This is the first time I tried GT31 sound system in the helmet. I could not hear the "bio-feedback" sounds during speed runs (more work to do!), but amazingly, results were well heard well when I stopped sailing or sailed upwind. I did not have a GPS on my hand and from GT31 sounds I could predict my 5*10 average with 0.1 knot accuracy - just from sound messages. The speed result sounds had to be repeated few times before I could be sure that I "read" the m correctly.

I tried 4 sails, 2 boards and 2 fins during this ~10 hour session on both sides on a high tide. Now I have a slightly better idea what equipment and its tuning is needed for what conditions.