Originally Posted by manyboats
Ranger I thought you really had something for a moment but what ever happened to 9,10, 11 knots ect ect?
But your numbers sure dramatically showed one thing. Slower = better (less) fuel burn and more mpg. Graphic evidence literally.
Those were the only RPM/speed combinations I could remember off-hand, my latest RPM/speed test table is on the boat, and I'm not (yet, today).
There's also a place in there around 1400-1600 RPMs (I think) where the boat is simply plowing, so it's neither fuel- nor speed-efficient in that range anyway.
In retrospect, I should have mentioned the engine setup is twin Cummins 6CTAs (450s), and speed/fuel consumption in the table is the total with both engines running.