Re: Extra fuel in Gas cans
My onboard tank is inside the hull. On my old starcrafts, my 2-3 6 gallon cans were inside the hull and under the transom compartment. I regularly transport up to 4 of those cans in a skiff to an island. There is nothing wrong with having fuel on board as long as you are smart about it.
For one thing, cans in the sun have to be vented, or at least released periodically. The "new and improved" cans you describe are not vented and will swell up. If you leave the caps loose to vent, they will splash gas out and/or splash water in.
And while this isn't as much of a concern with boats, cars have tanks inside the frame for protection from collision. yours would be vulnerable if someone rear ends you--I picture their bow eye about at your tank level.
In that case, or if there was a small electrical fire, you'd not want them tied so securely that you can't get them off the boat in a hurry.
So the only choice is to tow a fuel dinghy on 200' of line with a quick release, with vented cans and mooring bumpers all around, maybe some I-beam reinforcement, too. OK I'm just being sarcastic; the advice here is good but the point is there is no perfect method and you just have to be smart, and more important, vigilant. Like everything else in boating!
