A Reynolds-Averaged Navier-Stokes (RANS) method has been employed in conjunction with a chimera domain decomposition technique for time-domain simulation of transient flow induced by a berthing DDG-51 ship undergoing translational and/or rotational motions. The method solves the mean flow and turbulence quantities using an arbitrary combination of embedded, overlapped or matched grids. The unsteady RANS equations were formulated in an earth-fixed reference frame and transformed into general curvilinear, moving coordinate systems. A chimera domain decomposition technique was employed to accommodate the relative motions between different grid blocks. Calculations have been performed for a DDG-51 guided missile destroyer in translational and rotational motions to demonstrate the capability of the chimera RANS approach for time-domain simulation of the ship and berthing structure interactions. The numerical solutions successfully captured many important features of the transient flow around berthing ships including the underkeel flow acceleration, separation around the bow and stern area, flow recirculation behind the ship, water cushion between the ship and harbor quaywall, and the complex interaction among bow, shoulder and stern wave systems.