One gallon will provide 20hp for an hour. So at 130hp you will burn 6.5 gallons. A normal boat at normal cruise could mean anything from 40hp to 100 hp which would mean anything from 2 gallons an hour to 5 gallons an hour. Of course I have just generalized all boats which means there are numerous exceptions to what I just stated. More info on the JD application would net a more accurate response.
I’ve always read what has been stated above, however my Yanmar turbo running at close to 2250 rpm’s 4jh2-the says I’m using about 42 hp. And I know I’m diffidently burning less than 1 gallon an hour. Maybe close to 3/4 gallons an hour? So these fuel burn formulas have always have made me puzzled. Why he big difference. Am I reading, understanding something wrong?