Its not just boats, caravans and motorhomes use gas. To be honest, if I had a motor home, it would be gas for me.
Don't get me wrong, but propane WHEN proper precautions are used is actually less dangerous than the gasoline fuel used in many boats... It is extreemly difficult to develop an explosive mixture of alchol and air. rediculously easy with gasoline and only slightly more so with propane and most of the ease of doing it with propane is due to it's low boiling point so under virtually any normal temperatures humans will encounter propane will be a gas... Gasoline/air mixes have very broad explosion limits, the list of common materials that have broader explosion limits is fairly short But boats being a depression in the water and "tight" against leakage are a critical environment for saturation with fumes, a motor home or a camper does not create nearly the same risk. The thing is that many people choose diesel power in their boats to avoid the fumes from gasoline and consider replacing one risk with another is kinda silly so that's were the market for alcohol fueled stoves comes from. The other thing is that alsohol spills can EASILY be made non-flammible or fires from any fuel spills, easily extinguishable with a bit of water as alcohol is easily diluted below the point of flammibility. Generally gasoline, burning or not, can only be pushed around with water. (usually making the situation worse) The one "issue" with propane on a camper or motorhome is that roads with tunnels and even some bridges get all freaked out about propane.... propane is definatly safer that gasoline or coleman fuel... AD