Hydrodynamic forces acting on a ship hull can be obtained by model tests or theoretical prediction methods. Needless to say, precise hull shape is required to build model ship or to carry out calculation based on the theoretical prediction methods. Therefore these procedures are not suitable for application at the design stage. Simple and accurate prediction method for the evaluation of ship manoeuvrability is demanded for utilization at the design stage.

　

 Kijima & Nakiri [18] had proposed prediction formulae for hydrodynamic derivatives for even keel condition which consist of parameters such as ship length L, breadth B, draft d, block coefficient Ch and some coefficients which express the characteristics of frame lines on aft half hull as follows, k is defined by 2d/L, ea & e'a express fullness of aft run and σa is aft sections fullness metric respectively. K is the form factor. These parameters are defined by principal particulars with water plane area coefficient Cwa and prismatic coefficient Cpa of aft half hull between A.P. and s.s.5:

　

　

　

　

　

　

　

　

 The approximate formulae for even keel condition shown in equation (5) & (6) had obtained by using model test results data base involving 15 kinds of ships (container ship, bulk carrier, tanker, cargo ship and so on) and their 48 loading conditions. Simultaneously approximate formulae for trimmed conditions had pro-posed as follows,