The differences in estimated motion are caused by the difference of predicted hydrodynamic derivatives. Therefore, the relation between the hydrodynamic derivatives and estimated lateral force and turning moment acting on the hull are discussed. Fig. 3-1 show the estimated total force and moment acting on hull are indicated at initial turning situation and steady turning motion. Fig.3-1(a) also show the contents of total force and moment based on the each hydrodynamic derivatives. The condition of initial turning means the moment of turning angle 30 degree and steady turning condition means the moment of turning angle 180 degree. The force and moment are estimated based on the motion at the time. Predicting force and moment in case of limited range data, the motion at same motion situation estimated by using whole range data is applied. Vertical axis indicates estimated forces and moments. Fig. 3-1(a) show the force and moment at turning angle 30 degree. The forces and moments concerning linear derivatives are bigger than non-linear term's. The difference relating to the experimental range are small with regard to initial turning situation.