Like other offshore structures, floating wind turbines are subjected to stochastic wave and wind loads that cause a Dynamic Response in the structures. Wind turbines should be designed for different conditions, such as Operational and Survival conditions. In high sea states, the Response can be quite different from the operational condition. The present paper deals with coupled wave and wind induced motion in harsh conditions, up to 15 m significant wave height and 50 m/sec average wind speed. There are several ways to deal with the Dynamic Response of floating wind turbines. The Coupled Time domain Dynamic Response analysis for a moored spar wind turbine subjected to wave and wind loads is carried out using DeepC. DeepC is well known software for calculating the coupled Dynamic Response of moored floating structures. The aeroDynamic forces on a parked wind turbine are calculated, based on the strip theory, and imported to the DeepC through a MATLAB interface. At each time step, the relative wind velocity, based on the Response of the structure, is calculated.