Propane (LPG) Safety on Boats - Locker, Solenoid, Sniffer and Leak Test

After every use, turn off the solenoid switch and close the valve on top of the cylinder. BoatUS points out that the manual cylinder valve is what really keeps gas out of the boat when you leave.

Open the locker and look. It should hold only gas cylinders: no fuel cans, tools or ropes. It should open from the top, have a gasketed lid with a latch that needs no tools, and be built of or lined with a corrosion-resistant material. Water or rust inside means the lid is leaking; BoatUS describes a surveyor condemning a locker whose parts were all corroded by seawater getting in.

Find the drain at the bottom of the locker and follow its hose to the hull. It must run downhill and exit overboard above the waterline, with no loops or dips that can hold water. A drain hose teed into a cockpit drain, blocked by water or missing entirely is a serious problem for a technician to fix.

Each cylinder should be strapped down so it cannot move, in the position it was designed for: BoatUS warns that a cylinder made to lie horizontally, if stood upright (or the reverse), can send liquid propane into the system. Look for heavy rust, dents and damaged valves. BoatUS notes cylinders must be requalified 12 years after manufacture and then every 5 years; check the date stamped on the collar and ask your propane dealer. Rusty or damaged tanks will not pass and need replacing. Spare cylinders, including small 1-pound grill canisters, need the same safe, vented storage as the one in use, never a cabin locker or the bilge. If you own a composite (fiberglass) cylinder, check it against the Lite Cylinder recall described by BoatUS.

The regulator lowers cylinder pressure to what the appliances use. On deck installations, Discover Boating says regulators and valves must be at least 20 inches from any opening into the cabin or a locker. A pressure gauge does not show how much gas is left: the pressure stays nearly the same until the tank is almost empty. Its real job is the leak test.

Have a helper switch the solenoid on and off at the panel while you listen at the locker. You should hear a clear click each time. Solenoids are "normally closed": they need power to stay open, so losing power shuts the gas off. BoatUS notes some are prone to corrosion, so look for rust or green corrosion on the body and wires. If it does not click, have it replaced by a technician.

This is the check BoatUS describes from the ABYC guidelines, for systems with a gauge:

1. Make sure every appliance burner and valve is off.
2. Turn the solenoid on.
3. Open the cylinder valve to pressurize the system, note the gauge reading, then close the cylinder valve.
4. Watch the gauge. BoatUS cites at least 3 minutes with no drop; Discover Boating suggests 5 minutes. Waiting the longer time costs nothing.

If the pressure holds, the system passed. If it drops, there is a leak: close the cylinder valve, turn the solenoid off and do not use the system.

If the gauge dropped, or your system has no gauge, spray a non-corrosive leak-detection solution (or mild soapy water) on the joints you can reach: cylinder valve, regulator, gauge, solenoid and hose ends in the locker, and the connection at the stove. Growing bubbles mark a leak. Leaks often hide on the underside of a fitting, so check below each joint with a small mirror or your phone camera, as Practical Sailor's how-to suggests. Never use a flame to look for a leak. Mark the spot, leave the system shut off and call a technician.

Follow the line from the locker to each appliance as far as you can see. It should be one unbroken run per appliance, made of approved flexible propane hose or copper tubing. Look for chafe, kinks, cracks, splits and spots where it rubs on sharp edges. BoatUS notes that hose clamps on propane hose and compression fittings on copper are not acceptable. If you find any of these, have the line replaced.

Find the alarm panel and its sensor. The sensor should be low in the cabin near the propane appliance, because the gas sinks. Press the test button and confirm the alarm is loud enough to hear. Check the label for the sensor's replacement date and follow the maker's instructions. If the alarm is wired to shut the solenoid, confirm the gas turns off during the test.

Burners should light cleanly with a blue flame.

A gimbaled galley stove must be securely captive: Discover Boating suggests pulling up firmly on it to make sure it cannot lift out of its mounts. Any propane heater needs the same solenoid and sniffer protection as the stove. Never use the galley stove or a portable heater to warm the cabin; fuel-burning appliances make carbon monoxide.

BoatUS recommends a carbon monoxide detector in each cabin or enclosed sleeping space, in addition to the propane alarm. They detect different gases. The USCG notes CO can harm you whether you are underway, moored or anchored.

Discover Boating describes emptying the lines: with a burner lit, close the cylinder valve. When the flame goes out, turn the burner off and switch the solenoid off. Many owners take the cylinders home for the winter and store them upright outdoors.