The boat moves into the low pressure zone and is sucked forward. The wing’s advantages under sail include greater efficiency not just to windward—the wing-equipped boat points 10 degrees higher—but also on a reach, where it performs better in light air than the conventional rig. Beam reach: At 90° apparent wind, the wingsail, positioned across the boat, functions efficiently as a wing, providing forward lift, whereas the jib of the conventional sail plan suffers from being difficult to shape as a wing (the main sail is still relatively efficient). The wing tips often have small movable winglets, which decrease drag. A common misconception with soft wing sails is that just having an aerofoil section is enough. By James Wharram. “A wing lifts when the air pressure above it is lowered. The sail “lifts,” or moves, toward the lower-pressure side causing the boat to move. The best modern sailboats can sail as close as 17 degrees into the wind. The wing sail works because the air on the rear, or leeward, side of the sail travels faster than the air on the front, or windward, side. The rest of the time, a sail is essentially an airplane wing standing on end, and works the same way. How wings really work by University of Cambridge (PhysOrg.com) -- A 1-minute video released by the University of Cambridge sets the record straight on a much misunderstood concept – how wings … With a wing sail the pressure on the leeward side is lowest and air velocities are greatest around the leading edge. I start by giving the wrong explanation and asking who has heard it and every time 95% of the audience puts their hand up. Sailing for Beginners. The sail creates a low pressure zone in front of the sail and a high pressure zone behind the sail. With a triangular shape plan form, this becomes problematic as the lift coefficients need to be higher than lower in the sail. This happens because the sail isn’t a flat sheet of cloth, it’s curved, like a wing and the air traveling over the topside of the curved portion travels faster than that traveling on the underside. Whether you see the TIKI sail as an old fashioned gaff sail or a new evolved soft wing sail is a matter of dispute. Sails work by “catching the wind” only when the boat is sailing downwind. According to Bernoulli’s Principle this difference in speed creates a difference in pressure, the top side (our leeward side) having less pressure and the underside (our upwind side) having more. The wind fills the sail into the shape of a wing, but because the sail is held fast at both ends, the wind can't push it out of the way. Accidental jibes are a real and present danger when sailing wing on wing. This is a significant restriction that prevents many shapes from being built because they would not be able to support themselves in the wind. They are normally built from a flexible material in order to allow the sail to work with the wind on either side to allow tacking. It is useful to recognize what a typical sail is. It’s often said that this happens because the airflow moving over the top, curved surface has a longer distance to travel and needs to go faster to have the same transit time as the air travelling along the … As you can see, the curve of the sail causes the air particles on the lee side to have a longer way to go than the ones on the windward side. The tail parts of a plane include horizontal and vertical stabilizers, the former mimicking tiny wings in orientation and boasting elevator flaps , and the latter including a rudder, the airplane's primary means of altering horizontal course. This is very like the idea of an aeroplane wing, which is curved in a similar way to a sailboat’s sail as you can see below. As wind speed increases and the wing generates lift, the camber can be flattened, and the boat will sail even closer to the wind. How wings really work A 1-minute video released by the University of Cambridge sets the record straight on a much misunderstood concept – how wings lift. Drawings by Hanneke Boon 1997"It's a Gaff Sail", they say. A sail or wing with less area in the top requires a (relatively) higher lift co-efficient in the upper sections than one with greater area. Reefing the main is work, and when people are running, they don't want to work; Raising the topping lift will induce twist into the main and cause it to chafe on the rigging; Wing on wing is very prone to accidental jibes. A significant part of the benefit of a wing sail comes from eliminating the mast from the airstream. "No", I say, "What you and the wind are looking at is a soft Wing Sail." Sails are Flexible Wings. Instead the wind must change direction to flow parallel to the sail.