I have a 1974, 33 Morgan Out Island with an Atomic-4 and 2:1 reduction. The boat tips the scales at 12,500 pounds and at 2,000 RPM the boat cruises effortlessly at 6.5 to 7 knots. This is my second boat with an Atomic-4 and I love this engine. It's extremely reliable, easy to work on if the need ever arises and parts are readily available. I've calculated the gas mileage several times using the GPS trip-meter and on days when the weather's dead calm I'm averaging about 12 MPG. When the weather's nasty, the mileage drops to about 9 MPG. That gives me a pretty good cruising range with my 30-gallon fuel tank.