Hi Pat, All competition ski boats, prior to GPS speedos, have 2. For the most accurate reading, the boat speed is the average between the two. This is because unless you are in a slalom course, it is difficult to go in a perfect staight line, so each speedo pick-up is mounted on either side of the transom. All the newer boats have GPS which provides the correct speed along with throttle control etc. for maintaining boat speed for each event. You may want to use a GPS from a car, to get your speedo's dialed in correctly. If they are the old style "Airguide" speedos, they can be adjusted with a very small allen wrench on the bottom front. Use the auto GPS and get the boat to a set speed and turn the allen wrench on each one to match. Hope this helped, ski on, Mark
thank you very much this helps alot as i am new to these boats and going to be doing a mild restore over the winter from plumbing to electrical to replacing the transom and minor scratches and nicks to the hull, any info is going to help me greatly thanks again
Redundant speedos with pitot pickup's were also installed in case one would get fouled with floatsum (weeds) which happens a lot in the lakes around here .