The Manoeuvrability of Very Large and Ultra Large

Container Ship

IMPA 2014 Conference

Technical Presentation

April 2014, Panama

Captain S. M. GoagKOREA MARITIME PILOT’S ASSOCIATION

The enlargement of container ship

1970's : 2,100 TEU

1980's : 4,400 TEU

1990's : 6,400 TEU

2000's : 14,800 TEU

2013 : 18,200 TEU

1

Turning ability Course stability

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Ship manoeuvrability

History

- 4 Nov. 1993 Interim Standards for ship menoeuvrability - IMO Resolu-tion A.751(18)

- 4 Dec. 2002 The Standards for ship manoeuvrability - Resolution MSC.137(76)

- The Standards applied to ships con-structed on or after 1 January 2004

IMO standards for ship manoeuvra-bility

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Condition

.1 deep, unrestricted water; .2 calm environment; .3 full load(summer load line draught), even keel condition; and .4 steady approach at the test speed.

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Contents of Standards

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.

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Criteria

With the application of 10° rudder angleto port/starboard, the ship should nothave travelled more than 2.5 ship

lengthsby the time the heading has changed by10° from the original heading.

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Initial turning ability

.1 the first overshoot angle in the 10°/10°

zig-zag test should not exceed: .1 10° if L/V is less than 10 s; .2 20° if L/V is 30 s or more; and .3 (5 + 1/2(L/V)) degrees if L/V is 10

s or more, but less than 30 s where L : m, V : m/sec

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Yaw-checking and course-keeping abilities

.2 the second overshoot angle in the 10°/10° zig-zag test should not exceed:

.1 25°, if L/V is less than 10 s; .2 40°, if L/V is 30 s or more; and .3 (17.5 + 0.75(L/V))°, if L/V is 10 s or more, but less than 30 s.

.3 The first overshoot angle in the 20°/20° zig-zag test should not exceed 25°.

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Yaw-checking and course-keeping abilities

The track reach in the full astern stoppingtest should not exceed 15 ship lengths.However, this value may be modified bythe Administration where ships of largedisplacement make this criterionpracticable, but should in no case exceed20 ship lengths.

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Stopping ability

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Size categories of container ship

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Particulars of Container ship

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Turning circles of container ships

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Turning circles of container ships

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Comparison of turning circles VLCS and VLCC

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Comparison of turning circles VLCS and VLCC

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Initial turning ability

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Initial turning ability

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Yaw checking and course keeping ability(overshoot angle)

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Yaw checking and course keeping ability(overshoot angle)

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Pullout test

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Pullout test

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Stopping ability

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Stopping ability

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Stopping ability

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Stopping ability

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Stopping inertia

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Stopping inertia

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Stopping inertia

- Hull shapeThe block co-efficient of container shipsranges from 0.64 to 0.71.Though container ships are getting bigger,hull shape is little changed.Even the ULCV is much slimmer than VLCCin terms of length/breadth ratio.

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Conclusion

- Turning abilityThe turning ability of container ships,

largeor small, of which the length is largercompared with their breadth is not bet-

terthan that of VLCC.The advances of container ships rangefrom 3.1 to 3.4 times of their length

while VLCCs‘range from 2.5 to 2.8.

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Conclusion

Especially the turning circle of ballasted ULCV is almost 2 times as large as that of loadedVLCC.In case of VLCC, there is not so much difference in turning circle between ballastand loaded condition but in case of ULCV,the turning circle of trimmed ballast conditionis much larger than that of fully loadedcondition(abt. 1.37 times in tactical diameter).

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Conclusion

- Initial turning abilityIt is amazing that there is not so muchdifference in initial turning ability betweenBallasted container ships and fully loadedVLCCs. They range from 1.5 to 1.7 times ofTheir length.It can be thought that the speed differencebetween container ship and VLCC,

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Conclusion

poor turning ability of container shipand poor following response for rudder ofVLCC caused these results.But the elapsed time the heading haschanged by 10° from the original head-

ingof VLCC is much longer than that ofcontainer ship which means the followingability for the rudder of VLCC is poor.

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Conclusion

- Course stabilityIn terms of course stability, VLCC can notbe compared with container ship.The 1st & 2nd overshoot angles of containerships do not exceed 5° at 10°/10°zig-zag test and at even 20°/20° zig-zag test the 1st overshoot angles donotexceed 10°.

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Conclusion

318K VLCCs' are almost the criteria of IMO standards.At the pullout test, the residual rate of turnof container ship is near zero for both port and stb'd turns, which mean the ship isstable but VLCC's is 5°, which means she is unstable.

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Conclusion

- Stopping ability and inertiaAs the data for Full loaded condition ofcontainer ship is unavailable and theengine power is not same, directcomparison is meaningless.In any case, the track reach donot ex-

ceedIMO Standards, that is 15 times of

ship'slength. 36

Conclusion

It is heard that the track reach at crashstop astern test during sea trial of newships very rarely exceed 15 ship's

length.The result of crash astern and stoppinginertia can be used for guidance.

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Conclusion

- Though the data is unsufficient formaking a conclusion, it can be care-

fullythought that the manoeuvrabingcharacteristics remains unchanged

though ships are getting bigger unless the hullshpae is not changed.

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Conclusion

- THANK YOU -

KOREA MARITIME PILOT’S ASSOCIATION