I know everyone's going to say get a GPS, but are there any types of spedometers that are reliable? How much do they usually cost? At the moment we don't have one at all. Thanks a ton!
I took both speedo pipots off of the back of my boat and go strictly with RPM's. Way more accurate for a constant speed. Get a gps unit for the day and check your speeds. The more weight you put in your boat the higher the RPM's you'll have to go by though.