The problem of water shipping is studied by assuming two-dimensional flow conditions and using both experimental and numerical tools. Experimentally, the water on deck for a fixed barge-shaped structure has been analysed. Video images of the water-shipping events were recorded, wave elevation in the wave flume and pressure on a vertical superstructure along the ‘ship’ deck have been measured. Numerically, a boundary element method for unsteady nonlinear free-surface flows was developed and used for the analysis of water-on-deck phenomena. A comprehensive comparison between experimental and numerical data gave satisfactory agreement globally. The synergic experimental–numerical analysis highlights the main flow features during the water shipping and details of the water impact with the deck structures are discussed. In the model tests, the water on deck started as a plunging wave hitting the deck and entrapping air. This could be relevant for deck safety, but appears to be less important for the global evolution of the water along the deck and the later liquid interaction with the superstructure. The green-water loads on the vertical wall showed a two-peak behaviour typical of wave impacts.