Stability and Trim of Ships - Naval Architecture and Ocean Engineering - Naval Architecture & Marine Engineering Previous Year Questions

1

2022 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2022

A rectangular barge has length \(L\) of 100 m, breadth \(B\) of 18 m and depth \(D\) of 10 m. It is subdivided transversely into four equal compartments of equal length with the end compartments loaded fully with oil of density = 0.9 tonne/m³. The barge floats in water having a density of 1000 kg/m³. If the hull structural weight is ignored, then the transverse metacentric height of the barge is __________ m (correct to two decimal places).

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2

2023 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2023

In the following “GZ (righting lever arm) versus “angle of heel” curve, the point ‘X’ indicates

A

angle of loll

B

angle of vanishing stability

C

deck edge immersion angle

D

trim angle

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3

2023 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2023

Comparing a catamaran (with a separation between demi-hulls) and a mono-hull craft of the same displacement and water plane area, the initial metacentric radius of the catamaran will be

A

same as that of the mono-hull

B

one-half of the mono-hull

C

greater than that of the mono-hull

D

one-third of the mono-hull

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4

2023 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2023

The buoyancy curve variation of a ship floating in still water and in waves is shown in the following figure. The total area under each curve is the same. The cases 'X' and 'Y' correspond to

A

X: wave crest is amidships, Y: wave crest is amidships

B

X: wave trough is amidships, Y: wave trough is amidships

C

X: wave trough is amidships, Y: wave crest is amidships

D

X: wave crest is amidships, Y: wave trough is amidships

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5

2023 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2023

The heave natural frequencies of a Jacket structure, FPSO and a semi-submersible are ωJ, ωF and ωS respectively. Each one of them has a pay load capacity of 10000 tonnes. Which of the following is TRUE?

A

ωJ < ωF < ωS

B

ωJ > ωF > ωS

C

ωJ < ωS < ωF

D

ωJ > ωS > ωF

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6

2024 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2024

The GZ curve for a stable ship is shown in the figure, where P is a point of inflection on the curve. Match the labels in Column 1 with the corresponding descriptions in Column 2.

Column 1	Column 2
P	I: Angle of vanishing stability
ST	II: Maximum GZ
R	III: Initial GM
Q	IV: Deck edge immersion

A

R - I; Q - II; ST - III; P - IV

B

P - I; Q - II; ST - III; R - IV

C

ST - I; Q - II; R - III; P - IV

D

R - I; Q - II; P - III; ST - IV

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7

2024 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2024

A ship of 5000 tonnes displacement has a rectangular tank 6 m long and 10 m wide, half-filled with oil of relative density 0.8. The virtual reduction in the transverse metacentric height of the ship due to free surface effect of the oil in the tank is ________ cm.

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8

2025 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2025

A ship of 5000 tonne displacement has two empty rectangular double bottom tanks with dimensions:
Tank A: length 12 m, width 16 m, and height 2 m
Tank B: length 16 m, width 12 m, and height 2 m
The length of each tank is oriented along the length of the ship. It is required to ballast the ship with 192 m³ of seawater of density 1025 kg/m³. Which one of the following scenarios will minimize the free surface effect?

A

100 % of the given ballast water is filled in Tank A.

B

100 % of the given ballast water is filled in Tank B.

C

50% of the given ballast water is filled in Tank A and the remaining in Tank B.

D

40% of the given ballast water is filled in Tank A and the remaining in Tank B.

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9

2025 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2025

For a freely floating body in water, which of the following degrees of freedom has/have inherent restoring force?

A

Sway

B

Surge

C

Heave

D

Pitch

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10

2025 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture & Marine Engineering (NM) 2025

A ship of 3300 tonne displacement is undergoing an inclining experiment in seawater of density 1025 kg/m³. A mass of 6 tonne is displaced transversely by 12 m as shown in the figure. This results in 0.12 m deflection of a 11 m long pendulum suspended from the centerline. The transverse metacenter of the ship is located at 7.25 m above the keel.

The distance of the center of gravity from the keel is ______ m (rounded off to two decimal places).

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11

2026 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture and Marine Engineering (NM) 2026

Consider two configurations P and Q of a stationary ship floating in calm water with transverse sections as shown in the figure, where M is the metacentre, G is the centre of gravity, and B is the centre of buoyancy.
Which ONE of the following statements is TRUE regarding the static stability of the ship?

A

Configuration P is stable and configuration Q is unstable.

B

Both configurations are stable.

C

Configuration P is unstable and configuration Q is stable.

D

Both configurations are unstable.

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12

2026 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture and Marine Engineering (NM) 2026

Which ONE or MORE of the following methods of shifting weights can be used to improve the transverse stability of a rectangular pontoon?
Note: CG denotes the vertical centre of gravity of the pontoon.

A

From below the CG to above the CG

B

From above the CG to below the CG

C

From port to starboard at the same height from the keel

D

From forward to aft at the same height from the keel

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13

2026 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture and Marine Engineering (NM) 2026

A vessel of 5000 m³ displacement floating in seawater has a rectangular tank of length 6 m and width 10 m. The tank is half-filled with seawater as shown in the figure.
The virtual reduction in metacentric height due to free surface effect is _____ m (answer in one decimal place).

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14

2026 · Naval Architecture & Marine Engineering · Naval Architecture and Ocean Engineering · Stability and Trim of Ships

Naval Architecture and Marine Engineering (NM) 2026

A ship is undergoing a steady starboard turn. Assume that the total hydrodynamic forces (\(Y\)) including the rudder forces act at the centre of buoyancy (\(B\)).
If \(W\) is the weight of the ship, \(G\) is the centre of gravity and \(M\) is the transverse metacentre, then the magnitude of the heel angle (\(\phi\)) is given by _____.
Assume that \(\phi\) is small.

A

\(\left| \frac{Y \times BG}{W \times GM} \right|\)

B

\(\left| \frac{W \times BG}{Y \times GM} \right|\)

C

\(\left| \frac{W \times GM}{Y \times BG} \right|\)

D

\(\left| \frac{Y \times GM}{W \times BG} \right|\)

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