Next on the list of factors is pressure. When you increase the surrounding pressure, you can usually dissolve more gases in the liquid. Think about your soda can. It is able to keep the fizz inside, because the contents of the can are under higher pressure.
Assuming a prop, it depends on how you are propped but with a redline of 6000 rpm, most outboards perform best with a cruise in the 4000-4400 rpm range. If you want top fuel economy, get a floscan or such and see what is the most efficient for your engine and prop.
What does this information tell us?In order to use the same fan for an airflow of 41,500CFM, the RPM needs to be increased to 777 RPM.The new performance increases the fanâs horsepow-er requirement from 25 HP to 50 HP. If the fan issped up to 777 RPM the motor must be resized.