2.4 Carbon monoxide

Carbon monoxide (CO) is colorless, odorless, tasteless, and extremely dangerous gas.

All engines, generators, and fuel burning appliances produce CO as exhaust.

Prolonged exposure to low concentrations or very quick exposure to high concentrations may cause brain damage or death.

Open all doors, curtains, windows, and hatches to let fresh air circulate when running an engine or generator or burning any fuel while the boat is anchored, moored or docked.

If you can smell engine or generator exhaust, you are inhaling CO. CO can also be present without the smell of exhaust fumes.

If the CO alarm is activated, make sure all persons onboard exit the closed spaces.

  • If exhaust fumes are detected or if CO accumulation is suspected on the boat, take immediate action to ventilate these fumes.

  • Turn off all engines and generators.

  • Open all hatches, windows and ports to ventilate.

Changing course and speed to place the boat heading into the wind can improve ventilation.

Symptoms of carbon monoxide poisoning are dizziness, ears ringing, headache, nausea and unconsciousness. A poisoning victim’s skin often turns cherry red.

Because the carbon monoxide gas is odorless, colorless and tasteless, it is unlikely to be noticed until a person is affected.

  • If CO poisoning is suspected, have the victim breath fresh air deeply.

  • If breathing stops, resuscitate.

  • A victim often revives, but then relapses because organs are damaged by the lack of oxygen.

    Seek immediate medical attention.

High levels of carbon monoxide may accumulate in the following ways:

  • Blocking hull exhausts while operating at slow speed or if exhausts are submerged. 

  • Using canvas curtains.

  • Winds blowing exhaust toward boat occupants.

  • Operating engine or generator in a confined space.

  • Operating with the bow high.

Dangerous concentrations of carbon monoxide are present if:

  • the engine or generator exhaust systems leak

  • insufficient fresh air is circulating where people are present

  • fumes move from the rear of the boat into the cockpit and cabin area.

To minimize the danger of CO accumulation when the engine and generator are running or when using burning fuel applications:

  • Be sure to have sufficient ventilation when using canvas or window-type side curtains when underway, anchored, moored or docked.

  • Operate all burning fuel appliances, such as charcoal, propane, LPG, CNG or alcohol cooking devices, in areas where fresh air can circulate.

    Do not use such devices where there is no noticeable air movement, especially in the cabin, when anchored, moored or docked.

  • Do not idle the engine without moving the boat for more than 15 minutes at a time.

  • Inspect the exhaust system regularly. See the manufacturer's manual for instructions.