The paper follows a previous work of the author that dealt with ship resistance and self-propulsion numerical investigations, proposing a series of numerical simulations performed to assess the seakeeping performances of the KCS model which moves in regular head waves. Various simulations of the free-surface flow around the hull equipped with rudder moving either in calm water or in heading waves are proposed. For the calm water case, in which a series of six Fr numbers is considered, verification and validation based on the grid convergence tests are performed. Then, a series of five different simulations for various incoming wave characteristics are presented and discussed in every detail. Comparisons with the experimental data ,  are provided aimed at validating the numerical approaches in terms of the total resistance coefficients as well as the heave and pitch motions characteristics. Several remarks will conclude the findings of the present work.