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The earliest use of aircraft type wings to propel ships, so far as we know, was proposed by Anton Flettner in Germany just after the First World War.
As well as a successful and prolific inventor, he must have been a great salesman, because after making a modest fortune from the Flettner rudder, with which more than a dozen ships were fitted, he persuaded the board of Krupps to re-rig an elderly barquentine, the Buckau, with a revolutionary set of metal vertical wings, which would be angled to the wind for control purposes, like an aircraft, by a downwind tail.Work had already started in the giant Krupps yard in Hamburg when Flettner, on holiday on a Baltic island, was taught how to swerve a tennis ball by applying spin. Later that afternoon, relaxing on the beach, he was idly pouring sand grains down the slope of the dune while twisting a tennis ball in the flow. Suddenly, he realised that by spinning a tall vertical column in the breeze a propulsive force, more or less at right angles to the wind, would be generated.
Excited by this new concept, he rushed back to Berlin, and told the astonished board of Krupps that he no longer wanted his aluminium wings, he wanted tall spinning rotors.
As we have said, he must have been a super salesman, because Krupps agreed to scrap all work on the metal wings, and to replace them with tall metal rotors. The Buckau became the world's first, and almost the last, rotorship.
Flettner had in fact, in our opinion, made a serious mistake. His rotors, spun round by a steam donkey engine, certainly gave plenty of thrust, but the aerodynamic efficiency, the ratio of thrust across the wind to drag downwind, was not much better than the original cloth sail rig of the barquentine. So the Buckau could broad reach beautifully, but was pretty terrible at going towards the wind.And to make matters worse, there was no way to reduce the aerodynamic force from the rotors in strong winds. The poor Buckau could become “embayed” on a lee shore, desperately reaching backwards and forwards across the wind, unable to sail upwind and out of trouble. And finally, of course, if the steam donkey engine broke down or ran out of steam, there was no drive at all, just (too much) downwind drag.
The rotorship project fizzled out after one more ship, the Barbara, was built. We strongly believe that Flettner should have stuck to his original idea, because modern Walker-type thrustwings can survive hurricane strength winds, exert virtually no force on the vessel when put into neutral, and are highly efficient, so that wingships can sail very close to the wind. Best of all, small thrustwings can be operated by hand, while even much larger ones need very little power to operate. And they can be computer controlled, so that capsize and overpowering can be eliminated. A simple hand lever, like that of a power boat, gives thrust ahead, thrust astern or neutral, and tacking and gybing, to go from sailing with the wind on one side of the boat to sailing with the wind blowing on to the other side, can be completely automatic. You just steer the boat on to the new course, and your thrust wing does the rest.
After Flettner an occasional specialised wing was used on racing or experimental craft, and in Norway during the second world war Fin Utne built a dear little boat called “Flaunder” which worked just as Flettner's aluminium wings might have done twenty years before. Sadly, Norway was then occupied by the Axis powers, and “Flaunder” was confiscated by the Gestapo as a potential weapon of war, and destroyed.
The first truly practical wingsail boats were built by Walker Wingsail Systems plc (WWS) in the UK. In 1986 they put a big wingsail on a 6,500 ton dry cargo vessel, which could save up to 20% of her fuel costs, and then, when the price of fuel plummeted, they turned their hands to a range of trimaran yachts. The first WWS wingsail yacht was Blue Nova, a 54 foot twin wing trimaran. She carried the Walkers across the Atlantic to the US in 1991, safely negotiating Claudette, a category 3 hurricane, and back again.
She was sold in 1997 and was extensively modified by others for her quadraplegic owner. She has since been sold on again, and is currently awaiting major refurbishment.
In total four 45 foot Zefyrs have been completed, and all remain in successful service.
Zefyr 1, Sea Change, delivered to her first US owner by the Walkers in 1995, has been beautifully restored by Don Tugcu in Miami.
Zefyr 2, Ocean Tern, owned by Terry Harper, is sailing out of Long Beach in California.
Zefyr 3, Angel B, owned by a Dutch couple, Arth and Suzan Loos, has recently completed a full circumnavigation of the globe. She is usually stationed in South Africa.
Zefyr 4, Larinka, was completed for James Wright after the failure of WWS. He is currently undertaking a full programme of work to bring her up to the best possible specification.
All these Zefyrs can be made available for inspection and demonstration by prior arrangement through the company.