Sorry to jump into this thread, I have not read the whole thing, so if this is mentioned by anyone, apologies. When I first got my handheld GPS
it persistantly put my location about 20 miles away, and it took a long time to figure out why. The problem was the unit was set to read in degrees, minutes and seconds, while I was plotting in degrees and decimalized minutes, not seconds. 20' 30" is 20 minutes and 30 seconds, but would appear as 20.50 minutes as a decimal figure. I simply reset the GPS
to read the same way, and my position was spot on.