Carbon monoxide poisoning is one of the leading causes of boating-related deaths in the United States — and unlike CO hazards in a home, boat CO can accumulate in open-air situations that most people assume are safe. The U.S. Consumer Product Safety Commission (CPSC) warns that boat engines, onboard generators, and propulsion systems produce CO at concentrations that have killed boaters swimming near exhaust outlets, sitting in slow-moving or stationary boats, and sleeping below deck near a running generator.
The Three Deadliest Boating CO Scenarios
Swimming near a boat’s exhaust outlet. Boat exhaust is typically discharged from the stern near the waterline. Swimmers near the back of a boat — including children playing on a swim platform — can be exposed to high CO concentrations without realizing it. CO poisoning causes sudden weakness and loss of muscle control, resulting in drowning. CPSC has documented deaths from this exact scenario.
Slow or stationary boat operation. When a boat moves slowly or idles, exhaust may not disperse rapidly enough to clear the cockpit or rear of the boat. Passengers in enclosed stern areas or under bimini tops can be exposed to accumulating CO from the boat’s own engine.
Below-deck generator use. Running a generator below deck or in any enclosed boat space — including with hatches open — can produce CO at lethal levels. Deaths have occurred when boaters ran generators for air conditioning while sleeping, with exhaust infiltrating sleeping areas.
Safety Rules
- Never swim near the stern or exhaust outlets of any boat with its engine running.
- Never allow passengers to sit or stay in the area immediately around exhaust outlets.
- Install CO alarms in every enclosed cabin space on the boat and test them before every outing.
- Never run a generator below deck or in any enclosed area.
- Do not operate the boat at idle speed in an enclosed or partially enclosed marina for extended periods.
- If any person on the boat experiences sudden unexplained weakness, confusion, or nausea, move everyone away from the stern and into fresh air immediately and call for emergency assistance.
To report a dangerous product or a product-related injury, visit SaferProducts.gov or call CPSC’s Hotline at 800-638-2772.
