From the first post :
"Minimum wind strenght necessary to take off...12 knots
Maximum speed...45 knots"

I`m sure that when the windsurfers break 50 knots, Hydroptere`s web-site will claim "maximum speed ... 48 knots"
They can`t be seen to be lagging behind too much. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />