The effect of the dynamic loads due to waves is very significant and should be taken into account in the ship hull design. This is especially important for ships with a wider bow part such as container ships. Ship response to waves is a very complex hydrodynamic problem, and experimental trials to assess the seakeeping characteristics are very expensive and complicated. Much simpler and cheaper method is to use a variety of software packages. Most important definitions and equations for describing ship motions are given in this paper. The analysis of heave and pitch motions in time history domain is obtained in software packages WISDAM-X and HydroSTAR. The analysis is obtained for four different wavelengths where three were obtained for design speed and one was obtained for the speed greater then design speed. All analyses were made for regular head waves. Comparison was made for the heave and pitch motions calculated in the two software packages in the time history domain to give an insight into the differences between potential and viscous theory in determining the ship motions. To determine the accuracy of the two methods, heave and pitch motions calculated by numerical methods were compared with experimental data and the comparison gave satisfactory results. Sea state in which the ship operates is described with wave and ship response spectra. During the ship design phase it is necessary to ensure that the frequencies at which the ship response spectra and the transfer function reach maximum values are not the same frequencies to avoid resonance. The spectra of the waves and the response spectra are not time dependent but are frequency dependent so the heave and pitch motions are shown in frequency domain as well. Heave and pitch motions in frequency domain for model 1 and model 2 are calculated in the software package HydroSTAR and are compared in graphs. The maximum amplitude of the ship response occurs at different frequencies depending on the length of the model and the ship, so it can be concluded that the area of resonance depends on the main dimensions of the ship.