The depth of water at 40 points on a deck and the impact pressure acting on a water breaker were measured with a model of S-175 container ship in regular head waves. Then, the numerical simulation on shipping water in time domain by the Method of Characteristics, were carried out to recognize the complex phenomena. The expanded deck is introduced to simulate the wave spreading from the deck. The following simplified conditions are selected for the numerical simulation. (1) The wave heights along the boundary of the deck are given by the measured results. (2) The model ship does not move. (3) The speed of a water particle along the expanded boundary is that on the far field. The followings are found from the test results and the numerical simulated results. (1) The wave height of the simulated results are in good agreement with the measured results. It shows that the Method of Characteristics is effective for the analysis of the shipping water. (2) The predicted impact pressures acting on the water breaker are in good agreement with the measured. (3) In the higher wave height, the water on deck is concentrated along the center line and it crashes against the water breaker. In the lower wave height, the water on deck is also concentrated along the center line and the water spread to every direction.