Strava was mentioned. Does anyone know whether Strava is still calculating speed from positional data? Or is Strava now taking speed numbers out of the FIT file (like everyone else does)?

Select to expand quote

segler said..
Strava was mentioned. Does anyone know whether Strava is still calculating speed from positional data? Or is Strava now taking speed numbers out of the FIT file (like everyone else does)?

Pretty sure that Strava uses positional and then applies some filtering. I upload to both KA72 and Strava (same files) and Strava is normally lower speeds (probably due to filtering). Also strava only gives peak and average speed. No windsurfing specific metrics. There is a whole lot of stuff Strava does much better (like ease of uploading, searching for activities, heat maps, fitness analysis etc.), but most GPSTC sailors are not interested in much of that (except the eae of upload!!).

Yes, that's correct. Strava uses the positional data and uses their own filtering / algorithms.

It is obvious to pay out Strava for using positional data instead of doppler speed, but Strava is not about speed. Strava is about segments. A segment is a GPS based route which is positional. Strava tracks the time from a segment start position to segment end position whilst staying on the segment route inbetween. This was started for cyclists initially and then other sports were added using the same principal. There is no value for strava in using doppler speed.

GPS windsurfing is fairly unique in that position does not count for much (though it does on a slalom course), and speed is king. This is also why most sport based GPS devices do not cater well for windsurfing. Most sports do not care much about speed accuracy.

OK, thanks. Then I will keep using Garmin Connect with my 255. Connect collects doppler speed numbers straight off the watch.

That is a good plan to use connect.If you use a Garmin watch, you are pretty much gauranteed the activites will end up in Garmin connect (unless you don't use connect and upload via cable). Where you move them to from connect depends what you want. Moving to Strava is very easy (zero effort once setup), but Strava is not great for windsurfing speed analysis. Moving to KA72 (and then GPSTC) is pretty clunky, but provides good windsurfing analysis. I do both. This is mainly because I use Strava for non-windsurfing activities (swimming/cycling/running) so I just get it to move all activities I do to Strava. It allows me to do fitness analysis and heat maps and good activity search engine etc. Then I do the clunky task to get it to KA72/GPSTC for the windsurfing stuff.

I've never done much with connect. If it shows doppler speed, then that could be useful for max/average speed... but not sure how to use it to derive other paramters like alpha/10s/Nm etc.

I can see earlier in this thread that people hit the same problems and had a think about it.
I could get used to using watch data to upload, but motion was easier. With an iphone it's another step with the watch, to go into files and unzip, before uploading session. Bummer, i was hoping the watch would be one less step.

gp3s (www.gps-speedsurfing.com/) looks like it could help and also be fun to use. But auto sync from garmin connect for activity either gpstc or appro is not happening there for me yet.

Auto sync starting working, tracks go to gp3s automatically, then i go in to gp3s to post the track as a session, and send it to gpstc from there. Iphone can handle that no worries. But the numbers are blank on gpstc when i do that.
Anyway, i'm not sure i want to do it that way, because i like using KA72, Faaaast Feb! Budgy cup! Oz based gps comps, good stuff.

I've set up the phone with home screen favorites to garmin web version to save session files from there. Next to that home screen favorite there is one saved for the files folder, next to that is ka72.
It's complicated, but so is windsurfing, so i guess it's ok. I'll live with it like that i think.