Angle of loll

Angle of loll is the state of a ship that is unstable when upright (i.e. has a negative metacentric height, GMt) and therefore takes on an angle of heel to either port or starboard.

When a vessel has negative GM i.e., is in unstable equilibrium, any external force applied to the vessel will cause it to start heeling. As it heels, the moment of inertia of the vessel's waterplane (a plane intersecting the hull at the water's surface) increases, which increases the vessel's BM (distance from the center of buoyancy to the metacenter). Since there is relatively little change in KB (distance from the keel to the center of buoyancy) of the vessel, the KM (distance from keel to the metacenter) of the vessel increases.