Originally Posted by hank
I read somewhere that a outboard burns 1 gallon per hour per 50 hp.
That sounds really low to me.
Depends on a lot of things: Throttle setting is the main thing, but sea state, load, currents, and wind all play a part.
At cruise (24 or so mph) my 18'/F115 burns about 6 gph in reasonable conditions. WOT it's closer to 11 or 12 GPH at around 40 mph.
I'd guess the OP would get somewhere in the 6-8 mpg range if he stays off the stops (don't run wide open.) That is just a guess though.