I just did another walking test, and yes, it buzzes when it recognizes a tack.
That said, the display time is so short that when it buzzes and I turn my attention to the watch, I might catch the last moments of the display and can’t get numbers from that in some cases.
Also, it seems to miss tacks fairly frequently, so it’s possible that when I was sailing last it simply wasn’t recognizing tacks.
I’ll keep experimenting.
