Class 2 (2nd Engineer) SC&S 📅 Jan 2019

Exam Question

(a) With reference to dynamical stability, 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 15000 tonne displacement has righting levers of 0, 0.38, 1.0, 1.41 and 1.2 m at angles of heel of 0°, 15°, 30°, 45° and 60° respectively and an assumed KG of 7.0 m. The vessel is loaded to this displacement but the KG is found to be 6.80 m and GM 1.5 m. (10)

(i) Draw the amended stability curve

(ii) Estimate the dynamic stability at 60°

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:

Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.

View plans Browse library

← Browse more questions

Prepare on Android — MeoMock on Google Play