Hi Wouter,
Say where did you get THAT little piece of info ? Now I`m confused, a sailboard will cover more nautical miles in a 4 hour session of sailing than most other sailing craft can do in 24 hours, so I`m lost as to how you come to the fact that 1nm is a "24hr record" for windsurfers. Check in on
http://www.gps-speedsurfing.com/gps.asp?mnu=user&val=4082&uid=53

Date : Thursday, October 20, 2005
Spot : Strand Horst, Netherlands
Board : T1 RS60
Sail : Naish Stealth 6.5
Fin : Select Lightning Speed 30
Average speed : 34.9 knots (35.4 35.4 34.7 34.7 34.5)
Max. GPS (display) : 37.1 knots
Max. 2 sec. (software) : 37.5 knots
100 m run : 36.2 knots
250 m run : 34.4 knots
500 m run : 34.2 knots
Nautical mile : 26.2 knots
1 hour : 18.1 knots
Distance : 58.0 km
Windspeed : 15.0 knots
Windgusts : 20.0 knots

Interesting that these speeds are set in 15knots gusting to 20, and that he is using equipment that anyone can buy, it is not specialised custom stuff. In fact some fairly high speeds are being recorded on that site by weekend sailors with 5 or 6 year old sails such as the 1999 Neil Pryde Z1 (of which I have 2 sizes !!! )
Yes, maybe ORMA 60`s are faster (on the open sea), but I have 4 boards & 4 sails, and ummm... no ORMA 60 in my yard. (I have made sure there is space for one, though, you never can dream too big !!)