- Slamming is a common phenomenon as a ship navigates in rough seas, and it can cause severe structural damage to the hull structure. Full-domain Computational Fluid Dynamics (CFD) simulation of random wave and structure interaction is considered impractical by many researchers. Simplified approaches are usually adopted to alleviate the expensive CFD random wave simulation. In this paper, we present a rigorous methodology that solves the Navier-Stokes equations entirely without any need of matching. In our simulation scenario, a container ship cruising at a constant speed is allowed to heave and pitch in random waves. Both head sea bow slamming at 6 knots speed, and following sea stern slamming at 0 and 5 knots are studied. Irregular waves based on the Bretschneider spectrum for 25-year return sea states are used to simulate a realistic seaway environment. A very effective procedure is developed to capture the desired waves at a specific part of the sailing vessel. Our multi-block overset grid code is fully parallelized and greatly reduces the computation time to make the simulation practical. A level-set function is employed to capture the violent free surface and to simulate the interaction of the random wave and the ship. This rigorous Navier-Stokes numerical approach is able to capture complex mechanisms and show results that are possible only with CFD simulations, thus provides useful guidance for ship designs. Copyright 2014 by the International Society of Offshore and Polar Engineers (ISOPE).