For the second order calculations, the forcing in the free surface boundary condition must be integrated over the entire free surface. This is only necessary in the case of the complete second order so- lution, since the approximated solutions do not consider the free surface forcing. Free surface integration is done with an asymptotic approximation in the region away from the body. Close to the body, it is necessary to discretize the free surface with quadrilateral panels. This allows the forcing integration by means of a piecewise integra- tion. An annulus of panels distributed around the body is defined where the quadrature integration is performed. In the region outside this annulus, the integration is performed in a semi analytical way based on the asymptotic estimate of the integrand, as described by Lee [ 13 ].