Exam Question
Define the following stating how they affect the ship structure and what component parts of the ship structure help to resist the effect (4)
(a) Racking (4)
(b) Pounding (4)
(c) Panting (4)
(d) Vibration in engine and propellers. (4)
Class 4 (4th Engineer)
SC&S
📅 Oct 2025
Reference Answer
### (a) Racking
#### Definition
Racking is the transverse distortion of the ship's hull cross-section, primarily caused by the forces exerted during rolling in a seaway. As the ship rolls, the deck structure tends to move laterally relative to the bottom structure, causing the rectangular transverse profile of the ship (formed by the deck, bottom, and side shells) to deform into a parallelogram. This stress is most pronounced when the ship is in a light condition (low draft) with a high center of gravity, leading to stiff and rapid rolling.
#### Effect on Ship Structure
#### Definition
Racking is the transverse distortion of the ship's hull cross-section, primarily caused by the forces exerted during rolling in a seaway. As the ship rolls, the deck structure tends to move laterally relative to the bottom structure, causing the rectangular transverse profile of the ship (formed by the deck, bottom, and side shells) to deform into a parallelogram. This stress is most pronounced when the ship is in a light condition (low draft) with a high center of gravity, leading to stiff and rapid rolling.
#### Effect on Ship Structure
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