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Maritime Saftey and Security


Carbon Monoxide on vessels... The unseen Danger

 What is Carbon Monoxide?

Carbon monoxide (CO) is a colorless, odorless, and tasteless hazardous toxic gas – that can pose a real threat to your personal safety and to those onboard of your vessel.
Carbon monoxide may result from the burning of any carbon-based fuel— such as propane, charcoal, or oil. Sources on your vessel may include engines, gas generators, cooking ranges, space and water heaters.

Why is Carbon Monoxide so dangerous?

  • CO can harm and even cause death to you or to those inside or around your vessel.
  • CO symptoms do mimic those of seasickness.
  • CO may do harm at any stages of your navigation whether you're underway, moored, or anchored.
  • It is hard to smell, or taste CO, but if you are able to smell exhaust fumes, CO is definitely present.
  • CO does cause sickness in a matter of seconds. In high concentrations, CO is fatal at minimal breathing episode.

Symptoms of Carbon Monoxide poisoning

Early symptoms of carbon monoxide poisoning are headaches, nausea and fatigue. The manifestation of these symptoms indicate that a concentrated dose has been inhaled. Unfortunately, such symptoms may be mistaken for those of a flu as the gas goes undetected. Prolonged exposure can lead to brain damage and at worst, death.

Vessel owners and operators responsibilities

Vessels owners and/or operators should be aware of the risk of exposure to carbon monoxide poisoning especially in enclosed engine rooms or auxiliary machinery spaces whenever combustion engines are running.

Vessels owners and/or operators should also be aware that the configuration of vessels with partially-enclosed cabins, wheelhouses or passenger accommodation spaces combined with the prevailing weather conditions can create a situation where discharged machinery exhaust fumes overboard are wind-carried and drawn back into these enclosed areas.

Vessels owners and/or operators must maintain their vessels in accordance with the manufacturer's recommendations and ensure that the vessel/s engine is serviced adequately and on timely manner.

Watch out for these situations


Inadequately ventilated canvas enclosures

Exhaust gas trapped enclosed places

Blocked exhaust outlets

Another vessel's exhaust CO from the vessel positioned next to you can be just as deadly

The 'Station Wagon Effect' or 'Back Drafting' is caused as air moves around a vessel and forms a low pressure at the alt end. CO from the exhaust then enters the low pressure area and this is fed into the cabin of the vessel

At slow speeds, while idling, or stopped, CO can remain at dangerous levels in and around your vessel even if your engine or the other vessel's engine is off


Trip Checklist for Carbon Monoxide

Make sure you know where exhaust outlets are located on your vessel.

Educate all passengers about the symptoms of CO poisoning and where CO may accumulate.

When docked, or rafted alongside another vessel, be aware of exhaust emissions from the other vessel(s).

Confirm that water flows from the exhaust outlet when the engines and generator are started.

Listen for any change in exhaust sound, which could indicate an exhaust component failure.

Test the operation of each CO detector by pressing the test button.

Don't leave your engine idle for long periods of time. The best way to keep CO away is being on the move

The fitting of Carbon Monoxide Alarms/detectors in strategic positions on your vessel is a way to protect yourself, your family or passengers from CO poisoning.


United States Coast Guard website website and their brochures on CO Poisoning.