Concurrent advances in the large-scale deterministic simulation and prediction of nonlinear ocean wave-fields, wave sensing capabilities, large-amplitude ship motions predictions, control and optimization, and high-performance computing, have made it possible for the first time to radically increase the operational capability and survivability of ships in severe conditions. The goal is an integrated real-time deterministic predictive system that provides the optimal control commands and path selection for a single or networked vessels for a given mission and ocean environment. The main challenges to achieving this goal are associated with wave hydrodynamics — the sensing of the waves, and the deterministic reconstruction and forecasting of the wave-field based on the sensed data. In this talk, I will focus on the latter and the related developments that make the overall capability possible. I will also show a number of examples or demos of SWASH in realistic applications.