In the last 15 years an increased number of serious damages of protective structures such as groins and revetments have been observed in maritime waterways. The analyses of these damages have shown that the current design approaches for the rubble mound layers of such structures are not sufficient to ensure sufficient stability against ship-induced wave loads. Since these approaches are determined for wind-induced waves, they do not consider the long-period ship-wave components. Within a joint research project, the design loads of ship-induced long-period waves on rubble mound structures in maritime waterways are investigated. By means of first project results, the knowledge gaps with respect to the classification and parameterization of ship waves have been identified. The project has clearly shown the need for a 3D analysis of three-dimensional, nonlinear ship-wave fields. Therefore, another research project was initiated in order to generate the scientific knowledge for the parameterization of ship-induced 3D wave fields as required for the hydraulic design of rubble mound structures in maritime waterways with a special focus on the spatial and nonlinear properties of ship waves.