kite propelled motor boat design

[gabdab]

Hello,
me and a friend are fiddleing with the idea of adding kite propulsion to a motor boat.
We came to the conclusion that two characteristics of the boat would be mandatory:
- A frontal towing ring where to tie the kite lines and
- a rudder maybe .. if motor itself non suitable for turning pourposes.
Does it sound like a proper setting ?
Where do I eventually find a rudder for a motor boat ?

[gonzo]

You can either build a rudder or adapt an old one. I assume it is an outboard from what you are saying. It is better to pull it up out of the water. It will cause a lot of drag and turbulence.

[apex1]

It may help to have a look here:

http://www.boatdesign.net/forums/boat-design/get-home-kite-sail-27091.html

http://www.boatdesign.net/forums/boat-design/new-age-trawler-motorsailer-kite-assisted-poweryacht-20319.html

Regards
Richard

[gabdab]

..there is no actual motor boat avilable. it is merely an idea.
..I knew those posts before , but I feel the need of more informations ..
I guess I will concentrate on rudder , maybe trying to adapt a sail boat rudder to a motor boat .

[gabdab]

Would it be possible to use motor at low speed as a rudder ?

[eponodyne]

I've given this a great deal of thought and have conducted some experiments out on the lake.

Yes, in broad strokes, it will work and work well; a kite will certainly pull a motorboat along. If you want to move anything other than 45* each side of dead downwind, you will need a keel of some sort. Leeboards would work, but are unsightly and ungainly no matter what Mr Bolger said.

An outboard motor will work as a rudder, though poorly. Poorly. So poorly it is very much worth the effort to ship a real rudder of some sort, and of course if it's deep enough you pick up some lateral-plane area.

Don't attach the kite to a ring in the bow; someplace just forward of 'midship is much better, especially for reaching or pointing. For downwind work of course it's fine on the bow.

Think light; the less weight you have to drag around, the better.