anchorlt,
I have a hand held Garmin. When I first got it, and had tracking
enabled, I piloted a course that took me under a draw bridge. The tracking
showed that I was about a 1/4 mile inland, most disconcerting. I called Boat
U.S. where I had bought it and was advised to "reset" the unit by depressing
a button with a paper clip. After this it reported my track to be exactly
right. My experience has been very positive to accuracy.
Paul

"anchorlt" wrote in message
om...
I keep reading about GPS for boats and how innacurate it can be.

Why is the same not innacurate in cars?

My car GPS is so accurate it tells me I am on the white line at a
traffic signal stop light or in my driveway.

Why not the same for boats?