My brother in law did the same thing. Easy thing to do when you are tired. After a long, long drive up the coast we pulled in to fill up the cars and the boat in readiness to start the holiday. He undid the cap, got the bowser and stuck it into a rod holder that was next to the tank cap. After about 55 litres he figured out something was not right as the tank only held 50L I think. We managed to drain most of it out through the bung hole but the petrol dissolved all the buoyancy foam in the hull. Got it replaced under insurance but needless to say there was no smoking allowed in the boat till that was done.
