What is the issue?Carbon Monoxide is a by-product of petrol and diesel combustion engines. It is a colourless, odourless, and tasteless gas that, in high concentrations, can be fatal. The danger from carbon monoxide is when it collects aboard. That may happen because an exhaust leaks or an exhaust back-drafts due to a wind shift or from mooring too close to objects that obstructs the exhaust port venting.
Why address this?Carbon monoxide is a "silent killer" on pleasure boats. A lethal situation can develop when carbon monoxide builds up in confined areas such as below decks in the cabin.
How to address this?Implement a CO detector and alarm in the vessel.
It is just not worth the risk. Personally I was unaware of this danger until a friend lost two fellow sailors whilst charging batteries asleep on anchor. A plastic bag got caught in the water inlet causing the muffler to melt. The exhaust vented out below decks eventually filling the cabin with carbon monoxide leading to the fatalities.
Carbon monoxide effects depend upon the volume of exposure. You can feel unwell even with very small doses over periods, for instance breathing the exhaust from nearby jet skis. This is an outline of what can be expected to volumes of carbon monoxide parts-per-million:
A slight headache will develop within two to three hours at an exposure of 200ppm
A pronounced frontal headache will develop within one to two hours when exposed to 400 ppm.
Light-headedness, queasiness and convulsions within an hour of exposed to 800 ppm. Anaesthetise within two hours.
Headache, queasiness, light-headedness within twenty minutes when exposed to 1600 ppm. Fatal within ten minutes later.
Headache, queasiness, light-headedness within ten minutes when exposed to 3200 ppm. Fatal within twenty minutes.
Headache, queasiness, light-headedness within two minutes when exposed to 6400 ppm. Fatal within fifteen minutes.
In addition to having a CO2 alarm, and checking that it is functioning correctly, skippers and boat owners should be mindful of the safety of exhaust systems in daily use. Ensure that all exhaust clamps are in place and secure and that the rubber hoses are pliable and free of any kinks or have no heavy gear resting on them.
When starting the engine, confirm that water flows from the exhaust outlet and listen for any tonal changes that would indicate there are problems.
With thanks to:Michael Harpur, Yacht Obsession.
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