The best thing to do is run as empty as possible. In other words, don't run with full fuel and water tanks if you are going on a short trip somewhere. Don't load the boat up with stuff you really don't need. Make sure the bottom is clean and free from growth and barnacles and that the props and engines are in good shape. No matter what you do, you aren't going to see a huge increase in mileage. Make sure you are propped correctly and then sit back and enjoy your boat! If you want to get good mileage consider a sailboat with a nice diesel engine! Then it's possible to get 4 - 8 plus miles per gallon depending on the combination under power or zero gallons per mile under sail.
