Yes make sure you disconnect it at the pitot pickup or you will get wet for certain. If you don't think that much water would come into the boat, try it once and see... Amazing amount from just boating across the water.... Why the gauge doesn't see any water is because the water in the pitot tube forces the air in the tube to pressurize and that pressure is what the gauge sees and displays as speed. Notice how the graduations on the gauge are not uniformed. That's why. The pressure is not linear, and therefore the actual water never gets to the gauge unless there is a break in the tube or gauge.