Centre of Buoyancy and Meta Centre
Center of Buoyancy: Center of Buoyancy is the center of gravity for the volume of water which a hull displaces. Center of Gravity is the point in a body where the gravitational force may be taken to act.
• When the hull is upright the center of gravity and center of buoyancy are on the same vertical line, and the hull is stable.
• For most hulls the center of buoyancy is below the center of gravity and the hull is said to be metastable.
• When the hull tilts the center of gravity remains in the same position related to the hull. The center of buoyancy will move to fit the new center of gravity for the volume of water replaced by the hull. In the beginning the gravity force and the buoyancy force will create a righting torque that tries to move the hull back to the upright position.
• If the hull is tilted to much the center of buoyancy will move to a position where the buoyancy and gravitational force starts to create a moment that work in the same direction and the hull will capsize.
Meta center: When a floating body is slightly tilted from equilibrium position, the center of buoyancy shifts. The point at which the vertical line passing through the new position of center of buoyancy meets with the initial line is called meta center.