High-Speed Sailing

Now that I've identified stability as the number one barrier to high-speed sailing (last post), what's the next barrier? Structure; if it doesn't hold together, it won't go fast. We have a good example of this in Sailrocket's last crash. The new planing shoe had some problem resulting in it being torn off at speed. This is a problem in structure, either it wasn't strong enough or it wasn't oriented correctly etc. Now I know all about this as I've "gone down with the ship" a few times. That's often what it takes to learn when you're pioneering new territory. So the structure has to be strong enough, but next it has to be light enough and this is where we have a big advantage (with modern materials) over ancient sailors who had logs and plant fiber to work with and little else.

The last barrier to high-speed sailing is fluid dynamics. Many seem to think that it's the first barrier, but it's the last. The best recent example we have of this is Wotrocket. They crashed because they couldn't control the craft (stability) doesn't matter how good their fluid dynamics are. Interestingly enough we have two other types of craft proving to us that fluid dynamics is the least important factor (so far) in high-speed sailing. A few of you might be surprised at this but the windsurfers and kiteboarders are the least efficient sail craft in the high-speed arena and yet they are currently the fastest! We can easily see this by comparing the true wind speed (45 knots) with the record speed (50 knots). If we look at Yellow Pages 46 knot record in about 19 knots of wind we can see a huge difference in efficiency. The kiteboarders are going about 1.1 X the true wind speed and Yellow Pages about 2.4 X the true wind speed. Now the efficiency drops off as the speed increases but a craft as efficient as Yellow Pages could break 50 knots in 25 knots of wind.

Those of you, who have read Bernard Smith's book "The 40 Knot Sailboat", will know that Yellow Pages proved Smith was right in his calculations that we should be able to go 2.4 times the wind speed. But we can do even better than 2.4 times the wind speed by improving our fluid dynamics. There's a lot more speed ahead.

Bob