Ken,
It doesn't claim the 35.5 kts were done on the footage you can see!!! This spot can be a very very fast spot depending on wind conditions but also very choppy as can be seen on the video.
http://icks.icks.free.fr/phpBB2/viewtopic.php?t=2131
http://transjai.free.fr/speed_challenge.htm
These guys are at least as good at checking GPS tracks as gpsspeedsurfing. I believe they got all the tracks from the Canal, it must be posted somewhere on their forum.
Btw a *board Go is nowhere near a Formula board!!!