Wednesday, October 18, 2017

The Perils of Carbon Monoxide

May 1, 2017 by · Leave a Comment 

perils of co2 title

The subject of my story can’t be smelled, seen, touched, or tasted by boaters. However, these drawbacks don’t make my subject insignificant — I’m not overstating it to say that what you don’t sense can kill you.

Carbon monoxide (CO) is a byproduct of the incomplete combustion of carbon-based fuels like diesel, gasoline, kerosene, propane, butane, and charcoal. The completely odorless, colorless, tasteless gas is heavy and so it collects and lingers in enclosed spaces like engine rooms and cabins.

CO is termed a silent killer because it has an affinity for hemoglobin, the protein in your blood that conveys oxygen to your tissues. Chemically, it displaces the oxygen in your blood stream. Short exposure to a low concentration causes irritated eyes, headaches, nausea, weakness, and light-headedness — some victims think they are coming down with the flu.

Prolonged exposure to CO (or short exposure to high concentrations) can lead to death, as your body will shut down without life-sustaining air. According to the Centers for Disease Control and Prevention, about 400 people in this country die every year from unintentional carbon monoxide poisoning.

Exhaust leaks, blockage, or wear and tear allow the killer gas to migrate throughout the boat and accumulate in enclosed areas like the cabin and cockpit, especially when the windows and doors are closed. When an engine or generator is running, the rear of the boat is an especially unsafe area, as CO may flow backwards when the boat is operating at a high bow angle.

carbon monoxide detector

While CO can be present without the smell of exhaust fumes, if you smell exhaust fumes, take immediate action to dissipate them. In any case, if your CO detector is screeching or beeping, immediately let outside air flood in by opening the windows and/or pulling back the cover. If possible, turn the boat so that the winds take the exhaust away or shut off the engines so you won’t further jeopardize safety.

Don’t delay seeking medical treatment. Hail the U.S. Coast Guard or call 911 immediately and insist whoever is afflicted be rushed to the nearest hospital emergency room for treatment and monitoring. There is no effective self-remedy.

What can boaters do to assure safety onboard and prevent CO poisoning? All boats should have CO detectors in various spaces as recommended by the manufacturer or after-market installation guide. At a minimum, install marine CO detectors or alarms in both the engine room and the cabin (boats with a generator should also have a 110-volt detector).

As internal combustion engines are the main source of CO, strict maintenance of equipment and proper ventilation are the best lines of defense. Make sure the engine is running efficiently; unless you have the necessary skills, it’s worth the money to have a pro perform a tune-up that includes a CO test. Throughout the season, check for worn exhaust blowers and cracked hoses.

Even the most efficient marine engines generate small amounts of CO, normally blown out the exhaust system. Federal laws require that all recreational vessels, except for those powered by outboards, have an exhaust blower in the engine room. Make sure the lines are unobstructed. Other sources of carbon monoxide include cabin gas heaters and propane-fueled stoves. The flame on a stove should be blue, not yellow, and of course, never fire up a barbeque down below.

If your craft has a generator, turn on the blowers when it’s in use. Keep them on if you are rafting up with others if their generators are on. Finally, warn your passengers to never teak surf — an activity in which swimmers grab onto the swim platform while the boat is underway. Besides being generally dangerous, gases collect in that area and place the “surfers” at great risk.

 By William C. Winslow

The author is the Division 5 – Staff Officer Public Affairs, First District Southern Region, for the U.S. Coast Guard Auxiliary, the all-volunteer, non-military arm of the Coast Guard, teaching boating safety education and conducting search and rescue operations. Visit to join the Auxiliary or for class information.


is Division 5 – Staff Officer Public Affairs, First District Southern Region, U.S. Coast Guard Auxiliary, and a freelance writer for marine publications. His work has appeared in Sailing, Wooden Boat, and Good Old Boat; he is also the author of Cat Boat Tales.

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