AB Ship Construction and Cargo Questions and Answers

Question 1

Which of the following best describes the primary purpose of a cofferdam on a vessel?

Accepted Answer

To create a void space that isolates and separates tanks containing incompatible liquids.

Answer

A cofferdam is an empty space or void compartment between two bulkheads. Its main purpose is to prevent the mixing of liquids from adjacent tanks in case of a leak, providing a safe separation between incompatible substances like fuel oil and potable water, or different grades of cargo.

Question 2

A vessel is loading a heavy piece of equipment from the pier using its own deck crane. What is the immediate effect on the vessel's stability from the moment the weight is lifted clear of the pier until it is landed on deck?

Accepted Answer

The vessel's center of gravity (G) effectively rises to the head of the crane.

Answer

When a weight is suspended from a crane, its entire mass is considered to be acting at the point of suspension (the head of the boom). This causes a virtual rise in the ship's overall center of gravity (G), which reduces the metacentric height (GM) and decreases the vessel's stability during the lift.

Question 3

A vessel is loaded with heavy cargo concentrated in the midship holds, while the fore and aft holds are empty. If wave crests are supporting the bow and stern, what type of longitudinal stress is the hull experiencing?

Accepted Answer

Sagging

Answer

Sagging is the stress condition where the middle of the ship's hull bends downwards. This occurs when there is excessive weight in the center of the vessel and buoyancy is concentrated at the ends, such as when the ship is in the trough between two waves or loaded heavily amidships.

Question 4

Which of the following structural members are considered the 'ribs' of the ship, providing the primary transverse strength to the hull?

Accepted Answer

Frames

Answer

Frames are the transverse ribs of a ship that are attached to the keel. They give the hull its shape and provide the main strength to resist pressure from the surrounding water, acting as the primary transverse stiffeners for the shell plating.

Question 5

In the context of cargo operations, what does the 'stowage factor' of a particular commodity represent?

Accepted Answer

The ratio of a cargo's volume to its weight.

Answer

The stowage factor is a crucial figure in cargo planning that represents the volume (e.g., in cubic meters or cubic feet) that one unit of weight (e.g., one tonne) of a specific cargo will occupy. It helps determine whether a ship will 'cube out' (run out of space) before it 'weights out' (reaches its maximum deadweight).

(AB) Able Seaman Exam Practice Test

(AB) Able Seaman Exam Practice Test

AB Ship Construction and Cargo Questions and Answers