The present study deals with the influences of wave directionality on a generic point absorber. The work presented here, shows how the dynamic of axisymmetric wave energy converter can be affected when one consider a realistic wave spectrum. For this purpose a non linear numerical model was used. The fluid structure interactions are modelled by means of a bending method where the Froude-Krylov forces are non linear and the radiation-diffraction problem is solved by using a linear method. Mooring loads are modelled via a finite element method. A compliant catenary mooring system composed by 4 mooring lines is hence used. Different models of sea spectra are used to approximate a real sea spectrum. The differences between them are discussed and comparisons on the body motions are commented.