[flyhauler]

Which is more accurate? My GPS or my Garmin fishfinder. I recently installed a new fishfinder with transom mount speed wheel and have noticed a 10 mph difference. Any opinions out there?

 

[Bob H.]

GPS is more accurate for speed over ground. Does the delta reading change at different speeds? Are you sure the GPS is set to MPH versus KPH?

 

[Seahunter]

Go into setting and make the correction in setup:
Setup/Calibration tab/calibrate speed and follow the directions

 

[mikie]

Bob is right - your GPS is measuring the speed over the ground, while your depth finder is measuring the speed of the water pushing the paddle wheel. You could theoretically be anchored in a 10 mph current, and your depth finder would show that you were moving 10 mph because of the current flowing past the paddle wheel - while your GPS would indicate 0 mph because you are anchored and not moving over ground.