There is concern over the occurrence of huge earthquakes in the Nankai Trough, located in the Pacific Ocean off Shioku Island and Ki-i Penisula, Japan. It is estimated that there is a 50% possibility of a tsunami being generated by the earthquake in this area in the next 30 years. A tsunami attack on the coastal area of Japan would not only raise the height of the sea level, but also create strong horizontal flows in bays and ports. There are so many huge power plants and factories along the coastal area in Wakayama Prefecture and Osaka bay. Any ships entering or leaving ports near such areas would be subject to move by these strong lateral flows unless appropriate measures of ship handlings such as quick evacuation maneuver and/or anchoring are taken. The phenomena would generate uncontrollable motion, subject piers to tremendous forces, slam ships into breakwaters, set vessels adrift and ground them. Thus, it is very important from the viewpoint of marine-disaster prevention to understand such phenomena and ship motions and to consider the counter actions.

 It is considered that computer simulation runs according to reliable mathematical models are most effective to estimate and investigate such ship behavior under tsunami attack because that it takes a lot of time and budget to carry out ship model experiments under tsunami attack. It is shown in this paper that ship maneuvering simulation models and evaluations results by use of computer calculations.

 First, this paper describes mathematical models of tsunami flow and the maneuvering motions of vessels in navigation and mooring conditions. Next, simulations of evacuation maneuvering from a tsunami attack in offshore area of Wakayama prefecture are carried out. Then, the lateral behavior of the ship at an evacuation area in mooring conditions under a tsunami attack is shown.