I have one in my catamaran, and it has worked fine for 22 years. You need to be able to exhaust the fumes, and you need a carbon monoxide alarm to be safe, but otherwise they are fine in a cat or a mobo, but are no good in a raggie monohull, cause they dont work safely when heeled over.
Best place to get them is a caravan shop. They are normally gas/12v/240v Dont bother with the 12v as they are very hungry for amps. I use gas for cooking, fridge and hot water and reckon one 4.5kg lasts about 5 days.