Carbon Monoxide is the leading cause of accidental poisoning deaths in America, according the Journal of the American Medical Association. Boaters are only a small percentage of these, but much remains to be done to reduce the approximately 1,500 deaths (and 10,000 seeking medical attention) per year in the U.S.

Carbon Monoxide (CO) is a colorless, odorless, tasteless, toxic gas produced during the incomplete combustion of fuel, including gasoline, diesel, propane, CNG, charcoal, kerosene, wood, etc. It is a common misconception that diesel engines do not produce CO. Virtually any incomplete combustion process can produce CO. This includes heating and cooking appliances. Charcoal is one of the highest CO producing cooking fuels.

The danger from CO is that it attaches to hemoglobin and replaces oxygen in our blood. It is poisonous to all warm blooded animals. CO poisoning symptoms include shortness of breath, headaches, nausea, dizziness, confusion, fainting, coughing, watering eyes and at higher levels can lead to fainting and death. CO poisoning is often confused with the flu, sea (motion) sickness, colds or allergies, due to similar symptoms. Children, elderly people, people with respiratory problems or cardiovascular illnesses are more susceptible. First aid should include breathing fresh air immediately , followed by medical attention. If you suspect CO poisoning, be sure to mention it to your doctor, to prevent mis-diagnosis.

There are two steps which all boaters should do to prevent CO poisoning. Purchase and install CO alarm(s) and service all the devices which can produce CO regularly to assure they are properly functional and installed correctly.

Significant developments in the technology for CO detection and advancements in their ability to “average” the level of CO (over time) have occurred in the past 10 – 15 years. Previous detectors signaled false alarms frequently and thus became a nuisance and were ignored or disconnected. This is no longer true! Most CO alarms are currently very accurate and economical. Some companies make combination CO and fire/smoke alarms. Underwriters Laboratories (UL) has recently published a standard on marine CO detectors (#1524). It is important to use alarms rather than detectors, an alarm should provide visual and audible notification of dangerous levels of CO.

While researching for this article, I found no recommendations as to where to install CO detectors on a boat. The United States Consumer Protection Safety Commission (C.P.S.C.) recommends installation of CO alarms near the sleeping area, in the home. The International Association of Fire Chiefs also recommends installation of a CO alarm on every level of the home and in areas near combustion appliances. The proper location of CO alarms in a boat depends upon several factors. CO is about the same weight as air and will diffuse throughout a space. Most manufactures don’t specify installation near the top or bottom of a space. (Unlike smoke detectors which should be near the top of a space or propane detectors which should be low).
CO concentration is going to be highest near the source, thus it is logical to locate detectors in engine rooms of small boats (where the engine is the only source of combustion), but the alarm needs to sound where it will be heard. Some alarms/detectors have connections to allow for easy installation of remote alarms (bell, buzzer, etc.). Some environments will create more false alarms. You should read the instructions with your CO alarm. If the vessel has combustion appliances (heaters, stoves) a CO alarm should be installed near them. Since boats move and often moor next to other boats (with combustion devices), and a sleeping person remains in one space for many hours, a CO monitor in the normal living/sleeping spaces is also a good idea.

Of course a 30’ vessel with an engine, heater, and stove will not require three CO alarms, just one in the cabin should suffice, but use common sense as to its/their installation.
Most CO alarms cost only $35 - $40. Combination fire/smoke and CO alarms cost slightly more. The benefit outweighs the cost by such a large factor, that it is logical that every boat, which has an engine (or other combustion devices) and a cabin, or is ever moored or docked near other boats that have combustion devices should be equipped with a CO alarm.

There has been a recall of some CO alarms recently. In cooperation with the United States Consumer Product Safety Commission (C.P.S.C.), Kidde Safety is recalling about one million units including Nighthawks and Lifesavers. For the manufacture dates of the recalled units or more information contact Ken Giles at C.P.S.C. (301) 504-0580 ext. 1184 or Quinn Hudson or Bill Crane at Kidde (800) 880-6788 ext. 777.

Most CO alarms have a test button, to test the electronics and the audible alarm, but there is no field test for actual CO detection. Some of the products have planned maintenance/testing sold with the units and described in the manufacturer’s literature. There are hard wired units, battery operated units and hard wired units with battery back-ups.

Maintenance of your boat’s combustion devices will reduce your chances for exposure to CO. Properly tuning your engine(s), checking and servicing the exhaust systems and providing proper ventilation for combustion appliances and for the living spaces will go a long way to preventing CO accumulation. Do not procrastinate repairs to a smoking engine or a leaking exhaust system. Be conscious of exhaust accumulating about a stationary boat (remember CO is odorless), particularly if there is no wind and the generator is running on your boat or on an adjacent boat. One expert describes CO as a ‘puddle’ collecting around the source. Exhaust from your boat or another combustion device can be blown into your boat as well. Some boats create a back draft or “station wagon effect”, while running, drawing exhaust fumes back into a vessel, over the transom. Heed warnings by the boat’s manufacturer regarding running the vessel with hatches and companionway doors closed (particularly on express cruisers and sport fishing boats) and ventilate the boat well. Ventilate the boat, when possible, by opening forward hatches to allow air to flow through the cabin.

Combustion appliances are also potential sources for CO. Most boaters are not going to have an annual service on their heater or stove, so be aware of a yellow flame (incomplete combustion) and be aware of possible symptoms of CO poisoning. Contact the gas company or an appliance manufacturer’s representative to service suspect devices. Immediately consult with a doctor if you have current illness(es) which have not been properly diagnosed and discuss possible CO poisoning, then find the source and eliminate it.

Near the beginning of my professional boating career, friends of mine, a couple, were enjoying their express cruiser. It was a normal day. The wife began to feel ill. She went below to lie down. By the time they reached the marina, she was unconscious. Tragically, she died. She was a friend of mine, the wife of a friend and the mother of a friend. Since then I have read of many boating deaths each year, resulting from carbon monoxide poisoning. As I survey boats, I rarely see CO detectors and I often see poorly tuned engines, exhaust leaks and improperly vented heaters.

The price of a CO alarm is low, pay it - stay alive and healthy, and live to enjoy your boat for many years to come. Remember that CO can be produced in your home, automobile and RV as well and CO alarms should be installed there too. Many more deaths and CO poisonings occur at home and from automobile exhaust than from boating incidents.

Kells Christian is a marine surveyor and operates a marine surveying firm in San Diego, California. Kells is a graduate of the University of Florida and began surveying in Jacksonville, FL in 1990. Christian & Co. Marine Surveyors specializes in pre-purchase inspections and marine insurance claims on yachts and commercial vessels.