Andy Pitt

WINGS AROUND THE WORLD

Imagine there was a way of hassle free silent sailing with a controllable power source which could manoeuvre a vessel in any direction. Imagine also being able to do it all inside from a dry warm (or air conditioned) pilot seat using a power source which would allow all people, regardless of age, gender or physical handicaps to simply get out sailing and enjoy the sea. In short, almost a motor yacht without an engine and free of the word ‘fossil fuel’. Well the technology to do all this and more has steadily been developing during the last thirty years. It came, was developed, but did not stay long, at least not yet. Initial concept:

During the late 1960’s British Aerospace Engineer John Walker decided a new approach to powering yachts was both practical and timely. Low velocity Aerodynamics has a wonderfully technological ring to a science which has been known to sailing ship crews for thousands of years. The passage of air over an angled surface or plane creates an increase in pressure on one side and a decrease of pressure on the other. It is the decrease in pressure on the curved surface of a sail or wing, which is the driving force. The design of sailing ships their rigs and sails have changed vastly through the centuries as commercial and sporting pressures come to bare. The present day kevlar sails used on racing yachts may appear to present the peak of this technology but it seems unlikely development has reached the end of the line. Using aircraft technology and a new approach the first wingsail yacht ‘Planesail 1’ was built by John Walker and launched in 1968. This was followed by several other prototypes including ‘Flyer’ in 1981. All the yachts showed a marked increase of aerodynamic efficiency over the convention cloth sail. With the unexpected oil crisis during the 1980’ a major way point in the project was to unfold. Soaring oil prices on the international market made the wingsail system suddenly appear as if its day had come. A very powerful wingsail weighing seven tons was built and fitted to the 6,570 ton bulk carrier ‘Ashington’. Sea trials on this large commercial ship proved beyond doubt a considerable saving on fuel (some one wrote that at least 10%) could be achieved and it became worthwhile to build wingsails for commercial ships. Within a short time however oil prices fell again and the project was doomed.

Not to be beaten, John and Jean Walker looked again at the leisure boat market and in 1989 ‘Zefyr’ was built and successfully test sailed. This was a great step forward but it was the next yacht, ‘Blue Nova’ launched in 1990, which really turned heads and made the project world renown. Designed by John Walker and built at his company ‘Walker Wingsail Systems’ of advanced epoxy laminates often used in high tech aircraft, ‘Blue Nova’ at 55 feet proved a success. She was launched in 1990 and following sea trials sailed from Plymouth (UK) bound for the US in August of 1991. On board was John Walker his wife Jean and their son. Unbeknown to them at the time hurricane ‘Claudette’ was building in mid Atlantic. Powered by a powerful bi-plane wingsail ‘Blue Nova’ was fast, even when loaded with all the stores for an ocean passage she occasionally sailed at eighteen knots. It took seven days to sail from Plymouth to the Azores and after a short break they continued west across the Atlantic. In mid ocean ‘Blue Nova’ and her crew met violent winds and mountainous seas of Claudette. One can only imagine life on board a small vessel in such weather but ‘Blue Nova’ suffered no damage. What ever ones opinion of this type of vessel it has to be said that despite severe weather and at least three hurricanes none of the wingsail yachts have so far suffered damage, lost control or broached. ‘Blue Nova’ arrived in Bermuda and sailed on to New York where she was met with great interest. The followed a ten months was spent demonstrating the boat along the eastern seaboard. She then re-crossed the Atlantic returning to Plymouth in June 1992. During both Atlantic crossings the boat often had daily runs of 200 miles in twenty four hours miles, which again for a loaded cruising boat is not to be sneered at. This voyage had proved beyond doubt that wingsail sailing was fast and safe for long voyages.

How it’s made: The wing-sail is made in much the same way as a normal aircraft wing is built. The leading edges of the wing, flaps and tails are moulded of lightweight epoxy ‘nomex’ laminates. Ribs of PVC foam or press moulded epoxy/glass are added and the completed structure is covered with aircraft cloth. After ironing to tighten the cloth the material is coated with aircraft dope. The wing, flap and tail section are then painted with high gloss marine paints. When completed with controls and fittings they have a very distinct aircraft feel and quality about them. On the base of the wing is a large diameter specially designed self-lubricating bearing. The wingsail obviously has no rigging so the stresses are transferred through the complete vessel via a ‘spider’ moulding rather like the roots of a tree. The flap is positioned on the forward edge of the wing instead of the conventional trailing edge and can move from full port though negative to full starboard. The tail section, necessary on all wing-sails either mono or mulitiplane, is like the tail plane on an aircraft and controls the wing. Above the main support bearing is the main boom which supports the wing and the tail. In this boom is a small amount of lead ballast to balance the complete wing structure. The wingsail is slightly more expensive than a conventional rig using cloth sails but the aircraft cloth used to cover the structure is estimated to last twenty years. With the wing up and ready to go at any time it is as fast to get to sea as a motor yacht.

How it works: Sitting on its main support bearing when disengaged the wingsail rotates freely to the movement of the wind just like a weather vane. Main controls differ considerably from the conventional sailing yacht where rope sheets and winches are used to adjust the sails to the best angle and effect. The wingsail has an aircraft style instrument panel and pilots seat where the wing is controlled by an on board computer system called ‘Micro-mariner.’ This is normally powered by solar panels and is very reliable but a manual control is fitted as a back up. The steering wheel is connected to a conventional rudder. Positioned to the left of the helmsman the thrust control lever is rather like the throttle on a motor yacht. By adjusting this lever the wing is configured for optimum thrust. Unlike cloth sailed sailing yachts the wingsail has a very special way of sailing to windward. Cloth sails are firmly tied to the yachts decks and hull so wave movement will constantly change the angle of attack (angle of the wind to the sail). By comparison the wingsail is freely trimming and cancels out the effect of seaway motion, maintaining a constant optimum angle of attack. The wingsail is three times more efficient sailing to windward compared to a cloth sail of the same area. The precise control of the wing to the wind allows the boat to have remarkable handling ability. The yacht can sail sideways, slow down, brake and even sail backwards.

Attitude to wingsail sailing: Like all things new, particularly in the boat world, there’s a good deal of prejudice and uncertainty about the concept and as a traditionalist I’m no exception. At first it all appears ‘very strange’ but after a closer look it becomes obvious there are some serious advantages that have never been available before. Any boat than does not drag a third or more of its weight about in a ballast keel must be worth a second look. The main reason many have ‘steered away’ from multi hulls is the fear of a capsize. We have all heard of the thrill of high-speed sailing but also of the inverted dramas and the hopelessness of righting the boat. Capsize from strong winds are less likely on a trimaran than a catamaran and they say ‘unknown’ with a wingsail as the wind cocking effect of the wing makes it impossible for the wind to get any leverage on the boat. The computer senses the pressure of the wind on the wing and adjusts it to give maximum thrust which if over-loaded weathercocks in neutral. It’s perhaps a mistake to compare the wingsail directly with a cloth sail. Both harness the wind as a driving force but should be seen as two completely different power systems. Some say the overall way the wingsail boats are operated makes them more like motor yachts than sail. The wingsail should perhaps be seen as a third power source for yachts, separate and in its own league.

Obviously the wingsail will never replace the cloth sail and they are ideally fitted to trimarans. Due to the need of a tail plane the system requires a large turning circle. It would thus not be practical to fit the system to a mono hulled yacht as the ‘boom travel’ with the tail plane would be well out from the maximum beam of the vessel and could damage other vessels in marinas.

The wingsail is however more efficient, having at least twice the driving power of a traditional cloth sail of the same square area. In fact it is so efficient the wingsail is three times more powerful up wind than the cloth sail. For many the loss of fighting wet sails at night on a bucking fore deck or breaking your back grinding winches each time you tack has its appeal.

The Zefyr 43 ‘Blue Nova’ and her successful voyages was a proving ground in other many aspects. They were also used in market research and creating such an interest in sailing circles the inevitable feedback was put to good use. Following the ‘Blue Nova’ project John Walker decided the time had come to put his concept into full production. The Zefyr 43 was designed and the first production hull was pulled in 1996. She is a forty three-foot triamaran built of epoxy and carbon fibre laminates with a raked monoplane wingsail. At forty-three feet these boats were designed and aimed at a specific market. The owners are invariable mature couples or families who may lack the stamina or lust to wrestle a wet sail at night. They may have previously owned a motor yacht, like the power and ease of handling but not the noise, the fuel bill or cruising range. They are also often people who want to continue sailing but are short handed or simply not as active as they used to be. The Zefyr 43 was quite easy to sail and quite often wives who have never sailed before have picked it up during an afternoon. The new wingsail used on the Zefyr 43 had a single wing and tail section and looks by far the best of all the wings so far. It’s designed by aircraft engineers to withstand winds of a hundred knots. Advanced wind tunnel tests were successfully carried out at Southampton University and with British Aerospace.

The First production Boats: Z/001 ‘Sea Change’ was launched in 1996 and sailed to the USA. As far as we know she is still in good health and is presently in Florida. The second boat, ‘Ocean Tern’, was sold to a Scottish owner and was used on the locks and coastal waters of Scotland. Boat three, (Z003) was christened ‘Angel B’ by her Dutch owners Art and Suzan Loose. The boat was launched in May 1998 and sailed from Plymouth to Portugal on the first leg of their three year world cruise. They spent some time in Lisbon before sailing across the Atlantic to the West Indies. This couple eventually sail ‘Angle B’ around the world and back to Holland without any damage to the yacht or gear. Not the first wingsail to cross this ocean but no less of an adventure for the Dutch owners.

The future: Due in part to prejudice of the design and internal shareholder strife the project closed in late 1998. It’s not everyone cup of sailing tea but there’s no doubt some clear advantages of this revolutionary sailing system and it is just a question of time before we hear of the next group to take up the challenge; I have an idea it may well be in Asia.

Copy Ends.