As far as I recall, GPS accuracy is typically off +/- 50 feet since GPS is a military system, so civilian receivers are deliberately made slightly inaccurate. The satellites transmit a slightly erroneous signal in clear, plus a enciphered correction. Civilian units don't have the cipher key and can't use the correction information. Military units do have the cipher key, and they're accurate to something like two meters. When I am fishing, I notice that my way points, or even my lake contours are off a bit, but they can get me close enough to use the depth finder to find structure I am looking for. Hope this helps.

Hi
The Government removed the civilian limitations on GPS you can verify that by going to th garmin web site and all the new GPs allow you to enable what they call WAAS which is the most accurate setting on your GPS my Garmin GPSMAP 76s is used to help me survey and measure boundry markers (just to locate them 0 when they are out in the middle of no ware and I am with in three yards usualy of them. Just look up WAAS on GOOGLE and it will explain how the civilian GPS systems are now allowed the same as military use of the GPs system.