Had a good play about with my system yesterday with on skiers present.
Mapped the course a couple of times & was interesting to notice how the timer beeped
several metres before the boat got to each buoys.
I mapped it at about the ski pole & I'd guess the system triggered about 2 metres or more before the pole passed the buoys.
I Know GPS position is never much better than +/- 3 or 4 metres.
What do other people find?