Windsport Tracker is a very cool app for Android phones which uses the GPS in your phone to produce all the same info you get from a regular GPS, and graphics showing lots of detailed info you likely aren't getting. It's a free app available on the google play store. (Disclaimer - I have no idea what sneaky mean things they are doing with whatever data they get from me, but I guess I don't care.)

The tracker is made mainly for Windsurf and Kitesurf, however, that has minimal impact on the usefulness of the device. It can either record the GPS data as it goes, or import data from a Garmin GPS (the current.gpx file) to recreate past sessions, or to provide graphics from current ones. I've used it both ways since I installed it.

Here is the output from one of my buggy sessions last spring.

The map showing your track can be "stretched" to get a better view - here is one from a windsurfing session last week.

The "planing speed" is relevant to windsurfing or kitesurfing (as are some other features such as board and sail used, etc,) but the app is flexible so you can ignore that stuff and put in your own comments, etc. It would be nice if the planing speed where adjustable but it seems to be hardwired.

As for the accuracy - I had already made a spreadsheet to compute my speed v. time chart and their results seems about the same as mine (at least within the range of the approximations I was using). The max speed is usually a bit lower than my actual GPS readings, but I think that has to do with the time interval they compute speed over. I think the GPS will normally give an max instant speed, while these formulas compute over an interval of 2 seconds or longer. The smaller the interval the faster you are....

I've not checked the "polar" chart but it looks reasonable and provides some pretty useful info particularly for racers for figuring out which kites give best upwind performance.

Anyway, it's pretty cool and free. Fairly easy to use, but it is worth it do a few trial runs to figure it out. I'm using with my old cell phone so if it gets wet windsurfing it's not a big loss. Of course, for buggy that's not really a concern.

Nice find Randy, I will ahve to look for that one [no phone at work]

For other GPS alternative Apps I have had good luck and results with:
Strava: available free or a subscription upgrade [I am still using free]. The "same" app many use for their run and bike tracking. It has a Kiteboarding setting [which you can set in Kts and NM if you choose]
Samsung Health: part of the "bloatware" that comes with your Samsung phone. Same options as the Strava [except maybe the knots and nautical miles].


I regularly use both of these with my GPS Bike unit [run all three at the same time for redundancy and info checking] and get the same results from all three for accuracy, speed, and time.

Had been playing with an old Garmin 60csx and importing the data into Google Earth to view the track. Going a bit dicky in its old age though.

Then I found an Ambit3 Run on an Australian website for AU$130 and got that. Pretty impressed with it, although I wish the strap was longer. The Suunto app is not terrible.

There's a website a guy made to see polar diagrams, but it'd be nice to have it all in one place... There's freeware that apparently does everything, but it needs Java so ... no :D

Keep meaning to look at Strava...