The present study is concerned with predicting the resistance and vertical motions of the surface combatant DTMB5512 ship model in regular head waves. A series of numerical simulations are performed for various wave lengths, heights and different ship speeds. Computations are performed by making use of the ISIS-CFD solver of the commercial software Fine™/Marine provided by NUMECA, where the discretization in space is based on finite volume method using unstructured grid. The unsteady Reynolds-Averaged Navier-Stokes equations are numerically solved while the turbulence is modeled by making use of the k-ω SST model. The free-surface is captured through an air-water interface based on the Volume of Fluid (VOF) method. Computed results are validated through direct comparisons with the experimental data provided by IIHR test cases. For the sake of numerical results verification, a grid convergence study is performed on four computational grids and a time step convergence test is also included. Validation of the numerical results shows a reasonable agreement with the experimental data.