More notes on Sailien
15 May 2011
I’ve been following Paul’s blog on Sailrocket’s website and wish I was part of the fun. Note that they have been struggling with low-wind speed performance. This is unfortunately a major problem with high-speed sail craft. The fast sailboards sink if they are not planing and need about 15 knots of wind to sail. Similar for the kite-boards, but I believe they can get planing in less wind. Trifoiler went out of production by Hobie in part because of relatively poor low-wind performance (Ketterman told me he needed about 12 knots of wind to get up on the foils.) The foiling Moths have this problem as well, and so it goes.
I’ve been struggling with the same problem with Sailien, and improving low wind-speed performance has been my main goal. With sufficient wind, going fast was never a problem, since I had essentially eliminated the “normal” sailboat stability problem. I suppose that I should point out that I’ve never gone as fast as Sailrocket; my craft were too crude, but good materials, good structural engineering and good fluid dynamics would have solved that.
My main research has been how to design a practical craft that will sail well in the lightest of winds and be able to controllably handle high winds at high-speed. I’ve been doing this by searching out the best configuration and inter-relationship of the parts, and how best to control the craft. You can see the configuration I’ve been working with in my recently updated You Tube video (added prototype images near the end -- link on the right of this page – Sailien Video).
By designing my craft so the airfoil can rotate 360 deg., I can freely tack or jibe the sail, and just as freely rotate the keel. Note that the rig always stays to leeward (proa style) but since the keel rotates, the craft does not shunt (unlike a proa) and it does not slow to change tacks (when jibing). To be continued.