and it would be too much of a PITA to open the engine hatch and we have only one tank port cover that houses the level sensor and pick-ups. I installed one of those vent whistles to avoid overfill, and our VDO electric gage is pretty accurate despite the quarter-cylinder shape of our tank. I try not to let it go much below about 1/4, and would seriously avoid it unless we had at least one auxiliary jug of fuel aboard.

Hey it's a sail boat.