Exam Question
(a) Write short notes on Panting, Pounding and Racking (8)
(b) Explain with the aid of simple sketches hogging and sagging of a vessel. (8)
Class 4 (4th Engineer)
SC&S
📅 Feb 2023
Reference Answer
### (a) Short Notes on Panting, Pounding, and Racking
#### 1. Panting
* **Concept:** Panting is a localized stress phenomenon characterized by the repetitive in-and-out movement of the shell plating, primarily at the bow and stern of the vessel. This flexing motion is analogous to the chest movements during heavy breathing. (As per the context, "...bow plating to move in and out in a fashion as if a person is breathing heavily...").
* **Cause:** It is caused by the fluctuating, non-uniform hydrostatic pressure exerted by waves as they move past the hull. As a wave crest passes, external pressure increases, pushing the plating inwards. In a trough, the pressure decreases, allowing the plating to flex outwards. This cycle occurs rapidly, inducing high-frequency stress.
#### 1. Panting
* **Concept:** Panting is a localized stress phenomenon characterized by the repetitive in-and-out movement of the shell plating, primarily at the bow and stern of the vessel. This flexing motion is analogous to the chest movements during heavy breathing. (As per the context, "...bow plating to move in and out in a fashion as if a person is breathing heavily...").
* **Cause:** It is caused by the fluctuating, non-uniform hydrostatic pressure exerted by waves as they move past the hull. As a wave crest passes, external pressure increases, pushing the plating inwards. In a trough, the pressure decreases, allowing the plating to flex outwards. This cycle occurs rapidly, inducing high-frequency stress.
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