In windsurfing, pumping is a reference technique for improving sailing performance and speed. This technique depends on both navigation and athlete physical conditions. For coaches and athletes, the masthead trajectory during pumping is a good indicator to identify the technique being used. In this way, a method based on geometric model used in robotics is proposed to track masthead position using inertial sensors. The proposed mathematical model was validated by simulation; to study the performance of the proposed inertial-based tracking system, preliminary measurements have been carried out indoor on a commercial mast foot. The accuracy of the angles deduced from the inertial sensors measurements was investigated by comparison between the mast foot attitude obtained from nertial sensors' data and from a commercial video-based tracking system taken as reference. A maximum mean error below 10% has been found and the recreated top mast foot trajectory from inertial sensors showed a good similarity with that obtained from the video-based tracking system.