This thesis is about the design of a virtual sensor-based predictor for an offshore, single body, floating sea wave energy converter called ISWEC (Inertial Sea Wave Energy Converter). The pitch rotation of the floater, due to the incoming waves, is combined to the flywheel spinning velocity generating an inertial gyroscopic torque. The Inertial Sea Wave Energy Converter exploits the gyroscopic effect to generate energy. In order to maximize the generated energy, a model predictive control algorithm based on the prediction of future values of the pitch component of the incident wave force, has to be exploited. However, since no sensor is available on the ISWEC for measuring the pitch force, prediction of future values of such quantity is a challenging problem.