To calibrate your system, row or paddle over a measured distance on still water (on moving water row or paddle both up and down stream and average the results shown on your display). Then, use the following formula to obtain your calibration value: (Old Cal Value) (True Distance) / (Displayed Distance) = New Cal Value
Make a record of your calibration value for future reference. If you move your unit to a new boat, or modify the location of your impeller, you may want to recalibrate it. Remember, calibration is boat and location specific!