InOffshore wind this contribution, we present a systematic study aimed at understating the effects of some key features of the floating system on the dynamics of a 10 MW Floating OffshoreOffshore WindOffshore wind Turbines (FOWTs). Since FOWTs are prone to dangerous resonance phenomena that can be overlooked if the mutual dynamic interactions are not properly considered, the focus of the present work is placed on how the natural frequencies of some selected degrees of freedom are affected when, for a given platform concept, some geometric parameters are changed. This is done by performing modal analyses of the system considering the contributions stemming from the platform and the mooring system, varying the floater mass matrix, zero-frequency hydrodynamic added mass, hydrostatic stiffness matrix, and moorings stiffness matrix. Moreover, the effects of the mooring system characteristics, such as cable length, anchor, and fairlead positions are taken into account. Results show that for some of the investigated platform geometries internal resonances may occur.