Atwood's formula

Atwood’s formula gives the righting arm GZ at large heel angles, where the metacenter no longer holds, by accounting for the cross-transfer of buoyancy between the emerged and immersed wedges. In the form GZ = (v * gg1 / V) minus BG * sin(theta), v is the wedge volume, gg1 the horizontal shift between the wedge centroids, V the displaced volume, and BG the vertical separation of B and G. The first term is the buoyancy shift; the second corrects for the height of G above B. It underlies the cross-curves (KN) of stability and the GZ curve used in IMO 2008 IS Code checks. Named after Atwood and Vial (1796).