IMO’s activities on ship manoeuvrability

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Prearn b le

The subject of manceuvrabiiity of ships has been ou the

_{work proamme of the}

_Maritime _Safety

Committee through the Sub-Committee on Ship Design and Equipment since s inception in 196& A paper ou Manoeuvrabiiiry of Ships was presented by Mr. Fernando PLaza. Senior Depury Director, Sub-Division for Technology, tMO,at the Round Table -MARSIM & ICSM heldax Tokyo on 7 May, 1990. The paper described chronologically_{the development} of the work ou manoeuvrabilicy and related _matters based on technical submissions by Member Stares and discussions held at the DE Sub-Committee _sessions

and the meednzs of the Worting

Group on ship manoeuvraòüity. It presented Sub-Committee's views ou the necessity of esmbflshing m.atioeuvring

perfonn'e standards,

diffficulthes for developing mznoeuvring criteria, process and tasks co be

undertaken for the development of

_manceuvring performance standards, teutarive values for the manoeuvring criteria, etc., for further consideration by the DE Sub-Committee and the_{status of the work} up to

_{the thirry-hrd session of the DE}

Sub-Committee (May 1990).

The present paner, while presenting an overview of IMO's activities on ship msnoeuvrability,_{provides an} update on IMO's work lendingto the

izariou of

the LMO Inrerim Sndards for Ship Manoeuvrabiliry and the associated Assembly resolution by DE _36, which have been approved by _{the Maritime Safety} Committee at its siry-secocd session inMay 1993 for adoption by the eighteenthAssembly in November 1993.

rntrnduaion

During the Last 3 decades, the International_Maritime Orgrni7ition (Dv(0) bs been active in dealing with the following aspects of ship manoeuvrabiliry,which

are vital to achieve its objectives of safer shipping and cleaner oc-1ns:

IMO'S ACTIViTIES ON

sarg

MANOEUVRAB

ruTy

S.D. SrivaaTa

Technical Offlcer

Internatloual Maritime Organimtion

TEc;E UVESiJT

t.aboratorium voor

ScheeshydromcjpJ

ftrchiof Mekelweg 2,2628 CD

_Deft

r4L 015-788873 F8x _{01L 781833} 327

manoeuvting information aboard ships in order to rnhri'e the safety of naviga.don

impaired ma.noeuvrabiiiry of rrkrs to

reduce the risk of marine poiludon

tuanceuvring standards for ship designers co

ensure rhr

ships have manceuvring properties that may constitute a safety risk Manoeuvring Information on Board Ships

The value of readily available manoeuvring infommtion of ship's bridge need

_{not be}

over-empsised as it

is of crncial importance co the rnsrer, navigating officers and pio

for dichrging

their duties efficiently and enhnc'ing che safety

_of

navi.tion.

Having regard to the variety of circumstances a ship may encounter and its characteristic manoeuviing capabilities, the 1MO Assembly, in November 196g, adopted resolution A. i 6OÇES IV)_{on R.eccmmendation} ou Daza concerning Manoenviing Capabilities and Stopping Disrnr _{of Ships. The Governments were} urged co ensure that the mczer and officers should have readily available on the bridge alinecess.ry rir in accordance with this recommendation ander various conditions of draught and speed.

Tais was the first attempt by the 1MO co address and recommend the contents of the manoeuvring information on beard ships. Subsecuently. work was undertaken in order co ensure uniformity in the

information co be included in the nxanoeuvring booklets on board, particularly in large ships and ships cirrying dangerous chemicals in bulk.. The Mamme Safety Committee anproved and the

Assembly adopted in October 1971 by resolution A.209(VII) the 'Recommendation on Information co be Included in the Manoeuvring Booklets.'

ALI Governments concerned were invited to cake steps co give ¿feo: to this resolunon as soon as possible. Based ou new developments in techniques and in the

*

MR5!3! '93

xraxJXOLL takFtlt O LU.

s_Lro AI

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light of experiee gained in its application,

the Maritime Safety Committee kept the recommendation under review.

Recognizing the need to achieve a uniform format

and content of the pilot card and the

wheelhouse poster, and in order to establish a framework for the manoeuvring booklet which would provide navigators with more detailed information on the rnazxeuvring characteristics of the ship, the DE Sub-Committee,in co-operation with the NAV Sub-Committee, finalized a text of Recommendation on the Provision and the Display of Manoeuvring Information on BoardShips which iludes models for a pilot card, wheelhouse poster and maxeuvring booklet. The Committee approved it and the Assembly in Novemler 1987

adopted the Recommendation by resolution A.601(15), which superseded the earlier Recommendation adopted by resolution A.209(YU). Ail Governments concerned were invited totake steps to give effect to this resolution as soon as possible.

It may be pointed out rhr the mandatory provisions in respect of manoeuvring information under the

SOLAS Convention regulation 11-1/28.3 are as follows:

"The stopping times, ship headings and distances recorded on niais, together with the results of ttials to determine the ability of ships having multiple propellers to navigate and manoeuvre with one or more propellers inoperative, chl1 be available on

board for the use of the master or

designated personnel."

Although, 1MO Resolution A.601(15) is not

mandatory it provides the details of information to be included in the manoeuvring booklet and information to be displayed on board ships in the form of a pilot card and a wheelhouse poster, as required to comply

with the provisions of regulation 11-1/28.3. Impaired Manoeuyrabilitv of Ships

Having regard to the increasing number of VLCCS, and noting that tankers carrying oil, liquefied gases and other h7rdouS liquids in bulk, in emergencies such as complete mechanical breakdown, may need to be towed out of danger, primarily co reduce the risk of pollution. the Maritime Safety Committee, at its forty-eight session, approved a text finalized by the DE Sub-Committee on Recommendation on Emergency Towing Requirements for Tankers, which was adopted by the Assembly on 17 November 1983

by resolution k535(13).

This recommendation applies to all r2nkers grenier than 50,000 tonnes deadweight built after adoption of this resolution and requires rht they should be fitted with emergency towing arrangements at the bow and stern. It also requires that ail existing tankers ginater thrj 100,000 tonnes deadweight should be fitted with emergency towing positions at the bow and stern at the first scheduled dry dociting followingthe adoption of the resolution but not inter than 5 years thereafter. rh towing position should be fitted with strong

point, rhng chain and f2irlend.

However, the requirements

under

the

resolution

are

recommendatory in nature and not mandatory provisions.

The Maritime Safety Committee recently instructed

the DE Sub-Committee rht

requirements .inder resolution A.535(13) be revised and chis matter was considered by the DE Sub-Committee in February 1993. The Sub-Committee agreed that the emergency towing arrangement for tankers, fined at each end, should be made mandatory and this provision should apply to tankers of 20,000 dwt andabove. With this in view, the Sub-Committee 6nli7d a text of draft amendment to chapter V of the SOLAS Convention, which hs been approved by the Committee at its sixty-second session in May 1993. This amendment,

adding a new regulation V/IS-I to the

SOLAS Convention concerning Emergency Towing Arrangements on Tankers, is expected to be adopted by the Maritime Safety Committee at its sixty-third session in 1994, and enter into force on 1 January 1996. The text of this draft regulation is given in

annex 1.

The DE Sub-Committee, at its thirty-sixth session, also agreed char the towing requirements for tankers given in annex to resolution A.535(13) could be improved so that the equipment would be pre-rigged and capable of being rapidly deployed to facilitate safe and effective towing lineretrieval. The revision, incorporating new towing conceptsand technology, is expected to be finalized by the NAV Sub-Committee and approved by the Committee in 1994.

Mandatory provision of emergency towing arrangements for use on tankersand the capability for their rapid deployment and towing line retrieval must be regarded as major steps in reducing the risk of

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Interim Guidein

for E.stimatinz 4nnoetrvîirig Performance In Ship Design

All ships should have manoeuvxing _{qualities which} permit them to keep course, _{to turn, to check ruins,} to operare at acceptably slow speeds and to stop, and all

_{these should be performed in}

_a _cfactoty m2rr1er.

_{Since most maieuvring qualities}

_are inherent in the design of the hull and miehirrythey should be consciously estimated dnring the design process.

The work on formularion of guidelines_{for assessing} manoeuvring performance of ships

was iniriily

started by the DE Sub-omminee in 1982 _{when a} first draft based on submissions _{from Members w-as} prepared. _{rt was a2reed that the guidelines should} contain criteria

_{that would be needed by ship}

designers to describe performance standards _{to be} 2tieved when the ship is completed. triai _procedures that would be needed to verify these performance standards and informarion based on these investigations that would be of assistance to personnel on the navigating bridge.

This first draft of guidelines_{was refined by the DE} Sub-Connnirree on the basis ofcomments received and was

_{ntized in 1984.}

_{The Committee, at its} Eftieth session, approved Interim _{Guidelines for} Estimating Manoeuvring Performance in ShipDesign and circulated them by MSC/Circ.389of 10 January

1985.

These interim guidelines define soesiñcmanoeuvring characteristics which quantify inanoeuvrability and recommend estimation of these characteristics during design both for the ñally loaded andtest mnditions in

deep water. _{They also outline full scale tests to}

confini

the manoeuvring performa in test conditions.

They are intended

to estimate the nianoeuvring performance of all new ships greater

than 100 menes in length.

The guidelines are intended to apply to ships with rudders of conventional design. Ships with unconventional steering arrangements should be included by the use of an eouivalent coorrol setting.

3y MSCJC1rc.389, the Committee invited the

Member Goverenrs to recuest shipyards to apply the interim guidelines as ecrly as possible on a trial basis so that they may be assessed in the light of practical eoerience gained. They were also invited to collate the _{manoeuvrabilicv}

_dr

_on _ship

performance obtained, and to submit it to the DE

Sub-Committee where it would be e'1uared and

attplied in reviewing the interim guideiimes and

developing naateuwabiliry and

perforrrr

standards for ali types of ships. These submissions coinirg much valuable information are giving best picsure of the present state of art of naval architecture in the field of naanoeuvrability.

1MO Interim Standards for Ship

Manoeuc-rabilitv

In. 1990. the DE Sub-Committee, at its 33rd session, considered several submissions and background information pers concerning manoeuvriag standards and established a woridng group to develop manoeuvring standards and also to prepare eaplanarory notes for understanding their application.. A list of documents considered by the Sub-Committee from its 33rd session onwards is given in annex 2. The group's view was thai there was a clecr link

between safety and rnanoeuvrabiliry of ships, manoeuvrabiliry must be considered during the design stage and minimum standards of performance must be included in design procedures. The Sub-Committee concurred with these view and also agreed that ail manoeuvring performance criteria

and msures

should be simple, relevant, comprehensible, mmsuinble and practicable.

The group prenared draft manocuvring performance standards. The manoeuvring characteristics addressed in the manoeuvtnbilitv srmcirds are typical fennares of the performance quality and handling capacity_of the ship, which are considered to be of direct nittical interest. Moreover, they may all be rensonabiy well predicted at

the design stage, and they

can be mmsured or evaluated from accented _triai-type

manoeuvres.

During the development of the standards intersessiorUy and at

the 34th, 35th and 3th

sessions of the Sub-Committee the values for criteria were discussed and refined as follows:

Turnios ability - The limit ou advance was incensed from 4.0 to 4.5 ship lengths (L) and the tactical diame'er not to exceed 5 ship lengths in the turning circle manoeuvre:

Initial turnios ability - The proposal to reduce the initial turning distance from 2.5 ship 'engths to 2.25 ship lengths was not agreed:

(4)

Yaw checkin2 ability - Ithriilly, ranges of overshoot angles were used rather than a specific value of this angle which reflected the lack of consensus on the appropriate values of these angles for modern ships. However, finally, the upper limits of the ranges of overshoot angles were agreed as the specific values. The second overshoot ngle in the l0°/l0 zig-zag

test was modified from a constant value of 25° to a value which is 15° greater than criterion for the first

overshoot angle.

The 20°120° zig-zag test was also retained as a

means of having additional information on coiiner-rudder efficiency and to require the first overshoot angle not to exceed 25°.

Course-keepin ability

- The concept of phase

advance was considered

too complicated to be

included in a standard at the present stage, even if it is an effective means of introducing a measure of the human capability in the standard. It was agreed to intoduce the concept of spiral test hysteresis look characteristics as a function of ship length to speed ratio (LIU) as was also the concept of overshoot angle in the 10-10 zig-zag test as a function of LJU.

Stopin

Ability

- The necessity of a stopping

criteria, the predictability of the stopping ability and the practicability of the stopping test were considered in depth. The proposed conditions were:

(a)

full load, (b) r'm weather, (c) 'test speed' as

90% full speed or more, (d) full astern, and (e)

criteria: the track reach should be less than 15L. A decision on including in the standards a criteria for

stopping ability could not be reached

inirilly,

however, as several Member Governments were in favour of inclusion of such criteria, it was finally agreed that the track reach in the full astern stopping

test should not exceed

15 ship lengths (15L). However, recognizing that ships of large displacement might preclude compliance with this requirement, it was agreed that this value may be modifled by the Administratioa.

Test Conditions

The following test conditions, with the interpretations to the key condition requirements, were generally agreed but are yet to be finalized for inclusion in the explanatory notes to the manoeuvring standards.

1. deep unrestricted water: more than 5 times

the mean draught;

2. calm wind:

not to exceed 10

mis (20 knots);

3. no tide or current; 4. loading:

preferably at full load and even

keel

IT

-

D1I<0.05T1

-T: draught, with subscript for design waterlin', aft, forward and mean or alternatively,

heavy ballast with a minimum of

trim, with sufficient propeller immersion and as close to standard condition as possible;

5. test speed: 90% of the full speed or more. Spiral Test

It was recognized that the spiral testis recommended in MSCICLrc. 389

and its resuks and 'spiral test

diagram' would provide unique information, but it also hs the following possible didvantagcs

it is generally more difficult to predict the characteristics to be obtained from spiral test than those obtained from 10°/10° zig-zag

test;

it is time consuming to conduct a full spiral test;

the test is particularly sensitive to weather

conditions.

Considering rht the manoeuvring standards should be as simple and practicable as possible, it was decided not to include the spiral test in the standards but to include criteria for course-keeping ability based on l0°/10° zig-zag test alone, recognizing also that this test is also more widely accepted in the present trial routines.

(5)

However, considering the merits of the spiral test, it wa-s agreed that spiral test should be recommended for the analysis of dyiiimic instability, although not included in the standards. It was also agreed thr an appropriate recommendation to this effect should be

included in the explanatory notes. ?rediction Tethnolozv

Recogni7ing that it was not currently possible ax the design stage to predict manoeuvring characteriwcs with sufficient accuracy, the primary concern was that a ship, even though predicted to be in complir with the standards by employing the best prediction method available, might fuil to do so on trials and then be disqualified. After discussion, the Sub-Committee agreed that it would be permissible to

demonstrate compnre with

the standards by predicting trial performance through model tests andior computer simulation.. Moreover, a provision bas been included that during the interim period of the standards, when acceptable methods of prediction have demonstrated compJine with the standards, the results of full scale trials would not disqualify a ship. Concerning ships which undergo repairs, alterations or modification, the Sub-Committee agreed to include

a provision to the effect that the opinion of the

Administration should be sought whether these

modification influence the status of the ship or its

rnaxioeuvrability characteristics and, if so, the continued compliance with the standards should be verified.

.&ssembl

Resolution on Interim Standards for

Ship Manoeuv-rability

The draft Assembly resolution and its annex conrining the final text of the Interim Standards for Ship Manoeuvrability, agreed as a minimum performance standard by the DE Sub-Committee and approved by the Committee in May 1993 for adoption by the eighteenth Assembly in November 1993, is given in annex 3.

ExDlanatorv Notes to the Standards

[n order to facilitate the application of the standards, guidelines called the 'Explanatory notes

for the

rnanoeuvring standards' are currently under preparation by the DE Sub-Committee's working group. These notes include comments, clarifications

and guidelines on the general principles for the

interpretation and evaluation of manoeuvring characteristics from routine manoeuvres, on the

application of

the 1MO

Standards for Ship Manoeuvrability as a minimum performance standard and its validation by ship trials, and on the various

techniques available for prediction and trial corrections. These are scheduled to be finalized ax the

next session of the DE Sub-Committee in

February 1994, with a view to their dissemination by an MSC circular after approval by the Committee in May 1994.

While the [MO Ship Manoeuvring Standards are primarily for use by ship designers, it is necessary rhr crew members understand their implications in the proper dicrhrge of their duties aboard a ship. The DE working group on ship rnanoeuvrabiliry is also dealing with hIJm2n element aspects by recommer.ding an appropriate method to be used for explaining the manoeuvring standards in the training of ship crew members.

It may be pointed out that the seafarer is interested in the rnanoeuvring characteristics of the ship in service, in real sea conditions as opposed to the theoretical formulae derived by the scientist or the parameters adopted by the designer at the designing stage or the performance predicted through model tests or computer simulation. He is concerned with the actual manoeuvring parameters which the ship is showing when in service under different sea, weather, draft speed and load conditions. As mentioned earlier, 1MO standards for ship manoeuvrabiliry incorporare typical

features of the performance quality and

handling capacity of the ship which arc of direct nautical interest

Date of Application of the Standards

Considering that the explanatory notes are needed for the proper understanding and application of the Standards, the Committee agreed that [MO Interim standards for Ship Manoeuvrability should apply to ships consttucted on or after 1 July 1994.

A list of resolutions relating to manoeuvring and steering gear adopted by the [MO Assembly and circulais issued by the Maritime Safety Committee (as of June 1993) is given in annex 4.

Conclusion

[MO's activity ou ship rnanoeuvrabiliry started in 1968 with the adoption of resolution A. 168(1V) on

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Recommeixiarion on Data coteriiing Manoeuvring

Capabilities and Stopping Distaxes of Ships.

Essential manoeuvring information in some detail, as required by resolution A.601(15), is now available on the bridge of every ship for use by master, navigating officers and pilots and contributes to

safety of

navigation under various circumstaixes in which the ship operares.

The proposed mandatory provision of emergey

towing arrangements to be implemented on rankers of 20,000 dwt and above, the provision

of

technologically advaneed equipment and its ready availability in a pre-rigged condition would ensure that the risk of marine pollution is minimized from a tanker involved in an accident and resultant impaired manoeuvrability.

1MO Standards for Ship Manoeuvrabiliry provide for a minimum performanee standard which a ship would have to achieve to ensure acceptable manoeuvring properties.

The standards have been termed

interim' for the present and Governments have been invited to collect data by applying them and report the results to the Organirtion. Based on this feed-back and further informatiouldata gathered through research in Member Stares, the interim standards would be reviewed and amended by the Organization to develop both the

fint

standards and the

expInrory notez. However, the establishment of Interim Sr2n1ìrds for Ship Manoeuvrability in 1993

must be regarded as a major step in ensuring further improvement of maritime safety.

SR[VASTAYA, SATYA D., Fellow of the

Institute of Marine Engineers, holds an

Extra First Class Engineer Certificate of

Competency (UK). He served on merchant

ships to the rank of Chief Engineer Officer,

later joining the Directorate of Marine

Engineering Training, Calcutta, as Senior

Lecturer, rising to the position of Director.

In 1980 he joined 1MO as Training Advisor,

and in 1992 became Technical Officer in the

Maritime

Safety

Division

at

1MO

Headquarters, currently also the Secretary of

the Sub-Committee on Ship Design and

Equipment.

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_______

--ANNEX i

DRAFT AMENDMENTS TO SOLAS CHAPTER V ON EMERGENCY

TOWING ARRANGEMENTS ON TANKERS

1.

Add new regulation V115-1 as follows:

"Regulation 15-1

Emergency Towing Arrangements on Tankers

An emergency towing arrangement shall be fitted at both ends on board all tankers of

20,000 dwt and above constructed on or after (1 January 1996). For tankers constructed

before (1 Jannry 1996) such an arrangement shall be fitted at the first scheduled

dry-docking after (1 January 1996), but not later than (1 January 1999). The design and

construction of the towing arrangement shall be approved by the Administration, based

ori guidelines developed by the Organization."

Refer to the Guidelines on Emergency Towing Arrangements for Tankers to be developed

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ANNEX 2

MANOEUVRABILITY AND MANOEUVRJNG STANDARDS

List of documents considered by the Sub-Committee on

Ship Design and Equipment at the last 4 sessions

Symbol

Author

Considered at the 33rd session (1990)

DE 311313

Canada

DE 31/INF.2

Finland

DE 31/INF.3

Finland

DE 33/7

Federal Republic of Germany

DE 26/6

Federal Republic of Germany

DE/316

Federal Republic of Germany

DE1317

Federal Republic of Germany

DE 23/INF.2

Italy

DE 33/4

Japan

DE 33/INF.8

Japan

DE 32/INF.5

Japan

DE 30/4

Japan

DE3O/INF.10

Japan

DE 29/INF.3

Japan

DE 29/INF.4

Japan

DE/308

Japan

DE/323

Japan

DE/329

Japan

DE 28/4/1

Japan

DE

(fl19/3

Japan

DE 3113

Netherlands

DE 270

Poland

DE 27/5/3

Poland

DE/326

USSR DE1294

USSR

DE 33/4/1

United Kingdom

DE 3214

United Kingdom

DE 31/INF.5

United Kingdom

DE159

United Kingdom

DE Kl/lO

United Kingdom

DE 33/INF.9

United States

DE 32/3/2

United States

DE 3 1/3/1

United States

DE 31/3/2

United States

DE 25/5/1

United States

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ANNEX 2

Page 2

DE/319

DEI300

DE1307 DE1314

DE 331WP.1O

DE 25/WP.6

DE XXIV/5

DE 25/5

DE MSCICirc.389

Considered at the 34th session L1991)

DE 3414

Report of the working group

DE 341411

United States

DE 34/4/2

Norway

DE 34/4/3

United States

DE 34/4/4

Sweden

DE 34/4/5

China

DE 34/WP.7

Report of the working group

DE 34/INF.2

Japan

DE 33/4

Japan

DE 31/3/1

United States

Considered at the 35th session (1992)

DE 35/4

Japan

DE 35/4/Corr.1

Japan

DE 35/411

China

DE 35/4/2

Australia

DE 35/4/3

United States

DE 35/4/4

Norway

DE 35/4/5

Sweden

DE 35/INF. 14

Japan

DE 35/WPJ

Report of the working group

Considered at the 36th session (1993)

DE 36/4

Report of the working group

DE 36/4/1

United States

DE 36/4/2

Denmark

DE 36/4/3

United States

DE 36/4/4

Japan

DE 36/415

Sweden

DE 36/WP.3

Report of the working group

United States

Report of the Ad hoc working group

Report of the working group

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ANNEX 3

DRAFT ASSEMBLY RESOLUTION A

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INTERIM STANDARDS FOR SHIP MANOEUVRABILITY

THE ASSEMBLY,

RECALLING Article 15(j) of the Convention on the

1ntrnational Maritime Orgni7ion

concerning the functions of the Assembly in relation to

regulations and guidelines concerning maritime

safety and the prevention and control of marine pollution

from ships,

RECALLING FURTHER that by MSC/Circ.389 the

Maritime Safety Committee approved the Interim guidelines for estimating manoeuvring performance in ship design, whereby Member Governments

were invited to apply the guidelines on a trial basis so that they may be assessed in the light

of the

practical experience gained with a view to theìr possible

further development,

RECALl ING ALSO resolutions A. i 60(ES .1V), A.209(WI) and A.60 1(15) concerning information on ship manoeuvring,

RECOGNIZING the rnanoeuvring capability of ships to be an important contribution to the safety of navigation,

BELIEVING that the development and implementation of standards for ship manoeuvrability,

particularly to large ships and ships carrying dangerous goods in bulk, will improve maritime safety and enhance marine environment protection,

HAVING CONSIDERED the recommendations made by

the Maritime Safety Committee at it

sixty-second session,

i.

ADOPTS the Interim Standards for Ship Manoeuvrability, the text of which is set Out in the nrex to this resolution;

RECOMMENDS Governments to encourage those responsible for the design, construction, repair

and operation of ships to apply the Standards;

INVITES Governments to collect data obtained by the application of the Standards and report

them to the Organization;

REQUESTS the Maritime Safety Committee to keep the Standards under review on the basis

of

the information and data collected;

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ANNEX

INTERIM STANDARDS FOR STIl?

MANOEUVRABrLITY

i Principles

1.1 The standards should be used with the aim of improving shipmanoeuvring performance and with

the objective of avoiding building

shipsthat do not comply with the criteria.

L2

The standards contained in this document are based on the understanding that the manoeuvrability

of ships can be evaluated from the characteristics of conventional trial manoeuvres. The following two

methods can be used to demonstrate compliance with

these standards:

.1

Scale model tests andlor computer predictions using mathematical models can be

performed to predict compliance at the design stage. In this case full-scale trials should

be conducted to validate these results. The

ship should then be considered to meet these standards regardless of full-scale trial results, except where the Administration determines that the prediction efforts were substandard and/or the ship performance is in substantial

disagreement with these standards;

.2 The compliance with the standards can be demonstrated based on

the results of the

full-scale trials conducted in accordance with the standards.

If a ship is found in substantial

disagreement with the interim Standards, then the Administration may require remedial

action.

1.3

The standards presented herein are considered interim for a period of 5 years from the date of

their adoption by the Assembly. The standards and method of establishing compliance should be reviewed

in the light of new information and the results of

experience with the present standards and ongoing

research and developments. 2. Application

2.1

The standards should be applied to ships of all rudder

and propulsion types, of 10G m iii length and over, and chemical tankers and gas carriers regardless of the length, which are constructed on or after 1 July 1994.

2.2 In case ships referred to in paragraph 2.1 undergo

repairs, alterations and modifications which

in the opinion of the Administration may influence

their manoeuvrability characteristics the continued

compliance with the standards should be verified.

2.3

Whenever other ships, originally not subject to the standards, undergo repairs, alterations and

modifications, which in the opinion of the Administration are

of such an extent thr the ship may be

considered to be a new ship, then that ship should comply with these standards. Otherwise, if the repairs,

alterations and modifications in the opinion of the

Administration may influence the manoeuvrability characteristics, it should be demonstrated that these characteristics do not lead to any deterioration ofthe rnanoeuvrabiliry of the ship.

(12)

3 Definitions

3.1 Geometry of the ship

.1

Length (L) is the length measured beeen the aft and forward perpendiculars;

.2

Midship point is the point on the cenue line of a ship midway berwn the aft an

forward perpendiculars;

.3 Draught (Ta) is the draught at the aft perpendicular; .4 Draught Ç1'f) is the draught at the forward perpendicular: .5

Mean draught ÇT) is defined as T = ÇT, + Tf)/2.

3.2

Standard manoeuvres and associated terminology

Standard manoeuvres and associated terminology are as defined below:

.1

The test speed (V) used in the standards is a speed of at least 90% of the ship's speed

corresponding to 85% of the maximum engine output.

Turning circle manoeuvre is the manoeuvre to be performed to both starboard and por

with 350 rudder angle or the maximum rudder angle permissible at the test speed

following a steady approach with zero yaw rate.

.3 Advance is the distance

aveiled in the direction of the original course by the midshL

point of a ship from the position at which the rudder order is given to the position a

which the heading has changed 90° from the original course.

.4 _{Tactical diameter is the distance ravelled by the midship point of a ship from the positio} at which the rudder order is given to the position at which the heading has changed 180

from the original course. It is measured in a direction perpendicular to the origi

heading of the ship.

.5

Zig-zag test is the manoeuvre where a known amount of helm is applied alternately t

either side when a known heading deviation from the original heading is reached. .6 100/100 zig-zag test is performed by turning the rudder alternately by 10° to either sid

following a heading deviation of 10° from the original heading in accordance with di

following procedure:

.1

after a steady approach with zero yaw rate, the rudder is put ver to 10°

starboard/port (first execute);

when the heading has changed to 100 off the original heading, the rudder

reversed to 10° to pertlstarboard (second execute);

.3 after the rudder has been turned to port/starboard, the ship will continue n.irnin in the original direction with decreasing turning rate. In response to the rudder

(13)

the ship should then turn to port/starboard. When the ship has reached a heading

of 10° to port/starboard of the original course, the rudder is again reversed to

10° to starboard/port (third execute).

.7

The first overshoot angle is the additional heading deviation experienced in the zig-zag

test following the second execute.

.8 The second overshoot angle is the additional headIng deviation experienced in the zig-zag

test following the third execute.

.9 20°120° zig-zag test is performed using the procedure given in .6 above using 20° rudder

angles and 20° change of heading, instead of 10° rudder angles and 10° change of

heading, respectively.

.10

Full astern stopping test determines the track reach of a ship from the time an order for

full astern is given until the ship stops in the water.

.11

Track reach is the distance along the path described by the midship point of a ship

measured from the position at which an order for full astern is given to the position at

which the ship stops in the water.

4 Standards

4.1 The standard manoeuvres should be performed without the use of any manoeuvring aids, which are not continuously and readily available in normal operation.

4.2

Conditions at which the standards apply

In order to evaluate the performance of a ship, manoeuvring

ials should be conducted to both

port and starboard and at conditions specified below:

.1

deep, unrestricted water;

.2 calm environment;

.3

full load, even keel condition;

.4

steady approach at the test speed.

4.3

Criteria

The manoeuvrability of the ship is considered satisfactory, if the following criteria are complied with:

.1

Turning ability

The advance should not exceed 4.5 ship lengths (L) and the tactical diameter should not exceed 5 ship lengths in the turning circle manoeuvre;

Initial turning ability

(14)

With the application of 10° rudder angle to portlstarboard,

the ship should not have

travelled mote than 2.5 ship lengths by the time the heading has changed by 100 from the original heading;

.3 Yaw checking and course keeping abilities

.1

The value of the first overshoot angle in the 100/100 zig-zag test should not

exceed:

10°, if LP'! is less than 10 seconds;

20°, if UY Ls 30 seconds or more; and

(5 ± 1/2 (UY) degrees, ifL/V is 10 seconds or more but less than 30

seconds.

where L and V are expressed in m and mis, respectively;

2

The value of the second overshoot angle in the io°iio zig-zag test should not

exceed the above criterion values for the first overshoot by more than 15°;

.3

The value of the first overshoot angle in the 20°/20° zig-zag test should not

exceed 25° .4 Stopping ability

The track reach in the full astern stopping test should not exceed 15

ship lengths. However, this

value may be modified by the Administration where ships of large displacement make this

criterion impracticable.

5 Additional considerations

5.1

In case the standard trials are conducted at a condition different from those specified in 4.2.3

necessary corrections should be made in accordance with the guidelines contained in the explanatory notes

on the standards for ship manoeuvrabiity developed by the

Orgni7rion.

5.2

Where standard manoeuvres indicate dynamic instability, alternative test may

be conducted to define the degree of instability. Guidelines for alternative tests such as a spiral test or pull-out manoeuvre