Class 2 (2nd Engineer) SC&S 📅 Jan 2023

Exam Question

(a) Explain the concept of dynamical stability and describe the effect of an increase in wind pressure when a vessel is at its maximum angle of roll to windward (6)

(b) A ship of 5000 tone displacement has three rectangular double bottom tanks; A 12 m long and 16 m wide; B 14 m long and 15 m wide; C 14 m long and 16 m wide. Calculate the free surface effect for any one tank and state in which order the tanks should be filled when making use of them for correction. (10)

Reference Answer

(a) Dynamical Stability is defined as the amount of energy required to heel a ship from its upright equilibrium position to a specific angle of heel. It provides a measure of the vessel's stability by considering its behaviour in response to dynamic external forces , such as wind or waves.
The concept compares the heeling moment energy (from external forces) and the righting moment energy (from the ship's stability).
The ship will absorb the energy imparted by the heeling moment. If the righting energy is greater than the heeling energy, the ship will stabilize; otherwise, it may capsize.
Areas Under the Curve:

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