Kite Buggy/Boat

[upahill_chris]

I personally have no experience in boat building as i'm busy flying kites but the idea of making a small boat to be pulled by a kite has been there for a while.

Has anyone seen one of these ? Has anyone made one ?

I'm wondering how difficult/simple it would be to make and at what cost. Any thoughts and opinions would be appreciated.

The Buggy boats in the photo's have been made by well known kite manufacturers but never mass produced. I've been told the few that are about work well.

thanks.

[John Perry]

I called in at Weymouth Speed Week the other day and there were at least three kite propelled entries. Two were small and simple amateur projects, the third was the Windjet project, a sophisticated design aimed at eventually taking the sailing world speed record. I saw one of the small amateur boats sailing, it was a lot slower than a kite surf board, which is not surprising since it used a similar kite but pulling a lot more weight, and on displacement catamaran hulls too.

I wonder why most kite boat designs so far are multihulls. One of the main advantages of a multihull is the large righting moment to resist sail heeling moment, one of the main advantages of kite propulsion is that there can be no heeling moment, so isn't this rather an illogical combination?

Incidentally, the very fastest sailing boats, with one notable exception, are all monohulls, are they not?

John

[upahill_chris]

Have you seen the way in which a large kite will pull land craft sideways ??

The fastest sailing boats may only have one hull but its not a simple comparison. The traction created by a kite is rather different than that from a fixed sail.

The main problem would be getting dragged sideways and not being able to hold much of a line. Even worse being pulled over.

Converted kite buggies with floats on have been used but not very well.
Building a craft just for this purpose is what's needed.

I guess that nobody has seen anything that may be suitable ??

[tspeer]

Originally Posted by John Perry

...Incidentally, the very fastest sailing boats, with one notable exception, are all monohulls, are they not?

I think you have it backwards. Most of the speed record holders are multihulls, with the exception of the sailboards. Crossbow, Crossbow II, Yellow Pages Endeavor, Longshot, Mayfly, Icarus...

Date Boat Name Skipper/Crew Venue Speed
1972 Crossbow Sir Timothy Coleman Portland 26.3
1973 Crossbow Sir Timothy Coleman Portland 29.3
1975 Crossbow Sir Timothy Coleman Portland 31.1
1975 Crossbow II Sir Timothy Coleman Portland 31.8
1977 Crossbow II Sir Timothy Coleman Portland 33.8
1977 Crossbow II Sir Timothy Coleman Portland 34.4
1980 Crossbow II Sir Timothy Coleman Portland 36.0
1986 Board Pascal Maka Sotavento 38.86
1988 Board Erik Beale Stes.Maries 40.48
1990 Pascal Maka Stes.Maries 42.91
1991 Board Thierry Bielak Stes.Maries 43.06
1991 Board Thierry Bielak Stes.Maries 44.66
1993 Yellowpages Simon McKeon Sandy Point 46.52

Information compiled by the IYRU/WSSR Council

http://www.speedsailing.com/Background_records.htm

Offshore, the story is the same. 24 hr runs, Transatlantic, Jules Vern, ..., all multihulls.

[John Perry]

Tom: I stand by what I wrote. Even though my comment was made slightly in jest it is true. It is unfair to dismiss the achievements of the sail boarders so lightly. If you consider all the sailing boats in the world which are capable of achieving close to the world record speed (say within a few knots), the great majority of them are monohulls!

Chris: The pull of a kite rig is very much the same thing as the pull of any other kind of rig – i.e. both are the force of the natural wind on an aerofoil. Yes, a kite can pull hard, I know having been dragged face first across a field trying to hang onto one. But the rig on a large sailing boat in a gale also pulls hard, the crew just may not be so aware of that because the load is mainly transferred to the hull through steel cables. Because kites are usually higher above the surface than a conventional rig they are likely to be less affected by surface turbulence and may give a rather steadier pull. Also, under some operating conditions the pull of a kite has a large upwards force component whereas most, but not all, sailboat rigs give a downwards force component. However, from my observation of kite surfers, the highest speeds are achieved with the kite strings at a relatively small angle to the horizontal in which case the direction of pull is not much different to that of a sailboard rig.

John

[upahill_chris]

The pull from a kite can be far from steady....!

I've used landyachts and their sail is very different than using a kite.. It's much easier to tip over a buggy with a kite. I'm not sure exactly why but must have something to do with the different forces achieved from flying the kite in different areas of ther wind window. Kites can create amaising amounts of lift aswell as drag so as a craft turns and the kite is powered back up, if the craft isn't stable enough the initial jerk will flip it right over.
Trust me...i know how this feels as i've barrel rolled my buggy over many times.

[John Perry]

Chris,
I take the point that you can get big fluctuations in force when the kite is gyrating around the sky.

I havent tried kite surfing (yet) but watching expert kite surfers competing against a professional windsurfer for maximum speed over a 500 m course it struck me that at maximum speed the kites were pretty steady in the sky and under these conditions the pull looked pretty steady and it all looked very easy and relaxed, perhaps an illusion though. The windsurfer won in the end.

One point is that if you are sailing on a reach at windspeed or more the boat velocity is a large contribution to the apparant wind velocity and since the boat velocity is likely to fluctuate much less than the true wind velocity the apparant wind velocity will be increasingly smoothed in speed and direction as the boat goes faster.

John

[upahill_chris]

Anyway...back to the matter in hand..

Anyone fancy designing such a craft ???

[threehullbob]

Question: What do you call a painting of an America's cup race?

Answer: A still life