It is necessary to maintain certain maneuverability to perform missions or return to port for a damaged ship. In this work, the free-running turning maneuvers of a surface combatant with a damaged bow compartment are simulated numerically using an in-house unsteady RANS solver, coupled with the dynamic overset approach. The effects of damaged compartment on the turning capability are evaluated by several turning circle simulations of the ship with different initial floating/loading conditions and closed damaged opening. The numerical method is verified by grid/time-step convergence studies with free-running turning maneuvers, and the results have good matches with the benchmark data. The maneuvering parameters of the damaged ship towards the port side are compared against those of the intact ship, in which smaller turning circle as well as larger roll, pitch and heave motions are found in the damaged condition. The ship's initial conditions are adjusted to investigate the effects of changed heel, trim angles and increased displacement on the turning behavior of the damaged ship. It is proved that initial heel/trim angles have great impacts on the turning maneuvering but the increased displacement shows minor effects. The ingress and egress of floodwater will cause smaller turning indices.