Review on Sierra International 781 310 060P Gauge Speedometer by Richard Gross

If you are having trouble with your pitot speedometer and want to know how fast your boat is going, a GPS speedometer is the right choice. I currently have 2 of these (60mph and 80mph) and they work great. It only takes a second to turn on and they start displaying speed as soon as the sending device starts sending speed data. I connected one of them to a special Veethree GPS sensor hidden under the dash and the other I connected to NMEA 0183 data coming from my Lowrance navigation/sounding device. Great device, no more fumbling with pitot tubes and broken sensors.