A couple in Michigan arrived at their boat last October, started the gas generator, turned on the boat's electric heater, and set to work on a few end of the season projects. While they were working, carbon monoxide (CO) from the gas generator began creeping quietly into the main saloon somewhere down in the bilge.
Without a CO alarm, there was no way that the couple could have been aware-or even had the tiniest hint - that the deadly gas was mixing with the oxygen in the boat's cabin. CO is colorless and odorless, and it produces initial symptoms-drowsiness, headaches, nausea, or dizziness--that aren't especially alarming.
The unsuspecting couple soon "fell asleep," and would have died had it not been for the early arrival-almost two hours early-of their son. He quickly shut off the generator, opened ports, and phoned the rescue squad. They were extremely lucky; most CO claims have a much sadder outcome.
An investigation afterward concluded that the CO had come from a drain plug in the generator's muffler that had worked loose and lay in the bilge. The report also noted the lack of a CO detector aboard, which wasn't a surprise.
Of a dozen or so recent claims for CO fatalities or near fatalities in a boat's cabin, the lack of a CO detector is the only thing that all of them had in common.
CO can enter a cabin from many different sources, according to the claim files: from a hot water heater; from a galley stove; from the "station wagon effect"-exhaust from the boat's exhaust; from a generator; and even from other nearby boats. There have also been several injuries from people swimming under swim platforms when an engine or generator was being operated.
Certainly it is important to recognize the symptoms of CO poisoning: headaches, drowsiness, and nausea. With most of the BoatU.S. claims, one or more of these symptoms were present, but victims did not recognize the danger they were in.
It is also advisable to inspect the engine and generator for leaks in the exhaust system and to avoid, or try to avoid, the many different situations that could bring CO into a boat's cabin.
That isn't easy. Besides the station wagon effect, accidents have been traced to wind direction, proximity to a dock or seawall, boats rafted together, an open hatch or port, a canvas cover, or combination of several causes.
It isn't unusual after an accident, for an inspection to spend many hours, or even days, trying to ascertain how CO got into a boat's cabin.
While guarding against the many possible sources of CO is certainly advisable, the most reliable safeguard is a CO detector. As of August 1, 1998 the American Boat and Yacht Council (ABYC), the organization that writes the voluntary standards for recreational boats, began recommending that all boats with enclosed accommodation areas and a gasoline generator or a gasoline inboard propulsion engine have a CO detector installed.
(Diesel engines are not included because they are much less likely to produce deadly levels of CO.) The recommendation that CO detectors be installed on new boats is great news for anyone who will be buying a new boat, but what about boats built before August 1998?