MPG chart.

[SkunkBoat]

so many variables and inaccuarcies in fuel sending units/gauges..
Tank has a v bottom so the bottom holds less than the top..
If you are lucky, you get the sending unit to show full just as it spits. Usually it pegs full several gallons before it spits.(or it never pegs full)

fuel tank positioning... even when it spits full you don't really know exactly what you have.
If you are at a fuel dock by yourself, you are listing toward the filler. if you have a buddy standing on the bow with a line you are bow down...

estimates of gph

well, none of us are going to spend a day making precise 10 mile runs at 1000 rpm increments with precise measured fuel, charting out gph and mph and mpg...
and if it gets snotty, it won't mean a thing...

What you need is a fancy new 4 stroke with a computer readout to tell you gph and help you calculate out range at a given speed.
I ran a YamahaF250 this summer and it had a guage that did that....sweet

I wish I could add a Flow Scan but I don't believe they will work on a fuel injected motor with a 2 stage -low and high pressure- fuel pump system.

I need to upgrade to a 2017 DF150 zuki with all the bells & whistles