Abstract: An accurate and efficient 2-D time-domain coupled model fornonlinear wave forces on a ship in a harbor is developed in thepresent paper. The whole domain is divided into an inner domain and an outerdomain. The inner domain is the area around the ship, where the flow isexpressed by Laplace equations. The other area is the outer domain,where theflow is expressed by Boussinesq equations. Matching conditions on theinterface boundaries between the inner domain and the outer domain are thecontinuity of volume flux and the equality of wave elevations. Theprocedure of the coupled solution and the length of the common domain arediscussed in detail. In addition, the boundary element method in complexvariables isadopted to verify the coupled model and the relevant physical experiment isconducted to validate the two numerical models. It is shown that thenumerical results agree well with experimental results, but the computationalefficiency of the boundary element method is much lower than that of thecoupled model, so the coupled model can be used for the wave motions in aharbor with large area and is especially useful for the study on the effectsof harbor boundaries and bottoms on wave forces of a ship.