s head ing and t he helm angle, - The period lit " of t he movem ent s.

ur.ô

Helm angle " Ô"

Port

t (se c t Starboard

Zigzag manoeuvre

The sma ller t he head ing devia t ion 4J S and the per iod of movements "t'', the better the manoeuvrability. The diffe rence in heading and over shoot angles increases as the test goes on. They are also linked to the speed of th e test and t he length of t he ship . The IMO defines t he sta bility criteria for t his test. The values checked are the first and sec­ ond overshoot ang le (4JS1, ljJS2) for a 10/10 test, t hen t he firs t ove rshoot angle (ljJS1) for a 20/20 test.

Ove rshoot angle in

,

50 40

,

------- -- -

--

--

30e - - - - - - -

.>:"

20e

-- - --- -

, 10

o,

- - - - - - -

~

V

-- -- ---

10/10 Seco nd ove rs hoot

-- -- - - - -10/10 First ove rs hoot 20/20 First overshoot

~

- - - -- - -- - - -- -- - LN (sec)

10

[MO criteria for zigzags

20

30

40

6.1

Comparison between turn ing capacity and stability of heading

In it s circ ule r 1053 , t he IMû compares the capacities for t urning with th e course st ability of a ship as a function of it s shape s

and dimen sions ( Iengt h Land widt h l, and black coefficient Cs) ,

There is no ideal shi p. A ship with good turn ing capac ity oft en loses out on directiona l st abilit y and v ice versa.

~ L/beam

L/bearry'"

)

small

"--_

.

Cb larg e

C

)

_ _ _ _ _ _ _ _ _ _~small

- - ------

C---;:;;-:-:-:c:-;-, - - -- :::>

Ship "broad in t he bearn"

Ship wit h bulb

3

Negat ive trim

7

Cb small

Slim ship

Ship without bu lb

3

Comparing course stab ility and turning ca ­ Posit iv e t r im

pacity as a function of the shape of the ship

Good tu rning capacity

Good directional sta bilit y

Average directi ona l stability

Less good turning capa city

Use of turning in manoeuvring - Effect of a force

For a ship ma king head way, any force F (thrust of a t ug boat, wind effect, etc. ) app lied at a poi nt M m ay be lik ened t o two differen t app lied at poi nt T, gives the shl p a moveme nt of pure drift . fo rces, usin g t he logic develo ped above. The fi rst,

F;- ,

Th e second , ~, applied at point D, gives th e ship a t urn ing movem ent . Observ at ion of t he figure below shows (st raig ht lin es sho w­ ing the d rift movem ent and rat e of t urn ) tha t depen ding on t he position of point M, the effect of t he for ce F will be f undam ent ally diffe rent . For instance , t he for ce F ap plied at A (tug boat towi ng sidewa ys) gi ves th e greatest rat e of t urn com bined w it h t he gr eat est d rift ta port . Conversely, applied at B, t he fo rce m ovem ent The for ce

F

F

gives the ship a slower turn in the opposite dir ecti on , t oge th er wit h a less marked d rift

ap plied to point T (a t ugboat pushing ) drives

Th is approa ch shows that a ship with propelle r, rudder and bow t hruster (very commo n conf iguration toda y ) t urns with headway more easily by com bining the helm and eng ine t han by using it s bow t hrust er.

-

-

t he shlp int o a dr ifting m ovem ent wit hout t urning. Applied at point D, the force gives a t urni ng movem ent wit hout drift.

FT = Drift

F

M

T

Converse ly, the same reasoning may be appli ed to t he ship ma king way backwa rds . In t his case, it is t he actio n of t he bow th ruster t hat is most effective in providing t he turn ing movement. Since t he hull is not sym me trical, points D and T are placed differentl y for ward and astern. Tank expe r ime nts also confirm t hat t he position of points D and T varies wit h th e angle of dr ift, the rate of t urn , and the speed. Pract ising ma­ noeuvr es, and knowing the ship weil in different trim and load configurations means t hat t hese can be positioned int uiti vely. As a first approximatio n, w hen learn ing ta manoeuvre, point T can be vis ualised at one quarter of the way alo ng t he ship from t he bows , and point D at one f ifth . The m ain t hing is t o distingu ish between t he drift and tu rning movemen ts.

DB

G

A

1 1

ROT

15

1

1

1

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 1 1

1 1 1

1

A

F o =Turning

lB

G

Variation in ROT and D, with the transverse force exerted on the hull

Navigation in

shallow water

1

Content 1

2

3 4

The squat effect 1.1 The phenomenon of braking 1.2 The squat phenomenon Squat calculation: Barras formula 2.1 Barra s formula 2.2 Nationa l Physical Laboratory nomogra m 2.3 Digital modelling Influence on turn ing circle Influence on emergency stop distances

1

The squat effect

Ali t hese various fa ct ors are linked to 'squat ' . They become more sig nifi cant

A st at ion ary ship has a cert ain draught. When t he ship gets under way, t he press ure of wate r supporti ng its we ight is redu ced as t he speed of the wat er Flow along th e hull in­ creases ( Bern oulli's theo re m : P + p .g .z + 112 p.v 2 = constant-' ). Th is lead s ta add iti ona l sinkage and als o possible altera ti on t a the trim of the shi p2). Gener ally speaki ng , t he capt ain need onl y be conc ern ed wi th t he alt erat ion ta trim, since th is ma y change t he hull resistan ce and affect t he ship's st ability in holding it s course. Thi s pro blem may be overcome wit h a fa mi liar it y of t he ship 's behavi our and by adj ust ­ Ing it s draught at t he beginn ing of the voyage . Approac hing t he coa stline, t he squat and increase d draught of t he ship must be assessed in t erms of t he ship's safety. In t he shallow wat er of the harbo ur environ ment , t he confi nement of t he hull increases squa t and m ay even lead to gr ounding .

w hen t he ship rs manoeuvr ing in an in­ creasingly confi ned space (sh allow zone , channel, etc.) w here obst acles appe ar, which accele rate t he speed of th e wate r flo winq alo ng t he hull . Vari ous factors can thu s affe ct t he vessel's sq uat . These are mainly : - t he vessel's speed (essentia lly t he lon­ git udinal com pone nt) - conf inement (obstru ction of flow arou nd th e ship fro m below, t he channel, t he bank s, etc .) w hic h leads to forces th at te nd t o restrt ct the vessel whe n it is mov ing paralle l to t he bank s ( bank er­

-,

fect) and separate f rom it when it ls mov ing perpendl cula r t o t he banks (wa­ t er cushion effect s) . Confine ment is in­

5hip in deep water

-- -

-

-,

-~

5hip in shallow water

- -- - - --

-

coefficient of vessel Cb) sucti on of wat er by th e pr opelle rs, and t o a lesser ex tent t he shape of t he ves­

-

sel's st ern t he speed of t he ship's drift ( when t he vesse l experiences a crosswin d or cur­

Confine me nt also increases hull resist ance and the manoeuvrabi lity of th e shi p is sig nifi­ cantly reduced. Th e exte nt of t hese phenom ena varies especia lly w it h : - the dep t hj d raught ratio . Th ey a re at a m ax im um fo r a ratio close to 1; negligi ble fo r

-

a ratio greate r than 5. Squat becom es signifi cant when t his rat io of depth -t o-draught ( P/d ) is under 1. 5 veloci ty (w hen t he Froude number based on th e dep t h of wate r is gr eat er tha n 0 .6 ).3)

-

-

Fn h

=

In pra ct ice, whe n on board, the sig ns for identi fy ing the squat effect genera lly are : - Th e speed of the vessel, which falls , w ith no cha nge to t he engine speed Th e vessel pushes on the wat er. The acco m pany ­ ing wave s incre ase in stze and in som e cases ( high speed, very large ships ) can break and creat e a bore phenom enon on t he banks of t he channel The vessel's t ri m changes and it "squa ts" . The change of t rlrn is positi ve for vessels whose block coefficient Cb is below 0. 7. Ot herwise it is neça trve '' ! Navigation in shallow waterP/d < 1.5

The radius of t urn and stopp ing dist ance increase and th e helm cont rol is m ore sensitive The propeüer perform ance fall s, vi bratio n tncreases, pressure on the blades varies and the engine load is unsta ble

1See chapter ' vesser in motion, com plem entary aspects on ship hvdrodvnamtcs". 2The concept of squat , where the maxi mum draught of the ship is exceeded,

rs commonly used in English

lang uage

reference works, and representa th e altera tion to the trlm of the vessel t oget her wit h t he idea of vertical sinkage of the ship. ê

thrs Froude number Fnh rs different from th at used for calculating drag , stnce t he cherac terlsttc dim ension of flow ts Iinked t o the depth of water berow the keet and not to the length of th e hull L (see the chap ter, "Compl ementary aspects of ship hvorccvnerntcs'') .

4 See "Ship cbaracten strcs" chapt er; ~ ts O.SS for a very large crude carrier (VLCC).

rent ) heeling and ro lling caused by a g usty crosswi nd m ovem ents caused by th e vessel's own

waves, especially wh en approaching t he critic al speed range and w hen t he ship is push ing hard against the wat er (t he wat er form s a surg e on th e bow s) and the accomp anying waves are large

v v'g .h

dicat ed by the blo cking facto r CB . t he shape and size of t he vessel ( block

-

changes in dept h silt ing-up

There ar e also two m ain aggravating fac­ t or s th at can be ldentifled: - crossing / overt aking a second ship - t he effe ct of banks in th e channel (w it h t he ship passin g along one side of th e channe l, causing a suct ion effect) . I n pra ctic e, it is sensible to reduce t he squat pheno menon by keepi ng the ship's speed down as soon as the first signs appear (waves, vibration, etc). When crossing or overtaking another vesser, it is also important to preserve a minimum distance betwee n the ves­ sels equal to the w idth of the larger of the two, and of at least 30 metres. When circ umstances allow, this sefe­ t y dist ance m ust also be m ainta in ed bet ween the vesse ls and t he banks when passing t hrough a channel.

1.1

The phenomenon of braking

Because of th e sm all under- keel clearance! th e Ventu r i effec t increases the speed of the wat er Flow, in turn leading t a:

-

increased st resses caused by hydrodynamic pres sur e. The waves forrn ed by the vesser are larger, ta be precise . Overall , they indi­

cat e an in crease in hu ll resist ance, caus ing a 1055 of speed, estimated empi r icall y at 10 % for th e sam e deve loped power lower pr ope ller eff icien cy caused by th e loss of q uality of Flow ta the ste rn of the ship . Vibrati ons and cha nge s ta engi ne speed also appear

1.2

The 'squat' phenomenon

The speed of the water flows inc rease, sa t he under-ke el pressu re Falls further, causin g: - En bloc sink age, w hich can be several te ns of cent im et res. Nor mally, t he squat nomograms are displayed in t he wheelho use (wh eelhouse poster) . The sink age is pro portiona l to t he speed and confinement of t he hu!l. The squat phenomenon may app ear at the dockside or at anchor, wh en t he m oored shi p expe riences a strong current.

Deep w ater

a

Sinkage

-

Chan ge of trl m . Sorn e st ud ies show that if th e block coefficient is greater t han 0. 7 (slow ships, crud e carriers, bulk carriers, etc. ) , the cha nge of t rim is negative, w hich also corresponds t o a centre of gra vity forward of th e mi d -Iengt h between t he vessel's per ­ pend iculars Lpp' with the bow shapes fuller than th e ste rn shapes. The opp osite app lies if the block coeff icie nt is less t han 0.7 (fast shi ps, cont ainer ships, ferries, etc ), in which case th e chang e of trim is the n positi ve.

Change of trim

-

The lower press ure generat ed by the pr opeüer suctio n, leading to a positive change of t rim, is adde d to th is effect.

2 2.1

Squat c a lcu la t i o n: Barrass formula Barrass f o r m u la

Test s on real ships and t he many tes ts performed on models, demonstrate the differences, which might, depen din g upon the circumstances, be significant . Nonetheless, they have been useful in validating practical formulae ta pred ict squ at and to tmprove the safety of naviga ­ tion in confined waters. It must be noted that these formulae provi de a "static" and

It is also no te d that t he det erm ination of

involve considering t he shape of the chan ­

the limit conditions for t he passage of a

shi p depending on t he particu lar circu m ­

nel, th e proximity of t he banks, t he shape

st ances is specifie ta each channel.

It cannot be det er m in ed theoret icall y.

It actu ally req uires great experience, and

is normally dec ided by the port auth or ity

Whatever fo rmu lae are used to predict t he

In sorne ind ividual cases , when passing a port stll or bar for instance, "dy namic" squat can reach values greater th an th ose fo recast . Conve rsely, soft silt bottoms can redu ce t he effect of phenom ena associ­

squat, t he main three factors are :

- speed

- un der-keel clea rance and wi dt h of the

for naviga tion , which requ ir es perfect kno wledge of t he t opograph y of the chan­ nel and t he nat ure of t he bot t om .

(6C.+O,4).C• .V· e=

100

in cons ulta tio n with local pil ots.

"theoretical" va lue for squat.

ated with squa t . The behav iour of a vesse l in conf ined wa­ t er t herefore remains a serious problem

of t he hui l, etc .

Bar rass for m ulae (2002):

channel

hull shapes

The Bar rass formu la is the one used most widely today to calculate the squat of ships in different circum stan ces, especially in confi ned water s. There are many other possible approa ches. especially those t het

e : squat in metres

Cb : block coefficient

V : surf ace speed in knots

As : section of vessel amid ships ( b x d )

Ac : sect ion of chann el ( B x D)

A, Blockage factor Cs

=

The Barra ss form ula can be simp lifi ed in both t he follow ing sit uat ions : - depth is redu ced, but not th e brea dth of channel (ope n wate r); (rat io H / d varies from 1.10 to 1.20) : C ·y l b

e = -

100

dept h and width of the channel are bot h reduced; (t he block age facto r Cb is between 0. 06 and 0.30 ) :

2.C b ,y l e =

100 As

I n confined wate rs, t he squat is double t hat in open wat er. These sim plif ied form ul ae are mo re gen erous than t hose obt ained using t he precise form ula wit h it s furt her margin of safety. It is the surf ace veloc ity t hat has to be considered, since it corres ponds to th e speed of the water f low along t he hull f rom where th e squat or igin ates. A vessel mo ored

Ac cs: See values give n in section 4 of t he chapt er, "Definit ion and cha ract eris ­ ti cs of the shi p" .

in a river will t herefore experience squat.

1/ / f//

Aste rn 1/51 ~ L ____ Ahe d 1/10 L

fi l;!e/ »:

0_

~

if~/ ~ ~

o

2

4

6

f;:)j

r"

,6'

B oo ~ '"

96 .

s_~'"

.no ~

"_~.,..

2n~

open sea . When manoeuvring (speeds less t han 8 knots), the greater turning diameter is not necessarily the most im por t ant fact or t o be cons idered . lt is certa inly often m ore difficult ta turn the ship, but in th is case the effect of depth is felt mo re generally on directional stab ility, which is red uced as the transverse component of the hull re­ sistance increases. Simp le ru les are there­ fore insufficient to express the behaviour of a ship in confined wate rs. The on ly unanimously agreed r ule, which ensures contro l of the ship is ma intained, is ta keep ta a muc h lower safe ty speed tha n in open water.

,

..

Comparisan of turning curves in shallaw and deep water for a container sntp

' ...... _""'R ,__

~,-' ''''

.

.

i

,/ .'

.

.. "

Observing t he waves formed by the ship and the ship's response to movements of t he helm remains the easiest way to as­ sess the phenomenon of squat. This ap­

"

"

i

i

....

.\

...

i "

,,..

proach to speed fo rms the major difficulty with port manoeuvres,

~'

i

..

i

,.'"

...

~

...

~

~"

Comparison of turning curves in deep and shallow water for a ferry

..­

­-

_ -.". .

....

__

.

­

......

\i i

"~! ...

'\..00.

-,

\ i

f

..

-,

""R

~

\

\\ _

......

....•.

'

,

l

if

"

!,

Deep waters

~,

..

Comparison of tuming curves in deep and shaflow water for a VLCC

Shallow waters

4

Influence on emergency stop distances

The reduction in under-k eel clearance at- : fects the quallty of th e flow t a th e stern of the ship, causing cavitation and aeration phenomena (see "Propellers" chapte r) . that reduce the efficiency of t he pro pel ­ lers . The thrust effect increases. 5ince t hese phenomena are random, the load and number of ro ta t ions of the engi ne

vary. Although t he squat effect causes an in ­ crea se in hull resista nce, this lack of pro­ peller efficiency is ex pressed specifically by the increase in cras h stop (em erg en­ cy stop) distance and, for ships with one shaft line, by the increase in t he change of

heading (see chapter on "Em ergency ma­ noeuvres") . The following exa mpl es show

a cras h stop for a container ship and a VLCC at an ini tial speed of 8 kn ot s.

Shall ow wat er

Dee p w at e r In port ma noeuv res, t he main problem s caused by t he squat effect are t he diffi ­ cult Y in ar resti ng th e fo rward m ove m ent of large ships and t he r isk of grounding .

Comparison of crash stop distances in deep and shallow water for a container ship

A safety speed can be ma inta ined t o lim it th ese diffi cult ies. The easiest way to arrest t he ship's fo rward moveme nt is to st art it into a t urn. The increased hull resis t ance during the turn then allows t he shop's ki­ net ic energy to be abso rbed , t hus bringing tt to a hait.

Shallow water

Dee p wate r

u

Comparison of crash stop dis tances in deep and shallo w water for a VLCC

2

Navigation in rivers

and in channels

Content 1

2

3

Particula r features of navigating 1.1 Regulating ships in ri ve rs

1.2 Particular features of the river

Particula r features of the dynamic behaviour

2.1 Passing throug h a channel with or agai nst th e curre nt

2.2 Dynamic concepts

2.3 Physical phenomena invo lved

2.4 I nteractions between ships

Example of manoeuvring in the current

3.1 Eff ects of curr ent on hull

3 .2 Coming alongside agains t t he current

3.3 Moving off aga inst the curre nt

3.4 Comi ng alo ngs ide with t he current

3.5 Movi ng off with the current

3 .6 Turning in the current on the anchor

3. 7 Turning with one part in slack water

1

Particular features of navigating a river

When th ey are navigable by sea-go ing ships, large rivers and t helr estuaries are very specifi e areas infl uenced by the sea and the river t oge t her. The powe r of nature im poses it s laws (t ide, flood , tida l bore, etc. ), constantly m odify ing t he depths and shaping t hese nav igable wat er ways, which for m ost sailo rs re maln terra in co gnita . There are tw o regulat ory areas , one after anot her. Th e end of the marine zone ma rks the st art of t he ri ver zone. Regul at io n an d pra ctice differ in each of t hese zones. The sea and t he river - sailors often describ e th e st ream as a ri ver - are two di ffer ent

world s, w hic h have different cultu res and different referents . I n t he t idal part of t he stream, International Regulations fo r Preventing Collis ions at S ea app ly, and m ar ine cha rts keep t herr conve ntrona! reference point s (ch art datum level, etc. ), In t he river zon e, the ri ver regu lations app ly, with depths m easured accord ing to the special NGF datum and distances are expressed in kilometres. In t hese zones *, w hich form usefu l routes fo r t ransporting good s, safety of ma rit ime traffic is dependent upon kn ow ledg e and respect for t he int eract ion betwe en t he ships and the river. Ship mast er s t her ef ore normally need the help of pilo ts who kno w the channel topog raphy and w ho are familier with ail aspects of nav igati on on their river .

Chemi cal carrier in Martigues canal

A rive r will have many and varie d features ( bar, wi nd, mis t, c1 iffs, banks, flood , low water (Iowest level of a water course) , etc .) . We w ill only consider t he most signif icant aspects relat ing t o t he river and the ship, when nav igating a r iver towa rds a major mari­ t ime port ( Hamburg, Antwerp, Rouen, Nantes, Bordeaux, etc .) .

* Entri es to ports used by seagoin g ships vi a a r iver are gove rne d by ma ritim e

regulatio ns (navi ga ble wate rways open t o the sea).

The nav iga tio n charts are th e mar ine cha rts . In France, th e boundary of t he m ari­

t ime area ts m arked by t he first physical obst acle t o t he m ovem ent of seago ing

vessels (b ridge, lock, etc.). Th is boundary separates m aritim e nav igati o n, w ith its

ow n rul es (Co lregs) and rive r nav igat ion. There are other adm inistrative or bio­

geo graphical boundaries in estuaries (Transve rse boundary of the sea, saltwate r/

freshwater line, etc.) and particular regu lati ons (Natura 2000, etc.) w hich reinforce

th e part icu la r nat ure of th ese areas.

Ore carrier Anti cipat ion ls one of t he key s t o safe navigation . Th is rule is even mo re relevant w hen a ship ls in a ri ver, where , to some extent, it is

captive. Interact ion bet ween the ship and it s environme nt makes sailing m ore compl icated. It is affecte d by t opogra phy and cur rent ,

as weil as by t he ship's course and speed . It has to be caref ully contro lled . It m ust be possible to adjust engine speed continually,

in or der t o adapt t he ship's velocit y t o changes in nav igati on cond it ions. Sim ilarly, the helm control must be ext remely respo nsive

to com pensate for th e effects of interaction wit h the stream . When an automat ic pilot is used, it m ust be possib le to recover manu al

control at once, and use a steersman .

Traffi c mana gem ent is also a pri ority t o ensure safe navigation in rive rs, since any prob lem ( bend, shallow, crossing or overtaki ng

anoth er vesse l) mu st be anti cipated and involves org anisation and th e cooperat ion of ail the vessels passing alo ng t he cha nnel.

1.1

Regulating ships in rivers

It is essentia l t o regul at e t raffic for safe movement on t hese very busy nav igable waterways . The harbou r master normally provides t his cont ro l, working close ly with marin e pilots . The fact ors t hat affect t he regulati on of ships in the r iver are : - t im e of departure (moving off) and th e t ime t he ship enters the channe l to move to t he port - the t rans it t ime - avail ability effec t on t ransit t ime com bi ned with t ide - the water depth needed for th e ship in t ran sit , give n that the water level in the river depe nds on the t ide , the flow rate is never constant, and soun dings also vary ove r t im e - the heading of t he ship needed wh en coming alongs ide - expecte d cross ings with oth er vessels at specif ie points in the ri ver - avail ability of t urning spaces in t he river port ~ org anisation of avail able t ugbo at s

,

,1 1.2

Particular features of the river

1. 2 . 1 Currents

1.2.3 River flow rate

The current is t he horizo ntal m ovement of a m ass of water t a a

Th e curren t generat ed by t he gradient of the ri verbed prod uces

give n place. I n a rive r, it m ay origin ate in the t ide and/ of t he Flow of t he r iver it self. Its int ensit y varies according t a the effect of t hese two facto rs, as weil as topogra phic al changes in t he r iver. Generally spe aking, the stron gest stream curre nt is in t he deep­ est part of the river, where water mayes most eas ily. In so rne

a f low rat e. This cur rent var ies wit h seasona l and met eoro logi ­ cal effects (melting snow, rain) as weil as indust rial activit ies (dam s, etc.). The ebb ti de current lncre ases the river's nat ural current . The f lood tide can cou nte r t he cur rent generated by t he river f low rate. The river and marine regulatio ns are t herefo re

tra nsitio n zones, river water (Iess dense) and sea wate r (de nser) cannat mix (the reverse is the case for brackish water, which

app lied either side of a so-called "fluvial point " , Water leve! and f low rate meas uring stations are placed at reg ular int ervals along

does mix) , The tidal Fl ow propagates alon g t he bed of t he rive r, beneath the fres hwater current t hat cont inues t a Flow out (effect is also know n as "sa lt -we dqe") .

t he riverbanks, ta inform users of t he navi gat ion conditio ns. The access ibilit y lim its for shipp ing and t he conce pts of highest and lowest nav igable water levels are published by t he public body responsib le for mana ging nav igab le waterways (harbourmaster's

1.2.2 Tid al stream

office for t he ma rine env iro nment , or VNF in r ivers) . The acces­ sibility lim it for shipp ing is determined according ta t he comb ined effects of tid e and confinement, wh ich reduces manoeuvrability for ships.

The wave and saltwater fro nt m oves with t he tida l strea m and propagates ir regularly in rivers. It counte rs the nat ural f low of t he river, and reverses t he direction of the current as t he t ide rises. The inco ming t ide is calied t he "flood" and the outgoing t ide t he "ebb''. The f lood curre nt loses ene rgy wh eneve r it meet s an

1.2.4 Straight sections and curves

obstacle (ba nks clostnq in, bends, shallower bottorn). Its energy increases with a spring ti de. Its effect on the direction of the cur­

One of th e features of nav igati ng a river, unli ke a cana l (stra ight and with a consta nt cross -sec tion t hroughout ) , invo lves knowing

rent and the water leve l is felt wit h every tide, for miles inla nd .

and understa nding the ir regu larities in the nav igable chan nel that affects t he di recti on and force of the current . A narrowing of t he width between the banks increases the ve lee­ it y of t he curre nt 's constant Flow rate according ta Bernoulli's

The speed of the current increases as the river narrows

laws. (See chapter "Vessel in motion, complementary aspects on ship hydrodynamics") . The f low rate of a river is ex pressed as fo llows :

Flow r at e (m 3/s) = cross-section (m 2 ) x v eloci ty (m I s) Sim ilarly, wit h a constant Fl ow rat e, the speed of current in the bends ls not un iform . Speed is proportiona l ta the radius of cur­ vatu re C, faster on t he outsl de, slowe r on the inslde . This varia­ t ion in speed is equ ivalent ta :

A velocily (m/s) = A lenglh ( C, - C, ) / lime The hy draulic energy caused by the flow of t he water ero des the Steck water

g rou nd and shapes a riverbed t hat is often sin uous. The ma in curr ent nor ma lly follows t he concave line of t he bends. Counter­ currents, secondary stream cur rents and slack water lean against

. . Une of main cur rent __ Une of secondary cv rrent ......... Une of wea k curren t

the m ain f low.

Example of the distribution of stream currents in a river

Observation of t he surface of the water and ex perience of river navi gat ion allows t he current and topog raphy of the river to be made out. Manoe uvr ing or crossings in t he river are norm ally performed at specifie places,

Cross section of river A-A

o

El Accumulated

sm on

înside

of bend

Range of current speeds in the bend of a river

For a given speed throug h t he wa­

ter, the pilot and capta in mus t al­

low for depth and speed of current

w hen determ ining the cross ing

point.

It ls the refore necessary to know

the dimensions of t he various sec­

tio ns of th e r iver in order to assess

the force of the current and how tt

varies .

1.2. 5 Effect of current on a sh ip's manoeuvring in a curve Vari atio ns in the direct ions of cur re nt ahead and astern of a ship as it enters a curve create a torque of moments MF/ G and ,..,..--+ . MF't G around the centre of gravity called ship spins. This torque am plifies t he swi ng, helping the ship to t urn as it moves in th e direct ion of the cur rent (fi gure left). If the current is strong and the curve very pr o­ nounced, the re may be a significant shear­ ing effect as a result . It th en becomes dlf­ ficu lt to control the ship , especially its rate of turn , and careful steering is necessary. Genera lly it is preferable to avoid followi ng the outside of the curve , where currents

are strong er. I n the fin al part of t he turn,

the helm is reversed on the side opposi te

the turn , and t he engine speed may be in­

creased if necessary to kee p t he ship in

the line of the stream (figu re right ) .

...

-

...----..

....--..

When t he shi p is moving against t he cur­ rent, the reverse phenom ena take place . The ship's bow is exposed t o an oncoming current fro m t he outer bank . Turn ing be­ comes t ri ckier if th e ship is unprepared for this swing. Once again, increasing engine speed helps to ma ke the r udder contro l more effect ive, t hus im proving control of t he ship . I n bot h cases, therefo re, t here should be power in reserve when entering difficult curves .

... ~

( 1 Turning with the current

...

t

Helm over at the end of the turn

-

t

Turning in to the current

1. 2.6 Chan ge o f density Fresh water exerts less pressure on the hull because it is less dense . The ship ri des lower in t he water, and it s trim changes. The change of density varies as a function of depth and prog ress al ong the river.

level _ _ __ _ _ _ _ _ _River ________________ upstream Fresh water

._--------------------~:--_....------:s~a~l~tw a t e r

Difference in density

wedge

The change of dens it y caused by the transition from seawater to fresh water takes place gradually, and affects t he ship 's manoeu ­

vrability. For fast shtos, whose block coefficient is less t han 0.7, t he change of trim is normall y positive , while for ot her vessels it is

negat ive. This change is amplified by the squat effect.

5hip handlers have to pay attention to t he change of trim, since it signifi cantl y affe ct s dire ct ional stability and t he ship's behaviour

as it turns .

A positive t rim improves direct ional stability but increases the radius of t urn, while the opposite app lies for negative trim .

This can be a safety considerat ion, maki ng the shi p diffi cult t o steer in extreme condit ions.

1.2.7 Profile of the river

One of t he m aln factors in navigatin g in a r iver is t he rat io of t he cross-sectio n of the rive r and the cross-sect ion of t he shi p's bull underwat er, and t herefore of t he availa ble wat er around th e hull. Depth sound ings show the uneven nat ure of t he bott om and sides of t he channel. These differences in lev el have a direct effect on t he variation in un der -k eel pressure w hen t he ship is saili ng alon g a rive r, and alw ays affect the behavi our of t he shi p. Although the cross- section of a river can­

,.­2._

­

not be com pared to that of a st raight ca­

nai , tt is possib le to compare this cross­

.. ..0'.200 .­ t ,­

­

sectio n em piri cally to straight walls and

bottom .

Thi s cros s- section ratio ls known as t he

l . ...e .

0.­

"blocki ng factor " C. (C. = As 1 Ac) (See

section 2 .1 in the chapter "Na vigation in

Q.Te.

shetiow weter").

0.­ 0.­

Thi s fact or affects t he lim it ing (or cr iti cal) speed the ship can adopt in its t ransit . The shlp is found to reach its cri tical speed

0.­ 0.-

when its accom panying waves , ahead and astern ( more easily vis ible), form an angl e of aro und 90 ° to t he ship 's headi ng .

Irregular profile of the riverbed

0 . ...0 ­

~

}

-, ~

­

Modelling the effect of the river profile at

Het erogeneity of under- keel clearance

the surface

Th ere are sev eral for m ulas for evaluat­ ing this ve locitv. The veloci ty Vc provi ded by th e Schij f (1 949) mo del m ay be used , w hich rema ins a benchmark for m cd el­ ling hydrody nami c effects linked to ships moving along a river. The ta ble in gives the value of t his crit ical speed for a giv­ en block factor C B• For inst ance, t he Iim it speed passing th roug h the Suez canal for a 190,000 tonne ship in ballast is around 8.5 knots.

Accompa nying waves

Navigating th rough a channel at close ta

Vc 1v9Hen mIs

cri tic al speed, mean s that t he ship ls un­

st able between ail the dynamic int erac­

t ions, requ iring special care.

According ta t he regulations, seagoing

vessels m ust keep their engine at ma ­

noeu vring speed and the helm under man­

ual control, in order to qu ickly anticipate

any effect s of nav igating in a river.

1. 2 .8 Th e sl lt p lug

Accompanying waves astem

1k----.--.-------,-----,-- - ---, o.s 1\-- t -- -t-- -t-- -j-­ ----1 . . ._ 0,8 f-'I__--t---t-- - + - - + - - ---j 0,7 t----.>.,rl---t-- - + - - +-----j 0,6 t-----'t...,---t---+-- +-----j 0,5 t----t-""""d-- - + - - +-----j 0,4 1---+---+-""'-=-+-- -1------1

H

The strt plug is a natural phenomenon tvp­ ical of large t idal estuaries. It is created by organisms that live in fres h water but die w hen th ey come lnt o contact with salt­ wat er, m ix ing w it h suspended sediment to form a suspended silty mass t hat m oves wit h t he current . This silt rs deposit ed on

0,1

0,2

0,3

0,4

Schijf cri ticaf velocity as a function of block factor

t he bottom, and ports and channels canstructed in these estua ries mu st be m aint ained with fre quent d redging in arder t a ensure t hey rema in accessible . Although it is difficult t a check, squat and t ri m va riat ions are considered less pronou nced above a silty bot t om t han above a hard bottom . I n a confined space, w it h a silt plug , hull resistan ce fo r t he vessel increases, making it less ma noe uv ra ble.

2

Particular features of the dynamic behaviour in a river

2.1

Passing t hro ugh a channel with or against the curren t

It is generally easier t a t ravel with, rath er than against t he curre nt, si nce hyd rodynamic effe cts associated wit h speed t hrough t he

water (sq uat , ban k effec ts, et c.) are sim ple t a redu ce by limit ing eng ine speed . I n effect, t hen, the ship can cont inue ta ma ke way,

carried by t he current . Conversely, t rave lli ng against th e rive r current invo lves ma inta ining a speed t hroug h the wat er greater t han

tha t of the current . The Flow of wate r aro und t he ship is t heref ore fast er, and it is harder ta keep control. It is of course easier ta st op

or t a ma inta in a low speed over t he ground w hen st eering against t he current. Manoe uv ring along side is norma lly also done aga inst

t he current , particularly when t he current is stro ng . This em phasises the importance of t he regu lat ions for sy nchronising favoura ble

t ransit and port ma noeuvring cond it ions.

2.2

Dy n a m ic co ncept s

As prev ious ly seen, a mov ing ship disturbs th e mass of water that sur rounds it .

Th is dist urbance increases with th e speed of the ship and it s block facto r. Several effects seem am plif ied when t he shlp is turn ing in zones where water f low around t he hu ll is rest rict ed. As a first approxima­ t ion, hyd rod ynam ic press ure forces are distributed ail arou nd the hull in: a ma in overpressure zone fo rward and,

to a lesser ext ent, aft,

a low pre ssure zone in the centre .

2.3

Hydrodynamic pressure zones

Physical phenomen a involved

The ves s e! in t he rive r is exposed t o t he effects of navigatio n in t he current, w hich are signifi cant, as weil as to int eracti ons caused by the prese nce of shallow dep th s and bank s. Both of these t y pes of interac­ t ion are linked to speed through t he water and orig inate wit h the sam e t heoretica l pr inciples relating t o f luid flow (contin u­

5

--­

it y equations, Bern oulli 's theorem ). The waves for med by the vessel are larq er; Their power, linked t o t he vessel's s pe e d, can da mage th e banks.

3

..­ ..­ ..­ ..­ ..­ ..­ ..-

3

2

4.

Wave f ron t Secondary wave Reducti on in wate r leve! Refl ectio n current

5. 6.

Accompa nying wave Turbul ent propeller wake

1. 2. 3.

Wave system in a river

The main effects experienced by t he ves­

sel ar e:

- redu ced t urnin g rat e (go ing int o a turn

---

mo re quickly with an increa se in radius

of tu rn)

increased sensit ivity t o swin g (re d uc­

t ion ln direct ional sta bility)

v ibra t ion of the ship linke d to dlstu r­

bance of t he water Flow under t he keel

and especially aro und t he propeller

inc rease d emergency sto p distance, to­

geth er wit h greater propelle r t hrust ef­

fect, in ships with a shaft une

increased hull resist ance associat ed

with squat and change of tri m

prese nce of rest rict ions ( banks,

Upsurge of silt

Stirring up of the bottom *

wh arves, etc.) causing lat era l effec ts that ten d t o move th e wh ole shlp doser to t he side when it is m oving paralle l to it (ba nk effec ts) or move it away when ap proach ing at an angle (cushion effect ) prese nce of ot her ships nearby, increa sing confinement phen omena and creating a lat eral for ce whos e amp litude and moment vary with the relat ive position of the shi ps

* The

presence of gulls in the wake of t he ship is a sign t hat t he sut on the bottom has bee n stirred up .

2 .3.1 Reflection tram bank In pra cti ce, the bank effect and the cushion effect combine and are nor­ mall y linked : t he te rm "bank refle ction" is used. Th is phenomenon caus­ es a latera l suct ion force and a squat effect, wh ich directly affe ct s the ship' s directional stab ility.

The water is pushed towa rds t he front of the vessel and has t o pass to

the rear to fill the lowe r pr essure zone left by t he vessel. This causes t he

wate r st reams below the vesse l, and t hose bet ween the vesse ! and t he

bank, t o mo ve fast er.

The result rs a 10 55 of static pressure , and t hus squat. The lower press ure

ast ern is also increased by the ship's propulsio n.

As th e rudder loses eff iciency, there may also be Im mediat e 10 55 of con­

tro l.

Bank reflecti on may be lim ite d beto re tt act ually occurs by redu cing the engine speed and speed through th e wat er, as weil as preserving a m ini­ mum di stan ce of about 30 m etres, or one wi dt h of the vessel. Th is bank reflecti on effec t cha nges w it h the square of th e spee d through the wat er and t he block fa ctor.

Reflec tion from bank

The doser th e ship is to the bank, the more th e effe ct becomes pro­ nou nced and is difficult t o cont rol. If the bank re fl ecti on causes the ship to swin g, it Is better not t o redu ce engine speed but rather to increase it briefl y, to improve rudder perfor­ man ce, so t hat t he ship's heading can be corrected by an emerg ency m anoeuvr e. Th ere m ust t her efo re be a reserve of propu lsion po wer 50 that th e engi ne rp m can be incr eased if necessary to counte ract th e sw ing using the helm contro l (this is th e kic k ahead man oeuv re) . Cush io n effects m ay also, howeve r, in some circ umsta nces ( Ioaded ship, sig nificant block coefficien t, weak current), help t he shi p to turn t hroug h a bend.

I l

1

For a left -han d bend, t he ship may come close to the rig ht hand side of t he river, t o asstst the sw ing t o th e left . Sim ilarly, w hen ent ering a right­ hand bend, it can move to th e left side of t he rive r. Unless particular con ditions prevai l, t he ship's bow is "drive n" in the di rect ion of th e curve. Thi s t y pe of manoeuvre must be undertaken with g reat care by ex peri ­ enced and highly tra ined ship handlers.

Favourable bank retiectlon in a bend on the river

2.3.2 Turning drift in river (skidding) When tra ve lling along a river, th e phenomena caused by shallow dept hs m ust be ant icipat ed. Although t he ship is better able to resis t dr ift w hen in shallow water, its t urning inertia, to ­ gether w it h centrifuga i force, dr ives t he ste rn of t he ship ta slip towards t he outs ide of the t urn , t he phenomenon known as "sk idding" . Unless t his effect is contro lled and anticipated in canfi ned waters t he ship will leave the planned t rajectory during th e turn , and wi ll come danger­ ously close t o shallo w waters. Th e helrn is t here­ fore used to start t he turn and then gradua lly redu ced t o t he zero position, in order to control t he rat e of turn . Th e ship th en t urn s and skids w it h t he com bined effect of ru dder and hull re­ sist ance. The helm is then pushed hard over in t he opposite di rect ion, to stop the rotatio n and drift lnert la, and t he eng ine speed m ay be in­ cr eased to co rrect the ship's heading in t he line of t he river.

CD

Helm hard over and engine run ning ahead

Controlling the ship's turn ing motion (skidding)

2. 3.3 Bed effect The channe l profil es, w hose d ime nsion s are exp ressed using th e block ing factor CB, are divided into t hree categories: - closed channel - ope n chan nel half-o pen channel

Closed channel

Channel profiles

Open channel

Half-open channel

The sudden change From a deep to a sha llower cha nnel increases squat towards t he bow of t he ship . This dynamic effect crea tes a tempo rary extra squat effect. The squat will therefore be g reater tha n t hat ex per ienced by t he vesse l w hen it is on a stable head ing in t he cha nnel. Conversely, when m ov ing abruptly From a shallow to a deep part of the cha nnel, the ship will expe r ience greater squa t towa rd s the ste rn . The variable profil e of t he rive r cou Id t hus cause a natura l im balance in hy drodynami c forces, causing qrea ter squat than that expertenced in a canal. The bed effe ct occurs when there is a sudden t ransit ion From shallow t o deep water. The shi p is dr ive n faster towards the deeper water. Localised bed effe cts may be fou nd, depending on t he different ty pes of riverbed or thelr relief, leadin g to a sig nificant change in t he ship's heading.

Bed effects

Abrupt change of depth

2.4

Intera ctions betwe en s h ips

2.4.1 Crossing Whe n t wo ships pa55 each ether; t hey Experience lat eral effects cre ated by the int er act ion of t he hyd rody nam ic pr essure zones t hat

su rround th em . Th e ships Exp eri ence st resses propo rtional ta t he rela t ive approach speed and t he size of the pass ing ship . T hese

hydrody nami c pre ssure zones can be Felt up ta about one ship's width , L, either side of the hull. The ship that has the lowest ton nage ,

Expe ri ences t he greater swi ng effect , and if th is is nat ant icipated , it may bring lt dangerously close t a the banks of t he channel.

The lighter passing ship , A, w ill swing ta sta rboard when the ove rpressure zones of t he two ships meet. Once it reac hes t he zone of

lowest pressure , ship A will Experien ce "sucti on" From shlp B, in add ition t o it s yaw moment.

These success ive chan ges of zo ne are accompani ed by dece lerat ion. I n v ery na r row chan nel s, tt ls trick y for ships to cros s each other,

an d t he manoeu vre has to be coordina ted. The ships are sai ling on opposite head ings in t he centre of th e cha nne l t o ov ercome t he

ban k effects . Bef or e t hey cross, th e shi ps slow down t o redu ce t he effect s of hydrody nam ic pre ssure an d put t he helm ove r to move

ap art and come to port.

ln accorda nce with Co/reg ru /e 9. Each shl p stea dies its heading as lt ex per iences t he bank effects . As t hey cro ss, and espec iall y w hen t he bows of th e two ships ar e in line, each one corrects t he effec ts of the intera ct io n . For ins tance, when passing a/ong th e Huston river, each sh ip puts the tiller to port before cross ing the other, to counter the effect of the overpressure zones. This is the very trick y 'chick en r un' manoeu vr e.

Ships crossing in a channel

"Suction" of A towards B

Ship A swings to starboard

2.4.2 Overtaking When overtaking, t he blocking fac to r may suddenly tncrea se , causing the ships' Hrni t speed t o d ro p . Th e hyd ro dynamic pheno mena ge nerated will therefore be greater and will test longer t han for a cro ssing. First of ail, t he overtak ing ship's res istance t o forwa rd moveme nt increases, while that of the ship being overtaken falls. The ships are exposed to lat eral effe cts and yaw mom en t s t hat cre ­ ate awkward hyd rodynam ic bala nce situa t io ns . Whe n a sh ip with great er tonn age ove rha uls an ot her, t he phen om en on of in teractio n of water masses is felt fo r longer.

Ships overtaking in a channel

First of ail, the overtaken ship "B"

expe riences swing in the directi on of

t he overtaking sh ip "A", risking a col­

lision .

Secondly, the smaller ship will expe­

rience "suctio n", losing speed unt il it

A

has bee n overta ken .

The ships therefore have to reduce

speed befo reha nd . Overtaking is st ill

B

the most difficult ma noeuvre in a r Îv­

er and channel.

Swing of ship B

Suction of ship B

1

I n t his unst able env iro nme nt, t he helm alone m ay not be enoug h ta control t he ship. The speed of the t wo shi ps t herefore needs ta be care fully managed ta reduce hy dro dynamic stresses. If the overtaken shi p cut s it s speed, t his reduces the t irne needed ta overteke. Th e ship must , however, still kee p good hel m control. A tem porary increase in engin e speed here, will once m ore impro ve t he ru dde r efficiency and correct t he shi p' s headi ng . If a ship is ove rt aken by a sm alle r ship tha n it self, the interact ion effect s are prac t icall y Identicet. The fi g ure below show s t he chrono logy for swing (yaw Mz) , ap pro ach or separati on ( ~), and accelerat ion or decelerati on ( t he ships w it h respect t a each ot her. (A ccording to diagram )

~y ~) Fx

Mz

1)

Fx

Vs

...-. Max U Fy 0

Mz

IIl

)

,, 1 ,, ,,

... Min

,,, ,

,, ,

Max

... Min

,, , 1 ,

,,,

" Max

~ V

,, ,

.... Mln

Fy 0 -"""' Min

, , , ....Min

,, ,

.. Max

When the over pressure zones meet, the lighter shi p mo ves away from the heav ier one , and when the low pressure zones merge, the ship s are dra wn to wa rds each other. max) w hen The veloctt v of t he overtaki ng shi p dr ops sharply (

F::

,, ,

,,

~

.-

Interactions between an overtaking and overtaken ship,

... Min --...- 0

u:!.ng

~O

A~;;;'

of water, th e sum of t he volum e of th e t wo ships rs m uch greater than the vol um e of each one of them ) . This means that the squat of the two ship s will be greater than if

F: ,

~ and

Mz

~ 0,1 mille

the overtaken ship lurches ( MoJ t oward s t he ove rtaki ng shlp, in w hat m ay be a vi olent and difflcult to cont rol ev ent (4t h colum n). It should atso be note d t hat t he block factor of ships t hat are crossing or overtakin g each other increases (for t he same volume

they we re alone. It is onl y possib le, therefore, t o overtake in a rive r at slow speed, in the widest part of the channel, in arder ta limit t he effect of t he interaction s.

, ,,

.,.Max

.. .. .. .. ..

S 31

In itial pos itions of A and B - - - - 5 32

A

VesselA . VesselB .

B S 31 18 :53

18 :55

The river is not excessively large .

The black fact or is over 3.

18 :58 534

19 :01

S 33 l19:02 :40 collislon

elli ng faster than ship A.

The ships are bala nced , despit e t he hydr odynamic forc es pre­

sent, and t hey can still cont rol their course.

Ship A los es cont rol w hen ship B passes t he bow of ship A.

.... B~/

2.4.3 Ex ample tram real lite

Ship B, after agreement with ship A, begi ns to overt ake th e latte r.

The low und er - kee l clearance of the ship s causes a sign ificant

squat effe ct .

The overtaking manoeuvre begins comfortably, with ship B trav­

of

~

'.1

1

~

yJ

Helm hard ove r and engine runn ing ehead

Fx

Mz

~., .

I~ il-

F::)

_

Kinematics of A and B 5 hip 5hip

A_ B-

The latter can no longer st eer once its bow is in the low press ure

zone left by shi p B. The hydrodynam ic effects mean that ship A is

sucked towards t he st ern of ship B.

Given th etr respe ct ive tonnage , th e low under- kee l clearance and

\.­ " 10 'ese dt'cumoUu'ce5. Poo'! tow,..... w.v0œ5 t!lI to the ""-'"" ""P """"ooloQy, to ~ w~n tneo, ....."" ,m' P'"O"'O oecur>ry of ","ny _ _ ..k. _ _ "' SN-~~n~

,n

m.""""""......

.~

_

woth

~

_

~

.... _ ' .... poIOoes 10

imP'"O"'O oafetv -......rft for ~n t'rI>es of no< jus! _ the port. but .......... passong tno"Ou;I> I~""" ..II..... _ ...

""P.

inlI"" w.,.....lu9' ~

escort

.roc,... ta k•• ploce ..,tnin t he POrt e nvi· '"""""'t.

po""

.rou nd th" world ... ..il n . ped.l;st le /or . ny k ind

~

• a>mPIte!Y _rate

"'0""0 ...f.

pilat.

~ CO"

""0

be

" " " . . - ..... 'OIUoy_. It .. to oescroe .... me ...... nM'IM - . ,. ... . . t1'Ie ~

.

~

sœ-

that CO" be

- continuous environments. They allow the equation of the quantity movement for flu ­ Ids to be solved: I Forces Mass x Acceleration

=

Solv ing these equations allows accel­ eration of fluid particles to be quantified, along with pressure, friction and gravity forces applied at each point on the hull .

Solving these equations also allows a the­ oretical study of flow along the hull of a ship. Hull resistances can then be possible. Their complexity, however, means that they often have to be simplified (model­ ling turbulence for inst ance) and only a few experts, using powerful computers can solve them . At the moment, therefore, they cannot be used in real time during a manoeuvre , nor is on-board computer support possible. The simulators used provide " real tim e" simulation, which puts the 3D ship into its port environment (fi gure belo w). Reproduction of the navigation bridge and display of the port environ ment mean that the immersion experience is strlk­ Ingo Computers can reproduce the mo ve­ ments of ships using simple digital models as mentioned above, combining software for the ship dynamics with 6 degrees of freedom and hydrodynamic data bases . These models need prec ise confi gurati on for each ship, normally obtained from tank tests on models . The rea lism of t he sim ulations th us mainly depends on t he qua lity of these param ­ eters ( numerous tests of hull resist ance, aerod ynamic resistance, manoeuvrab ility and propulsion are needed in order to un ­ derstand thoroughly ail the coeffi cient s for quantifying forces and moments exerted on the ship) . In some cases, parameters are not accu rate enough and ship rnove­ ments are only reproduced app roximately. During simulator exercises it is therefore im port ant to preserve a critical attitude and sea sense in order to validate their results . Before accepting the result of an equation, it is always necessary to know the basic assumptions used to write it , A firm lesson may no netheless be drawn from training on simulators, especially if care is taken in selecting ship models and t he exercises are limit ed to simple ma ­ noeuvring phas es, sim ilar t o situations t hat hav e been tested in the tan k.

Full Mission bridge on the manoeuvring simulator at ENSM, Marseille centre

ENSM mainly relies on simulation to train future sailors. The Marseille centre with simulators for manoeuvring, navigation, radar, Ecdis, engine, SMDSM, dynamic po­ sitioning, oil, gas and tank, VTS, lee-Navigation is one of the largest marine simulation facilities in Europe.

Simulated ship

This is generally the case for standard sailing, approach, and port transit situations. Other than that, when the ship movements are sign ificantly accelerated, e.g. if the wind is blowing in strong gusts, if the engine power is varied frequently, or even when manoeu­ vri ng in "catastrophic" scenarios, simulators are still not realistic enough . It is then generally preferable when considering the limits of the feas ibility of a manoeuvre to refer to similar, real situations and th us to the professional experience of masters and pilots. Similarly, to ma intain a rational approach , tra ining in berthing or moving off manoeuvres is a special case in which care is often needed . It is still difficult to quantify ail interactions between the ship and the environ ment, and thus to programme simulators to reproduce perfectly the most complex port situations. It is also difficult to simulate the ship precisely in ail sail ing, trim and loading conditions, or even adjust to its changes over time (wear on the engine, distortion of the hull, etc .). The bases are nonetheless useful and already allow a really consistent initial training, although performance of the different simulators available on the market varies considerably Th e computer simu lation therefore appears to be a good approach with development oppo rtun ities, and is in some ways more realistic than the "simulati on" on ship mod­ els , especially because it allo ws a rational approach to speed in manoeuvring (speed is fundament al, since it s square is used for calculating inertia, lift and drag of the ship). Realism of the v isual and sound ambiance recreated in the simulators also allows stress­ fui human situations to be reproduced, which are very useful in terms of train ing and behaviou r stud ies (Bridge Resource Management). The increasing size of ships and ever greater safety demands have also led marine train­ ing schools and most pilot stations in French ports to purchase simulators. AHTS (Anchor-Handling Tug Supply vessel for oil platform).

Secondary Bridge 2

urs

litE

srAND"'~

The plan of the manoeuvring simulator installations at ENSM,

Secondary Bridge 3

2

Training on scale manned ship models

In Europe there are several training centres for manoeuvring on ship models. These centres offer courses at which trainees manoeuvre sm aller models, representing different types of ships, which are placed in sma ll-scale port environments. Channels, locks and wharfs are reproduced, along with swell, wind, current or the work of tugs. It is therefore possible to highlight reactio ns of models in different situations found in port environments . Interactions between models passing each other or between a model and the banks or bottom of a canal are shown realistically. Berthing and moving off manoeuvres are also undertaken in different wind and current configurations, to study the difficulties of the most relevant manoeuvres and scenarios . Special efforts are made to ensure that the behaviour of the models resembles as closelv as possible that of a real ship. Nonetheless, the complex nature of the rules on similarity mentioned in the chapter about knowledge of the ship shows that models should not be seen as simulators but rather as realistic resources for studying the behaviour of the ships. The more the size of the model differs from that of the actual ship, the more difficult it is to determine references in terms of the speed of the ship, the wind force and intensity of current.

Models in channel at Warsash Finally, sailing and manoeuvring a ship is not a matter for improvisation. Solid training is needed, especially before taking responsibil ­

ity for a manoeuvre . In its resolution A960, (IMO Resolution A960 - January 2004; see chapter, "Cooperation with pilots") the IMO

perfectly summarises the procedure to be used when training pilots.

The same approach can be followed by masters and officers.

This resolution recommends a training programme including practical experience, gained under the close supervision of experienced

pilots . Th is practical experience (a few hundred manoeuvres, or thousands of hours training for most ports), gained on board ship in

real piloting situations, may be supplemented by computer simulations and small-scale models of piloted ships, by theory courses,

or through other training methods.

1

Regulations

-

ail helm systems must be checked and tested 12 hours before moving off, an exercise should be run every three months to set up the emergency helm, the ship must have a main control sys­ tem and an auxiliary, or two identical systems, the main control system must be ca­ pable of moving from 30° on one tack to 35° on the other within 30 seconds, when the ship is running at her ma xi­ mum weight. This procedure must have

There are numerous national and interna­ tional legislative bodies in the area of ship manoeuvring. They cover ship-building, . ­ design of gear, regulations for manoeu­ vring capabilities and their limits. They also set rules relating to functional checks on equipment and ship operation. These include: - Solas (International Convention for the Safety of Life at Sea) , an int ern at ional t reaty defining the various rules on se­ been tested , curity, safety and operation of ships, - the auxiliary control system must take - certification and control bodies , defin­ less than 60 seconds to move from 15° ing for inst ance the number of fittings on one tack to 15° on the other, with fo r moo ring lines , and monitoring ship the ship having maximum draft and running at haIf speed or 7 knots, operation. - the IMO whose resolutions define the - the control gear and the shank must be manoeuvrab ility required of a ship and designed to tolerate maximum reverse its limi t at ions, speed without damage. - national authorities ( in France , "Marine Affai rs") applying the policy of the State Except for helm tests running at maximum concerned, delivering sailing licences speed in reverse, ail other limitations are subject to mandatory t esting . and certificates and monitoring ships. A survey of ail the regulations lin ked to ship ma noeuvrability would be outside the 1.1.3 Visibility on the bridge scope of t his work, but we note the most im port ant, espec ially IMO resolutions that Ships over 45 metres long must comply give th e boundaries with in wh ich a ship with the following provisions : should move . Ali ship-handlers should be - The view of the surface of the sea ahead aware of these lim itations, wh ich are spe ­ of the bows from the bridge shall be un­ cifie to each ship. obstructed for over two ship's lengths or over 500 metres . - The horizontal field of view from the 1.1 Safety regulations bridge shall be 225 ° with an acceptable (Solas) blind area angle of 20° (lifting gear) . - The horizontal field of view from the 1.1.1 Using engine in reverse main helm control must be 60° either The engine started up in reverse must be side of the ship's axis. able to stop the ship 's forward movement within an appropriate period and over a 1.2 IMO Recommendations reasonab le distance, and this should be on ship manoeuvrability tested . For ships with twin-shafts, the ship The International Maritime Organisation itself must have measurements available has adopted the following recommenda­ of t ime and stopping distances using one tions relating to ship manoeuvrability: shaft line, made during the commission­ - MSC/Circ. 389 of 10 January 1985: ing tests . provisional directives for estimating manoeuvring performance in ship de ­ 1.1.2 Using automatic pilot and sign , - resolution A.601 (15) 19 November steering gear Manufacturing and usage standards for 1987: presentation and display of in­ the control surface gear, set by Solas and formation about ship manoeuvrability, the classification com panies, should corn ­ - resolution A.751 (18) 4 November ply with a number of crit eria : 1993 endorsed by resolution MSC 137 - it must be possible to resume manual (76) 4 December 2002, replacing the control of the helm in zones of heavy annexed provisions : provisional stand­ traffic and in reduced visibility, ards on ship manoeuvrability: - the helm must be trimmed after an ex­ - MSC/Circ. 1053 of 16 December 2002: tended use of the automatic pilot, explanatory notes on conditions for - the ship must have two helm motors in ship manoeuvrability tests as specified in MSC resolution 137 (76). service in hazardous zones,

1.2.1 MSC/Circ.389 Circular 389 defines the ship manoeuvring characteristics. These data are used to estimate manoeuvrability and handling properties. They are determined for a fully-Iaden ship in deep water. It also describes the real-life tests to be per­ formed in order to confirm a ship's manoeu­ vring performances . These specifie manoeuvres include : - Turning circle - The Z-manoeuvre : ship's yaw checking ability - zigzag test ), - Initial turning test on 10° helm, - manoeuvres to test the ship's capacity to stabilise its heading:

-

• pull-out test, • direct and reverse spiral tests, Emergency stopping tests:

1.2.2 Resolution A.601 (15) Resolution A.601 (15) specifies the regula­

t ion documentation and its content Iinked

to ship 's characteristics and manoeuvrabil­

ity. This documentation must be ava ilable to

ship-handlers and to the pilot:

- Pilot card showing the characteristics of

the ship and its equipment in normal operating and loading conditions, - the Wheelhouse Poster is displayed in the wheelhouse giving deta ils of the manoeu­ vring capabilities of the loaded and light ship within a deep and shallow water en­ vironment, - Manoeuvring booklet contains the cherac­ teristics of the ship that affect it s manoeu ­ vrability. It covers ail the information not­ ed in the Pilot Card and the Wheelhouse Poster. Most of this information comes from studies into ship-building, as weil as from the tests. This booklet is filled in throughout the ship's service life.

1.2.3 Resol ution A.751 (18) ( 7 6) ;

Resolution MSC 137

1.3

Resolut ion A.7 51 ( 18) app lies to ships over 100 metres long, to

gas carriers and chemi cal product tankers.

It defi nes regu lat ions and the ir limits for the following manoeu­

v res :

- Turn ing ability,

- I nit ial t urn ing ability,

- Ship's yaw check ing and course keeping abilities,

- St opping ability.

1.2.4 MSC / Circ 1053 Circular 1053, adopted by A.751 (18) is intended to give admin­

istra t ive authorities specifie directives on defin ition and e xecu­

ti on of manoeuv res as weil as rules relating to ship manoeuvra­

bilit y.

It is intended for both research offices and test tanks, as weil as

for ship-handlers.

IMO rules on manoeuvring defined in resolution A.751 (18)

Resolution A.751 (18) defines the manoeuvrability Iimits a ship must not exceed in each of the following manoeuvres: - Turning ability determines (figure above right): 1. The distance between the moment where the ship sets th e helm 35° to starboard , and the moment it is at 90° of its initial course shall be wit hi n 4.5 ship's lengt hs. 2. The distance between the moment where the ship sets the helm 35° to starboard, and th e moment lt is at 180° of its init ial course shall be within 5 ship's lengths (tactical diameter). The initial turning ability requires the distance travelled to be less than 2.5 ship's lengths between the moment t he hel m is at 10° and the moment the ship's head ing chariges by 10°:

,

- -----

-r----+--""""*-~>-'"

10· 1 Change of heading

Forw ard /

30 seconds. The second overshoot sho uld not be greater than 15° of t he sam e values of the first one. For the test with 20° helm angle, th e first overshoot should not exceed 25 ° .

10· Starboard

Yaw checking ability 10 °/10 °

Lateral deviation -

The stopping ability indicates the distance travelled during a crash stop. The ship with an initia l speed VT, having put its engine in Full astern, should stop over a distance less than fifteen times the ship's length (figure 4).

Forward

Reverse propeller rotation Full astern order - _ - - - - - - - - - ' Stopping distances

1.4

Manoeuvring tests

Relying on rules defined by IMO, the organisations covering test tank research centres, such as ITTC 2002 have developed and

standard ised their own procedures.

Ali the tests quantified in the test tanks comp/y with the same specifications, using terminoloçv and measurement conditions com ­ mon to ail leboretoties.

The table summarises the tests recommended in the IMO resolution, and those developed by ITTC.

IMO A601

IMO A751

ITTC 2002

Turning circle

X

X

X

Z-manoeuvre test

X

X

X

Modified Z-manœuvre Test Z-manoeuvre at low speed test

X X

X

Direct spiral test

X

X

Reverse spiral test

X

X

Pull-out test

X

X

X

Stopping test

X

X

X

Stopping inertial test

X

X

Man-overboard test

X

X

Parallel course manœuvre test

X

Initial turning test

X X

X

Accelerating turning test

X

X

Thruster test

X

X

Crabbing test

X

New course keeping test

X

Acceleration / deceleration test

X

Crash stop ahead test

X

Minimum revolution test

X

2

Helm arder

The ship-handler must always keep a close eye on the helm angle repeater, to check on the helm movements and notice how the ship behaves.

Hel ord ers are inst ruct ions for the head­ ing, and th e regul ati on helm movements the ship- hand ler gives to the helm officer . to perform a man oeuv re. They are stand­ The 1. ard ised t o ensure the settings are properly unde rstood by t he helmsman or woman. It is essenti al to maintain this formai lan­ guage, to avo id any ambiguity about the t yp e of th e order to be fo llowed. "Thanks" or "ok", "heading to be followed by helms­ man only using a designated land mark" , are abso lutely forbidden. It is essential to verify that the order given has been ex­ ecuted . A helmsman or woman who puts the helm hard to starboard when the set­ 2. ting was hard to port is putting at risk the safety of the ship with possibly irreversible consequences.

helm commands are: Helm commands are given using the words: "starboard ", "port " cor­ responding to the direction towards wh ich a ship making headway should come . The cont rol gear must be in­ stalled so that for instance when a ship going ahead has to bear to star­ board , the control dev ice and helm repeater also turn to starboard . The use of the words: "right", " Ieft" is for­ bidden . The terms to use for these commands are : - "Starboard" (or "Port") meaning: put the helm over to the right (or to left),

-

when necessary, the terms "star­ board" , " port" are followed by the num ber of degrees indicating the angle the helm must make with the ship's longitudinal plane , - The commands "starboard" and "port" preceded by the words "hard to" indicate that the helm must be placed at the extreme ang le to right or to left. 3. "Helm am idships", meaning: put the helm in line wit h the ship's longitudi­

4.

5.

nal plane. "Steady", meaning : keep the head ing as it is. With th is latter com mand, the helm is manoeuvred in order to keep the vessel at its present heading. Commands are repeated by the per­ son steering, at the tim e the order is given; this person the n checks that the command has been carried out . "

Examples

2.1

Instructions: Ship-handler "Starboard 15" (*)

"Good "

Change head ing wit h 15 0 of helm angle . I nit ial course 000 0; final cou rse 055 0. The Ship-hand ler controls the turn to br ing t he ship round to 0550. Helmsman/woman

comments

"Starboard 15" (* )

The helmsman/woman repeats the command given by the ship -handler to indicat e it has been properly heard. The helmsman moves the helm 15 0 to starboard.

"Whee l is 15 sta rboard" (* *)

The helmsman reports tha t the helm is 15 0 to starboard.

"01 0, 020 , 030 , .. . "

The ship-hand ler collates the informati on. The helmsma n "sings out" headings every 10 0.

" Ease helm to 5"

"Ease helm to 5"

During the turn , the ship -handler may reduce the hel m angle.

"helm ami dsh ips"

"helm am idsh ips"

The ship-ha ndler orders the helm to be put to 0 0. The helmsman repeat s and moves the helm to 0 0

" Helm amidships".

The ship-handler orders a head ing of 0550.

"St eer to 055"

"Good "

The helmsman reports when the helm is amidsh ips . The ship-handler collates.

"Goo d" .

"Steer to 055 "

The helmsman collates and adj usts the head ing to come to 055 0.

"Steer on 055 "

The helmsman reports when the helm is at 055 0.

The ship-hand ler collates. 0 Change heading wit h 15 of helm , giving the new head ing to follow directly (* * *) . I niti al course 000 0; final course 0550. The ship- han dle r inst ruct s the helmsrnan/wornan to go to the heading indi cated .

"Starboard 15, steer to 055"

"Helm is at 15 sta rboa rd " (*)

The helmsman repeats the command given by the ship-hand ler. The helmsman moves the helm 15 0 to starboard . The helmsman report s that the helm is 15 0 t o starboard.

"Ste ady on 055 " .

The helmsman reports wh en the helm is at 055 0.

"St eady as she goe s"

The helmsman stops immediatly t he giration and steers t o the present course"

"St arboard 15, steer to 055"

The ship-handler collates the information .

"Goo d"

The ship-handler collates.

"Good" "St eer at this course "

* **

***

The wo rds are "St arboard fift een" , or else "Helm starboard 15" The ship-handler first gives the direction of turn, then its angle . Once the helm is at 15 0 starboard , the helmsman/woman reports, first giving t he ang le then the side to which it is turned. Th is dist inct ion is mad e in order not to confuse the command given by the ship-handler wit h t he inst ruct ion carried out by the helmsman . This procedure is valid for a change of heading less that 090 0 •

3

STCW 2010

The required skills demanded by STCW 201 0 to exercise the raie of ship -handler responsible for manoeuvring a ship are as follows: 1. to be able to manoeuvre when approaching pilot st ations to emb ark and disembark the pilot, taking account of weather, tide, distance to travel and stopp ing distances, 2. to be able to navigate a river, est ua ry and confined waters, allowing for the effects of current, wind and shallows on the action of the helm, 3. to be able to turn the ship at a constant rate, 4. 5. 6. 7. 8. 9.

1

10. 11. 12.

J

13. 14.

to manoeuvre in shallow water, allowing for the reduction in under- keel clearance caused by squat, roll and pitch, to handle interactions between ship and banks (bank effect), to be able to berth or move off under ail wind, tide and current conditions, with or without a tug, to handle interactions between ship and the tugs, to be able to use propulsion systems and manoeuvring systems, to be able to choose a mooring; to moor using one or two anchors in restricted spaces; to assess the various factors that deter­ mine the length of anchor warp to drop, to be able to notice an anchor dragging, and know how to release a fouled anchor, to be able to enter a dry dock, when damaged or undamaged, to be able to sail and manoeuvre in bad weather, including when coming to the aid of a ship or aircraft in distress; to be able to carry out emergency towing operations, and take the steps needed to make a ship safe if it is difficult to steer in the hollow of a wave , and reduce drift, to be able to manoeuvre with care in order to launch lifeboats and to release survival gear in bad weather, be able to winch survivors on board from rescue craft or Iiferafts,

15. to be able to assess the manoeuvring characteristics of the main types of ship (stopping distances, turning circle at different speeds and drafts), 16. to be able to sail at reduced speed to avoid damage being caused to other ships by bow wave or wake, 17. to be able to take the necessary precautions for sailing near to ice, or when ice is accumulating on board, 18. to be able to sail close to or within traffic separation zones, and in zones covered by the VTS. STCW 2010: Standards of Training, Certifications and Watchkeeping. VTS:

Vessel Traffic Service

Appendices Anchoring pre paration sheet Pilot Card Ferry 11 046T Wheelhouse Poster Ferry 11,046T Pilot Card VLCC 1 Load 159,584T Wheelhouse Poster VLCC 1 Load 159,584T Pilo t Card Container 5h ip 32,025T Wheelhouse Poster Container 5hip 32,025T

1. 2. 3. 4. 5. 6. 7.

Fiche N°

ANCHORING

Yes

Designation

N° A

Has an anchoring plan been prepared taking into account :

1

Speed reduction in ample time ?

2

Direction/strength of wind and current ?

3

Tidal stream when manoeuvring at low speeds?

4

Depth of water, type of seabed and the scope of anchor cable required

5

Have the engine officer on duty and anchor party been informed of the time of 'stand-by' for anchoring?

6

Are the anchors, Iights 1 shapes and sound signalling apparatus ready for use?

7

Has the anchor position of the shlp been reported to the port authorlty?

8

Make confirm by anchor party that swlvel, anchor shackle, anchor ring and ail pins ln good order and position?

Whlle dropplng the anchor 9

Record on GPS the anchor position as the center of swinglng c1rcle

Comments

ISSUED: MASTER

FlIIed by

CONTROLLED:

DATE OF ISSUE:

Signature:

Date :

REFERENCE: INDICE :

No

Na

Pilot Card Ferry 11046T

Ship ruune IMONumber Load Condition Displacement Deadwei2ht Capacitv Airdraft

Passe~r

carfenv (Dis.11046t) v41 ICallSign Fullload and .50~. bunkers and Forward deckhouse 11046 tonnes Dtaftforward NIA tonnes Dtaftforward extreme NIA Dtaftaller 38.68 m 1 127 ft 2 in Dtaftallerextreme

Date Yearbuilt

12.1 2.2008 1

.5 .0.5 m 1 16 ft .5 .0.5 m 1 16 ft .5.32m 117ft .5.32m 117ft

7 in 7 in 6in 6in

Ship's Particulars Lerurth overall Breadth Anchor Chain(Port) Anchor Chain(Statboard) Anchor Chain(Stem)

14.5 m 25.2 m 14 shackles 14 shackles NIA shackles

112

Typeofbow Type ofstem

1Bulbous [Il-shaped

(1 shackle =27.5 m/15 fathoms)

33

r--------f

i:r>

~=====:::::i'~

.

44

L~

49 .3

4ft

c1)

~J

Steering characteristics Ruddel(s) (typelNo.) Maximum~

Semisuspended 12 35

Rudder a%Uile forneutral effect Hardoverto ovel(2 pumps)

20..5 seconds

o deegres

Number ofbow thrusters Power Number of stemthrusters Power

Stoppings Description FAHto FAS HAHtoHAS SAH to SAS

FullTime 123.5 s 138.5 s 147 s

2 .590 kW1590 kW

NIA NIA

TlUl1Ïl12 Headreach 3.03 cbls 2.6.5 cbls 2.11 cbls

circle

Ordered Ellgine: 100%, Ordered rudder: 35 degrees Adwnce 2.17 cbls Transfer 0.8.5 cbls Tactical diameter 2.22 cbls

ManI E112Ïne(s) Type ofMain~ Number of Main~(s) Maximum powerpershan Astempower Time lirnit astem

Medium sneeddiesel 2 2 x95.56 kW 60 %ahead

NIA

Number of propellors Pmpellor rotation Propellor type Min.RPM FullAhead to FullAstem

2 OutWllId CPP 170 30 seconds

En!i:ne TelelmlDh Ta1Ile ~order

100 % 80 % 60 % 40% 20 % -20 % -40 % .60 % -80 % ·100 ~.

Speed, knots 20.92 18.57 15.08 11.07 .5.54 -3.77 -6.15 -7.41 -8.85 -9.9

~power,kW

9.5.56 6304.7 3747.3 2193.3 1276.7 1249.7 1489.1 1739 2193.3 2604.6

RPM 170 170 170 170 170 170 170 170 170 170

Pitchratio 1.4 1.16 0.87 0.57 0.15 -0.12 -0.3 -0.42 -0.57 -0.67

Wheelhouse Poster

Pilot Card Ferry

11046T

~~HOUSE PO STER

Sbip's name Pass=er car ferry l'Dis 1l046t) v41. can sign NIA . Gross tonnage NIA . Nettonnage NIA .

Load Condition FuI110ad and 50"10 bunkers and Forward deckhouse • Displacement 11046 tones . Deadweight NIA tones

DRAFTS IN PRESENT CONDITION Forwml 5D5m Forwml. xtre.... 5.05m Aller 532m Aller. _.... 532 m

STEERlNG PARTICULARS SemisosDetded Tvee ofI1dler Maximum rudder ...... 35domes HOlld-owr to hard-over(1 pumps) 41seconds HOlld-owr to hard-over(2 numns) 20..5 secoJlds 0_ Neullo1 .ffect...Ie

PROPUlSION PARTICULARS Type ufMain En,jne Medium speeddiesel Nuof>er ofnrollOllers No.of MainEœines 2 ProllOller rotation 2x 9556kW ProDeller Ivt>e Mu. "" wor IlOr.hafl êstem tower 60 11. ebeed Min.RPM Time limit estera NIA FAHto FAS EJt me Tele=h Tobie ErU!ine erder Sneed. krot. Emne power, kW 100 % 2092 9556 80 Y. 18..57 6304 60 Y. 15D8 3747 40 'Y. 11.07 2193 20 Y. 5.54 1276 -20 11. -3.77 1249 -4:J 11. -é.15 1489 .so 11. -7.41 1739 -80 11. -8.85 2193 .100 11. -99 2604

ANCHOR CHAIN No.of ,hockles Mu. me ofboovino 14,hockles Port 30 mis 30 mis SlaroO'" 14.hocklt, NIA,hockles Siem NIA mis (1 ,hocklt- 27..5 mIlHeth:lms ) THRUSTER EFFECT Timedelay 10 lNol effective P .1 7imedelayl Tummg . Thruster lNo. of p'~wor for full me al zero W) ~.) .~degreesImin) ~,:, full ~ speed s)

2 Outwud

F'

CPP 170 30secoJlds RPM 170 170 170 170 170 170 170 170 170 170

s)

Bow 2 Stem 1 NIA Cumbinedl NIA

PitchrelD 1.4 1.16 0.87 0.57 0.15 -0.12 -03 -0.42 -0..57 -0.67

1180

19

15)

38

27.2

6

1

1

1

1

DRAFTINCIŒASE IN PRESENT CONDmON Heeleffeet sauateffect Urdorkeelcle8rerlce SMn'"n-l Bow.nual Slem.nuat Heel.- Dreft ircreese 2 de. -O ..57m 0.71m 034m 189krols 4 les O.66m 3m 16.74krot. -o37m O.69m 8dO.­ 1427 krols O.46m l.26m O.09m 1.8m -O .68m 0.76m 12 ile1z 1821 krot. 2m 2.29 m 16 cW 16.18krots -O .4Sm 0.75m

TURNINGCIRCLES

-

4

o

rr'.....

/4t3" ,­

mÎ"rf

1

5

1

10 ,:;. ,, ~. :

o

Ir 'S

14

...

12

'f ' .a::.. • • .1

2 Se IeilCl 2.22obis .2.22 cbls 0.62cbls -0.62 cbls Ocbls

10..­

1 l .c

eo

ll:llOO.allOlOtOO

t:olO

DDIDDDb

D

B

a

.40«)4000

a

a

o

loF

,)

Iltl.: JIO.l

ID

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r:"'" ':- ... • ~

o.

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'î r r .. 'l' . ..'" ItG .1

('".:

1

o6000Q)ao

e

D

ID

Il'

«>

40

~

33

~..I

lIilDraft(G) Forwm BIilJd lonen

lbO

J> {Û--- =1

J~ tl=>__ u . u= _ . =====::::­ :

f4t3\

5

2

~

1

........... ;

'-lS : .15

145 112

4

2

:. •.., "" ~ ~ 1)-;::

.:., ~~ 'X' :~: .~o 'Y ~ . . 1. 1'. 01,. ~ 7 t' ~~ ;l;~ - , :r' ..~ ~

10

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~ 4

:

o

~ Full tirN HeM !elle] 100 100. 154cbls .35 100 100. 1.54cbIs 35 -&0 90. 2.35cbls -35 -&0 90s 2.35cbls 0 -80 120. 351 cbIs

[fin31IirM.rnin.s ] [FlIllll speed, kl\CU] I Finlll c..... . . 0.01

'-not; I l .'' tO .~. I ~" I~=

2

-2 2 3

Hei dil!r struet: [Tl'ilck .....ch. cbl$]

SIli;> p'ftion m"1t'Y Qf po..Ü>I.)

5

2

Emergency Manoeuvers(SW*)

STOPPING CHARACI'ERlSTICS Track DW R ach SW

EmergencyManoeuvers(DW)

·2

o

2

No R1ililEM Full lime HeM IeIlCl 1 35 100 128. 1.18cbls 2 •35 100 128 • 1.18cbls 3 35 -&0 104• 2 55 cbls -35 -&0 104. 255cbls 4 3.06cbls 5 0 -&0 124.

Sile 1eIlC} 1.51 obis ·251 cbIs 032 cbls -032cbls Ocbls

M....NOVERBOARD

RESCUE MANOEUVRE

SEQUENCE OF ACTIONTO BETAKEN:

• TO CAST .... BUOY • TO GIVETHEHElMORDER • TO SOUND THEALARM • TO KEEP THE LOOK OUT

....nnroxirnale ManUYe' P=ar.I

Aclion

Timel lSeIrudder 35 STBD. Wail

o• bUship CQ1IlSf alteJOd

'10 31de""'.s frommitial

ISeIrudder 35 PORT. V/ail till

23. po1llSf alt.red to .170 deglOOS fromU'jtial

TumAP on.

163. diffe ~~~ btt_n AP

a.'ld DUlis!

1

3868rn 1 127 ft 2 in 37m

.

f:: b,um

cours.

""tbeI8O~' .

Pilot Card VLCC1 load 159584T

PILOT CARD Ship name

VLCC 1 (Dis.159584t) v54 1CallSign FuIlload 159584 tones NIA tonnes NIA 43.6m 1 143 ft 5 in

IMONumber LoadCondition Displecement Deedweisht Capecity Air chaft

Draftforward Draftforward extreme Draftailer Draftailer extreme

Date Yearbuilt

12.1 2.2008 1

16.51 ml 54ft 16.51 ml 54ft 16.88m 1 55 ft 16.88 m 1 55 ft

3 in 3 in 6 in 6 in

Ship's Particulars Length overall Breadth Anehor Chain{Port) Anchor Chain{Sta:rboard) Anchor Chain{Stem)

2613 m 48.3 m 15 shackles 15 shackles NIA shackles

Typeofbow Type of stem

1Bulbous

IV-shaped

(1 shaekle =27.5 m 115fathoms)

261.3 : 51.8

209.5

J.~L1------------,

{f[]

L

77 .3

_..1

CI>

Steering characteristics Rudder(s) (type/No.) Maximum angle Rudder angle for neutral effect Hardoverto over(2 pumps)

Semisuspended Il 45 0.32 degrees 34 seconds

Number ofbow thrusters Power Number of stem thrusters Power

TIU1Ullg cu-cie

Stopping Description FAHto FAS HAHtoHAS SAHto SAS

FullTime 666 s 789.5 s 1133.5 s

NIA NIA NIA NIA

Headreech 10.95 cbls 10.75 cbls 10.93 cbls

Ordered EJ:Iltine: 1000/., Ordered rudder: 45 degrees Advance 4.07 cbls Transfer 1.72 cbls 4.04 cbls Tectical diarneter

:TYran1 Enginefs) Type of Main EJ:Iltine Number of MainEngine(s) Maximum powerper shan Astempower Time 1imit estem

Engine order FullSeaAhead FuIlAhead HalfAhead SlowAhead DeadSlowAhead DeadSlowAstem SlowAstem HalfAstem FullAstem "'Modd:

VS'i02 : ;

Slowspeeddiesel 1 1 x 15500 kW 40 ". ahead NIA

Number of propellers Propeller rotation Pmpeller tvee Min.RPM FullAhead to FullAstem

In2ine Teleln'lQlh Table Speed, knots EJ:Iltine power, kW 15 154292 12.5 9008.5 10.1 3909.5 7.3 1256.4 4.7 530 -1.7 553.7 1494.8 -2.5 -3.7 3924.2 -4.4 6552.9

1 IRWtt FPP 27

10 seconds

RPM 90.35 75.25 57.22 38.41 27 -28.4 -39.73 -55.92 -65.96

Pitchratio 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8

Whee lhouse Poster

VLCC1 load 159584T

Ship's naine VLCC 1 (Dis 159584t) v54, caU sign NIA. Gross tonnage NIA. Net tonnage NIA . Load Condition FuI1 1oad. Displacement 159584 tones . Deadweight NIA tones DRAFTS INPRESENT CONDITION Forwud 16.51m Forwudext.. me 16.51m Aller 16.88m Allerext. .me 16.88m

STEERlNO PARTICULARS ANCHOR CHAIN Typeofrodder Semisuspendod NO.of.hockJe. Max. raieofhoavill2 Malcimum rodder ."gJe 45degree. 1~ ,hockJe. 18m1min Pori HOld·over 10lwd·ove>(1 pumps) 68.econds 18m1min SIOlboerè 1~ .hockJe. NIA ,hockJe. NIAmimin HOld·over 10lwd.ove>(2 pumP' ) 34.econds Siem Neulreletreel."gJe (l,hockJe- 21.5 ml1~ falhorns) 032 delllO" THRUSTER. EFFECT PROPUlSION PARTICULARS Nol.tr.el .... TypeofMeinEr1rÎM Slow,pe.d die••1 Numb.rofpropellers 1 Tnl.r No. of Power ime delay TumirJg raieal z.ro lTime de~ 10 obove sp•• d Right Prop.llerrotation 1 No. ofMeinEr1rÎM' W) ~orfull .) ~t. p•• d(degree.lmin) rm:~.) k nl(,) !

Ship Handling 2019 - PDFCOFFEE.COM (2024)
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