Ship manoeuvring motion is usually treated as a coupled motion of surge, sway and yaw in a horizontal plane. However, if transverse metacentric height GM is small and ship speed is high, we cannot neglect effect of heel on ship manoeuvrability. In such a case, estimation of ship manoeuvrability by numerical simulation needs to estimate heel effect on hydrodynamic forces acting on a ship in manoeuvring motion. In this paper, the author apply one estimation method of hydrodynamic forces acting on a heeled ship hull, and show that this method is useful in order to estimate heel effect on hydrodynamic forces acting on a ship in manoeuvring motion. This estimation method is derived by extending the method that was proposed before by the author. As to heel effect on hydrodynamic forces, published experimental data show that sway force becomes small and yaw moment becomes large as heel angle becomes large outwards in turning motion, and that heel effect on hydrodynamic forces become large as drift angle and turning angular velocity become large. Agreement between calculation results by this estimation method and experimental results is not necessary sufficient quantitatively, but is good qualitatively. These calculation resuls explain heel effect on hydrodynamic forces well globally. Therefore this estimation method is useful as a tool for a quick check of heel effect on hydrodynamic forces acting on a ship hull in manoeuvring motion.
