Carbon monoxide poisoning

Carbon monoxide (CO) is a colourless and odourless gas produced when carbon based fuel, such as diesel, gasoline, propane, charcoal, or oil, burns.

Long periods of exposure to low concentrations or short periods of exposure to high concentrations of carbon monoxide can result in death or serious injury. Carbon monoxide in high concentrations can be fatal in a matter of minutes.

To keep carbon monoxide levels at a minimum and prevent poisoning, regular maintenance and proper boat operation can reduce the risk of injury.

Sources on a vessel that produce carbon monoxide include gasoline or diesel engines, generators, fuel burning cooking equipment, and space or water heaters.

The areas of concern for recreational boaters are the build up of carbon monoxide emissions inside and outside the vessel. Passengers, swimmers and teak/drag surfers should be aware of the carbon monoxide levels that dissipate from rear-vented generator exhausts situated close to the rear deck and the swim platform. Those in the water should not approach the area until the motor generator has stopped running for at least 15 minutes.

The U.S. Coast Guard website has a list of ways CO can accumulate.

Increased carbon monoxide levels could accumulate inside the cabin, cockpit and bridge due to blocked exhaust outlets, or the effects of back drafting when operating at a high bow angle or with improper and heavy loading.

When idle or travelling at slow speeds, boats should be a minimum of 6 metres from the nearest vessel that is running an engine or generator alongside, to prevent exhaust fumes or tailwinds increasing carbon monoxide levels.

Always keep forward facing hatches open to allow fresh air to circulate the living spaces. When possible, operate the vessel so that prevailing winds help dissipate emissions of the exhaust in order to prevent the accumulation of carbon monoxide in the cabin or cockpit.

Taking steps to correct rear venting generator exhausts of manufacture designs is one step to prevent the build up of carbon monoxide concentration, however scheduling regular engine and exhaust system maintenance inspections by trained technicians is most beneficial. Cold and/or poorly tuned engines produce more carbon monoxide than warm, properly tuned engines.

Educate family, friends and boat passengers about carbon monoxide so that they aware of the possible symptoms. Early symptoms of carbon monoxide poisoning include irritated eyes, headache and dizziness. These should not be confused with the flu, seasickness or intoxication.

Steps to prevent carbon monoxide poisoning:

  • Find out where the exhaust outlets are located on your vessel and ensure that they are properly vented away from living areas
  • Install a CO detector alarm and test its operation before each trip
  • Educate passengers on the symptoms of CO poisoning, causes and areas to avoid
  • As part of the monthly maintenance check, inspect components of the exhaust system and check the condition of rubber hoses. Look for any signs of leaks in the exhaust system including water leaks, rusts, corroded, cracked or loosened fittings
  • As part of the annual maintenance check, have a qualified marine technician clean, inspect and confirm proper operation of the engine, generators and metallic exhaust components. Replace any worn parts and ensure the cooling systems are in proper working condition.

If you suspect someone may have carbon monoxide poisoning contact your nearest emergency medical service.

Teak surfing

The obvious thrill of teak surfing, also known as drag surfing is the exciting pace of being pulled through the water and swimming the waves. Teak surfing involves people body surfing or taking hold of the swim platform of a vessel while it is underway and then letting go to ride the waves created by the vessel. It can also include water skiing within 20 feet of a moving watercraft.

Teak surfing is a dangerous activity because it positions the individual directly in path of the vessel's exhaust vents where they could breathe in dangerous levels of carbon monoxide. It becomes a recipe for disaster, if the individual choses not to wear their lifejacket, added to the threat of possible propeller injury or drowning, if any miscalculations cause the individual to be thrown.

As engines and generators are kept running to power the vessel or while idle to support the air conditioning, entertainment centres or electronic facilities, the accumulation of carbon monoxide fumes can become hazardous to the health of those persons near the exhaust vents.

Every safety precaution should be taken to prevent the lethal combination of carbon monoxide fumes and teak surfing. People should be discouraged to participate in this activity.


US Coast Guard website section on carbon monoxide and their brochures on CO Poisoning.

State of California - Department of Boating and Waterways brochure on CO Poisoning.

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