Propane Cabin Heater
I found that installing a proper propane system to be quite expensive. So much so that rather than bring the propane system up to regs on my boat I took out all of the existing propane system. A proper systems includes a tank locker that is sealed from the boat (and cockpit)but vented to the atmosphere at the top and bottom of the tank. It requires a tank and regulator and electrically operated solenoid valve that can be turned off from down below. Ideally there should be a passive bilge venting system and a bilge blower. There should be a sniffer system with a propane/carbon-monoxide sensor in the bilge and near the appliance. It requires hoses and connectors designed for use with Propane. If the propane lines run near the engine compartment you should be using an explosion proof electrical system (alternator, etc)on the engine similar to what is used on a gas engine.
If you don''t already have propane, I certainly would not put it aboard. I am always amazed at people who say, "I would not have a gas engine, it is too dangerous" but who think nothing of having a propane system.