Wingsail

[3] Wingsails are of two basic constructions that create an airfoil, "soft" and "hard", both mounted on an unstayed rotating mast.

[4] L. Francis Herreshoff pioneered a precursor rig that had jib and main, each with a two-ply sail with leading edges attached to a rotating spar.

Englishman, John Walker, explored the use of wingsails in cargo ships and developed the first practical application for sailing yachts in the 1990s.

Wingsails have been applied to small vessels, like the Optimist dinghy and Laser, to cruising yachts, and most notably to high-performance multihull racing sailboats, like USA-17.

High-performance rigs are often assembled of rigid components and must be stepped (installed) and unstepped by shore-side equipment.

[3] Wingsails change camber (the asymmetry between the top and the bottom surfaces of the aerofoil), depending on tack and wind speed.