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Peter Lynn

October 2006

How Not To Go Kitesailing

I'm just back from 2 months away- and leaving again in just two days.

It's a life, but one day I really should settle down.

The following is a compressed version of the address I gave last weekend at the Drachen Foundation's seminar on kite sailing held in Seattle.

Entitled "How Not To Go Kitesailing", it's a history of my kitesailing related prototyping and testing (with the help of various fellow travellers and crash test dummies) from 1987 until now. I'd meant for it to be an instructive and helpful history for those coming new to the field, but it was more generally received as comedy. Understandably so given some of the, ahem, less than successful attempts revealed. Even at the time (early '90's), a visiting kite flier (Andrew Beattie) suggested that I should speed up the development process by completely eliminating actual testing and transferring new designs directly from the workshop to the long grass out the back.

There are 57 photographs, rather too many for emailing, so this is just the text and a few representative photos. Click here to view the entire photo set.

I was already aware of some of the history; Ben Franklin's kite swimming for example, and Ian Day's Flexifoil powered Tornado catamaran- when I started developing kite powered things, mainly boats, from October 1987. The inspiration had came from John Waters at Lincoln City (Oregon) who could see it was a field that was about to become interesting. In the now nearly 20 years since then I've built and tried something like 200 different layouts, mostly failures, maybe some pointers. Here's a selection: (Dating is rough enough but can be pinned down if this ever becomes useful).

During the first year or two, we used a converted skydiving 'foil (ex John Waters) called 'Adam'. It would steer, sort of, had an l/d of 2.5 to 3 and was auto stable to a degree even when flying from just one of it's two lines.

From '89 we also used large (6m span) almost un-flyable 2 line delta style power kites and stacks of smaller (2.5m span) stunt kites (Excaliburs).

From 1990 we mainly used Peels (2 line soft 'foils) and from about '95, 4 line 'foils of various style. C Quads came along in '97, Arcs from '99.

My first attempts at kite sailing, there's no photo, were using a catamaran style windsurfer that someone had built a few of. It was sailed standing up while flying Adam thru a deck mounted double pulley. For boat steering there was a ratchet set rudder that could be kicked to different angles from time to time. It worked- upwind the first day- but was a devil for getting caught aback, tipping over, snaring the flier in the process and churning on up the lake regardless- nearly ending me and this developmental series right then and there.

The next attempt, late '87, was a purpose built 3m flat hulled catamaran. The seat rotated 360 degrees so that the flier always faced the kite. Steering was by foot bar and a push/pull rod through the pivot centre to rear rudders. It could be fast and exciting but was a poor performer in light winds and severely limited by the kites we had then and our lack of flying skills.

By this stage we were also water skiing using kites-see photo of Pete when he was 13, in a strong gusty (always) Lake Clearwater nor'wester out under a single 2.5m span (about 1sq.m area) Excalibur. In two TV sequences kite water skiing across Auckland Harbour in 89/90, I was, respectively, backed over by the chase boat (propeller churning) and nearly run down by a container ship. We were never as good at kite water skiing as Corey Roeseler who visited us at Lake Clearwater about '93. He could go up wind really convincingly, we couldn't.

By this time we were also trying to wobble along while balancing on boards of various types- without conspicuous success.

The next major kite boat project, late '89, was a trimaran, 9m long, steered by turning the front central hull. In various versions it had mast launching for the kite, a 2 line winch that allowed steering while pulling in (ratchet lever on the column mounted steering wheel) and letting out (clutch and brake). It was nearly impossible to keep the kite up- the record was about 6 minutes I recall, the average was more like 30 seconds. Because of line stretch and differential take up on the winch, the flier had no central reference for kite steering, and unlike the docile LEI's and Arcs we use now, it just wasn't possible to predict what delta style kites were about to do by observing them. Without a line length reference, they could and would suddenly tip into a death dive.

One of the next attempts was a water ski based trimaran. The idea was to have a wide enough base to allow the use of deep fins so as to enable useful upwind performance. It didn't work as expected- see the photo of it at top speed, never ever managed to plane- but I bet it would with the kites we have now. However, as I still had some hopes for it and with winter ice coming on, the skis were replaced with wheels to allow testing to transfer from lake to park. It worked immediately as a kite buggy- and is the very one that started kite buggying as a sport. It's now in the Longbeach (Washington State) Kite Museum (and painted red, which made it go faster).

After this, as buggying took off, we started fitting hulls to buggies. There were four main hull styles used, perhaps as many as 100 buggy boats sold in subsequent years. They work but are speed limited in displacement mode by lack of hull length. Unfortunately, kite boats sail in displacement mode most of the time, especially on upwind courses, on account of kite performance not yet being up with conventional sails in respect of l/d.

The "Kitesurfer" style buggy boat of '93(?) was by far the fastest kite sailing boat we've had, and still is (now 4 hull layouts rather than the original 3). Development of this form has continued.

By about '95, there was a sense that kitesurfing was going to happen- but it wasn't at all clear as to what its form would be.

I pursued some hopeless dead ends (that would definitely have benefited from Andrew Beattie's suggestion) such as the "Proa Board", The "Hydrofoil Seat" (see the photo of it at the top speed ever achieved!) and "Jesus Feet"- yes they worked, but were, um, 'directionally irresponsible'.

There was one attempt at kite boarding though that was, I think, not so crazy- even in retrospect. This was a windsurfer style board with a radio controlled servo operated rudder. The operating controller for this was strapped to my wrist. Twisting the wrist (which I could do without interfering with kite control) caused the board to steer. As I flew the kite while balancing on this large (by today's standards) board, I could also change it's direction. It worked fine, was my first ever successful sustained kite boarding ('93-'94?) and when I fell off (often), the radio control could then be used to direct the board back to me as it drifted with the wind- provided it was right way up. Sorry, no board photo, just one of the wrist mechanism.

Having by now decided that balancing on a board while flying a kite was going to be just too difficult for most people (i.e., me), I then tried a monohull boat form. In various guises, but eventually in 4 rudder, central seat roto-moulded style, it was very manoeuvrable, quite good upwind, portable and compact- for a boat. Something less than a 100 were made and sold up to about 2002. The 3m monohull kite boat's nemesis was that it tipped in waves of more than about 0.5m,- and negative comparison with the by that stage rapidly developing new sport of kitesurfing.

This 3m monohull kite boat did serve to expose a stability problem that all single hull rear-rudder-only kite boats have when they are sailed aggressively. Lacking form or keel stability, if a sudden turn is executed while travelling at high speed, the boat immediately inverts because of the unbalanced tipping moment of the rudder action. Opposite turning rudders at front and rear were developed to solve this.

Through the period '89 to '99 , many attempts at conventional hydrofoil supported craft were made here, but none as successful as Bruno and Dominique Legaignoux's bruce foil/T foil layout that we tried when we first met up with them at Cervia in Italy about '93.

An aside here; their early LEI kites, that we also first tried at this time convinced me that I'd missed the big idea for water re-launchable kites and might as well concentrate on craft development rather than kites from then on. This was notwithstanding that at that time, pulling on their right line made them turn left and that on looping, Bruno said- 'hey, you're not supposed to do that- the idea is just to lean them to one side or the other'. Fortunately for me, development of the LEI kite was so slow even into the early 2000's, that other water kite opportunities did open for our business.

There was one hydrofoil development we did (that is, myself, Robert and Pete) that I'm not yet completely sure was mistaken. This was the "mophs" initiative. Standing for "mode optimising planing hydrofoils" these are hydrofoils that work as such until a certain threshold speed, then rise to sit on the water's surface and plane. The problem they solved was the speed limitation that hydrofoils are subject to by ventilation- in practice, about 45knots (certainly less than 50kn anyway). Mophs aren't subject to this limit. In chop or waves they blast through the wave tips with un-attached flow over their top surfaces rather than rising to each wave- which is also less bumpy than a conventional planing hull in such circumstances and may even generate less drag. For kite sailing though, mophs don't become necessary until speeds are above what we're limited to (for now anyway) by other considerations, so moph development ceased by about 2001.

From '87, catamaran style kite boats had been a constant theme- there were always a few on the go. Their disadvantage is size/lack of portability; their advantages are stability and performance- consistently the best of all layouts for small kite boats (not excepting trimarans) and probably for large ones, in widely different wave and water conditions. A series of comparative tests between an early catamaran form and the fully developed 3m monohull kite boat from above showed that the mono could never win on any course or in any conditions- much to the surprise of the users, who often thought that the mono 'felt' faster. The yellow 6m Cat (2001) was a technical high water mark in this development. It had four rudder steering, a swinging seat, kite attachment so that the leeward hull lifts when at speed, and in it's final form, a 4 line winch system that allows for kite control even while letting out and pulling in. The current kite catamaran state of the art is the 4.2m 'KiteCat'. A boat for all seasons; it's car roof portable, very manoeuvrable (4 rudder steering), handles surf, goes well to windward and is fast. They're selling consistently and could pass the sales numbers of either of my previous attempts at commercialisation next year. I'm basically waiting for user maturity (all those kite surfers who are getting older and less agile) and kite development to catch up.

During 2002 to 2004, I also tried a 6m open boat style monohull. Behind this was the principle that kites don't cause heeling in the way that sails do. When a kite boat is large enough not to be tipped by wave action, there is no advantage in multihull form stability. Large monohulls have less drag (especially aerodynamic) so will be faster, are much easier to fit accommodation to, are inherently stronger, and are less expensive for the same size. The 6m mono takes up to 6 people, is easy and comfortable to sail, good upwind, and is surprisingly fast even when used with smaller than optimum kites. It has an auxiliary motor, fore and aft opposite turning rudders to eliminate steering induced capsizing, and the kite is attached to the boat in such a way that all the crew have access to the various kite release systems. It was used as a model and test boat by Dom Mee for his attempted trans-Atlantic and is currently in England. My view is that by 12m or so, even for blue water kite sailing, mono's might come to prevail.

All lots of fun; but in retrospect, too many boats, not enough kites.

The fact is, current sailing craft are already adequate for use with kites given relatively minor modification, and optimising these and other layouts for kite use will only take a few developmental generations. Boat development is not holding kite sailing back.

On the other hand, kites are not yet up to the job.

Even after the considerable progress of the last 10 years- driven largely by the substantial market opened by kite boarding- kites are difficult to launch and land, require constant skilled attention, are poor upwind when compared (read; 'beaten') with conventional sails, aren't yet manageable in large enough sizes and are dangerous.

Their upwind performance is poor largely because they will not fly controllably at lower angles of attack- lift to drag ratio being inversely proportional to angle of attack in its most fundamental relationship. Current kites at the least won't steer, and at the worst, luff uncontrollably below 5 degrees or so. In contrast, a conventional sail on a mast 'sheets' from 90 degrees to zero, is easily manageable at angles of attack coincident with it's best l/d and doesn't fall out of the sky no matter what is done with it.

Kites are dangerous because their apparent wind speed is not limited to that of any craft they're attached to. High performance kites can and do accelerate to something approaching the true wind speed x their l/d- and at that maximum, apply loads of up to 10 times or more as much as an equivalent conventional sail- and for long enough to ensure disaster.

For kite sailing to become mainstream, fully de-powerable kites that remain steerable even as their angle of attack approaches zero must be developed. When this is accomplished-and in the last 2 years there's been more progress towards this than in the previous 180 (George Pocock, rest his soul)- kite's upwind performance will approach that of conventional sails and over-pull can be controlled.

So, for now, goodbye fiberglass, hello sewing machine.

Thank you to Scott, (the Gordon Bennet of the kite world?) Ali, Renea and all the others- at Drachen and co-opted- who made this event possible. From the demonstrations, information exchanged and relationships formed, like Rheims in 1908 was to flying, this may well come to be recognized as the breakthrough event in the developing fields of kite sailing and kite energy.


Peter Lynn,
Ashburton, October 2 ‘06

 

 

 

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