Fast boats often operate in planing regimes when they skim on the water surface and their weight is supported primarily by hydrodynamic forces. In the presence of waves, such hulls may experience large nonlinear motions and hydrodynamic loads, which limit their operational capabilities. To predict hull motions and loads and to optimize the hull shape and structure, one can take advantage of computational fluid dynamics tools that simulate these complex nonlinear flow processes and provide detailed hydrodynamic data, including pressure distribution on the hull and water spray. However, validation of these modeling approaches is needed in order to confidently use numerical tools for the boat design. In this study, numerical modeling is accomplished for dynamics of a realistic hull previously tested in controlled wave environments in towing tanks. Time-domain simulations were first carried out in regular head waves. Mesh-verification studies suggested appropriate numerical grid resolution. The hull’s heave motions, drag forces and bow accelerations were captured and compared with experimental data. The formal validation procedure was applied to confirm suitability of the current numerical approach. In the investigated regular-wave conditions, very pronounced slamming phenomenon was observed, when the hull re-entered water and experienced peak hydrodynamic loads. Pressure distributions on the hull surface and water surface deformations are presented for several time instances around the slamming event. In addition, numerical simulations were also conducted for random waves with statistical sea-wave parameters resembling those of the studied regular waves. The statistical boat responses, such as bow accelerations, heaving motions and drag forces, are compared to the corresponding metrics obtained in regular waves.