So off the boat, it seems more accurate for sure. I need to do some more testing, but if I forget to “stop” my track and jump in the car, the speed measurement starts to record far more accurately. So couple additional things I have noticed:
1. Higher speeds (like the car) are more accurate. On the sailboat, going below 4kts say in light winds - it almost always stops recording.
2. The area I sail in is the mouth of the lower York river, south Chesapeake Bay. The area right outside the marina is a coast guard station and just up river is a naval station. I’m wondering if there is any type of disruption of signal given the sensitivity of these areas. Again though, my track is recorded, so it tells me my coordinates are updating and my watch and other speed apps work perfectly.