Hi...new to boating, new to the forum. I inherited a 1981 20ft Sunrunner. It has an OMC engine / sterndrive, it's V6 so I think it's the 3.8L engine ? The prop is 15x17. When the boat has just me and my wife, and a full tank of gas, I get 3200rpm, maybe 3300 max according to the boat tach...