I just computed mine as I just filled the fuel tank and after 3 trips fishing and logging (Per the GPS) over 100 miles I got 8.78 miles per gallon.
This is on a 150CC with a 4 stroke Yamaha, and before you ask I haven't been ham handing the go fast lever, mostly just getting the boat up on plane and scooting along at 18-20 kts, there was also several hours of trolling at 2-3 kts.
But with fuel at $3+ I'm happy as a clam.
