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LPG Gas Safety on Boats: Lockers, Hoses, Leaks and CO Alarms

Checked against its sources on 20 Oct 2026.

Most narrowboats and many cruisers use LPG for cooking, heating or hot water. Used and maintained properly, it is safe. This guide covers the two main risks, what the Boat Safety Scheme (BSS) checks, and what to do if something goes wrong.

The two main risks

Explosion. LPG is heavier than air. If it leaks, it flows down into the cabin, engine space or bilges and can form an explosive cloud.

Carbon monoxide (CO). When fuel does not burn completely, it makes carbon monoxide. You cannot see or smell it.

Storing cylinders

All cylinders, whether full, part full or empty, must be stored where any leaking gas will go safely overboard. That means a proper cylinder locker, a cylinder housing, or a suitable open position on deck. Do not keep spare cylinders inside the boat.

Cylinders must be:

  • upright, with the valve at the top
  • secured so they cannot pull on pipes or hoses or damage the regulator

Do not refill standard cylinders yourself. The BSS says this is dangerous and unlawful. Some specialist refillable cylinders are designed to be filled at service stations.

The cylinder locker

The BSS checks that:

  • up to the top of the cylinder valves, the locker has no holes, cracks or failed welds that would let gas into the boat
  • there are no hatches into the boat inside that part of the locker
  • the locker has a drain, with the opening no more than 30mm above the lowest point of the locker
  • the drain outlet is on the outside of the hull, above the waterline
  • the drain line falls all the way to the outlet and is not blocked
  • the locker holds nothing that could block the drain, damage the cylinders (such as anchors or mooring pins) or ignite gas

The drain must be big enough for the gas you carry. For up to 18kg in total, the minimum is 12mm internal diameter. Larger loads need a larger drain.

Check the drain regularly. Clear any leaves or debris.

Before your examination, empty the locker of loose items so the examiner can see its condition. If the cylinders are in the way, the examiner may not be able to finish the check.

Regulators

Use a regulator that matches your gas. Propane systems usually run at 37 mbar and butane at 28 mbar. Dual-fuel regulators run at 30 mbar. Regulators must not be the manually adjustable type.

Propane works better in cold weather than butane.

Pipes

Fixed gas pipes must be seamless copper, stainless steel or copper nickel tube. They must:

  • not move when pushed lightly
  • be free of kinks, damage and corrosion
  • be protected where they pass through metal bulkheads or decks, for example with grommets
  • be at least 75mm from exhausts and flues
  • have joints that can be seen and reached

Do not box in pipe joints where they cannot be inspected.

Hoses

Flexible hose may only be used to connect the regulator or an appliance to the fixed pipework. Each of these hoses must be no more than 1m long.

Hoses must be marked BS EN 16436 Class 2 or Class 3, or BS 3212 type 2. They must be free of cracks, brittleness, kinks, soft spots and joins.

Replace any hose that is cracked, brittle or discoloured.

Appliances

  • Only use appliances suitable for LPG and for boats.
  • LPG appliances fitted on or after 3 January 2000 must have a flame failure device on every burner. This cuts off the gas if the flame goes out.
  • Appliances designed to have a flue must have one.
  • Burners should give a crisp blue flame. Investigate any yellow or flickering flame.

Never use portable camping stoves or portable gas heaters inside the cabin.

Ventilation

Gas appliances need air to burn safely. Never block your vents. See our ventilation guide for how the BSS works out how much ventilation a boat should have.

Carbon monoxide alarms

Since April 2019, carbon monoxide alarms have been a BSS requirement.

  • Any boat with an accommodation space must have at least one CO alarm.
  • An alarm must be within 10m of any door that links accommodation spaces.
  • Alarms must be in open view, certified to BS EN 50291 or equivalent, and have a test button.

Follow the alarm maker’s advice on how many to fit and where. Test it routinely and never take the batteries out.

A CO alarm will not detect a gas leak. It only detects carbon monoxide.

Signs of an unsafe appliance

  • A lazy yellow flame instead of a crisp blue one.
  • Soot or staining around the appliance.
  • Excess condensation.

Symptoms of CO poisoning

The NHS lists headache, dizziness, feeling or being sick, weakness, tiredness, confusion, chest and muscle pain and shortness of breath. Symptoms may ease when you go outside.

If you think you have CO poisoning, stop using the appliance, go outside and get medical advice straight away. Call 999 if someone is struggling to breathe, confused or unconscious.

Checking for leaks

  • Use a proprietary leak detection fluid on joints.
  • Never test for a leak with a naked flame or anything that could spark.

A bubble leak detector is a device fitted in the cylinder locker that lets you check the whole system for leaks. It is not a BSS requirement, but the BSS strongly recommends one. It must be fitted by a Gas Safe registered engineer who is qualified for LPG on boats.

If you smell gas

  1. Turn off the gas at the cylinder.
  2. Put out all flames and cigarettes.
  3. Do not use any electrical switches.
  4. Open up the boat to ventilate it, and get everyone off if you can.
  5. Do not use the system again until a competent engineer has checked it.

Servicing and who can work on gas

The Canal & River Trust advises having your appliances checked every year by a Gas Safe registered engineer.

Not every Gas Safe engineer is qualified for LPG, and not every LPG engineer is qualified for boats. Check the engineer’s ID card shows the right competence, or call Gas Safe Register on 0800 408 5500.

On hire boats, business boats and boats used mainly as homes, the law says anyone working on the gas system must be Gas Safe registered with the right competence.

What the BSS examination checks

The BSS checks include:

  • cylinder storage and the locker, including the drain
  • the main gas shut-off valve, which must be in view or clearly labelled
  • regulators, pipes, joints and hoses
  • flame failure devices and burner flames
  • a gas tightness test to show there are no leaks
  • carbon monoxide alarms

Leaks, joints, burner flames and an unmarked main shut-off valve are all on the BSS list of the ten most common failures.

Sources

All read 20 Oct 2026.