Originally Posted by Unregistered
Why are board volumes decided by sail range and not body weight? .
I had the same question last year. The reason is linked to both sail and board geometry. A large sail will require more distance between the mast foot and the fin, in order to have the CE of the sail aligned with the CLR of the board. (CE=Centre of effort, CLR=Centre or lateral resistance). So it is not exactly the volume that is important, but the lenght of the board.
If you go to extremes, a small 3.5 sail will always have it CE in front of the CLR of an ultrasonic board. Because of this, the board will always head downind.
Now if you take a specific 100l board with it's optimal 6.0 sail, it can be used with two people of vastly different weight. I guess my wife at 60 kg could plane with this in 14 knots. Myself, at 95 kg, will need more than 20 kts. Somewhat independantly, the water state will also be important. My wife will want to use that board in flatish water, but I will like it in chop.