The result of the previous validation study has shown a significant error especially for the prediction of course stability of an unstable ship. To improve the accuracy of the prediction, it will be required to estimate high accuracy hydrodynamic interaction among ship hull, propeller and rudder as well as hydrodynamic forces acting on a bare hull taking account of the detailed ship form such as stern profile and frame line. This paper describes a study on the application of CFD (Computational Fluid Dynamics) to ship's manoeuvrability prediction at design stage. A numerical method has been applied to compute flows around a ship with a rudder in several oblique motions. Calculated interaction forces between ship hull and rudder are compared with measured ones. From this study, it is found that this hydrodynamic approach would be useful for prediction of ship manoeuvring motion