Oliver Bennett
Why Gas Deserves Your Full Attention Afloat
On a narrowboat you are living inside a steel tube with your cooker, your boiler and your fridge. That is a wonderful arrangement until something leaks. LPG is heavier than air, so any escape from a cylinder, hose or joint will not drift politely out of a window — it will sink into the bilges and sit there, waiting for a spark from a bilge pump, a battery switch or a cigarette. Add the fact that a poorly maintained appliance can produce carbon monoxide, an odourless gas in a space where you sleep and eat, and you can see why gas work is the one job aboard where shortcuts have no place.
The good news is that narrowboat gas systems are simple, and most problems announce themselves early if you look for them. A five-minute bubble test every few weeks, plus a proper annual inspection, will catch almost everything before it becomes dangerous.
Know What You Are Dealing With
A typical boat installation runs from a cylinder in a self-draining locker, through a regulator and a flexible pigtail, into copper pipework, along to an isolator valve, and finally to the appliance. Each of those junctions is a potential leak point, and each has its own failure mode.
- Cylinders should live in a sealed, self-draining locker with ventilation at both high and low level, venting overboard. Never store a cylinder inside the cabin, in a cockpit locker or under a bed.
- Propane is the sensible choice for year-round boating. Butane stops vaporising in cold weather, which is exactly when you want a hot drink.
- Pigtails and hoses have a date stamp. Replace them at the interval stated by the manufacturer, generally every five years, and immediately if you see cracking, stiffness, chafing or green corrosion on the brass fittings.
- Isolator valves at the appliance end let you shut off a single cooker or boiler without killing the whole supply. Test that they actually turn, and turn them off when the appliance is not in use.
The Bubble Test, Done Properly
You do not need a manometer for a routine check, but you do need to be methodical. Buy a proper leak detection spray rather than fairy liquid, which can corrode brass over time.
- Make sure all appliance valves are closed.
- Open the cylinder valve fully, then paint or spray each joint in turn: the cylinder connection, the regulator, both ends of the pigtail, and any visible compression fittings.
- Watch each joint for a full sixty seconds. A single bubble that appears and stops is usually harmless. Bubbles that keep growing or foam steadily mean a leak.
- Wipe the solution off afterwards with a damp cloth, then dry the joint.
- If you find a leak, close the cylinder valve, tighten the fitting with two spanners — one to hold, one to turn — and retest. Do not overtighten, as you can distort the olive and make things worse. If it still leaks, replace the fitting or hose.
Never use a naked flame to hunt for a leak. It is the oldest mistake in the book and still the one that puts people in hospital.
Habits That Keep You Safe
- Turn the gas off at the cylinder whenever you leave the boat and overnight while you sleep.
- Keep low-level ventilation clear. Those vents near the floor are there to let heavier-than-air gas escape, and blocking them because of a draught defeats the whole design.
- Check the cylinder locker drain is clear so any escape cannot pool inside the locker.
- Fit a carbon monoxide alarm certified to BS EN 50291, positioned according to the manufacturer's instructions and away from draughts, and test it weekly.
- Fit an LPG detector low down near the appliances. Gas sinks, so a detector mounted at eye level is close to useless.
- Look and smell. LPG has a distinctive odour added deliberately. If you catch even a hint of it, treat it as real until proven otherwise.
Annual Service and the Boat Safety Scheme
DIY checks complement professional work, they do not replace it. Have your gas appliances serviced every year by a Gas Safe registered engineer with experience of LPG on boats. They will carry out a pressure drop test on the whole system, inspect flues and ventilation, check combustion, and clean or replace injectors and seals. Book it before the season starts, not when the boiler fails in November.
Private boats also need a Boat Safety Scheme examination, typically every four years. The examiner checks the gas installation alongside other systems, and a failed gas item will stop you getting your certificate. Keep a simple log of every service, hose replacement and inspection in a notebook aboard. It takes seconds to write down and it tells you instantly when something is due.
If You Smell Gas
Do not touch any electrical switch, and do not strike a match to check. Turn the cylinder valve off, open doors, windows and hatches, and get everyone off the boat and onto the towpath. Let the bilges ventilate thoroughly before you go back aboard, and do not use the system again until a qualified engineer has found and fixed the fault. A wasted afternoon is a small price for peace of mind — and the same applies to that faint, intermittent whiff you have been meaning to look at for weeks.
