# Center of gravity

The center of gravity of a body , which is surrounded by a liquid or a gas or floats on a liquid, is the center of gravity of the liquid or gas that it displaces. The center of gravity is thus the point at which the static buoyancy acts and is therefore also called the buoyancy point .

## Submarines

In a submerged submarine , the spatial position of the center of gravity of the form relative to its center of gravity, on which the weight acts, is decisive for stability : so that the submarine does not capsize , the center of gravity should be above the center of gravity .

## Ships

In the case of ships on the water surface, on the other hand, the center of gravity of the underwater ship is usually below the center of gravity without overturning. This is because the center of gravity moves: the side the ship is heeling  ( leaning ) to dips deeper and creates additional buoyancy; the opposite side emerges and loses lift. The ship behaves as if it were suspended like a pendulum at a point called the metacenter . Only the metacenter, not the center of gravity, has to be above the center of gravity. The height of the metacenter above the center of gravity depends on the area moment of inertia of the waterline around the longitudinal axis and is therefore very large in catamarans .