Beginners with Fuel Storage
Ideally portable gas tanks should be stored in sealed lockers vented top and bottom directly to the atmosphere. This is pretty typical of new outboard powered well. Older boats often had tanks stored in lockers that were not sealed but had intake and exhaust vents with the intake venting high and the exhaust at the lowest point of the bilge. When the tanks are stored within the interior volume of the boat, the boat should have explosion proof switches, bilge blower and bilge pump. The bilge blower should be run 5 minutes before starting the engine, the bilge should be sniffed for fumes and then the engine started. If you store fuel within the interior volume of the boat, The blower should run the entire time the engine runs whether you are using the interior tank or not. The tank vent needs to be open when you are using the tank to supply fuel to the engine of the engine will vacuum lock. When I had an outboard powered boat, I carried the spare tank on deck in the atmosphere. Its not a great solution but it worked.