Last weekend (7/5/5) during the Round IJsselmeer race in The Netherlands I clocked a speed of 17.1kts (20mph/31kph). Wind conditions where NW F6-F7 with nasty short steep waves. My boat is a Hobie FX-One, during the topspeed I was sailing with just the mainsail with an AWA of +/-120°.

Topspeeds are always a bit doubtfull but exporting the GPS track to Excel showed I have 13 occurences of 16kts (without the spi), which accounts for a total of 180 meters or 00:01:07 minutes. So, if 16 knots is a "normal" speed I would say that the 17 knot topspeed is very real. I'm convinced if I wasnt sailing in survival mode ;-) 20kts+ is possible.

Anyway, an hour later after I pitchpoled, poked some battens through the main, and blew the spi panels apart (Yes the glue let go!) I abandoned the race. When I came ashore someone measured 30kts+ of wind, only 17 out of 65 cats made it to the finish. Texel is easy compared to this ;-)
(ps.Wouter, will you be there next year? ;-) )

Complete GPS track available upon request...
(Garmin's Foretrex 201 rocks!)