Kites

[ath]

Out of pure curiosity, is anyone experimenting with or using some form of kite down wind?

Some years ago I had read about a ULDB that had used a kite similar to a skydiving shute (rectangular) set around mast height or higher and attached to chain plates on either side of the hull midway between mast and bow. I think that a lighter line was attached to the middle of the kite as it collapsed the shape and made it easy haul in with a windlass or by hand (maybe not by hand since it was a lot of line).

But I have never seen this developed. On first thought, I would think that it would take advantage of the wind gradient effect in some areas and in lighter conditions and in heavier conditions, with a smaller kite, would it not help to lift the bow slightly and help planing for certain flatter monohulls? Is it that they are simply too unmanageable? I wonder what happens? Would the kite stay aloft or does it lay low and pull out to the front of the boat? Couldn't it be designed to stay lifted at a certain angle to the bow?

I searched the forum and didn't find anything... just curious

[Sketch]

Check out www.kiteship.com

The video streams are pretty cool

[ath]

Ha. Interesting. Makes perfect sense.

[Skippy]

Why only downwind?
Here's a discussion of kites: ISAF vs KITE Sailing

[yipster]

I searched the forum and didn't find anything... just curious

allways good to do! but when i type "kite" in the search field onder the search button i get 2 pages with dozens of kite related threads. hope this helps.

[daveculp]

Originally Posted by Skippy

Why only downwind?
Here's a discussion of kites: ISAF vs KITE Sailing

There are dozens of types of kites, Skippy, just as there are dozens of types of sails. Some are simple, cheap and have limited performance envelopes, and some are complex, powerful and expensive.

I could fairly easily design and implement a rig-replacing kite for your boat, which would do everything the current rig can do--and more. Trouble is, it would cost almost as much as the rig it replaced--i.e.: many thousands of dollars--not counting the R&D work to get it right.

At KiteShip we have been doing just this since 1978. We have found that sailors--as a market--aren't quite ready to chuck their entire existing rigs over the side and pay for a second, free-flying one. It's a cost entry issue, do you see? In the meantime, we have found that a simple, inexpensive replacement sail for existing spinnakers--using all the boat's existing rigging and sail handling equipment--and costing about the same as an ordinary spinnaker--has a ready market, today.

OH, and did I mention, they are perfectly legal under ISAF rules? There's a storm coming, but, according to the ISAF Equipment Rules of Sailing, OutLeader spinnaker replacement kites are perfectly ordinary asymetrical spinnakers; they were carefully designed to be so. Rules such as "kitesails not allowed" are meaningless in the context of OutLeader kites and ISAF.

You may be ready for the whole shebang (rig replacement kites)--please tell us if so. The first one's gonna cost a couple of hundred throusand dollars, but if we can spread it over an entire market...

Cheers,

Dave Culp
http://www.kiteship.com

[FAST FRED]

Seems like there would be a good market as a get home for the power boat folks.

Most are far to old , ignorant ,lazy or just predjuced to contemplate a motor sailor , but the options for realistic get home are not great.

Somthing to do 3/4 hull speed over a 180 deg choice of heading should be enough.

FAST FRED

[CT 249]

Dave, how would a "rig replacement kite" work well offshore in light and sloppy winds????? You know, the annoying 0-2, circling the compass for a couple of hours sort of stuff.

Just curious.

[daveculp]

I dunno, Chris. How well does YOUR present rig work under these conditions?

Serioiusly, there are at least 3 answers, off the top of my head, for kites capable of "flying" in 0-2 kt winds. Each of them would offer more performance than a masted rig under these conditions--and each would cost more than you're willing to pay...

Dude, open your eyes. All the answers aren't on the chandler's shelf, nor in the local OD class regatta. Sometimes you need to look outside the box.

[daveculp]

Before you ask, yes, I'm willing to seriously "blue sky" about how sailing MIGHT be improved. I'm not particularly interested in throwing out ideas for conservative laggards to shoot down. Decide which shoe fits and get back to me.

Dave

[CT 249]

Dave, if you recall during your trip out here I asked whether about coming out on two kite boats. Surely that's not much evidence of being bigoted. Nor is it easy to see see exactly how owning two development-class boats and two OD boats is evidence of an OD mindset - apart from the fact that racing in a 100 boat OD regatta is more fun than sailng in a 7 boat development-class title.

My mindset is that sailing is declining in many ways and the classes that are surviving best are fairly simple, medium to slow, fairly economical one designs. The expensive fast development classes are often doing badly. Developments should surely been thought about, queried, studied in that light.

Surely the most important thing is "development" that increases and maintains popularity AND tries to improve the health of the development classes that remain. That may be a different goal to just hoping to go half a knot faster; if speed was the issue A Class cats would be more popular than Hobies, and International Canoes would be more popular than Lasers. They aren't.

And OK, kites may well be the answer in more ways than speed. I never said they weren't, but what's wrong with asking how they perform in conditions where spinnakers and kiteboard kites don't really go all that well?

My rig works pretty well in those conditions, which is very important because performance those light and sloppy conditions (too light to support a spinnaker and the sort of stuff that drives you to short-foot windseekers) can of course make an enormous difference. Surely it was reasonable to ask whether your proposed rig could work in such conditions, as a boat that stops each time the wind drops loses many, many miles in "holes".

[cristofa]

Backalong in '82, I worked on an interesting kite project ... I designed and built a dedicated kite boat to take part in the 'Mini Transat' race. The kite (which was produced by someone else) was D shaped in plan, aerofoil in cross section and filled with helium. The whole project became feasible when kevlar line (with its very high strength to weight ratio) became generally available.

The 6.5m boat was very light and, to exploit the kite's advantages, the design departed significantly from conventional sailboat practice; in fact, the low-slung, mast-free, planing hull looked more like a powerboat, than a sailboat.

It had a working (coverable) cockpit up front for deploying the kite, but the boat was 'driven' from a comfortable (car) seat, under cover, amidships. A dagger board provided lateral resistence and a 1.2m horizontal arm, rotating about a point just ahead of the dagger board, directed the lines to the kite side of the boat.

The 'working' kite was a mere 5 square metres, so it was easy to handle at sea level. It was generally flown on a 70-100m lines where it provided plenty of power ... you don't have to go very high to see a substantial increase in wind speed. Reefing was achieved by simply shortening the lines.

Once I got the hang of it, driving the boat was surprisingly easy. Without any control input, the kite would sit quietly aloft, producing no drive. Swing it down, and off you go ...

Lots of people could NOT get their heads around how you could sail a kite-powered boat to windward but, in fact, it pointed very well. And it worked very well indeed too ... most of the time.

I didn't have a speedo on board during most of the trials but, at times, it felt extremely fast, planing with ease. It was also possible to engage the self-steering and 'set and forget' the kite for passage-making.

The absence of heeling took a bit of getting used to and, with no mast/sails to bury the bows, and a lift component from the drive, the boat felt uncannily light and quiet.

There were two problems which, together with the usual 'insufficient funds', prevented the boat from entering the race. One was annoying, but not serious. On a damp drizzly light wind day, enough moisture would settle on the kite to sink it to sea level and deprive the boat of power. The other problem was much more serious though ... it occurred twice and was due to the 'grippiness' of wet kevlar line at the time. If the control lines crossed, they could lock solid and I would get what I called a 'twister' ... the kite would begin to rotate increasingly quickly, generating a whole heap of unwanted power along the way! As soon as it happened, I'd have to start the outboard and motor flat out towards the kite to relieve some of the pressure, while I frantically winched in the lines ... I could have 'cut free', of course, but couldn't bear the prospect of losing kite or line.

The boat did amply demonstrate the significant advantages of kite power, though, and also the need for further development of the kite. It's disappointing that there's so little work being done in the field.

atb ... Christopher

[FAST FRED]

For the anoying 0 to 2k winds the only thing I have found that works is a BIG fully battened main.

The area is there , with a "proper" airodynamic shape , just waiting for some push.

They can be vanged down hard , and arent too noisey while they wait at zero wind in a slopy sea.

FAST FRED

[daveculp]

Originally Posted by cristofa

Backalong in '82, I worked on an interesting kite project ... I designed and built a dedicated kite boat to take part in the 'Mini Transat' race. The kite (which was produced by someone else) was D shaped in plan, aerofoil in cross section and filled with helium. The whole project became feasible when kevlar line (with its very high strength to weight ratio) became generally available.

I would be VERY interested in learning more about this boat. I receive inquiries from Mini Transat guys most every day; if I htought there was a potential for a purpose-built Mini boat, I'd jump on it.

The 6.5m boat was very light and, to exploit the kite's advantages, the design departed significantly from conventional sailboat practice; in fact, the low-slung, mast-free, planing hull looked more like a powerboat, than a sailboat.

Helium inflation is one of the 3 light-wind methods I was speaking of. Not only does it make the rig truly self-supporting (and maintaining its airfoil shape to instantly take advantage of the first and lightest zephyr), it also lets you maintain the kite at 100' or so altitude--typically above the worst of the "light variables" which plague rigs down on the surface.

The 'working' kite was a mere 5 square metres, so it was easy to handle at sea level. It was generally flown on a 70-100m lines where it provided plenty of power ... you don't have to go very high to see a substantial increase in wind speed. Reefing was achieved by simply shortening the lines.

Intertesting about the "reefing." 5 meters is really pushing the minimal size capable of buoyancy with helium; both of your difficulties have been effectively solved; Modern kites are capable of depowering substantially, so can be made a good bit larger--with sufficient buoyancy to carry the condensate weight which defeated you. Also, spectra line is an order of magnitude "slipperier" than kevlar; it is not uncommon for competition fliers to fly with 8-12 full wraps in their lines and several wraps are almost not felt at all, even with quite large kites.

Lots of people could NOT get their heads around how you could sail a kite-powered boat to windward but, in fact, it pointed very well. And it worked very well indeed too ... most of the time.

Nothing has changed; it is still easy to get to windward, and people still do not believe it possible. There are real limitations with "modern" kites, only in that most laypeople regard windsurf kites as "state-of-the-art." These kites are highly specialized to have high drive and be easily water-launchable--not for windward ability or efficiency. A purpose-built helium inflated kite would be quite different, as you will recall.

I didn't have a speedo on board during most of the trials but, at times, it felt extremely fast, planing with ease. It was also possible to engage the self-steering and 'set and forget' the kite for passage-making.

This is perhaps one of the best attributes of HE filled kites, but we still find strong opposition to "cheating" with buoyant kites. Fact is, helium buoyancy cannot drive the boat. In fact, many years ago (about the time you were experimenting with it), the precurser to the WSSRC ruled helium-filled rigs to be perfectly legal for speed records.

The boat did amply demonstrate the significant advantages of kite power, though, and also the need for further development of the kite. It's disappointing that there's so little work being done in the field.

Exactly my feelings, Chris.

Dave Culp

[daveculp]

Originally Posted by CT 249

Dave, if you recall during your trip out here I asked whether about coming out on two kite boats. Surely that's not much evidence of being bigoted. Nor is it easy to see see exactly how owning two development-class boats and two OD boats is evidence of an OD mindset - apart from the fact that racing in a 100 boat OD regatta is more fun than sailng in a 7 boat development-class title.

Here you demonstrate the very thing you deny. This is an opinion, not a fact; I personally would prefer the 7-boat fleet; if I had the opportunity to break through some tradition or other with new technology. Different boats--different long splices.

I don't believe I claimed you were bigoted; apologize if I did. I did fly 8000 miles to your home waters, offered half a dozen invitations (not 2) to take you kite sailing. It was a shame we could not quite put it together... We still have a willing representative in Australia and 3-4 demo kites here and there. Contact Rob Denney for a demonstration: proa@iinet.net.au

My mindset is that sailing is declining in many ways and the classes that are surviving best are fairly simple, medium to slow, fairly economical one designs. The expensive fast development classes are often doing badly. Developments should surely been thought about, queried, studied in that light.

Surely the most important thing is "development" that increases and maintains popularity AND tries to improve the health of the development classes that remain. That may be a different goal to just hoping to go half a knot faster; if speed was the issue A Class cats would be more popular than Hobies, and International Canoes would be more popular than Lasers. They aren't.

I presume, then, that you drive a Ford sedan, and have little use for the odd Aston Martin; after all, it is "fact" that the most popular sedan is the best...

And OK, kites may well be the answer in more ways than speed. I never said they weren't, but what's wrong with asking how they perform in conditions where spinnakers and kiteboard kites don't really go all that well?

My rig works pretty well in those conditions, which is very important because performance those light and sloppy conditions (too light to support a spinnaker

Again, I think you answer your own question, at least regarding spinnaker-replacement kites; they will not excel in places where spinnakers won't work either.

Then again, the genus "kite" of which OutLeader spinnaker replacement kites are a single species, offer a huge set of potential performance--which includes continued drive in sloppy light and variable conditions.

Cheers,

Dave Culp