How do I find a propane or LPG gas leak on my boat?

To detect an LPG leak on a boat, use a dedicated liquid leak detector spray on every joint, valve and union from the gas locker to the galley appliances, watching closely for expanding bubbles. For long-term safety, install a marine-grade inline bubble tester in the gas locker and a hard-wired electronic gas alarm low down in the bilge to catch leaks you cannot see or smell.

Inline Bubble Testers

The most reliable method for spotting a leak in a marine gas system is an inline bubble tester like the Alde model. This unit costs around £75 and sits inside the self-draining gas locker. You plumb it into the 8mm or 10mm copper pipe immediately after the 30mbar bulkhead regulator.

A bubble tester allows you to check the entire system for pressure drops without relying on electricity. To test your system:

• Turn on the gas cylinder valve using a proper gas spanner (remembering that Calor Gas propane cylinders have left-hand threads).
• Ensure all cooker burners and oven valves inside the boat are completely turned off.
• Press and hold the red button on the bubble tester for 10 to 15 seconds.
• If bubbles rise through the fluid in the sight glass, gas is flowing. This means you have a leak somewhere downstream. If the fluid remains still, the system is gas-tight.

Tracing Leaks with Spray

Once you know a leak exists, or if you smell the cabbage-like odour of mercaptan (the chemical added to LPG), you need to pinpoint the exact joint. Purchase a commercial leak detection spray. A mixture of washing-up liquid and water works in an emergency. However, household soaps contain salts that will eventually corrode brass fittings. A dedicated spray is always better.

Work systematically from the gas locker to the galley:

• The Gas Locker: Spray the high-pressure pigtail hose, the regulator connections and the test point. Check the bulkhead fitting where the copper pipe exits the locker.
• The Isolation Valves: Move into the cabin and spray the inline isolation valves. You will usually find these in a cupboard near the cooker.
• The Cooker Connections: Pull the gimballed cooker forward. Spray the connections on the armoured flexible hose, both at the copper pipe union and the back of the appliance.

Wait a minute after spraying each joint. A leak will cause the liquid to foam up and form distinct, growing bubbles. If you find a loose compression joint, use two spanners to tighten it. Use one to hold the fitting body and one to turn the nut, so you do not twist and kink the copper pipe. Usually, a quarter turn is enough to reseat the olive.