This paper describes the application method of CFD (Computational Fluid Dynamics) to the ship manoeuvrability study on the initial stage of hull design. The present method is a method of estimating the linear derivatives of hydrodynamic forces acting on a hull, by using the correlation of CMT (Circular Motion Test) data and CFD computations on two conditions of oblique towing (β=6deg.) and circular motion (r'=rLpp/U=0.2) without drifting angle. Hydrodynamic forces acting on a hull in manoeuvring motion can be calculated by the combination of the linear derivatives obtained by the method mentioned above and the nonlinear ones estimated by CMT database. Authors applied the present method to the estimation of the hydrodynamic forces measured by CMT and the manoeuvring motion at Sea trial, and confirmed its validity.