Carbon Monoxide is the leading cause of death by poisoning. Every year, people die needlessly because they didn't realize the danger. This colourless, odourless gas is given off by the normal operation of any fuel-burning appliance or engine aboard a boat. It may escape from exhaust systems into the cabin area, where the concentrations of the gas can quickly become high enough to kill you.
Canada has no regulations, but the ABYC (American Boat & Yacht Council) standard requires CO detectors aboard boats with enclosed living space. The RV (motorhomes) industry has required CO detectors installed since 1993. Unfortunately, consumer testing has shown that detector technology doesn't work well on boats. One test in homes showed a one third failure rate. Some older units have had recalls to replace detector units - check with manufacturers! According to Powerboat Reports magazine (Sep/99), Fireboy/Xintex is one of only two makers of CO detectors made specifically for boats. They report that Figero USA has a new sensor ready for testing. Use a CO detector in your boat, but do NOT depend on it. Until we have better detectors, prevention is imperative.
Studies show CO output of an inboard marine (gas) engine is equivalent to 188 car engines according to U.S. National Institute for Occupational Safety and Health (NIOSH). Anyone standing, sitting or swimming around a running engine are at risk of poisoning. When a boat is moving, air moving around cabin structures can create a vacuum or station-wagon effect - exhaust and CO can be sucked into the aft deck and even the cabin if doors and hatches are open. CO levels at the back of a ski boat are high enough to be cause for concern; levels 20 feet behind the boat are still high enough to affect towed tubers -- who tend to be young children."
In the U.S.A., CO detectors are required on boats with gas engines or generators. The standard doesn’t apply to diesel engines, which produce about 10% as much CO as gasoline.