In order to forecast maneuverability of ships,based on the correlation analyses and statistics functions of the SPSS software,two formulae of estimating K and T are obtained through multinomial regression analysis of 59 ships' K and T statistical data.Considering the nonlinear effects of ship forms,two four-element,second-order polynomial regression equations are set up.Also,this regression equation can be used more extensively by including some smaller ships,such as fishing vessels.Compared with existing regression model,the model improves the precisions of the multiple correlation coefficients of K and T by 8.5% and 7.2% respectively.Besides keeping the explicitness of existing regression equation,the polynomial regression equation improves precision of data fitting and simplicity of regression polynomial.It is valuable in navigation practice for sailors to evaluate ship maneuverability.