Inclining Moments
A ship may be disturbed from rest by conditions
which tend to make it heel over to an angle. These
conditions include such things as wave action, wind
pressures, turning forces when the rudder is put over,
recoil of gunfire, impact of a collision or enemy hit,
shifting of weights on board, and addition of off-center
weights. These conditions exert heeling moments on
the ship that may be temporary or continuous.
When a disturbing force exerts an inclining
moment on a ship, there is a change in the shape of the
ship’s underwater body. The underwater volume is
relocated, its bulk being shifted in the direction of the
heel. This condition causes the center of buoyancy (B)
to leave the ship’s centerline and shift in the direction
of the heel. (The center of buoyancy moves to the
geometric center of the new underwater body.) As a
result, the lines of action of the forces of buoyancy and
gravity separate and in doing so exert a MOMENT on
the ship. This moment tends to restore the ship to an
even keel.