An efficient implicit/multigrid algorithm has been developed for obtaining the free-surface turbulent flow solutions around an advancing ship. The artificial compressibility form of the three-dimensional incompressible Navier-Stokes equations is solved using an approximate Newton relaxation approach. The multigrid scheme and local time stepping method are applied to accelerate the convergence of the solutions. The nonlinear free-surface conditions are implemented and the re-gridding technique is used to treat the free-surface deformation. Computed results of the free-surface flows around a Series 60 (C_B=0. 6) hull were presented to demonstrate the efficiency and accuracy of the present algorithm.