I had no idea there is a "sweet spot" where fuel economy jumped like this

Interesting data and information Ken. You've probably seen my post about my prop and boat ergo Steve's Prop Shop post. It never registered on me that lift would influence gas milage. I just assumed by the time you got to the bow lift of a run you were dumping the maximum amount of fuel in the engine and getting the absolute worst fuel milage, not the other way around. As I said in my other post my boat has the negative wedges between the jackplate and the motor to tuck in further to get a better hole shot, it came with them. I was planning on taking them out later but after seeing your presentation I think I'm going to get that done as soon as the fall feed is over.
When we did the prop test yesterday I had my son driving and I sat in the passengers seat and was able to turn around and watch the motor as it trimmed up. I did that with the turn signal trim while he kept it under full throttle. It just barely got past vertical when I hit maximum trim and there was almost no rooster tail so I know it had a lot more to give. The boat doesn't seem like its getting up on the pad much at all as well.
One other bit of information I can put out there for all you Yamaha guys is to go to your App store and download the Yamaha outboard app on your phone. This app has performance bulletins on it for almost any popular Yamaha and boat combo and these performance bulletins have the fuel milage detail per 1000's of rpm's, weather details and Yamaha prop that was used for the test and more.

Great info Ken

Even better MPG by changing hulls.
Allison haters ----GO !!

Something does not look right to me.
You went from turning 5800 rpms @ 60.9mph to 5300 rpms at 61.8mph. That is not how they work. I am guessing you were actually turning around 6000 rpms when your metering told you it was 5300. Your fuel was likely low because of that.

Props do not lose that much grip at different rpms. I have never seen this although I have not seen everything.
I would like to see that boat test at a steady 5300 rpms and 61.8mph and compare it to 5800 rpms @ 60.9 mph.
The engine pitch should be a good indicator.