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ORAL QUESTIONS

4 Bad weather

1 Bad weather maneuvers View ans

----------------------------------------------------------------------------------------------------

Ans

BAD WEATHER MANEUVERS

Following options are available to the master in case of badweather

Head to sea

Stern to sea

Heave to

Anchoring

Altering course

Head to sea or wind and sea on fine bow at reduced

speedMost suitable for deep draft vessels

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Leeward drift is minimized (vessel is liable to sustain considerable pounding) Weather is allowed to pass over the vessel The speed is considerably reduced It affects the period of encounter of the oncoming wave formation and

subsequently reduces pounding

Course and speed to be altered to remove possibility of hogging sagging andsynchronism Situation becomes uncomfortable when violent pitching results in lsquoracing

propellersrsquo puts excessive stress on engines Absolute control of rudder power is essential

Power should be reduced to minimum necessary to maintain steerage way and

avoid undue stress on machinery Two steering motors to be operational Critical rpm to be avoided

top

Stern to sea at reduced speed running before the wind

When bad weather overtakes vessel she will find herself running before the

wind Preferable to take a course with wind on the quarter rather than stern which may

cause lsquopoopingrsquo Vessel will not move as violently as a vessel head to sea Speed adjustment together with long period of encounter will probably reduce

wave impact without any great delay A distinct danger with stern to sea is when the vessel required to turn across the

wave front is lsquobroach torsquo top

Heaving to preferably on the lee of an island

Necessary when due to the stress of the weather the voyage is required to be

temporarily discontinued

The vessel is maneuvered so as to ride the sea in the most favorable position Problems may be encountered associated with crew fatigue or damage to cargo

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for a lengthy period of time Most effective when taken advantage of a lee of an island or land mass Action will depend on the type and form of the vessel A reduction of speed will probably be the earliest action to reduce motion of the

vessel and avoid cargo shift

Power not to be reduced to an extent of stalling the main engine or revolutionsare critical If it is decided to stop the vessel sufficient sea room should be available Heavy rolling can be expected There is risk of synchronism and cargo shift Vessel needs to have a good water tight integrity and adequate GM

top

Anchoring in shallow waters

Used when the vessel in shallow water Employed to prevent blown down to a lee shore Two anchors may be used Engines can be used to reduce stress on the cable Anchor will reduce the rate of drift If grounding is not prevented refloating may be assisted by heaving on the

cables top

Altering course to avoid bad weather To be used before encountering bad weather

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Take an alternative route to destination Take evasive actions to be away from bad weather Likely to result in more distance If alteration is not well planned or substantial bad weather may suddenly change

direction and vessel may be caught into it

top

Updated

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2 Precautions at anchor and at sea View ans

----------------------------------------------------------------------------------------------------

Ans

Contingency planning in heavy

weather Follow contingency checklist in heavy weather Verify vessels position Obtain up-to-date weather forecasts and expected weatherprediction for surrounding areas Warn all departments of impending weather Rig lifelines fore and aft

Check anchors and securing lifeboats and lashing water tightdoors general cargo stowage and securing especially lashing of

deck cargoes Close up ventilators removing cowls (gooseneck) whereappropriate Check stability reduce free surface effects Note preparations in log book Contact shore station passing position and obtain constantplotting of storm track Secure derricks cranes hatch covers Clear surplus gear from deck Close down deadlights (porthole covers)

Slacken off signal halyards and other relevant cordage Drain swimming pools

7242019 4 Bad Weather

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Reduce manpower on deck by operating heavy weather workroutine Take down awnings Secure bridge for excessive rolling and pitching Warn engine room in plenty of time to reduce revolutions

Check distress rockets and LSA gear Organize meal reliefs before bad weather arrives

View special answer from COs point of view

Heavy weather precaution

From chief officers point of view

Follow the heavy weather contingency checklist

Divide crews in three groups Deck securing party Headed by bosun Cargo lashing anchor securing party Headed by senior cadet LSA FFA and accommodation securing Headed by third officer Deck securing party will secure deck including

Rigging of life line (25-30mm fiber rope)

Complete weather tightness of hatches by cross wedges sidecleats extra covers if required Closing of all ventilators air pipes sounding pipes Secure derricks cranes Cover cargo winches mooring winches etc with tarpaulins Clear scuppers and freeing ports Secure all loose gears on deck Secure all booby hatch covers Take sounding of all tanks Cargo lashing anchor securing party will secure check

Any loose lashing to be tightened Anchor is properly lashed and secured Sparling pipes and hawse pipes to be covered Rope lockers are secured LSA FFA and accommodation securing party will ensure

Life boat and life raft lashings are adequate Pyrotechnics and LSA equipments are ready Dead lights port holes accommodation doors cabin stores areclosed Bridge is secured I myself will

Check stability Reduce free surface effects

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Plan a heavy weather duty routine Tell chief cook to secure galley crockeries and prepare for heavyweather Report master about all the preparation Note preparations in log book

Updated

----------------------------------------------------------------------------------------------------

3 Use of oil View ans

----------------------------------------------------------------------------------------------------

Ans

Use of oil in bad weather

Storm oil may be used to reduce heavy seas

It prevents seas from breaking

Reduces hazards of bad weather

May be used to in heavy seas to

Turn the vessel Lowering life boats Rescue persons Hove to Towing operation Crossing a bar Vegetable animal or fish oil may be used

If not available lubricating oil may be used

Fuel oil and crude oil not recommended as they may congeal ormay cause harm to men in water

A small amount of oil can quench a comparatively large sea area

About 200 Liters of oil can quell 4500 m2 sea area

To be distributed from both bows when heading into wind and

7242019 4 Bad Weather

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seas

To be distributed from weather side when lying stopped orrunning with seas on the quarter

Should be used gradually

It may be done by

Trailing a punctured hose full of oilThrough a punctured canvas bag which have been weighted andfilled with oil soaked cotton Flushing through water closets

Updated

----------------------------------------------------------------------------------------------------

4 MSC-707

----------------------------------------------------------------------------------------------------

5 TRS

a Actions in TRS View ans

----------------------------------------------------------------------------------------------------

Ans

Actions in a TRS

Upon receiving the weather report I will Inform CO order him to secure deck Inform CE order him to secure ER

Plot stormrsquos position and observe its movement

Draw fan diagram to Determine safety sector

Possible course to avoid storm

Ascertain shiprsquos position in relation to the storm Bearing of stormrsquos center

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From weather report Buys Ballotrsquos law

Semi circle where the vessel is in Path of the storm

Order OOW to Update and monitor weather information and reports Record hourly in log book

Wind direction and force Wind shift Barometric pressure Swell direction and height

Arrange a FSA for storm

Strengthen the bridge watch and ensure proper look out

Change over to manual steering if auto pilot cannot cope up with weather condition

Continuous watch as visibility can be reduced

Instruct CO to Check shiprsquos stability draft trim Press up tanks to reduce FSE and windage area Propeller and rudder sufficiently immersed to prevent

Loses of their efficiency Racing of engines Excessive vibration

Take heavy weather precaution

I will remain outside of a radius of 200nm from storm center If necessary Alter course to keep away from storm Heave to to let the storm pass by a safe distance Reduce speed if helps to avoid storm

Ensure vessel does not roll or pitch heavily as it may cause May be damage to cargo

Shifting of cargo Damage to shiprsquos structure Damage to deck equipments cranes derricks etc

All preparations for heavy weather to be entered in official log book in details and

deck log book

I will keep in mind Storm can be erratic and different from weather forecast Engine and any navigational communication equipment may fail any time

Ensure personnel get enough rest considering fatigue due to storm

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 971

No body to go on deck without COrsquos permission

Instruct CE to check steering gear and ME performance regularly

Inform following parties about storm and amended ETA

Owner Charterer Agent of next port

Updated

----------------------------------------------------------------------------------------------------

b Masterrsquos obligations in TRS View ans

----------------------------------------------------------------------------------------------------

Ans

Masters obligations in a TRS

Masters of all ships which encounter a TRS for which no warning was

broadcasted are obliged to

Report to the nearest coast radio station

All nearby shipping

By all available means at his disposal

He should also place his ship in a safe position by

Avoiding passing within 75nm of storm

Preferably outside 200nm of center

The format of the message is not obligatory It may be in plain English language or

ICS

It shall be preceded by ldquosecuriteacuterdquo or ldquoTTTrdquo

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Statement that a TRS is encountered

Barometric pressure with unit whether corrected or not

Barometric tendency for last 3 hrs

True wind direction

Wind force

Sea state Swell

Own shiprsquos course and speed

Message to be transmitted every 3 Hrs

Updated

----------------------------------------------------------------------------------------------------

Questions

41 What is synchronized rolling What to do when you experience

this View ans

----------------------------------------------------------------------------------------------------

Ans

Synchronized rolling

Synchronized rolling to be determined immediately Occurs when the period of roll is equal or nearly equal to theapparent period of encountered wave A very dangerous and undesirable condition Successive waves tend to increase the angle of roll of the vesselthereby produce danger of capsize More dangerous in small vessels or vessels with low stability Most dangerous when a beam sea is experienced and the shipreaches a greater maximum inclination at each trough and crestof wave Danger of cargo shift Danger of damage to vessel

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To determine synchronized rolling

Vessel rolling heavily There is no period of lull rolling angle is almost same or

increasing in every roll Vessel is encountered by the same phase of wave almost all thetimes

Corrective actions

Change apparent period of waves by

Alteration of course

Alteration of speed

Change vessels rolling period by changing GM

By ballasting

By deballasting

Shifting of ballast FO FW etc and changing transverse position of G

Updated

----------------------------------------------------------------------------------------------------

42 How would you determine that the ship experiencing synchronizedrolling View ans

----------------------------------------------------------------------------------------------------

Ans

Synchronized rolling

Synchronized rolling to be determined immediately Occurs when the period of roll is equal or nearly equal to theapparent period of encountered wave A very dangerous and undesirable condition Successive waves tend to increase the angle of roll of the vesselthereby produce danger of capsize More dangerous in small vessels or vessels with low stability

Most dangerous when a beam sea is experienced and the shipreaches a greater maximum inclination at each trough and crest

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 1271

of wave Danger of cargo shift Danger of damage to vessel

To determine synchronized rolling

Vessel rolling heavily There is no period of lull rolling angle is almost same orincreasing in every roll Vessel is encountered by the same phase of wave almost all thetimes

Corrective actions

Change apparent period of waves by

Alteration of course

Alteration of speed

Change vessels rolling period by changing GM

By ballasting

By deballasting

Shifting of ballast FO FW etc and changing transverse position of G

Updated

----------------------------------------------------------------------------------------------------

43 What are the following seas and quartering seas What you woulddo if you encounter them View ans

----------------------------------------------------------------------------------------------------

Ans

Definitions

Apparent period

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The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer It is sometimes called period of encounter

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thickerplating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

Backing

Change of true wind direction to an anti-clockwise direction

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httpslidepdfcomreaderfull4-bad-weather 1471

Veering

Change of true wind to a clockwise direction

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

Surf riding

Broach to

Synchronous rolling

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 1571

Pooping

Breaking of rising wave over the stern in poop deck area Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed

Alter course and head sea

back

Surf riding

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 1671

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities Vessel may be accelerated Vessel rides on advancing wave slope

This phenomenon is called surf riding

Result

Vessel slewed violently (broach-to) Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

Broach to

May occur when a ship is surf ridden in a following or quarteringsea The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 1771

Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicLin the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling periodof a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

View more

back

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httpslidepdfcomreaderfull4-bad-weather 1871

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of thenatural rolling period of the ship

Occurs particularly if initial metacentric height height is small andnatural roll period is very long Unstable and large amplitude roll motion takes place May occur in head and bow seas

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

back

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httpslidepdfcomreaderfull4-bad-weather 1971

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2071

Successive wave attack

Occurs when ships speed component in the wave direction isnearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wavecomponent

The ship is attacked successively by high waves Expectable maximum wave height can reach almost twice ofobserved wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling Parametric rolling Combination of various dangerous phenomena Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

----------------------------------------------------------------------------------------------------

44 What is synchronized pitching How would you determine What

actions will you take View ans

----------------------------------------------------------------------------------------------------

Ans

Synchronized pitching

Occurs when the pitching period is equal to or nearly equal to the

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2171

apparent period of encountered wave Causes excessive racing of of the engines Propeller emerges from the water or approaches the surface Cause longitudinal straining of the hull May cause heavy damage due to shipping seas

Cargo shift or damage to cargo may occur Damage to engines due to racing

To determine synchronized pitching

Vessel pitching heavily There is no period of lull pitching angle is almost same orincreasing in every pitch Vessel is encountered by the same phase of wave almost all thetimes

Action

Same as in synchronized rolling Alteration of speed preferably reduction may be the best action

Updated

----------------------------------------------------------------------------------------------------

45 Heavy weather to be encountered What actions will youtake View ans

----------------------------------------------------------------------------------------------------

Ans

Contingency planning in heavyweather

Follow contingency checklist in heavy weather Verify vessels position

Obtain up-to-date weather forecasts and expected weatherprediction for surrounding areas

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2271

Warn all departments of impending weather Rig lifelines fore and aft

Check anchors and securing lifeboats and lashing water tightdoors general cargo stowage and securing especially lashing ofdeck cargoes

Close up ventilators removing cowls (gooseneck) whereappropriate Check stability reduce free surface effects Note preparations in log book Contact shore station passing position and obtain constantplotting of storm track Secure derricks cranes hatch covers Clear surplus gear from deck Close down deadlights (porthole covers) Slacken off signal halyards and other relevant cordage

Drain swimming pools Reduce manpower on deck by operating heavy weather workroutine Take down awnings Secure bridge for excessive rolling and pitching Warn engine room in plenty of time to reduce revolutions Check distress rockets and LSA gear Organize meal reliefs before bad weather arrives

View special answer from COs point of view

Heavy weather precaution

From chief officers point of view

Follow the heavy weather contingency checklist

Divide crews in three groups Deck securing party Headed by bosun Cargo lashing anchor securing party Headed by senior cadet LSA FFA and accommodation securing Headed by third officer Deck securing party will secure deck including

Rigging of life line (25-30mm fiber rope) Complete weather tightness of hatches by cross wedges sidecleats extra covers if required Closing of all ventilators air pipes sounding pipes Secure derricks cranes Cover cargo winches mooring winches etc with tarpaulins

Clear scuppers and freeing ports Secure all loose gears on deck

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2371

Secure all booby hatch covers Take sounding of all tanks Cargo lashing anchor securing party will secure check

Any loose lashing to be tightened Anchor is properly lashed and secured

Sparling pipes and hawse pipes to be covered Rope lockers are secured LSA FFA and accommodation securing party will ensure

Life boat and life raft lashings are adequate Pyrotechnics and LSA equipments are ready Dead lights port holes accommodation doors cabin stores areclosed Bridge is secured I myself will

Check stability

Reduce free surface effects Plan a heavy weather duty routine Tell chief cook to secure galley crockeries and prepare for heavyweather Report master about all the preparation Note preparations in log book

Updated

----------------------------------------------------------------------------------------------------

46 Your ETA delayed by 10h what actions will you take Under whichrule

----------------------------------------------------------------------------------------------------

47 You have received a TRS forecast What are your

actions View ans

----------------------------------------------------------------------------------------------------

Ans

Actions in a TRS

Upon receiving the weather report I will Inform CO order him to secure deck

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2471

Inform CE order him to secure ER

Plot stormrsquos position and observe its movement

Draw fan diagram to

Determine safety sectorPossible course to avoid storm

Ascertain shiprsquos position in relation to the storm Bearing of stormrsquos center

From weather report Buys Ballotrsquos law

Semi circle where the vessel is in Path of the storm

Order OOW to

Update and monitor weather information and reports Record hourly in log book

Wind direction and force Wind shift Barometric pressure Swell direction and height

Arrange a FSA for storm

Strengthen the bridge watch and ensure proper look out

Change over to manual steering if auto pilot cannot cope up with weather condition

Continuous watch as visibility can be reduced

Instruct CO to Check shiprsquos stability draft trim Press up tanks to reduce FSE and windage area Propeller and rudder sufficiently immersed to prevent

Loses of their efficiency Racing of engines

Excessive vibration Take heavy weather precaution

I will remain outside of a radius of 200nm from storm center If necessary Alter course to keep away from storm Heave to to let the storm pass by a safe distance Reduce speed if helps to avoid storm

Ensure vessel does not roll or pitch heavily as it may cause May be damage to cargo Shifting of cargo

Damage to shiprsquos structure Damage to deck equipments cranes derricks etc

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2571

All preparations for heavy weather to be entered in official log book in details and

deck log book

I will keep in mind

Storm can be erratic and different from weather forecast Engine and any navigational communication equipment may fail any time

Ensure personnel get enough rest considering fatigue due to storm

No body to go on deck without COrsquos permission

Instruct CE to check steering gear and ME performance regularly

Inform following parties about storm and amended ETA Owner

Charterer Agent of next port

Updated

----------------------------------------------------------------------------------------------------

48 How will you get position of TRS if your weather fax machinebreaks down View ans

----------------------------------------------------------------------------------------------------

Methods of receiving TRSforecast

Various methods are available for receiving TRS or gale warningforecast

VHF weather forecast from coast radio station

MF-HF radio telephony weather broadcast from met stations

MF-HF telex from met stations

MF-HF weather fax from met stations

EGC messages

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httpslidepdfcomreaderfull4-bad-weather 2671

Navtex

Inm-B fax from met stations (paid service)

Visual observation by barometric pressure and wind force

Pressurebelowmean

Wind force(Beaufort

scale)

Bearing ofcenter from

wind direction

Approximatedistance

5mb gt 6 12 Points Within 200nm

10mb gt 8 10 Points Within 125nm

20mb About 12 8 Points Within 75nm

Updated

----------------------------------------------------------------------------------------------------

49 Despite the evasive actions ship entered TRS What is your

actions View ans

----------------------------------------------------------------------------------------------------

Ans

Ship entered in TRS

Inform CO order him to secure deck

Inform CE order him to secure ER

Plot stormrsquos position and observe its movement

From weather report

Buys Ballots law

Pressurebelow

mean

Wind force(Beaufort

scale)

Bearing ofcenter from

wind direction

Approximatedistance

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2771

5mb gt 6 12 Points Within 200nm

10mb gt 8 10 Points Within 125nm

20mb About 12 8 Points Within 75nm

Determine sector in which the ship is in

From the weather report

From the observed storm position and movement

Heave to for a few hours and observe the change of wind direction

In dangerous semicircle in northern hemisphere the wind will veer baro

will fall Barometer will rise after passing the trough line

In navigable semicircle in northern hemisphere wind will back barometfall Barometer will rise after passing the trough line

Wind direction will remain steady if the vessel is in the path of storm

Use appropriate bad weather maneuver as per the ships position relative to storm

In dangerous semicircle keep the wind on starboard bow about four points Keep

on altering to starboard as the wind veers

In navigable semicircle or in the path keep the wind on starboard quarter keep on

altering as the wind backs

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2871

Order OOW to

Update and monitor weather information and reports

Record hourly in log book

Wind direction and force

Wind shift Barometric pressure

Swell direction and height

Arrange a FSA for storm

Strengthen the bridge watch and ensure proper look out

Change over to manual steering if auto pilot cannot cope up with weather condition

Continuous watch as visibility can be reduced

Instruct CO to

Check shiprsquos stability draft trim

Press up tanks to reduce FSE and windage area

Propeller and rudder sufficiently immersed to prevent

Loses of their efficiency

Racing of engines

Excessive vibration

I will remain outside of a radius of 200nm from storm center If necessary

Ensure vessel does not roll or pitch heavily as it may cause

May be damage to cargo

Shifting of cargo

Damage to shiprsquos structure

Damage to deck equipments cranes derricks etc

All preparations for heavy weather to be entered in official log book in details and

deck log book

I will keep in mind

Storm can be erratic and different from weather forecast

Engine and any navigational communication equipment may fail any time

Ensure personnel get enough rest considering fatigue due to storm

No body to go on deck without COrsquos permission

Instruct CE to check steering gear and ME performance regularly

Inform following parties about storm and amended ETA

Owner

Charterer

Agent of next port

Updated

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2871

Order OOW to

Update and monitor weather information and reports

Record hourly in log book

Wind direction and force

Wind shift Barometric pressure

Swell direction and height

Arrange a FSA for storm

Strengthen the bridge watch and ensure proper look out

Change over to manual steering if auto pilot cannot cope up with weather condition

Continuous watch as visibility can be reduced

Instruct CO to

Check shiprsquos stability draft trim

Press up tanks to reduce FSE and windage area

Propeller and rudder sufficiently immersed to prevent

Loses of their efficiency

Racing of engines

Excessive vibration

I will remain outside of a radius of 200nm from storm center If necessary

Ensure vessel does not roll or pitch heavily as it may cause

May be damage to cargo

Shifting of cargo

Damage to shiprsquos structure

Damage to deck equipments cranes derricks etc

All preparations for heavy weather to be entered in official log book in details and

deck log book

I will keep in mind

Storm can be erratic and different from weather forecast

Engine and any navigational communication equipment may fail any time

Ensure personnel get enough rest considering fatigue due to storm

No body to go on deck without COrsquos permission

Instruct CE to check steering gear and ME performance regularly

Inform following parties about storm and amended ETA

Owner

Charterer

Agent of next port

Updated

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 2971

----------------------------------------------------------------------------------------------------

410 What is surf riding View ans

----------------------------------------------------------------------------------------------------

Ans

Definitions

Apparent period

The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer

It is sometimes called period of encounter

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thicker

plating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3071

Backing

Change of true wind direction to an anti-clockwise direction

Veering

Change of true wind to a clockwise direction

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea

Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3171

Surf riding

Broach to

Synchronous rolling

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

Pooping

Breaking of rising wave over the stern in poop deck area Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it

It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed Alter course and head sea

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3271

Surf riding

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities

Vessel may be accelerated Vessel rides on advancing wave slope

This phenomenon is called surf riding

Result

Vessel slewed violently (broach-to) Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots

Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3371

Broach to

May occur when a ship is surf ridden in a following or quarteringsea The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicLin the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling period

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3471

of a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

View more

back

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of thenatural rolling period of the ship

Occurs particularly if initial metacentric height height is small andnatural roll period is very long Unstable and large amplitude roll motion takes place May occur in head and bow seas

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3571

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

back

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3671

Successive wave attack

Occurs when ships speed component in the wave direction isnearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wavecomponent

The ship is attacked successively by high waves

Expectable maximum wave height can reach almost twice ofobserved wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling Parametric rolling Combination of various dangerous phenomena

Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3771

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411 What is broaching to View ans

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Ans

Definitions

Apparent period

The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer

It is sometimes called period of encounter

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thicker

plating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3871

Backing

Change of true wind direction to an anti-clockwise direction

Veering

Change of true wind to a clockwise direction

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea

Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 3971

Surf riding

Broach to

Synchronous rolling

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

Pooping

Breaking of rising wave over the stern in poop deck area Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it

It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed Alter course and head sea

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4071

Surf riding

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities

Vessel may be accelerated Vessel rides on advancing wave slope This phenomenon is called surf riding

Result

Vessel slewed violently (broach-to) Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots

Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4171

Broach to

May occur when a ship is surf ridden in a following or quarteringsea The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicLin the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling period

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4271

of a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

View more

back

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of thenatural rolling period of the ship

Occurs particularly if initial metacentric height height is small andnatural roll period is very long Unstable and large amplitude roll motion takes place May occur in head and bow seas

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4371

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

back

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4471

Successive wave attack

Occurs when ships speed component in the wave direction isnearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wavecomponent

The ship is attacked successively by high waves

Expectable maximum wave height can reach almost twice ofobserved wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling Parametric rolling Combination of various dangerous phenomena

Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4571

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412 Suddenly wind force 10 or above actions View ans

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Ans

Suddenly wind force 10 orabove

Take heavy weather precautions

Heavy weather maneuver to ensure safety of the vessel

Transmit a danger message with the suitable equipments to theships in the vicinity and to the nearest coast station The messageshall include following information

Barometric pressure Barometric tendency True wind direction Wind force in beaufort scale State of the sea True course and speed of the ship

The message may be transmitted by telex VHF or by any meansand may be preceded by securiteacute or TTT

Updated

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413 What is parametric rolling View ans

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Ans

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4671

Definitions

Apparent period

The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer It is sometimes called period of encounter

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thickerplating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4771

Backing

Change of true wind direction to an anti-clockwise direction

Veering

Change of true wind to a clockwise direction

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern

The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea

Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

Surf riding

Broach to

Synchronous rolling

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4871

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

Pooping

Breaking of rising wave over the stern in poop deck area

Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area

Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed Alter course and head sea

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 4971

Surf riding

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities Vessel may be accelerated Vessel rides on advancing wave slope

This phenomenon is called surf riding

Result

Vessel slewed violently (broach-to)

Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

Broach to

May occur when a ship is surf ridden in a following or quartering

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5071

sea The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicLin the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling periodof a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5171

View more

back

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of the

natural rolling period of the ship Occurs particularly if initial metacentric height height is small andnatural roll period is very long Unstable and large amplitude roll motion takes place May occur in head and bow seas

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5271

back

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5371

Successive wave attack

Occurs when ships speed component in the wave direction isnearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wave

component The ship is attacked successively by high waves Expectable maximum wave height can reach almost twice ofobserved wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling

Parametric rolling Combination of various dangerous phenomena Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

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414 Buys ballots law what is it Describe View ans

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Ans

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5471

Buys Ballots Law

In north latitudes face the wind and the barometer will be lowestto your right

In south latitudes face the wind and the barometer will be lowestto your left

Explanation

Wind flows almost parallel to isobars cutting them at small angle Wind always blows from high pressure to low pressure This phenomenon is simplified in Buys Ballots Law Using this principle the position of a law may be determined

Updated

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415 What do you know about gale warning signals View ans

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Ans

Gale warning signals

The meteorological office sends warning to signal stations When these warnings are received by the stations it is displayedby a black canvas cone The cone is of one meter height and one meter width appears asa triangle A north cone (hoisted upward) is displayed when gale expectedfrom Nly direction North cone may be displayed to an Ely or Wly gale when it isexpected to change to a Nly direction A South cone is displayed when gale expected from south South cone may be displayed when Ely or Wly gale expected to

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5571

change to a Sly direction

Updated

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416 What is backing View ans

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Ans

Definitions

Apparent period

The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer It is sometimes called period of encounter

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5671

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thicker

plating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

Backing

Change of true wind direction to an anti-clockwise direction

Veering

Change of true wind to a clockwise direction

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5771

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea

Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

Surf riding

Broach to

Synchronous rolling

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

Pooping

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5871

Breaking of rising wave over the stern in poop deck area Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it

It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed Alter course and head sea

back

Surf riding

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities Vessel may be accelerated Vessel rides on advancing wave slope

This phenomenon is called surf riding

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 5971

Result

Vessel slewed violently (broach-to) Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

Broach to

May occur when a ship is surf ridden in a following or quarteringsea

The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots

A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicL

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6071

in the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling periodof a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

View more

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6171

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of thenatural rolling period of the ship

Occurs particularly if initial metacentric height height is small andnatural roll period is very long

Unstable and large amplitude roll motion takes place May occur in head and bow seas

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6271

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

Successive wave attack

Occurs when ships speed component in the wave direction is

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6371

nearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wavecomponent

The ship is attacked successively by high waves Expectable maximum wave height can reach almost twice of

observed wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling Parametric rolling Combination of various dangerous phenomena Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

----------------------------------------------------------------------------------------------------

417 What is veering View ans

----------------------------------------------------------------------------------------------------

Ans

Definitions

Apparent period

The apparent period of wave is the time interval between thepassage of two successive crests relative to a shipborne observer It is sometimes called period of encounter

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6471

Synchronism

Occurs when rolling or pitching period is equal or nearly equal tothe apparent period of wave Synchronism may be synchronized rolling or synchronizedpitching

Panting

Tendency of the bow plating and to a lesser extent the sternplating to work in and out when the ship is pitching Fore and aft regions of the vessel are extra strengthen by thicker

plating panting beams and stringers reduced frame spacing indesigned to withstand panting stress

Backing

Change of true wind direction to an anti-clockwise direction

Veering

Change of true wind to a clockwise direction

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6571

Following and quartering seas

Following seas

Occurs when vessel running before the sea

Sea comes from the stern The ship encounters various dangerous phenomena

Quartering seas

Occurs when vessel running before the sea

Sea comes from the quarter The ship encounters various dangerous phenomena

In a following or quartering sea following dangerous phenomenonmay occur

Pooping

Surf riding

Broach to

Synchronous rolling

Parametric rolling

Combination of various dangerous phenomenon

Successive wave attack

Pooping

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6671

Breaking of rising wave over the stern in poop deck area Develops when bad weather is directly from stern Vessels with less freeboard may suffer from popping Occurs when a vessel falls into the trough of a wave and does notrise with it

It may occur if the vessel falls as the wave is rising Causes following wave to break over the stern or poop deckareas

Result

May cause considerable damage to stern area Damage to propeller and rudder due to severe buffeting Engine room can be flooded if the openings which face aft are notproperly secured

Corrective actions

Occurs when velocity of sea is equal to or greater than shipsspeed Alter course and head sea

back

Surf riding

Occurs when a ship situated on a stiff forefront of high wave in afollowing or quartering sea Vessel and waves have equal velocities Vessel may be accelerated Vessel rides on advancing wave slope

This phenomenon is called surf riding

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6771

Result

Vessel slewed violently (broach-to) Vessel heeled over and swamped

Action

Critical speed for surf riding is considered 18radicL knots Reduce ship speed to less than 18radicL knots to prevent surf riding(L= ships length)

back

Broach to

May occur when a ship is surf ridden in a following or quarteringsea

The vessel is slewed violently Ship heels suddenly and unexpectedly to a large angle

Result

Positive stability disappears to the existing angle of heel Vessel may cause a vessel to capsize due to sudden change ofheel and heading

Action

Reduce speed below 18radicL knots

A marginal zone (14radicL to 18radicL) below critical speed may cause alarge surging motion (broach to) Speed to be reduced below 14radicL

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6871

in the case

back

Synchronous rolling

Large rolling motions may be excited when natural rolling periodof a ship coincides with the encounter wave period It may happen in following and quartering sea It happens when natural roll period is longer due to marginaltransverse stability

View more

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 6971

Parametric rolling

Occurs in a following or quartering sea Occurs when encounter wave period is approximately half of thenatural rolling period of the ship

Occurs particularly if initial metacentric height height is small andnatural roll period is very long

Unstable and large amplitude roll motion takes place May occur in head and bow seas

Result

Unstable and large rolling motion takes place

Action

Reduction of speed

back

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 7071

Combination of various dangerous phenomenon

May occur in a following or quartering sea

Various detrimental factors may affect ships dynamic behavior

These factors are

Additional heeling moment due to deck water Water shipping and trapped on deck Cargo shift The factors may be occur with other dangerous phenomenon

They may create extremely dangerous combination to capsize theship

back

Successive wave attack

Occurs when ships speed component in the wave direction is

7242019 4 Bad Weather

httpslidepdfcomreaderfull4-bad-weather 7171

nearly equal to the wave group velocity It is equal to the half of phase velocity of the dominant wavecomponent

The ship is attacked successively by high waves Expectable maximum wave height can reach almost twice of

observed wave height May be evident when average wave length is larger than 08Lsignificant wave height is larger than 004L

Result

Reduction of intact stability Synchronous rolling Parametric rolling Combination of various dangerous phenomena Vessel may capsize

Action

Reduce ship speed to go out of dangerous zone Combination of appropriate speed reduction with slight coursechange

back

Updated

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