I’m not sure about this.I have to have the throttle open a lot more with a dirty hull than a clean hull so it take more fuel to achieve the rpm.
Agreed. However as proven by personnel experience, a fouled prop will reduce the RPM for a given throttle position. The dirtier the greater the reduction.Dirty or clean the RPM should yield nearly the same fuels consumption but vary the distance traveled in a fixed amount of time based on the hull’s condition.
NOT SO FAST THERE!! There are a lot of other factors to consider. How far is your pickup from the bottom? You lose some capacity there. What is the shape of the tank, tapered/square etc (Doesn't impact fuel usage but may impact what your gauge reads) Is there wind and are there waves slamming you from head on slowing your progress so that the 12 hour trip you planned will take 16 hours or that are causing the boat to pitch and/or roll, exposing the pickup to momentarily sucking air? Are you really "full" - how do you know? Don't ask me how I know . Explaining to the Admiral why you really weren't in danger after that long offshore passage when you ran out of fuel isn't something you want to do.Yes: 3 Hours of motoring at an average of 2500 rpm per gallon. With a full 26 gallon tank of fuel I should be able to run 75 hours before panicking that I'm going to run out of fuel.