Hi Gill,

Sure I want to have a look at your Track!

At Smiths_Cat,
I did use several gps already, and it seems they don't differ that much, as long as you remove spikes and take at least 10 seconds interval. See picture. For a test, I did use a Garmin 301 and a Qstarz 1300s gps during a regatta (almost no wind).
Scale is up to 10 knots and 500 meter. Black is Garmin, Blue is Qstarz. software is gpsar.

Interesting to see that the Garmin's output is more smooth. But in the end they are almost identical, if you would average the qstarz output.

This was typical for the whole track. Knowing that a GPS should get more accurate at higher speed I would think one should be able to compare pretty reliable different gps brands.

Geert