This page contains answers to Seagull *CES* test about Vessel Stability, and serve as a database of questions and answers, using which seafarer can prepare to exams for getting certificate of competence, or just to challenge yourself with knowledge in this theme.

CBT CD 0033 – Stability.pdf

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Amount of questions: 62.

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A ship floating on an even keel and upright has a weight loaded on the port side of the deck and towards the stern of the vessel. What will be the final condition of the ship after loading? Select the ONE right answer:

Listed to port and trimmed by the stern.

Heeled to port and trimmed by the stern.

Upright and trimmed by the stern.

Heeled to port and trimmed by the head.

A ship has a Water Plane Area of 2 000

*m*^{2}and is floating in water of relative density 1,1. What is the ship’s tonnes per centimetre immersion,*TPC*? 1 818.

2 200.

22.

20.

A ship has an initial total displacement of 2 800

*tonnes*and*KG*5,0*metres*. A weight of 200*tonnes*is then removed from amidships on the deck at a height of 8*metres*above the keel on a ship. What is the final*KG*of the ship after unloading? 5,2

*metres*. 4,77

*metres*. 4,43

*metres*. 4,55

*metres*.A ship with a

*TPC*of 10 unloads 80*tonne*of cargo. What will the change of draught be? The draught will decrease by 80

*cm*. The draught will decrease by 8

*cm*. The draught will increase by 8

*cm*. The draught will decrease by 0,8

*cm*.A ship with a large Transverse

*GM*will have which one of the following rolling periods? Select the ONE correct answer: Fast and to small angles of heel.

Very slow and to large angles of heel.

A moderately comfortable period with medium angles of heel.

Slow period of roll either side of an angle of loll.

A tank on a vessel can hold 100

*tonnes*of*FW*when full. How many tonnes of liquid (relative density 0,5) could it take when full? Select the ONE correct answer: 50

*tonnes*. 100

*tonnes*. 150

*tonnes*. 200

*tonnes*.A weight of 100

*tonnes*is loaded amidships on the deck at a height of 8*metres*above the keel on a ship of 2 900*tonnes*and*KG*5,0*metres*. What is the final*KG*of the ship after loading? 5,2

*metres*. 5,1

*metres*. 5,0

*metres*. 4,9

*metres*.A weight of 200 tonnes is loaded amidships on the deck a height of 7

*metres*above the keel on a ship of 3 800*tonnes*and*KG*5,0*metres*. What is the final*KG*of the vessel after loading? 5,2

*metres*. 5,1

*metres*. 5,0

*metres*. 4,9

*metres*.At what point during the dry docking of a ship does the up thrust from buoyancy become zero? Select the ONE correct answer:

When the water drops below the keel.

When the vessel touches the blocks aft.

When the vessel settles on the block overall.

Never.

How can a ship’s officer change the value of the Transverse Metacentric Height? Select the ONE correct answer:

By loading or discharging cargo and in other ways changing the positions of both G and M.

Only by loading cargo and changing the position of Centre of Gravity G of the ship.

By loading or discharging cargo and changing the position of G only.

By vertically shifting cargo already on board and changing the position of both G and M.

How can the adverse effects of Free Surface on a ship be reduced by a ship’s officer? Select the TWO best answers:

Loading more ballast and increasing the displacement.

Transferring ballast from high tank to a low tank.

The pressing up of the liquid within any slack tanks.

The draining of the liquid from any slack tanks.

If a ship develops an angle of inclination during a voyage, what background knowledge can be used to determine whether the ship is lying inclined at an Angle of Loll or at an Angle of

*“List”*? Select the ONE correct answer: The duration of the rolling period prior to the angle developing.

It is not possible to determine which it is.

Knowledge of the internal distribution of cargo when loading.

It will be obvious, because of conspicuous broken lashings.

If a vessel is rolling heavily in a seaway and has a negative

*GM*and a small Angle of Loll, describe how the vessel will roll. Select the ONE best answer: Roll unevenly flopping over between the Angle of Loll on each side.

Roll evenly either side of the upright position.

Roll evenly each side of the Angle of Loll.

Roll between the Angle of Loll on each side.

In the added weight method, the free communication effect in damaged condition:

Gives the ship decreased

*GM*when the damage is symmetrical. Reduces the

*GM*and increases the dynamic stability of the ship. Reduces the

*GM*and decreases the dynamic stability by sinus correction of the*GZ*curve. Reduces the

*GM*and decreases the dynamic stability by cosinus correction of the*GZ*curve.The buoyancy forces upwards act at what points on the hull?

All over the underwater volume.

At the Centre of Gravity G.

At the Centre of Buoyancy B.

Along the keel.

The condition of Equilibrium for a floating vessel is which of the following conditions? Select the ONE best answer:

When G is vertically below B with equal and opposite forces of displacement and buoyancy.

When the vessel is upright and on an even keel and

*GM*is positive. When the ship is upright, the Fore and Aft draughts are steady and the

*GM*is positive. When the vessel completes loading or discharging cargo.

The ships own derrick is used to discharge a heavy weight from the centreline of deck to the jetty. At what instant does the most dangerous situation occur with respect to the ships effective stability? Select the ONE correct answer:

When the weight is swung out over the jetty and starts to be lowered.

When the weight is landed on the jetty.

When the weight is being swung over towards the jetty.

When the weight is lifted off the deck.

What are the units of Relative Density? Select the ONE correct answer:

Has no units.

Tonnes.

Tonnes per cubic metre.

Cubic metre per tonne.

What does the term

*“Block Coefficient”*mean? Select the ONE correct answer: The ratio of the ship’s underwater shape to a rectangular block of the same extreme dimensions.

The efficiency of the derrick topping lift used to load cargo.

The ratio of the ship’s Waterplane area to a rectangle of the same extreme dimensions.

The ratio of the vessel’s even keel, underwater shape to the actual underwater shape when trimmed.

What does the term

*“Layer Coefficient”*mean? Select the ONE correct answer: It is the correction between the Draught Amidships and the True Mean Draught.

It is the vertical separation between two parallel waterlines.

It is another term for the Dock Water Allowance.

It is a correction to apply to the lightship draught to allow for ballast already on board.

What is Relative Density? Select the ONE correct answer:

Relative Density is the ratio of the weight of a substance to the weight of an equal volume of fresh water.

Relative Density is the mass of a substance divided by its volume.

Relative Density is the mass of a substance multiplied by its volume.

Relative Density is the ratio of the weight of a substance to the weight of an equal volume of salt water.

What is a

*“Righting Lever”*? Select the ONE correct answer: The vertical distance between the Centre of Gravity (G) and the Centre of Buoyancy (B).

The perpendicular distance between the ship’s Centre of Gravity (G) and the vertical up thrust through the ship’s Centre of Buoyancy (B).

The horizontal distance between the Centre of Gravity (G) and the Centre of Buoyancy (B).

The vertical distance between the Centre of Gravity (G) and the Keel (K).

What is lever, which returns the vessel to the upright? Select the ONE correct answer:

*GZ*.

*KM*.

*GM*.

*BM*.

What is minimum value of the

*GM*allowed under the international Load Line Rules? Select the ONE correct answer: 0,15

*m*. 1,5

*m*. 2,0

*m*. 0,25

*m*.What is the Curve of Transverse Statical Stability? Select the ONE best answer:

A graph, showing the

*GZ*values for different angles of heel. A graph, showing the value of

*GM*at different displacements. A curve, showing the stability of a vessel at different displacements.

A graph, showing the values of

*KM*for different angles of heel.What is the Fresh Water Allowance? Select the ONE correct answer:

An allowance, in centimetres, for the change of draught of the ship between sea water and fresh water.

An allowance, in metres, for the change of draught of the ship between sea water and fresh water.

An allowance, in millimetres, for the change of draught due to the use of fresh water on the voyage.

An allowance, in millimetres, for the change of draught of the ship between sea water and fresh water.

What is the change in the apparent loss of

*GM*due to free surface effect, when two transverse bulkheads are introduced into the tank holding the liquid? 1/2.

1/4.

1/9.

Nothing.

What is the danger of having a large bunker tank only partially filled with bunkers? Select the ONE best answer:

Free Surface Effect and virtual loss of

*GM*. Structural damage due to liquid movement in the tank.

Excessive corrosion of the tank sides.

Insufficient bunkers to complete the voyage.

What is the difference between mass and weight? Select the ONE correct answer:

Weight is the mass multiplied by the Density.

Weight is the mass multiplied by the Acceleration due to gravity.

Weight is the mass multiplied by the Volume.

Weight is the mass multiplied by the Moment of force.

What is the meaning of the term

*“Ship’s Displacement”*? Select the ONE correct answer: It is the weight of the ship and everything on board.

It is the weight of cargo on board a ship.

It is the underwater volume of a ship.

It is the lightship weight of a ship only.

What is the minimum required

*GM*for a ship with following*GM*(min) curves and draught 6,3*metres*? 1,7

*m*. 2,0

*m*. 2,5

*m*. 1,3

*m*.What is the minimum required residual dynamic stability for a damaged passenger ship at equilibrium?

0,15

*metres*. 0,05

*metres*. 0,015

*metre-radians*. 0,05

*metre-radians*.What is the minimum required righting lever for a damaged passenger ship at final state of flooding?

0,15

*metres*. 0,10

*metres*. 0,10

*metre-radians*. 0,05

*metre-radians*.What is the minimum required righting lever for a damaged passenger ship at intermediate state of flooding?

0,15

*metres*. 0,05

*metres*. 0,05

*metre-radians*. 0,10

*metre-radians*.What is the purpose of the inclining experiment? Select the ONE correct answer:

To see if the ship is stable.

To establish the position of the light ship Centre of Gravity.

To establish the position of the light ship Metacentric Height.

To establish the position of the light ship Righting Lever,

*GZ*.What is the purpose of the

*“Inclining Experiment”*? Select the ONE correct answer: To determine the lightship

*KG*of a vessel. To determine the

*GG*_{1}when shifting a known weight across the deck. To determine the lightship displacement of a vessel.

To determine the angle of inclination when a known weight is shifted a known transverse distance across the vessel.

What is the relationship between

*GM*and the righting ability of the ship? Select the ONE correct answer:*GZ = GM×sin*.

*GM*is the righting lever returning the vessel upright.

*GZ = GM×tan*(Angle of Heel).

The Curve of Statical Stability.

What is the

*“Angle of Loll”*? Select the ONE correct answer: The angle of equilibrium for a ship with a negative upright

*GM*. The maximum angle to which a vessel inclines when discharging a heavy weight using the ship’s derrick.

The angle of heel experienced in a steady beam wind.

The trim angle measured at the after perpendicular.

What is usually the effect on G when the ship is damaged?

It rises.

It lowers.

It is unchanged.

It first rises, then lowers.

What statement is true about the metacentric radius?

The distance between the keel and the metacentre depends on the speed and the location of G.

The distance between B and metacentre depends on the displacement and the moment of inertia of the waterplane area.

The distance between G and the metacentre depends on the displacement and the location of G.

The distance between the keel and G depends on the waterline area and the location of G.

What statement is true about volume permeability?

If the volume permeability is 0 %, no water will enter the compartment in case of damage.

If the volume permeability is 100 %, the damaged compartment below the waterline will be completely filled with water in case of damage.

If the volume permeability is 100 %, no water will enter the compartment in case of damage.

The volume permeability in machinery spaces is 50 % according to

*SOLAS*.Where is the Forward Perpendicular drawn? Select the one correct answer:

At the collision bulkhead.

At the most forward part of the hull, wherever this occurs.

At the most forward part of the hull, at the summer load line.

At the most forward part of the hull, at the mean draught.

Which ONE of the following options best describes the conditions for a ship to in equilibrium?

When the centre of gravity and the centre of buoyancy are at the same height above the keel.

Only when B, G, and K are all in the same vertical line.

When G and B are in the same vertical line and the forces are of the same magnitude.

When the force of buoyancy upwards is exactly equal to the force of the weight downwards.

Which ONE of the following would NOT be shown in a table of hydrostatic particulars? Select the ONE correct answer:

The displacement for any given draught.

The height of the ship’s Centre of Buoyancy above the keel.

The position of the ship’s Longitudinal Centre of Flotation.

The height of the ship’s Centre of Gravity above the keel.

Which ONE of the following would be the specific point about which a ship will roll in a seaway? Select the ONE correct answer:

The Centre of Flotation, CF.

The Centre of Gravity, G.

The Centre of Buoyancy, B.

The Centreline, CL.

Which ONE of these items is NOT included in the Deadweight of a ship?

Cargo.

Fresh water.

Deck stores.

Main engine.

Which THREE of the following items of information can be determined from examining the Curve of Statical Stability? Select the THREE correct options:

The Initial value of Transverse

*GM*. Angle of Maximum Stability.

The Righting Moment of the vessel at a specific angle of heel.

The maximum value of the Righting Lever.

Which TWO of the following cause a small positive

*GM*at the start of a voyage to become dangerous during the passage? Select the TWO correct answers: Consumption of bunkers in a low tank.

Consumption of bunkers in a high tank.

Partially filled tanks giving free surface effect.

Distribution of weights due to bad stowage.

Which of the following initial conditions on board are required to conduct an inclining experiment? Select each correct option:

No free liquid surface in any tanks.

Minimum bunkers, water and ballast.

No cargo on board.

Minimum of personnel on board to conduct experiment.

Which of the following statement(s) are true?

Cross flooding arrangements stop the water from reaching the opposite side of the damaged compartment.

Cross flooding arrangements reduce the heeling angle in damaged condition.

A damage control plan shows the boundaries of watertight compartments and openings therein.

Valves of scuppers, that go through the damaged compartment should be opened.

Which of the following statements are true, with respect to change of stability parameters for a damaged ship?

B moves and M remains on its original place.

M moves, but B remains on its original place.

M moves, B moves and

*GM*is always constant. M moves, B moves and

*GM*increases or decreases.Which of the following statements is true? Select all applicable options:

Cross flooding arrangements stop the water from reaching the opposite side of the damaged compartment.

Cross flooding arrangements reduce the heeling angle in damaged condition.

A damage control plan shows the boundaries of watertight compartments and openings therein.

Valves of scuppers, that go through the damaged compartment should be opened.

Which of these statements about the Longitudinal Centre of Flotation (

*LCF*) is most accurate? Select the ONE best answer: The

*LCF*is the geometrical centre of the ship’s underwater volume. The ship will heel and trim about the

*LCF*. The

*LCF*is always at amidships. The position of the

*LCF*remains constant for a given ship.Which statement is true about the metacentric radius?

It is the distance between the keel and the metacentre, depending on the speed and the location of G.

The distance between B and metacentre, depending on the displacement and the moment of inertia of the waterplane area.

The distance between G and the metacentre, depending on the displacement and the location of G.

The distance between the keel and G, depending on the waterline area and the location of G.

Which statement is true about volume permeability? Select all applicable answers:

If the volume permeability is 0 %, no water will enter the compartment in case of damage.

If the volume permeability is 100 %, no water will enter the compartment in case of damage.

If the volume permeability is 100 %, the damaged compartment below the waterline will be completely filled with water in case of damage.

The volume permeability in machinery spaces is 50 % according to

*SOLAS*.Which statements are true concerning the Lost of Buoyancy method?

The damaged compartment is still considered intact.

The damaged compartment is considered non-existing.

The original

*KN*-values can be used for calculating*GZ*. The method is suitable for computer programming.

Which statements are true concerning the added weight method:

It is a suitable damage stability calculation method for manually calculations.

You have no use of the hydrostatic tables and cross curves for the ship, due to increased displacement.

You can disregard the change in trim caused by the damage, when calculating the new

*GZ*-line. The free surface effect from the water in the damage compartment has influence though the damage is symmetrical.

Why can the draught amidships not be used to extract the value of displacement from the displacement table? Select the ONE correct answer:

The draught amidships is not the true mean draught.

The displacement is not dependent on the draught.

The draught amidships is not the mean of the draughts at the forward and after perpendiculars.

The arithmetical mean of the end draughts should be used to determine correct displacement.

Why does a ship with an initial negative Metacentric height not always capsize? Select the ONE correct answer:

The Centre of Buoyancy moves down as the ship moves away from the upright.

The Centre of Gravity moves down as the ship moves away from the upright.

The position of the Metacentre moves up as the ship moves away from the upright.

The Centre of Buoyancy moves up as the ship moves away from the upright.

Why is a ship not dry docked on an even keel? Select the ONE best answer:

To allow better manoeuvring when first entering the dry dock.

To counteract the

*“Correction of Layer”*. To allow drainage of water off the decks.

To position the ship easily over the blocks.

Why is a vessel entering dry dock normally slightly trimmed by the stern? Select the ONE best answer:

To position the vessel easily over the blocks.

To minimize the loss of stability.

To allow drainage of water off the decks.

To allow better manoeuvring when entering into the dry dock.

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