Autark-Zero is the first motor sailer to be equipped with a wing-sail; this type of sail has gained name & fame in the America’s Cup high performance foiling catamarans. The Autark-Zero however, is not a high-performance catamaran, instead this yacht is aimed at sailors looking for a relaxing experience without the hassle of lines, winches, hoisting and lowering sails. A wing-sail has much higher lift-coefficient providing more forward propulsion than a traditional fabric sail. Using a A-symmetrical foil even more lift can be generated. The pressure and propulsion power can be adjusted by means of flaps at the front and back of the wing, when jibing the flaps change position so the A-symmetrical foil is maintained.
When the wing-sail is not in use the complete mast and sail assembly can be folded down and turns into a cockpit roof / bimini top. The raising and lowering of the wing-sail, like the control of the wing and flaps is a completely automated process. The central, on-board computer / autopilot effortlessly controls all moving parts and ensures the most efficient setting for the wing, flaps, rudders and dagger boards. The skipper and crew don’t need any sailing experience to enjoy a relaxing cruise on the Autark-Zero!
On november the 18th 2019 a patent is granted by the Rijksdienst Voor Ondernemend Nederland for the design/concept of the wingsail. The patent is registered under number 1042863 in the patent register with the description: ‘Sailing vessel with a center sail and two hinged side-sails of which the outer form resembles the form of an aircraft wing.’
With this, Green Marine Concepts hopes to eventually demonstrate in practice the use of a wing sail on a touring sailboat; and that the intended advantages over a conventional sail hold up in practice.
On a traditional sailing yacht the mast and sails only have 1 function: propulsion by means of the wind. On the Autark-Zero 3 functions are incorporated in the wingsail:
- sailing: the A-symmetrical wingsail generates with a proportionately smaller surface a higher lift hence an more efficiënt propulsion
- cockpit/bimini cover: When folded down the wingsail provides cover of the whole cockpit of the ship. The side flaps can be fully folded so the cover is open on the sides, when opened the flaps close of the sides of the cockpit to give shelter from rain or wind.
- solarcollector: the whole surface of the wingsail is covered in PV solar cells; totalling almost 30 square metre on the whole ship the generated electrical energy is more than enough to operate the ship autonomously (autarkic)
The concept of the wing sail is that it has an A-symmetrical profile; this will create a greater elevator force than a symmetrical profile with the same angle of attack. To create the A-symmetrical profile, a sophisticated design was made with flaps that fold in and out. When tacking; the mast then rotates 90 degrees, 1 wing flap folds in and the other out creating the same profile again. Using an A-symmetrical profile as a starting point, various analyses were done of the different profiles and the resulting differences in elevator, drag and stall behavior. This is a process of compromise; a modified profile was chosen in the tables/graphs shown here and below named with AutarkZero-clean.