Accurate estimation of the drag coefficient of sea-ice is very important for reliabile prediction of seaice behavior. For improving the accuracy of the drag coefficient, we have carried out a measurement of wind and turbulence on the sea of Okhotsk on board of the ice-breaking patroll ship Soya of Japan Coarst Guard. In this study, we evaluated the influence of the superstructure and the hull of ship on the measurement of wind and turbulence by numerical simulations using a commercial CFD code Fluent (Fluent Inc.). The simulations of wind flow around the full scale ship indicated that the measuring instruments should be located at least 6m above the front-deck or at least 4m away from the bridge-house towards the upwind direction.