Velocity prediction program for windsurfing: A hierarchical approach integrating biomechanical insights

Abstract

Windsurfing sails have three degrees of controllable angular freedoms and rely heavily on the sailor’s gravity to balance the heeling moments. The position of the sailor’s centre of gravity that affect the moment generation is greatly influenced by the posture. These factors result in the complexity of predicting windsurfing velocity during steady sailing, which is shown to be an under-defined problem. To address the challenges, this study proposes a hierarchical approach. At the lower levels of the hierarchy, a mechanical model of windsurfing is constructed by incorporating a tailor-made biomechanical model of the sailor, as well as the aero- and hydrodynamic properties of the sail, board, and sailor. The mechanical model allows the investigation of control variables that lead to different steady states, including sail roll, yaw and hydrofoil roll. At a higher level, these variables are optimized to maximize sailing speed. The proposed approach provides intermediate results that explore factors affecting sailing velocity, such as sail and board orientation angles, the sailor’s center of gravity, and wind conditions. Furthermore, the approach generates a velocity polar chart that illustrates the maximum sailing speed for different travel directions. The chart indicates the maximum VMG and optimal sailing angle for achieving an upwind or downwind mark. This study contributes to a deeper understanding of the critical variables influencing windsurfing velocity and provide insights for improving sailing performance.