Page:Self-righting boat design.pdf/5

 c) A ship with negative GM: In this condition, the center of gravity is above its metacenter point. The slope of the righting arm curve is negative at zero degree heel.

Self-righting stability is an old term in naval architecture history but, it is relatively new practical concept. On any self-righting vessel, GZ curve does no turns negative throughout 360° of roll cycle.
 * 2.2 Self-Righting Stability

All traditional boats have a heel angle which righting levers have degraded to zero. This term is defined as Point of Vanishing Stability. Frequently, this point does not occur until ship is completely inverted, but for those have enough buoyancy to stay afloat, any heel angle beyond