ABSTRACT
A floating body is said to be in equilibrium if resultant forces and moments acting on the body are zero. In case of a floating body in water, this is achieved because the downward force, weight of the body, is equal to the upward buoyancy force which is equal to the weight of the displaced water and the centre of gravity and the centre of buoyancy act in the same vertical or, for a ship, LCB = LCG. This equilibrium is stable if the body, displaced from its equilibrium position due to an external force or moment, comes back to its original position after the force or moment is removed. If the body moves away further from its original position, it is said to be in unstable equilibrium. If the body stays in the displaced position, it is said to be in neutral equilibrium. In case of a floating body like a ship or any floating platform, it has to be in stable equilibrium for survival. A submerged body could be in stable or neutral equilibrium for survival, whereas it must be in stable equilibrium for effective operation at sea. At design stage it is not enough to ensure stability in intact condition, but also in a probable damaged condition for its survival. It is necessary to understand and estimate the geometrical properties of the body so that its mechanics in water can be studied properly.
