Gasoline and diesel powered engines, onboard generators, cooking, heating, and some cooling appliances can produce carbon monoxide gas.

Carbon monoxide (chemical name CO) is a colorless, odorless gas produced by burning material containing carbon.  Carbon monoxide replaces the oxygen in your red blood cells and can cause brain damage and death.

Carbon monoxide poisoning can be especially dangerous for people who are sleeping or intoxicated since the fumes may be fatal before they realize there is a problem.

You can not see, smell, or taste carbon monoxide, but it can kill you.

Exposure to carbon monoxide is most commonly accompanied by the following symptoms:

• headache
• dizziness, nausea
• flu-like symptoms, fatigue
• shortness of breath on exertion
• impaired judgment
• chest pain
• confusion
• depression
• hallucinations, visual changes
• agitation
• abdominal pain, vomiting
• drowsiness
• fainting
• seizure
• memory and walking problems
• unconsciousness

If you suspect carbon monoxide poisoning, move the victim to fresh air immediately and contact the nearest emergency service. Unconscious victims should be placed in the first aid recovery position and closely monitored for breathing. CPR should be administered to victims who have stopped breathing.

It is essential to get medical support as quickly as possible so that appropriate treatment, such as oxygen, may be administered quickly to minimize long term effects such as brain damage.

At the same time, if possible, investigate the source of CO and take corrective action, such as ventilating the area or shutting off the source of the CO.

Carbon monoxide can accumulate anywhere in or around your boat. It can accumulate in the following ways.

• inadequately ventilated canvas enclosures
• exhaust gas trapped in enclosed places.
• blocked exhaust outlets.
• another vessel's exhaust.
• traveling at slow speeds or idling in the water can cause CO to build up in a boat’s cabin, cockpit, bridge, aft deck, or in an open area.
• wind from the aft (stern) section of a boat can increase the buildup of CO.
• back drafting can cause CO to build up inside the cabin, cockpit, and bridge when a boat is operated at a high bow angle, is improperly or heavily loaded, or has an opening that draws in exhaust.
• at slow speeds, while idling, or stopped.
• be aware that CO can remain in or around your boat at dangerous levels even if your engine or the other boat's engine is no longer running.

Take the following precautions to prevent carbon monoxide poisoning.

• install and maintain a working CO detector inside the boat to alert people when dangerous levels of CO have built up inside the boat cabin.
• only heat the cabin or cook when in a well-ventilated area.
• properly install and maintain all fuel-burning engines and appliances.
• educate passengers about the signs and symptoms of CO poisoning.
• swim and play away from areas close to where engines vent their exhaust.
• avoid swimming between the pontoons of houseboats or pontoon boats and under swim platforms. These are high risk areas.
• never block exhaust outlets.
• dock, beach, or anchor at least 20 feet away from the nearest boat that is running a generator or engine.