Carbon Monoxide Safety

There is a risk to boaters from carbon monoxide generated by their own activities such as use of portable generators on board rather than on the towpath, as well as the more obvious use of inadequately ventilated stoves, cookers, heaters or other combustion appliances.

Boaters are also at risk from others’ use of such appliances in close proximity, where significant levels of carbon monoxide from others’ activities can be propelled into boats through open doors and windows. 

Carbon Monoxide Alarms on Boats

IWA advises that all boaters fit a carbon monoxide alarm on their boat, and for people to expect to see alarms fitted and working on boats they hire or otherwise use.  Appropriate carbon monoxide detectors are readily available to the safety standard EN 50291-2:2010 and suitable for marine use, and appear to be the only defence against passive accumulations of the gas from other sources by alarming at low levels. These can be obtained on-line for less than £20.

MAIB video highlighting the dangers of carbon monoxide poisoning on boats:

What creates Carbon Monoxide

Carbon Monoxide is a colourless, odourless, invisible, and very toxic gas. It is the product of incomplete combustion. If a carbon-based fuel - such as petrol, diesel, LPG (liquid petroleum gas), wood, coal, or charcoal briquettes - is burned in an atmosphere with insufficient oxygen, Carbon Monoxide results.Carbon Monoxide is heavier than air, and will sink to bottom of holds or accommodation space on boats, as well as in caravans and tents, etc.  People asleep are particularly susceptible to Carbon Monoxide poisoning, and many deaths are recorded annually from Carbon Monoxide produced by malfunctioning or improperly vented appliances.

Symptoms of Carbon Monoxide poisoning

Carbon Monoxide poisoning symptoms may easily be overlooked because of their similarity to other health-related problems aboard boats - including seasickness, colds, flu and overindulgence of alcohol. One or more of the following symptoms may signify the adverse effects of Carbon Monoxide accumulations: watery and itchy eyes, flushed appearance, throbbing temples, inattentiveness or lack of concentration, inability to think coherently, ringing in the ears, tightness across the chest, headache, drowsiness, nausea, dizziness, fatigue, vomiting, collapse, and convulsions.

If you get any of these symptoms get to fresh air quickly.

How to stay safe

  • Ensure that all appliances you purchase comply with the latest standards and are sold as suitable for use in boats.
  • Ensure the appliances are properly installed and maintained by competent gas fitters.
  • Provide adequate ventilation to all fuel burning appliances in accordance with the appropriate BSS Standards.
  • Do not use damp fuels in fuel burning appliances, doing so could cost you more, damage your appliance and put you at a higher risk od Carbon Monoxide poisoning. Find out more.
  • Regularly inspect all appliance flues for damage and blockage and for signs of leaks, such as the discoloration of nearby surfaces.
  • Check for signs of faults on any LPG appliances including yellow-tipped flames; excessive deposits of soot around the burners; pilot lights that often go out; or even increased condensation inside windows.
  • Be alert, check that vents and flue terminals, especially on cabin tops, are not damaged, blocked or restricted by stowed equipment such as boarding planks, tenders, boat hooks, lifebuoys, decorative objects, etc.  Beware of engine exhaust gases in the accommodation space.
  • Regularly inspect the exhaust system of inboard engines and check it for leaks.
  • Ensure generator exhaust fumes cannot drift back into the cabin.

What is unsafe

  • Never block cabin ventilators, particularly those at low level.
  • Never use LPG cooking appliances for space heating.
  • Never leave LPG appliances on overnight, unless they are designed to be left on and are of the room sealed type.
  • Never use mobile (cabinet) gas heaters on board - they are not suitable for use in boats and introduce a fire safety hazard.
  • Never bring lit barbecues into a boat. Smouldering charcoal gives off Carbon Monoxide gas.
  • Never cover the air inlet or heat outlet of a cabin heater.
  • Never use an appliance you think may be faulty or unsafe.
  • Never operate petrol generators inside an enclosed space, or close to any opening or ventilator which leads into the cabin space.
  • Never run a boat's engine with the craft moored against another object such as a wharf, lock wall or another boat as the exhaust gases could easily deflect back into the boat.
  • Avoid running your engine when moored in a crowded marina, particularly when the air is still.

Fit a Carbon Monoxide Detector

Make sure it is suitable for marine use, as many are not.

Further Reading

The Council of Gas Detection and Environmental Monitoring
Tel: 01462 434322

The Boat Safety Scheme - Boat Safety Scheme CO Awareness Information

Gas Safe Register - for a list of registered fitters that work on
Tel: 0800 408 5500

HSE leaflet “Gas Appliances - Get them checked, Keep them Safe” ref: INDG238(rev2).

Warning Against Use of Damp Fuel

Boat Safety Scheme

Find out how you can limit the fire and carbon monoxide risks arise from the way that engines, appliances, systems and fuels are used and maintained on the Boat Safety Scheme website.

Find out more about Carbon Monoxide safety on the Boat Safety Scheme website.