Parlier's Kite Powered Planing Cat

Very interesting! http://www.parlier.org/beyond_the_sea/fr/multimedia.php
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Stumbled on to this incredible video of a kite powered "displacement" cat: http://www.kiteboat.com/kb_videos.html

[Spiv]

Great video!
That Hua Rari is not going to pichpole in a hurry

Going back in time to when we were struggling with the "new" invention, the Spinnakers, make me wander: "Could this be the propulsion of the future?"

[Capn Mud]

The "sail trimmer" - the guy controlling the kite - looks most uncomfortable most of the time - need a better arrangement for him.

I have seen the kite boarders reaching back and forth - but how high can one point with a kite?

[RHough]

Originally Posted by Capn Mud

The "sail trimmer" - the guy controlling the kite - looks most uncomfortable most of the time - need a better arrangement for him.

I have seen the kite boarders reaching back and forth - but how high can one point with a kite?

Not very. About like a well sailed square rigger.

[Capn Mud]

"Could this be the propulsion of the future?"

but how high can one point with a kite?
Not very. About like a well sailed square rigger.

So...... still gonna need something like the "standard" rigs for going to windward right?

So what does a kite offer that a spinnaker doesn't?

Possibly larger thrust for less material by getting it up higher above the water where the wind is stronger.....

Anything else?

[Bruce Woods]

Originally Posted by Capn Mud

So...... still gonna need something like the "standard" rigs for going to windward right?

So what does a kite offer that a spinnaker doesn't?

Possibly larger thrust for less material by getting it up higher above the water where the wind is stronger.....

Anything else?

Have they got the kite retrieval systems sorted yet, or is the use of a kite by short handed cruising boats in light weather going to lead to lots of grief in the lulls. ie when the whole lot ends up in the water?

Regards

[eponodyne]

The leading edge of those kites is inflatable, so they float. They're a hassle to relaunch (at least it is for me) but... the whole point is that the kite is controllable.

Dammit, Parlier beat me to it! I've got sketches in a drawer somewhere that look just an awful lot like what he built! My control system is better, though

[Capn Mud]

New Age Trawler/Motorsailer; Kite assisted PowerYacht

I got this stuff from another Forum on this site above...

http://kiteforsail.com/

Q&A
1. On a ship can you use a kite for propulsion power on all courses?
Today's high tech kites can be used for power on all normal sailing courses up to 50 degrees into the wind.

2. What about light wind conditions?
During unfavorable wind conditions the kite can be easily packed away and takes up little deck space.

3. What types of ships can use kite power?
The technology can be retrofitted to all types of ships and boats and pays for itself with fuel savings.

4. What kind of wind speeds are needed to use a kite for propulsion power?
A minimum of 12 knots is needed and the kite can be used in up to 70 knots of wind. In Hawaii we have ideal wind speed and wind direction to use kite power for inter-island shipping and shipping to the mainland USA.

In terms of going to windward 50 degrees to true wind aint too bad - I dont think the old squareriggers quite achieved that did they?

[Chris Ostlind]

Originally Posted by Capn Mud

So what does a kite offer that a spinnaker doesn't?

Possibly larger thrust for less material by getting it up higher above the water where the wind is stronger.....

Anything else?

Virtually zero rig stress, as it is flown from the deck; the hull is being lifted, reducing wetted surface; there is no heeling, as there is from a spinny; kite powered boats are faster than spinnaker equipped craft; can easily adjust pull by moving the kite through the power window; wind is not just stronger up high, it is also more steady.

Chris

[RHough]

Originally Posted by Capn Mud

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In terms of going to windward 50 degrees to true wind aint too bad - I dont think the old squareriggers quite achieved that did they?

It is my impression that 50 deg is about the theoretical best that a kite rig can do. Maltese Falcon (a square rigger) does better than that.

There is no doubt that a kite type rig on reach is very fast, but the windward ability is limited by the L/D of the rig (as it is with any sailing craft). IIRC kites are in the 6-8:1 L/D range. The higher you fly the kite, the worse the L/D becomes as you add windage from the lines.

[tspeer]

Originally Posted by Capn Mud

...So what does a kite offer that a spinnaker doesn't?...

Safety. A kite does not produce heeling moments, since it's connected to the deck. So it's not going to capsize the boat the way a spinnaker will.

I have an Outleader kite for my boat to use as a heavy-air spinnaker. It pulls from the bows and a point to leeward and aft, so not only does it not tend to capsize the boat, it actually lifts the bows. So far, I've only flown it in light winds, and not at all, yet, on my new boat. But I'm looking forward to getting it rigged up and crew trained to fly it in demanding conditions.

The big weakness of a multihull is diagonal stability downwind. Especially for trimarans. The problem is the downwind trap, where things are OK as long as you're going fast enough that the apparent wind is reduced compared to the true wind. Then something happens - overpowered in a gust, or you stuff the bow in a wave, and the boat slows down. Then the apparent wind increases at the very worst time. With a spinnaker, peak performance occurs when you're on the edge of disaster. That's not the case with a kite.

The fact that a kite doesn't need a tall mast also makes it a good jury-rig, as was shown when the Newick Traveler 50, Alacrity, lost her rig in St Maarten and sailed all the way home under an Outleader kite:

From rconn Sun May 16 16:27:39 2004
From: rconn (Rex Conn)
Date: Thu Dec 16 19:33:59 2004
Subject: [MHml] Delivering Alacrity under kite power
References: <001201c430c7$79be3430$640200c4@burner2>
<001e01c43124$0ae6ad50$3e02a8c0@hepler>
Message-ID: <018b01c43b5a$1436fd20$e500a8c0@asusp4>

Alacrity is back in the Chesapeake after a delivery trip from St. Maarten (with a stopover in Puerto Rico after both autopilots failed!). Dave Culp and Dean Jordan (from KiteShip) did the trip with me, and we had three kites to experiment with (a small 40sq.m, a 90, and a 200). (The last four days we were mostly becalmed, so a lot more motoring than we would have liked.)

We erected the mast stub with the boom lashed to the top, giving us about a 25' mini-mast to hoist the kites with.

The kite results were mixed -- we had much more difficulty launching them than expected, but once they were up they drove Alacrity faster than expected. The 90 sq. m. (about 35% of my usual downwind sail area) drove us at a steady 18-20 and peaked out at 25.9 knots in a 15-18 knot breeze broad reaching. Dave and Dean were initially baffled about the difficulty in launching (something they hadn't experienced on other boats), particularly since we didn't have any mainsail to disturb things.

KiteShip's normal launch sequence is to head downwind, launch the kite, then bring the boat back upwind a bit once the kite was flying and moved away from the boat. The kites like 10-12 knots true and a minimum of 5-6 across the deck to inflate & launch. This works fine in something like a J-105 or an AC boat like Oracle, but we eventually realized this wasn't going to work on a more slippery boat like Alacrity. As soon as one half of the kite started to fill, Alacrity would accelerate to 8-9 knots and the kite would promptly collapse. Repeat 20 times, with much muttering and scratching of
heads.

The solution seems to be to launch on a hotter course with the kite already tilted forward and driving, but doing this properly requires (1) a taller mast, and (2) rearranging the halyard (moving it towards the leeward wingtip). We're going to experiment some more in the Chesapeake over the next couple of days and see if we can perfect the technique.

Rex Conn
Newick Traveler 50 "Alacrity"

Performance: We don't know what the limiting factors are for how much kite you can carry with a given size boat. Obviously, equipment breakage is a factor. As is keeping the boat in the water and not letting it be lifted completely in the air. But in between...

[eponodyne]

I'm guessing a velcro patch, or tying it together with breakable yarn stoppers might be a help in launching.


Or a good big drogue off the stern.

[Nordic Cat]

I have a 70 m2 one. For launching in light winds, I reverse the engines, get the kite flying and then slowly lower the revs down to idling and neutral.

I use bungees mounted like barber haulers, to soak up wave motion when in choppy waters.

Move the attachment points aft for wind from the sides.

I find them easier to launch without the mainsail up, no turbulence...

Regards

Alan

[Spiv]

Originally Posted by Nordic Cat

I have a 70 m2 one. For launching in light winds, I reverse the engines, get the kite flying and then slowly lower the revs down to idling and neutral.

I use bungees mounted like barber haulers, to soak up wave motion when in choppy waters.

Move the attachment points aft for wind from the sides.

I find them easier to launch without the mainsail up, no turbulence...

Hi Alan,
can you tell us what is the range of wind speeds and angles that your kite can be used please?

[Nordic Cat]

Hi Stefano,

Wind speed from around 5 knots and the maximum I have tried is a bit over 20 knots, but I didn't launch at over 20, it was around 16 and wind increased to around 22-24.

I am considering using some reels for launching in strong winds, as it's tough on the hands even with gloves. Line diameter is stripped 6mm so around 4 mm!

We did play with a small 25 m2 one in 25-30 knots, and it worked well.

Wind angles: Aft of the beam only, I doubt that it will work even on the beam, but haven't tried, as I use the gennaker or Code 0 instead.

If i decide to get one for my new 49 footer, i would go for at least 120m2. Once it's up and flying, and the boat is moving, the loads on the ropes are low.

With my present 5 ton cat and the 70m2 kitesail, the pull at 16 knots is less than 20 kgs.

I fly it about 25- 30 meters out, so maybe 5-10 meters above the mast and forward of the boat. I have 50m lines.

Retrieving is actually easy with a guy on each of the 2 middle ropes. Let go the side lines and pull in fast, the sail collapses and is just like a big flag.

I have a small block that i pull up with the spinnaker halyard for the top line.

Downwind more or less directly I attach the 3 guy lines at the front of the boat. For wind closer on the beam I move them aft, to just in front of the mast, otherwise you can't steer the boat. Try and keep the same spacing between the lines to keep the sail open, so the leeward line is aft of the mast and the windward one nearer the winward bow.
At the front they create a nice lift to the bows.

I will try and take some pictures this year.


Regards

Alan