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.
Outboard: This drive system has a motor, reverse gear, shaft, and propeller that is mounted on the transom of the boat, but is independent of the boat hull. The engine can be removed or replaced very easy when compared to an inboard or stern-drive. just now. Report Abuse. There is no difference between an inboard/outboard and a stern drive. The inboard part means the engine is inside the boat. The outboard part means the outdrive including the transmission is outside the boat as it is on an outboard motor.