A marine propane locker has to be an airtight enclosure that isolates the propane from the interior of the boat. This project involved not only sealing a massive hole in the existing propane locker compartment but also extending the locker to fit a new propane regulator.

Propane locker with a new side compartment for the regulator

Disclaimer: Working with Propane on a boat is dangerous. This site is for information only and can not be held liable. If you are not comfortable doing this project please hire a licensed professional.

The original locker that came with the boat had a hole cut out by the previous owner that led the copper propane pipes into the boat and eventually leading up to the stove and furnace. Unfortunately by having a gaping hole, it completely defeated the point of having a propane locker at all and the use of the metal piping (with soldered T joints) was breaking ABYC rules.

This propane locker had a hole where the piping lead into the boat. This is bad.

Propane happens to be heavier than air so any propane that might manage to leak out would eventually accumulate in the bilge and would eventually end in a disastrous explosion. The right way to deal with propane on a boat (if you absolutely must) is to first, seal away the tank in an airtight locker. Place a drain hole at the bottom of the locker and have that vented out overboard. The propane line must run through a proper regulator as well as an electronic shutoff solenoid, and then run to the appliance via a solid propane certified line. In my case I used a flexible proper rubber hose and removed all the soldered pipe.

The propane locker was a tight fit for this tank, so I decided to enlarge the locker.

The existing rusty old tank was a tight fit in that locker. And even when getting the tank in, in order to fit the regulator onto the tank and close the top lid, involved bending the hose in unnatural angles, and pinching it between the tank and compartment. My plan was to build a new side compartment for a proper regulator that I could monitor the pressure via a gauge. I would also replace the brass tubing and install a drain plug below the tank that leads out the aft of the boat.

The first step was to remove all the existing hardware. The shoddy patch job already in place fell off with a slight tug. I can see why the previous owner gave up on it. Its quite a tight fit to reach in the back corner. I spent many a night in the dark underbelly of the boat staring at that hole wondering how I was going to fill that hole with fiberglass and not make a mess everywhere.

Propane lockers original hole filled, and a new side area cutout.

I managed to fill the hole by shaping a piece of thick cardboard that was similar in size and mixing up a thick batch of epoxy. It is important to follow the rules when doing fiberglass work like this. Sand the area down properly with rough sand paper to create a bumpy texture for the epoxy to mechanically bind to. Make sure the area is clean and you mixed the epoxy very heavily so that it sets properly. Once I had the cardboard area held in place, it was easy to layer more layers of fiberglass on top. Once it cures you can sand it down good as new and paint it.

Side compartment using test fit using a carboard tube I bought at home depot as mold.

I was toying with the idea of cutting all of the old locker away and building a much larger box compartment. I shied away from that idea because I felt the existing locker was so strongly glassed into the hull of the boat and it would have made a huge mess cutting it all out. It would also be extremely difficult to cut wood panels to fit in all the strange angles which are not very accessible to begin with. In the end I decided to create a rounded additional compartment and epoxy that to the existing panel. I found a large circle cardboard tube used for pouring concrete post anchors and used that as a basic curved shape.

I was also careful not to make the addition of the new compartment too large or it would have blocked precious room in the lazarette where I store safety gear and fenders. Once I had the right shape cut out of the cardboard I wet it out with epoxy resin and layed on fiberglass sheets.

Cardboard tube wet out with epoxy resin and layers of fiberglass layed on.

After a lot of sanding and grinding edges I had a good fit. The curves made this step tricky!

Once the outside was cured, I layered more on the inside. One trick I did was when the outside layer was curing, I covered it in clear plastic sheets. This allowed me to push out the air pockets, and I ended up with a nice smooth finish. Once the epoxy cured I could peel of the plastic as the epoxy wont bind to it. After the cardboard resembled a good strong fiberglass partition, I trimmed off the excess edges with a dremel and started test fitting it onto the old compartment.

I should mention that grinding fiberglass is a dusty, messy nightmare. I was living on the boat and that fine fiberglass dust got everywhere. I made sure I wore my dust mask and I tried to contain the dust by taping up plastic bag walls but that dust will settle everywhere regardless. I probably lost a few years of my life from that experience. Be carefull.

Wish I had a better photo of the compartment epoxied on.

To attach the side compartment I could have used a thickened epoxy paste but I happened to have one of those easy premade epoxy glue guns. The epoxy glue gun was basically 2 compartments holding the resin and hardener which are squeezed together in a large applicator tube where they combine. I was doubtful the epoxy would mix properly in this process but it did end up curing properly so I can’t fault it there. They are expensive however and bulky to deal with as is applied with a heavy metal caulking gun device. In the future I would stick with regular West System epoxy thickened with various fillers. In the photos here the fancy epoxy is green. I applied it liberally to all the joints.

The entire compartment painted white with Interlux Brightside paint

After sanding off the sharp edges I painted all the surfaces down with white marine paint. I believe it was brightside paint from Interlux. Its a strong powerful paint so use an organic gas mask and give it the proper time to cure before you continue working the area.

You can see in the previous photo 2 holes I had drilled into the side. This is where the propane line and the wiring for the solenoid shutoff valve would run into the boat. I found airtight gromets (if thats what its called?) that let me run the cables through the compartment and still keep it sealed. You should be able to find that online at West Marine, Defender or just pick it up at a local Chandlery.

New regulator with solenoid switch attached.

Closeup of the regulator and pressure gauge.

You can also see where the propane hose runs out of the compartment here. The final step was to seal up the top part of the new compartment. A friend of mine had an extra piece of Lexan that I shaped as the top panel. I used a piece of cardboard to finesse the desired shape and transfered the shape to the Lexan before cutting it to shape with an electric saw. That Lexan is also pretty tough. Go slow or you will melt the plastic to the blade.

I affixed the Lexan with screws and also applied a line of silicone to guarantee an airtight seal. So there it is. I had a sturdy sealed propane locker that passed ABYC inspection. Oh I havent shown the drain valve under the locker yet. I will need to dig up that photo or take a new one. The main idea is to run that drain downhill and out of the boat. Make sure that drain exits the boat well above the waterline or you will find your propane locker filling up with water!

Propane locker with a new side compartment for the regulator

So the way this all attaches together is you connect the top of the propane tank to the regulator, which drops the pressure down to normal appliance levels which is then run through the electric shutoff switch and out of the locker straight to the stove. Make sure you use a teflon propane sealing tape on every joint you connect. The trick to make sure it isn’t leaking any propane is to mix up some soap and water and put it into a spray bottle. Close up your stove and spray every joint from the stove to the propane tank. Open up the propane feed and observe every joint closely. If you see any airbubbles forming you have a leak. Close up the propane tank and fix that joint until it is sealed.

Its important to check the joints periodically. When using the stove, always keep an eye that the flame is still burning. There have been a number of times when I was boiling water and I had the stove set to the lowest setting before the flame died out. If the flame dies out, your just pumping propane straight into the boat.

One vital component is the propane sensor under your appliance. This is where the electrical wire from the solenoid shutoff runs to. The idea is if the sensor smells any gas (presumably from the leaking appliance above it) it will shut off the feed and avert a disaster.

Heres a tip: When your done cooking and finished with the propane, I would first turn off the propane from the tank outside rather than turning off the stove. This allows the stove to burn off the last few traces of the gas in the lines before it flickers out. This also forces you to not forget to shut off the tank after you are done cooking.

One final tip, another way to test that your lines are sealed is to open the gas feed but leave the stove switched off. The pressure gauge should shoot up on the dial. Mark the pressure on the dial and then shut off the tank and leave it for an hour or so. When you check the pressure dial later it should be at the same spot. If it has started dropping then you have a leak somewhere to attend to.

Thats it. Be safe around the propane. It’s dangerous stuff to have on a boat so follow all the safety precautions.