Carbon Monoxide Alarms

Boats are built to keep water out, but this also makes them good containers for gases and fumes – especially carbon monoxide. ‘Black-spot’ colour-changing CO indicator cards are not good enough: they do not give an instant warning of dangerous CO levels and have no alarm to wake you up. CO alarms are designed to protect you from CO produced by incomplete combustion of any fuel (including LPG, coal, charcoal, wood, paraffin or diesel used in domestic appliances such as cookers, boilers, stoves, etc.), or from exhaust fumes from a boat’s engine or generator. The main causes of CO build-up in a cabin are faulty, badly maintained, or misused appliances and escaped flue gases from solid fuel stoves.

10 tips to keep you and your crew alive

  1. Install fuel-burning appliances properly, in line with manufacturer’s instructions.
  2. Follow servicing guidelines, with routine and competent maintenance.
  3. Use appliances as per their instructions (e.g. never use cookers for space heating).
  4. Don’t allow any bodged repairs, adjustments and adaptations to appliances.
  5. Never use equipment you suspect has problems; deal with them immediately.
  6. Don’t block ventilation.
  7. Don’t bring charcoal BBQs on board, or have them near a cabin during or after use – only stone-cold charcoal is safe.
  8. Prevent engine fumes from entering the cabin and never use a portable generator in or near a cabin.
  9. Learn about the danger signs; identify potential hazards before CO can be produced and make sure that all crew know the symptoms of CO poisoning and how to react if it is suspected.
  10. Install a certified CO alarm (BS EN 50291-2), test it routinely and never remove the batteries.

How many CO alarms do you need and where to fit them?

If the boat has a single multi-use cabin, one alarm is sufficient, but otherwise all cabins with a fuel-burning appliance should have a CO alarm fitted. If fuel-burning heaters, generators or engines are used while people sleep, all bedrooms should have their own alarms. Follow the alarm manufacturer’s installation instructions as far as the space and nature of the boat allow, but if the directions are difficult to meet on your boat, the following are best practice points:

Place the alarm:

  • in living quarters between 1 metre and 3 metres from the appliance;
  • in living quarters high up on a wall, at least 150 mm from the ceiling and where the indicator lights can be seen;
  • in sleeping quarters in the ‘breathing zone’ near the bed head.

Before fixing, check that you can hear the alarm from any position in the boat (or buy additional alarms). Test the alarms when you first board the boat and then weekly when the boat is in use.

Write a replacement date on the alarm. Do not use it beyond that date and if in any doubt, replace it earlier. When working on the boat with paints, solvents, degreasers etc., cover the alarm or remove it temporarily to protect the sensor. Replace the alarm as soon as the air clears and before you use any appliance or the engine. Consider removing the alarm from a winterised boat to prevent long periods of sub-zero temperatures affecting its sensor and battery.

Note that CO alarms:

  • only detect CO, they cannot prevent it;
  • do not detect fires, smoke or leakages of petrol or LPG fuel vapours;
  • can activate if they sense hydrogen (e.g. from the boat’s batteries gassing off when under charge).
  • may not fully safeguard individuals with specific medical conditions;

Both smoke and CO alarms are available for people with hearing loss.

The CO alarm manufacturer’s association, CoGDEM, has published a list of alarms produced by its members that are suitable for use in boats (