America’s Cup: the Wingsail

This video from SailingNewsTV explains what a wingsail is and how it works. A wingsail is similar to conventional sails. However, rather than being made of canvas or nylon or other flexible material, a wingsail is a built-up stiff structure made of carbon fiber composite or similar material, with an airfoil cross-section. The airfoil is shaped like an airplane wing, which the video shows can provide a much better lift-to-drag ratio than conventional sails.