Date: 6/23/03
Author:
Captain Scott Evans
Chief, Office of Boating Safety
U.S. Coast Guard

Most boaters know that Carbon Monoxide (CO) is poisonous. They know CO can be present in their homes, so they install detectors. They know it's present in a car's exhaust, so they don't run the engine in enclosed spaces like garages. Some even know it can collect in a boat's engine space, and other interior compartments. But very few know that Carbon Monoxide can be present in dangerous concentrations outside a boat -- around exhaust outlets, under swim platforms, even in an open cabin under certain conditions. The results can be dangerous, even fatal.

The good news? CO poisoning is easily prevented through awareness -- and a few simple steps all boaters can take.

Silent Killer

Carbon Monoxide is a colorless, odorless, tasteless and highly toxic gas. It is produced when a carbon-based fuel -- such as gasoline, propane, charcoal or oil -- burns. Sources on a boat include engines, generators, cooking ranges and space and water heaters.

Carbon Monoxide enters the bloodstream through the lungs, blocking oxygen the body needs. Prolonged exposure to low concentrations -- or very brief exposure to high concentrations -- can kill. Early symptoms of CO poisoning include irritated eyes, headache, nausea, weakness and dizziness. On the water, these symptoms are often confused with seasickness or intoxication, so those affected may not receive the medical attention they need.

CO is often emitted through a boat's engine or generator exhaust outlets -- on a typical powerboat, toward the stern and at or slightly under the waterline. As a result, CO can accumulate almost anywhere in or around a boat. It can collect under swim platforms, around the stern and inside canvas enclosures. It can build up from exhaust outlets blocked when boats "raft up" or drift to one boat from an adjacent vessel's exhaust. At slow or no-wake speeds, especially with a following wind, CO can be drawn into a cockpit by backdrafting -- the "station wagon" effect. And it can remain in and around a boat for some time after the engine or generator is shut off.

Certain trends are fueling growing concern about Carbon Monoxide poisoning on recreational boats. As boaters enjoy more ancillary equipment -- air conditioners, stereos and televisions -- they run gas generators for longer periods of time, sometimes when swimmers are in the water near generator exhausts.

A dangerous fad called "teak surfing" consists of young swimmers holding onto the swim platform of a boat as the boat accelerates -- then letting go to "surf" the wake. Teak surfers cannot avoid the risk of inhaling dangerous levels of CO. This is an extremely risky activity because the boats' propulsion engines are in use during teak surfing. These engines produce a very high volume of exhaust gases, usually directed straight into the area behind the boat where the teak surfers are located.

New research is suggesting that deaths previously attributed to drowning may have in fact occurred when a boater or swimmer was already unconscious from CO poisoning. As much as 15% of drownings may be due to Carbon Monoxide from recreational boats.

Close Call

One of the best-known victims of CO poisoning is legendary racecar driver Al Unser, Sr. In 1995, Unser was boating when his anchor line became entangled in the propeller. He dove under water several times trying to free the prop -- breathing in dangerous concentrations of CO every time he surfaced.

"I knew I was in trouble," Unser said, recalling that horrifying incident. "I don't know how I got out from underneath. I had to be helped out. I couldn't walk. I could barely crawl."

After a lifetime of driving high-performance automobiles and working around gas engines, Unser was well aware of the dangers of Carbon Monoxide, but had never considered that CO could be a threat to a boater.

Others have not been as lucky as Al Unser, Sr. A teenage girl died after washing her hair in the warm water flowing overboard from a generator exhaust outlet. Two young children were overcome while swimming in the cavity under a swim platform. A young woman suffers from permanent brain damage after "teak surfing." These stories are tragic because all of these deaths and injuries could have been prevented through simple awareness of the problem.

Steps To Safety

The U.S. Coast Guard Office of Boating Safety offers these safety tips to help boaters prevent CO poisoning.

• Learn where engine and generator exhaust ports are located on your boat. Place a warning sticker and keep swimmers clear of those areas. Never run the engine or generator when people are in the water near the boat.

• Maintain fresh air circulation throughout the boat at all times. Although CO itself is odorless, remember that CO is present in all exhaust gases. Take immediate action if exhaust fumes are detected on the boat.

• Take care when "rafting up" or in other situations where air circulation around exhaust ports may be restricted, and remember CO entering your boat from another boat is as dangerous as CO generated by your own engines.

• Educate your passengers about Carbon Monoxide as part of your pre-trip safety briefing.

• Treat symptoms of seasickness as possible CO poisoning. Get the victim into fresh air immediately, and seek medical attention unless it is certain that CO is not the cause.

• Install and maintain CO alarms inside your boat. NEVER ignore any alarm. Replace batteries as recommended by the alarm manufacturer.

• Get a free Vessel Safety Check every year. These bow-to-stern examinations help identify safety problems and violations before they become emergencies.

Boating is an enjoyable, relaxing, and safe activity and the U.S. Coast Guard wants you to enjoy your time on the water. Learn the facts and remember, when it comes to Carbon Monoxide, what you can't see can harm you.

You're In Command. Boat Safely.

For more information on ways to boating safely, call the U.S. Coast Guard Infoline at 1-800-368-5647 or visit www.uscgboating.org.

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