How Many Hours to a Gallon of Gas

i just filled up my 2002 v230 sanger with a acme 911 prop on it 330hp black scorpion ...... the boat took 51.62 gallons of gas at $4.17.9 a gallon cost $215.76 and the boat has 391.2 hours on it ....... going to see how many hours per gallon i get wakesurfing ........ my boat is in the delta and we really dont have much run time to a spot as its essentially a 2 minute drive ...... so we are going to be very cautious on how we drive to see what our gas consumption is

be interesting to know how many hours of running time do you get on your boat with year, make, model, and prop!