Angle of Vanishing Stability

Heel angle at which the GZ righting arm becomes zero — beyond this angle the ship will not return to upright but will continue heeling and capsize. The 2008 IS Code requires the angle of vanishing stability to be at least 60° in normal conditions (40° in some restricted-service ship types). The angle is read from the GZ curve and is sensitive to deck-edge immersion and downflooding through openings. Loading conditions producing reduced angles of vanishing stability are typically rejected at the loading-manual approval stage.