Ports are more and more planned directly facing the ocean. Breakwaters are built to protect the berths against ocean waves. However, protection against long waves, mainly associated with wave groups at the ocean, is much more difficult. Calculations should be performed in the design stage of the port to verify whether the motions of the moored ships are vulnerable to waves from the ocean. In this problem it is not only required to have a good description of the waves in the port, but also a proper description of the interaction between these waves and the moored ship is needed. Two methods have been developed and are described in the thesis. The first solution focuses on the long waves with an infragravity wave model and a strip theory method for the forces on the ship. The second solution combines a Boussinesq-type wave model with a time-domain panel model. The first method is especially suitable if the berth is sufficiently sheltered for short waves, but if e.g. low-frequency harbour oscillations are expected. The method has the computational advantage that a large domain can be treated. The second method considers also forces due to short waves including second order wave drift forces and is therefore suitable for more exposed berths. The methods are verified against model test experiments and prototype measurements carried out in a port in Japan.