I guess i explained that the wrong way.

The analog with paddle wheel gives me the true speed of my lure running thru the water with current.There are times my GPS shows 1 mph and the lure will not run true because the paddle wheel is reading 2.5.which is the true speed of my lure.As an example you could troll up a river with a 7 mph current and have you GPS read 0 mph over ground.Your lure will act as though you are trolling at 7 mph because that is how fast the water is passing over the lip.
I guess what I am trying to say is that the GPS is not the Holy Grail.It is only a reference just like the #'s on a line counter.A properly mounted paddle wheel will tell you more about how fast the water is passing over the lip of your lure.
This is a big part of why you only catch fish in one direction on a windy day.
If you remember one thing.Remember this;A GPS only measures speed over ground as in the bottom of the lake.It has no idea how fast the water is flowing beneath you boat.
