Abstract
A component-type mathematical model of hydrodynamic forces acting on a hull in steering motion have been developed by means of simplified vortex systems by us. This paper proposes the mathematical model modified to improve the accuracy of cross flow forces in ship's pivot turning motion. The modification of the model is supplemented by the effects of vertical bound vortices located at midship part generated by the cross flow in ship's turning motion, which compose a pair of ring vortices with horizontal bound vortices and contribute to lateral forces as the interactive forces of cross flow vortex system. The model was applied to experimental data of four model ships in the pivot rurning motion and could describe very well the experimental data.
