Dangers of Carbon Monoxide

Carbon monoxide (CO) is a toxic gas made by incomplete ignition or burning of carbon-based fuels like petrol, propane, charcoal, wood and oil.

  • You cannot see, smell or taste CO
  • CO symptoms are similar to seasickness or alcohol intoxication
  • CO can affect you whether you are underway, moored or anchored
  • CO can make you sick in seconds. In high enough concentrations, even a few breaths can be fatal.

Carbon monoxide poisonings are preventable.

Carbon monoxide (CO) is a common part of exhaust gases from engines, generators and stoves using any kind of fuel. It is colourless, odourless and very toxic. It is heavier than air so it accumulates in restricted spaces such as cabins and engine bays, and on low surfaces such as the water beside exhaust ports and under duck boards at the stern of powerboats.

Carbon monoxide can remain in or around your boat at dangerous levels even if the engine is no longer running.

Carbon monoxide poisoning can be especially dangerous for people who are sleeping or intoxicated.

• Ensure inboard engines exhaust outside the vessel
• Make sure canvas enclosures are adequately ventilated
• Ensure stoves and fuel heaters are exhausted outside the cabin
• Never use a gas range or oven for heating
• Keep cabins and engine bays well ventilated
• Make sure the engine bay vents are outside the cabin
• Be aware of another vessel’s exhaust. Carbon monoxide from the boat berthed next to you can be just as deadly
• Install carbon monoxide alarms in cabins and keep them serviced regularly
• Be wary when external exhaust gases are blown by the wind into the cabin or into a sheltered part of the deck for any length of time
• Always have your equipment installed and serviced by a competent person

  • Dull headache
  • Weakness
  • Dizziness
  • Nausea or vomiting
  • Shortness of breath
  • Confusion
  • Blurred vision or irritated eyes
  • Loss of consciousness
  • Get the victim into fresh air, being careful not to be exposed yourself
  • Seek immediate medical attention
  • Shut off the potential source of carbon monoxide if possible.
  • At slow speeds, while idling, or stopped. Be aware that carbon monoxide can remain in or around your boat at dangerous levels even if your engine or the other boat’s engine is no longer running!
  • Blocked exhaust outlets
  • Exhaust gas trapped in enclosed places
  • Inadequately ventilated enclosures
  • “Station wagon effect” or back drafting
  • Another vessel’s exhaust.  Carbon monoxide from the boat docked next to you can be just as deadly


  • Test the operation of each carbon monoxide alarm by pressing the test button.
  • Confirm that exhaust cooling water flows when the engines are started.
  • Listen to changes in exhaust sound—this could indicate an exhaust part failure.
  • Know the sources of carbon monoxide on your boat (such as exhausts and gas appliances).
  • Educate everyone on board about where carbon monoxide may accumulate and the symptoms of carbon monoxide poisoning.
  • When moored alongside or rafted with another boat, be aware of their exhaust emissions.
  • Ensure rain and weather covers are not blocking the free flow of air around the boat.
  • Keep forward facing hatches open to allow fresh air to circulate.
  • Check and maintain your exhaust systems—check mounting clamps are in place and secure; there is no rust, exhaust soot, water leaks, corroded or cracked fittings; rubber hoses are pliable and free of kinks with no burned or cracked sections
  • Check and maintain the burners on your gas appliances
  • Check and maintain your carbon monoxide detector—check the battery is installed properly and is in good condition; never remove the battery unless replacing it with a new battery
  • Have a qualified marine mechanic check your engines every year
  • Have a qualified gas fitter check your gas installation and appliances every year