When setting up the rig, the two mains are hoisted up the A-frame legs, and the leading edge slides up the tracks in front of the mast.

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The angle the boom makes with the leading edge, can then be adjusted to control camber by bending the battens of the double-skinned mainsail, allowing camber to be controlled either manually or electronically.

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Once underway the helmsman has just two sail controls to deal with: the mainsheet and the hydraulic ram that controls the camber.

Despite having 15 percent less sail area, Omer wing-sail outperforms the conventional rig on every point of sail except dead downwind. A gennaker can be set to improve downwind speed.

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The wing’s advantages over sail include greater efficiency not just to windward. The wing-equipped boat points 10 degrees higher, but also on a reach, it performs better in light air than the conventional rig.

While pointing, as wind speed increases and the wing generates more lift, the camber can be flattened, and the boat will sail even closer to the wind.

Below about 135 degrees, the Drag becomes the driving force instead of Lift and the gap between Wing sails and conventional rig closes, until the greater sail area takes the lead going dead downwind.

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The reason for this increased performance is that:

a. The wing has an aerodynamic profile with higher Lift/Drag ratio than two dimensions conventional sails. The product is greater driving force. 

b. Wings work best at lower angle of attack (the angle of a line drawn between the leading and trailing edges of the sail and the apparent wind direction) than a conventional sail, and the lower the angle of attack the higher the boat can point.

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The angle of attack on an Omer wing is between 0 and 10 degrees, while on a typical conventional rig it is never less than 15-20 degrees, and can be as much as 90 degrees on a well-eased headsail. This lower angle of attack translates into less heeling moment and more driving force.

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Tacking takes 5 seconds only and is pretty much a case of putting the helm over and pushing a preset button that changes the camber. 

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The Omer wing has two reefs, which can be managed from the cockpit. Should the boat be overpowered by a gust, all you have to do is let the mainsheet go and the sail will feather with no slams across the boat.

(SAIL/May 14, 2014)

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