Looks like it's a bug, I'll look into it. The correct 2 second speed is 25.569.

Ok, found the reason. Your watch set the clock back by 2 seconds about 7 minutes into your run, so it has 9 points with exactly the same time stamp twice in a row:

This trips up the speed calculation. I have never seen this before in any GW60 files. I will have to change the calculation method to account for artifacts like that. Might take a couple of days. Please go ahead and edit your 2 second speed to 25.569. Sorry about the false PB.

Oh well back to reality . Maybe a 35+ next year at LG.

Thanks for your assistance Peter.

Nice sesh all the same! good to be on the water

Jacko, I just uploaded a new version of GPS Speedreader (1.2.9) that fixes the bug you discovered. It now gives the correct 2 second top speed. Downloads are at https://ecwindfest.org/GPS/GPSSpeedreader.html 

Thanks for mentioning Speedreader in your comment, that made me look at the session and realize we had a problem. It's pretty rare that the GW-60 does a 2-second rollback like it did in your track. Was this a new watch, or had was the battery completely empty before the session?

" Was this a new watch, or had was the battery completely empty before the session? "

No, an old one, one of the first released. ( No strap issue ).  Watch was fully charged prior to session.