The chart below is the same as the one above, only in a simpler format.
Bill and I did a 60 mile round trip in his SkiffAmerica 20 using an 11 ¼" pitch propeller cruising at 4,000 rpm and burned about 1.2 gallons per hour. I have not done fuel burn tests with the 12" pitch prop but we do know that it only requires 3800 rpm with the 12" pitch to maintain the same speed as the 11 ¼" pitch prop at 4,000 rpm. We probably won't know much more until we do more trips in my SkiffAmerica.