That is a 19 year average. So 13.3 mpg. I was referring to Dave Evans Sabre 34. He mentioned 3 hours per gallon. Based on 5.5 knots that is 16.5 mpg. A third of a gallon per hour is about right for a 10,500 lb Sabre 34 at 5.5-6 knots.

My 32' 10,000 lb powerboat burns about a quart an hour at 5.5 knots and a bit under half a gallon an hour at 7 knots.

I would expect your fuel consumption to be closer to 0.75 gph at 6 knots given your waterline length and displacement. Displacement and waterline length are the big factors determining fuel consumption at a given speed.