"Mike, I think you are compari
"Mike, I think you are comparing apples and oranges. My current 22.5 foot boat weighs over 6000 lbs and planes at the same RPM as yours, but both of us have 350 V-8 engines (around 300 HP), and the gear ratio in our outdrives is 1.61:1. Lawrence's boat has a 4 cylinder engine 140-145 HP, and a gear ratio in the outdrive of 2.15:1. 2600 RPM on your V8 engine would produce approximately the same propeller shaft RPM as 3500 RPM on a 4 cylinder engine.
I agree that 80% of WOT will prolong engine life, but that is not necessarily the best setting for your fuel bill. I have observed on several boats the size of yours and mine with 350 Chevs that the fuel consumption per mile is pretty steady between 3300 and 3900 RPM, but skyrockets at 4000 RPM and above (or below 3200 RPM). My engine currently burns 1.9-2 liters of gasoline per nautical mile in the above RPM range. For comparison purposes, I would be interested in finding what is your engine fuel consumption per nautical mile (mine is a pre-Vortec, though)."