Exam Question
(a) What is free surface effect ? (6)
(b) Explain the methods used to reduce the free surface effect in ship construction and while operating the ship. (10)
Class 4 (4th Engineer)
SC&S
📅 Nov 2025
Reference Answer
### (a) What is Free Surface Effect? (6 Marks)
**1. Definition:**
The Free Surface Effect (FSE) is the virtual loss of a ship's initial stability (reduction in Metacentric Height, GM) caused by the movement of liquid within a partially filled (slack) tank as the vessel heels. This phenomenon is a direct consequence of the liquid's center of gravity shifting as the ship inclines, which in turn shifts the ship's overall center of gravity, reducing its righting ability.
**2. Mechanism of Action:**
**1. Definition:**
The Free Surface Effect (FSE) is the virtual loss of a ship's initial stability (reduction in Metacentric Height, GM) caused by the movement of liquid within a partially filled (slack) tank as the vessel heels. This phenomenon is a direct consequence of the liquid's center of gravity shifting as the ship inclines, which in turn shifts the ship's overall center of gravity, reducing its righting ability.
**2. Mechanism of Action:**
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