T&T: GPS Error?

[capteric36]

 I don't think there is anything in a GPS system
that could possibly place your boat's position
always to one side of your actual position.
 When you are headed North if the GPS placed you
slightly to the East, then when you turned around
and headed South the GPS would STILL place you
slightly to the East.
 The GPS receiver chip does not know your boats
heading when it computes your position. That
information is calculated by comparing one
position to another.

 Check your chart plotter's manual. It may have an
'offset' value that you need to set to zero.

Eric Thompson
S/V Procrastinator
South San Francisco
capteric36 at sbcglobal.net