[pikfish]

I suggest that you should test the boat out on a calm day with a light fuel load and just you onboard. This should give you an indication if your problem is weight sensitive. The first test you listed you were carrying 900lbs+ 360lb in passengers and 360+lb in fuel, on the second 600lbs+ plus & fuel. Running alone with a light fuel load you could be as much as 1000 lbs lighter! If this does not make a big differance in the speed/rpm than your problem is probably not a weight related one.