Re: GPS Accuracy - how much is actually needed
Here's an interesting article on WAAS and GPS accuracy :
The coastguard reported real world performance for Loran-C of 50m (return to position accuracy). WAAS-enhanced GPS guarantees 7.6m, although real-world performance is considerably better. I routinely see accuracy of about 1m.
Sometimes when I record my GPS track with my handheld and paste it into Google Earth, I can see where I walked down the dock, to the restroom, and back. The accuracy looks like about 1m to me.
Bristol 31.1, San Francisco Bay