Saturday, January 16, 2016

Your Deadliest Cruising Challenge

Marathon, FL

I wish I could think of a more captivating title for this blog.  That is because today's subject is about something quite deadly, and nearly ubiquitous among cruisers -- the handling of propane on board.

Propane is a wonderful fuel, at least in the USA and many other places.  It burns clean, it is inexpensive, the energy density in joules per pound, or joules per liter, is high.  It is the fuel of choice.  We love it.

But propane has one deadly quality.  It is heavier than air.  If propane leaks inside, it will not disappear upward through open hatches or ventilators, it will sit in the lowest point for years, waiting for a spark.  If the spark happens, it can cause a devastating explosion that demolishes the boat, and that can kill everyone on board.

In West Charlton, where I once belonged to the volunteer fire department, we had a dramatic demonstration.  There was an alarm at 3 AM for a propane leak.  When the men arrived at the fire house, they started the engines and tried to drive away.  The diesel engines stalled on the apron and would not restart.  That is because there was no oxygen out there, just propane.  The leak was 3 miles away, and the gasses followed a small brook winding through the fields and the woods to the fire house.  Thankfully, there was no fire or explosion that

The safe way to use propane on board needs three factors.

  1. The propane tanks need to be stored somewhere that if they leak, the gas will spill overboard into the water.
  2. The hoses and fittings are special kinds designed for this application.
  3. An electric solenoid valve near the tanks shuts off when you aren't using the gas.   With that valve shut, a leak in the piping or the connections will spill only the volume of gas in the pipes, not the whole tank.

On Tarwathie, we carry two 20 pound propane bottles.  They are stored in the lazarette compartment in the stern.  That compartment is sealed from the rest of the boat, and it has it's own drain right out to the sea.  Other people use deck locks or merely strap tanks to the stanchions to achieve the same.

I think that most cruising vessels do a pretty good job in safely handling the primary propane source.   However, many of them then violate those same principles when storing portable propane bottles commonly used for BBQ grills, camp stoves and camp heaters.  They store those bottles any old place, and they ignore the rule about safe places to store them.

Bottles used for propane torches are equally dangerous. I've used them twice, and I stored them back in the lazarette with the other propane tanks.  Twice I went to use them some months later only to find that they rusted out holes and were empty.

On the cruisers net last week, one of our friends cheerfully announced that they used a propane camp heater inside their boat when it was cold.  They felt that they were safe because they have a carbon monoxide alarm.  They really missed the point, the propane tank itself is a much bigger hazard than carbon monoxide.


Some units such as the one below, are marketed at "indoor safe."  Well, in my opinion "indoor safe" is not "below decks safe" on board a boat.  A house or a tent has places for heavy gasses to escape. The bilge of a boat does not.   A house or a tent also can have safe places to store extra fuel tanks, safe storage on a boat is harder to achieve.  For that reason, the safety standard on a boat needs to be higher than for a house or a tent.

Update: The manufacturer of the heater above says this in the product manual. Note that it does not mention boats.
This heater is safe for indoor use in small recreational enclosures, having means for providing combustion air and ventilation, such as enclosed porches, cabins, fishing huts, trailers, tent trailers, tents, truck caps and vans.

Update: Blog fan Pam & Dave informed me about something I hadn't known about. He said, "I did everything you recommended plus I added a propane sniffer down in the bilge"  I didn't even know that such things existed.  But after a quick Google search, I found many of them.  Yes, I agree Dave,  good advice.  Thank you.
I'm going to shop for one right now.   The face of the detector below says "automatic valve control" which sounds like another good feature.


  1. Dick: you can also add that some parts of the world don't ordorize their LPG... REALLY BAD! also that Batteries can do the same "explode the whole boat thing"... Sarah my daughter is in Spain studying Spanish and has an appartment - there or maybe just her part of town.. - you must order your propane to be delivered in small tanks for each apartment - delivered on certain days and you have to pay at delivery.

  2. Good advice, Dick. On my sailboat, I did everything you recommended plus I added a propane sniffer down in the bilge, which sounds a really loud alarm if it detects propane. They're not expensive and it is good insurance.


Type your comments here.