My 28 ZXO gets about the same. I fill up at the beginning of summer (95 Gallon tank) and add about 20-30 gallons over the summer and that's it. So I burn roughly 100 gallons per year (I don't let it get below quarter tank).

On the last run I did (just last weekend in Sarasota) I was cruising 50-55 for a solid half day and didn't burn a quarter tank.

Im jealous!!
I go thru that much in a normal 2 day weekend on the water!!
Then again I typically cover 80-100 miles every weekend I am out,
sometimes twice that much on our long poker runs

Half day at 50mph would be 200-300miles in 4-6 hours, if you burned less than 25g
your telling me your boat gets around 10mpg!! Holy smokes!!