Carbon monoxide (CO) is often called the silent killer for a reason. It is a colorless, odorless, and tasteless toxic gas that is formed as a product of the incomplete combustion of carbon or a carbon compound and is slightly less dense than air. It can build up quickly without anyone noticing. Engines, generators, or fuel-burning appliances can all produce CO, turning an enjoyable trip into a dangerous situation within minutes. It is important to note that the source of CO can be also located on another boat.
The 2025 revision of ABYC A-24, Installation of Carbon Monoxide Detectors and Alarms, brings clearer guidance on how people should be protected, including a better definition of what areas actually require CO detection.
Where should CO detectors be installed?
ABYC A-24 requires carbon monoxide detectors to be installed to monitor the atmosphere in habitable spaces. The definition of habitable space is a new addition to the standard that covers spaces surrounded by permanent structure in which there is provision for any of the following activities:
- sleeping
- cooking
- eating
- navigation or steering
- washing or toilet use
In simple terms, if people spend time inside the space, it should be monitored. Storage lockers, open cockpits, and engine rooms are not considered habitable spaces and typically do not require detectors.
Installation location matters
Even the best detector cannot work properly if installed in the wrong place. Detectors must be installed in locations to avoid:
- physical damage, including harm from rain, water, or sunlight; and
- dilution of sampled air (e.g., near hatches, ports, or forced ventilation openings); and
- inadequate natural air circulation (e.g., in corners).
Use marine detectors
Only detectors tested by an independent laboratory to comply with the requirements of UL 2034, Single and Multiple Station Carbon Monoxide Alarms, including the applicable sections pertaining to use on recreational boats should be installed onboard.
Keep them working
- Check detectors regularly following manufacturer guidance.
- Replace units before the indicated replacement date.
- If an alarm sounds: evacuate, ventilate, investigate, and take corrective action.
A properly installed CO detector plays a critical role in protecting everyone onboard. Take a moment to check your boat. Make sure your CO detection system meets these requirements.
For more information, refer to ABYC A-24 or contact the Standards and Compliance Department at [email protected].