Hi Everyone

I'm very new to speed sailing as I only took up windsurfing three years ago and have just bought myself a GT-31 having been inspired by the Dunkerbeck GPS speed challenge at my local surf spot in Fuerteventura. I aim to enter next year but I need to understand all the terms used so that I can best improve my results.

To this end can anyone recommend a site where the whole business of speed sailing and GPS measurement is explained in a way that a novice like myself (and I'm sure I'm not the only one) can get to grips with it all. Basically Speed Sailing for Dummies!

My best speed to date on the site is 25.58 but if I uncheck the doppler box I get a max speed of 28.03. The trouble is I have no idea what the doppler reading signifies. Sure feels more like 28 than 25!

Any help would be greatly appreciated and I won't be offended if it's in terms a five year old can relate to.

Hi Paul, I am not sure if there is anything exactly like you are looking for, but there are many guides out there and many forum posts where these things have been covered. May I suggest you do a Google search of the GPS-SS forums?

Also search through the 'Into and Rules' section from the link above.

You might try these simple giudes as well:

If you can narrow it down to specific questions about a particular aspect, there are many here who can help.

Hope this helps. as a start.


Oh sorry. I meant to add a few comments about your question about Doppler speed measurement.

When we first started way back in about 2004, the only GPS data we had acces to was 'trackpoint' data. In other words, data about where we were in space at a particular moment. Our precise location every second. Unfortunately, we soon found that the data was all but preciseand we were often were not where the data said we were. There are many inaccuracies built into the location data that can make speed measurement very inaccurate. Thankfully, a couple of clever guys, Keen Rogers and Tom Chalko realised that some GPS were capable of recording the speed over ground calculation from the GPS system using Doppler shift. They have found this method of measurement to be massively more accurate than using the trackpoint locations. This is why we use the Doppler speed measurement in preference.

Regarding your results: The very short time measurements like 2 seconds are much more subject to trackpoint error than longer periods where the errors tend to cancel themseves out to some degree, but not entirely. Sorry to tell you, for top speeds, your Doppler speed is far more accurate. :-)

Hi Andrew


Thanks for that and the Doppler measurement was the one that gave me the problem. Always has done ever since the Old Bill figured out how to nick me more often than I would have liked. Speed has always been my downfall on land and that is why I love speed sailing. No blue lights in the rear view mirror!

I'll check the other sites out you mention and post any queries I have with regards to my hopefully increased knowledge.

Off to the PWA championships over the weekend at Sotavento to pick up a few tips and I'll stop off at Matas Blancas for a couple of hours on the way home to put them into practice so hopefully I'll be posting some better doppler speeds and improve my PR.