CO Poisoning Situations: Blocked Exhaust or Another Boat's Exhaust
Blocked Exhaust Outlets can occur when you are docked beside a seawall or pier. This can cause carbon monoxide to accumulate in the cabin and cockpit area.

Another Vessel’s Exhaust that is alongside can emit carbon monoxide into the cabin and cockpit of your vessel. Your vessel should be at least 6 metres (19.7 feet) from a vessel that is running a generator or engine.
