Earlier this year, a prominent and experienced Annapolis yachtswoman died aboard a sailing yacht after he was overcome by carbon-monoxide fumes while taking a shower. A few weeks ago, another experienced boater had to be revived after he was overcome and passed out while below deck.
Carbon-monoxide poisoning is not a new cause of death, but it is perhaps more often associated with automobiles than large, gasoline-powered boats.
Carbon monoxide is a clear and odorless gas that, in large enough concentrations, can dull the senses, erode the will and, within an hour of causing unconsciousness, kill.
The American Boat and Yacht Council has completed a report that attempts to categorize potential causes of carbon-monoxide poisoning aboard boats and suggests methods by which the chance of death or impairment may be reduced greatly or eliminated.
The ABYC report cannot claim to be the last word in preventing CO poisoning, but it is the latest and most complete word.
The report is the result of research and testing conducted by a committee of more than two dozen representatives from all areas of the marine industry -- boat builders, insurance companies, the coastGuard surveyors abd equipment manufacturers among them.
The following is a look at the major problems and the possible solutions based on a copy of the report and USCG Boating
Safety Circular 74.* What is CO poisoning? CO is caused any time a carbon fuel (gasoline, natural gas, oil, propane, coal or wood, for example) is burned. When CO is inhaled, its molecules attach to red blood cells. The resulting combination is called carboxyhemoglobin (COHb).
Because oxygen molecules also must attach to red blood cells to be transported through the body, as more COHb is formed, less oxygen is available to the body, and an oxygen deficiency may occur. There is no accepted safe level of carbon monoxide exposure, but an average occupational day exposure of 50 parts per million would be acceptable at sea level, according to the USCG. Such exposure might produce a COHb level of 10 percent and might cause headaches, dizziness and diminished coordination. Levels between 10 and 15 percent cause nausea; levels as high as 40 percent are associated with collapse; and levels over 60 percent usually are fatal.
* The symptoms of carbon monoxide poisoning: Watering and itchy eyes. Flushed appearance. Throbbing temples. Inattentiveness. Diminishing coherence. Ringing in the ears. Tightness in the chest. Headache. Drowsiness. Nausea. Dizziness. Fatigue. Vomiting. Collapse. Convulsions. According to the ABYC report, the order of symptoms listed is generally the order in which they will occur.
* Treatment and follow up: Move the person to fresh air. Administer oxygen if available. Contact medical help. If victim is not breathing, perform artificial respiration until help arrives. Ventilate contaminated area of the boat and find the source of CO leak and take corrective action.
-! Regular inspection and mainte
nance of exhaust systems for engines and generators is the best way to prevent problems with CO.
Start where the exhaust manifolds join the engine, and work your way along the full system. Manifold connections should be bolted tightly to the block, all rubber hoses should be checked for aging and double clamped to prevent slippage or leaking, all passages for hoses, pipes or wiring that go from the engine room to cabins should be sealed, and all sections of the exhaust system should be accessible for inspection -- even if the system runs behind cabinets, for example. When inspecting the exhaust system, look for telltale weeping of hoses or fittings or a steady drip when the engine is running.
Inspection and maintenance of the exhaust system will eliminate only part of the problem, especially on motor cruisers, which may be susceptible to back-drafting.
According to the ABYC report, motorboats with squared deckhouses may be very dangerous because of back-drafting. What happens, particularly when the boat is running fast with the wind ahead or abeam, is that as the boat passes through the air, a lower air pressure develops behind the deckhouse and air from the back of the boat rushes in. Air from the back of the boat usually is contaminated heavily by CO.
If, for example, a door to the cockpit from the cabin is open, the low pressure will extend inside the boat and CO will be drawn below deck or into the living area.
Squared canvas enclosures may have the same effect.
When running under these conditions -- and in all conditions, for that matter -- be certain there are hatches and windows open. The flow of air through these ports will go a long way toward eliminating CO contamination of living spaces.