Med, a blower is a good idea, and if you have one already you could always physically mount it around the other way if swapping the wires doesn't work. Just make sure you can get plenty of air in at bilge level and that the engine (preferably) isn't running at the time. Diesels run just fine on gas..
Originally Posted by MedSailor
As for opening up all the hatches and sitting on the beach, not such a great plan if you're not near a beach. Even underway near land it would be nerve racking to be in a boat full of propane.... I hear it's 8 times heavier than air, so it seems like opening the hatches might not be enough.
Well, there's always the dinghy.
Actually, what you have to be careful of is maintaining the air/fuel ratio within the explosion limits (between 2.4% and 9.6% roughly) for long periods of time and, as MarkSF pointed out, the alarm will go off well before then. The stuff might be heavier than air, but with an SG of 1.52 (air=1), 8 times heavier it isn't. If the wind is blowing, it's surprising how much you can move through a boat if you need to.