High-Speed Sailing

Gj Robb has been very helpful by posting website addresses for other high-speed sail craft. (Check the comments). I'll discuss one a bit: "Le Projet Dared"

http://www.projetdared.com/

The website is in French, but I was able to decipher the drawings. If they get this thing going, look out! They are using a kite to power a craft which is configured like an iceboat. It has a forward steer-able plane with a fin and two rear planes with fins. The rear fins can swing up out of the water and the craft is run with the windward fin down and the leeward fin up. This set-up will balance the driving forces properly, if done right. Based on the drawings, they understand that the airfoil force has to align properly with the hydrofoil force as I've been explaining. The site shows drawings and some photos of a model. It appears they have a team to forward the project but I'll need a translator to read the text. So far I can't tell if they've gone beyond the model stage yet.

I previously mentioned that one problem with kites is that they move around relative to the craft, both vertically and horizontally. I realize that feature is used to advantage by kite boarders, but it means the force from the kite feeds into the craft at varying angles. There is only one precise position the kite should be in vertically, or the craft will destabilize. (This is particularly critical at high power with light craft.) Horizontally, the kite's position is dictated by the tack and velocity and if that position changes, the craft will change direction. (Again this is more critical with light craft and high power.) As an aside, this horizontal shift is the problem the Sailrocket guys have been struggling with and is the cause of their control problems. (No they're not running a kite but the result is the same.)

Bob