Angle of vanishing stability (AVS)
B1. Naval ArchitectureDefinition
Heel angle at which the righting arm GZ returns to zero on the static stability curve.
The angle of vanishing stability (AVS) is the heel at which the $GZ$ curve returns to zero, marking the limit of positive righting arm; beyond it the ship capsizes. It bounds the range of stability measured from upright. A high freeboard, large reserve buoyancy, and watertight superstructure push the AVS out, often past 70 to 80 degrees on a seagoing cargo ship, while low-freeboard or deck-cargo cases can fall below 50 degrees.