Method of reducing the roll amplitude of a deep-vee hull at zero speed

A series of resistance and roll decay model tests are conducted in order to solve the large roll amplitude problem of one kiloton deep-vee ship with zero speed under rough sea condition. The roll re-sponse in regular waves is first obtained by solving the nonlinear roll motion equation, and the roll ampli-tude of the full scale hull in seaway is then predicted in the ITTC wave spectrum. The influences of length, width, location, and continuity of blige keel on resistance, roll damping, and roll amplitude are studied, re-spectively. The results indicate that incorporating a kind of bilge keel can reduce the rolling amplitude at zero speed by 25% and control the drag addition within 4.5% from cruising speed to maximum speed. These tests provide technical support to reduce the roll amplitude of kiloton deep-vee hull under the moor-ing state in seaway.