Good kite for boat

[Munti]

I know this is not what you guys use your kite for, but I can't find anyone that seems to know much about kites in boat forums. So for now you have to be the expertice for kite as boat propulsion systems as well.
I have been sailing for 20 years, and now I want to buy a motorboat because of the much higher speed. I don't want to give up wind propulsion though, and therefore I'm considering kite. My potential use cases are:
1. Slow sailing (3-5 knots) in good weather.
2. Stabilizing the boat in bad weather (not sure if that is possible with kite, but I do it all the time with traditional motor and sail combo)
3. Emergency propulsion if/when motor failure.
4. Kite and motor combo for increased speed and/or fuel saving
5. Active kite sailing

For 1, 2 and 4 I'm looking for something that requires as little activity/adjustments by me as possible. I'm guessing that means the most stable kite that money can buy? Is there any kite that you can "set and forget"?
Also keep in mind that unlike you guys, I often have a destination. So upwind abillity is rather important. Is that in conflict with the stability I want? And of course, unlike many in here, I never, never, never want to jump.
Another consideration is that the space on a fordeck is limited, so the kite(s) should be as small as possible.
I have been playing with a training kite a little to understand the discussions in here and other places a little better, but I don't expect I'll ever reach the skill level many of you guys have.

I do know about Peter flynn, but although he does valuable research, he doesn't have any solutions to offer atm other than his own boats. There have been a few attempts to offer kite based propulsion systems, but looks like Skysail is the only one still alive. And their systems costs more than any boat I would consider.

Oh, the boat will be in the 42-46 ft range. Made of wood with a semi planing hull. Weight 6000-12000 kg.

[andyjiggs]

Might be worth trying to get in touch with Don
Montague.

[Munti]

I already tried a few months back. Didn't get a reply. And although I'm sure he could give valuable input, his focus is different than mine. I want to see what I can do with equipment you can get off the shelf, whilst he seems to focus on the future of kite as probulsion.

[jakemoore]

One of the big problems you are going to have with off the shelf gear is the loads are totally different. 6-12 metric tons vs 100 kgs is a world apart.

Also, I think you can forget about stabilizing the boat and autopilot.

I would learn to kite surf. Then decide if you are up to the challenge of scaling up. Or if you even want a boat anymore.

Good luck! I'm hopeful for a kite sailing future.

[Munti]

I'm aware of the difference in loads. But I'm not trying to acheive 30 knots. Most of my sailing is in the 3-10 knots range.
My training kite (HQ Symphony Beach III 2.2) was able to pull a small rowing boat (17 ft) at 3 knots in 8-10 knot wind.
I kind of suspected I can forget about stabilizing and autopilot unless I build some advanced system for that, but threw it in there just in case. I would like to learn more about the obstacles for autopilot though. Based on youtube videos it looks like the kites you guys are using are a lot more stable than my training kite. How stable can they be?
I do intend to learn kite surfing. Just have to wait a few months. I live north of the polar circle, so a little to cold to get into the water atm. The boat I'm buying no matter what. And there will be a kite onboard for emergency propulsion at the very minimum

[knotwindy]

Sounds like you are looking for a drag chute not a kite. Have you talked to any skydivers? Maybe a small round emergency chute could be attached and modified? Although upwind will be more difficult.

[Munti]

I might end up using both. For downwind it could be good and hassle free. And then add a kite for upwind.

[Regis-de-giens]

My own experience 2 years ago , lot of fun ...

[Munti]

Sure looks fun
Can you give me more details? Windspeed? Speed of boat? What kite did you use?
What kite would you use if you were to do it again?
Does the stability of a boat compared to a kite surfer have any impact on upwind ability?

[jakemoore]

So in Regis-de-giens video the kite is attached to a person. If the kite were to end up deep in the window and suddenly powered the load on the lines would be limited by how fast the kite flier accelerates out of the boat. Worst case scenario is a skilled kiter in the water body dragging back to the boat.

Long ago when I was learning to fly traction kites I attached a 12.5M Flysurfer Psycho to the roof rack of my car. It was a windy day and I didn't feel confident to launch the kite and hold it myself but really wanted to fly. The kite dragged my car about 50 feet then ripped the roof rack off my car.

I think you are doing the right thing by starting small e.g. with the trainer and a rowboat. Next might be a kitesurfing kite attached to a kiter in the rowboat as shown by Regis-de-giens video. I have seen similar video using a Hobie-Cat. You might try a kitesurfing kite attached to a kiter standing on the deck of your yacht?

You might check out Peter Lynn on the Max/Min problems and also Dave Culp Speed Sailing

http://www.peterlynnhimself.com/Kites_For_Yachts.php
http://www.dcss.org/speedsl/

Kites have come a long way since then, but we still are not seeing a lot of kite boats. As I see it the challenges requiring significant development are:

1) get enough sail area,
2) have a very simple drop the bar/control line depower system
3) have a weak link/fuse so if too much line tension is generated it breaks in a controlled and safe way, bringing the kites down on a safety line
4) have a traveller to adjust COE fore and aft, starboard and port

I think a Flysurfer Peak 4 would be a fun and interesting kite to play with for these purposes and at minimum would offer a nice experiment attached to a kiter sitting in a row boat.