6 gallon tank for a 50hp - can fish all day on it. On two day tourneys, I fill up the tank after day one. Ran out of gas ONCE in the WI tinboats tourney in Madison, but that was not filling up after scouting the day before and then LOTS of bathroom runs at WOT for my fishing partner (daughter).
A few years back, I calculated we went nearly 40 miles in one tourney, and used about 10 gallons of gas. The launch was WAY south, clean water was WAY UP NORTH -we spent some time looking for it.