Wingsails

Wingsails are a form of sailing propulsion in which the wind's energy is captured by a rigid or semi-rigid aerofoil-shaped sail mounted on a frame, often extending above a conventional mast. Unlike traditional fabric sails, wingsails generate lift by the airfoil principle, with the sail acting similarly to an airplane wing. The wing is usually fixed to a mast or separate rig and can be rotated to adjust the angle of attack. Some designs include endplates or winglets to reduce induced drag.

Wingsails may be fully rigid (a solid aerofoil) or semi-rigid with a rigid leading edge and flexible skin. They are trimmed by actuators that change camber, twist, or trailing-edge deflection. The structure must withstand significant aerodynamic and structural loads, requiring high-strength materials and complex control systems. Endplates minimize wing-tip vortices; some designs use multiple sections or flaps to vary camber.

Performance and considerations: Wingsails offer high aerodynamic efficiency, enabling strong upwind performance and good power across wind speeds. They can outperform traditional soft sails in steady winds but are more sensitive to gusts, require precise tuning, and entail higher costs and maintenance. In production boats they remain uncommon outside specialized racing programs.

History and usage: The modern wing-sail concept gained prominence with high-performance racing in the late 2000s and 2010s, notably in the America's Cup, where teams built large rigid wing rigs for foiling catamarans and other designs. Since then, wing sails have been the subject of ongoing experimentation in racing and research, with variants and control strategies continuing to evolve.