Exam Question
(a) What is free surface effect? How can be avoided or reduced.
(b) Give the components of ships resistance while vessel is 'enroute'.
Class 2 (2nd Engineer)
SC&S
📅 Jul 2019
Reference Answer
(a) Free Surface Effect:
The free surface effect (FSE) is a reduction in the metacentric height (GM) of a vessel due to the movement of liquids within partially filled tanks when the ship heels. When a ship tilts, the liquid in a partially filled tank shifts to the lower side, causing the centre of gravity (CG) of the ship to move laterally. This lateral shift of the CG reduces the righting lever (GZ), effectively decreasing the ship's stability and increasing the angle of heel. This apparent loss of GM is the free surface effect.
Minimizing Free Surface Effect:
Partially filled tanks should be avoided to minimize liquid movement.
The free surface effect (FSE) is a reduction in the metacentric height (GM) of a vessel due to the movement of liquids within partially filled tanks when the ship heels. When a ship tilts, the liquid in a partially filled tank shifts to the lower side, causing the centre of gravity (CG) of the ship to move laterally. This lateral shift of the CG reduces the righting lever (GZ), effectively decreasing the ship's stability and increasing the angle of heel. This apparent loss of GM is the free surface effect.
Minimizing Free Surface Effect:
Partially filled tanks should be avoided to minimize liquid movement.
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