Re: GPH
your gph will change based on rpms. you can mess around, burning lots of fuel at different rpms, but do you really want to do that? pick up several copies of "boating magazine". every month they do a dozen or so "short tests", which are simply 1/2 page reviews of different boats and engines. they provide a great graph showing mph, kts, gph, noise, range, etc at different rpm points. you'll be able to find a test that closely matches your rig.