In article ,
larry wrote:

Y'all give a cheap boat GPS WAY too much credit for position fixes!
It's only good to about 3 feet, on a sunny day, with no reflecting
airplanes making multipath signals, far out away from any land.

I guess that is still very optimistic - 15-20 m, ie 50-60 ft are more
like it.
If you use SDGPS with corrections by satellites, it might come down to 3
m, or 10 ft.
No way navigating a channel with 3 m leeway on each side by GPS (even
SDGPS). Tested! In perfect conditions ...

HTH

Marc

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