29 October 2019
In a recent incident, four Victorian boaters were hospitalised following exposure to carbon monoxide (CO).
CO is a colourless, odourless gas that has approximately the same density as air and so flows freely through and into spaces. Because no appliance completely combusts its fuel, CO is produced whenever a material that contains carbon is burned.
Exposure to CO limits the ability of the bloodstream to carry oxygen. Symptoms include headaches, drowsiness, nausea, vomiting, irritated eyes and collapse. Unfortunately, these symptoms can be mistaken for the effects of sea sickness, fatigue, sun exposure and alcohol.
Exposure to CO can prove fatal. Dangers can arise both from a high dose over a short period of time, or exposure to low doses over a prolonged period.
Occupants of boats are at risk because of the presence of engines, generators, stoves and heaters and because of the enclosed and confined spaces found on vessels. In particular, fumes can build up in a boat’s cockpit if it is enclosed by windscreens and canopies. The ‘station wagon’ effect draws in exhaust from behind the vessel when operating at slow speeds.
High risk factors in vessels
- Inboard petrol engines
- Presence of multiple powered appliances such as heaters, stoves, generators, refrigerators etc
- Modifications that impede airflow, such as canopies and screens installed around the cockpit
- Poorly maintained machinery – a poorly maintained engine will produce higher levels of CO
- Poor ventilation
- Sleeping accommodation on board.
High risk factors associated with activity
- Tying up in busy marinas for prolonged periods where other vessels or land facilities are operating engines and generators
- Using your own engines and generators while moored
- Motoring for prolonged periods at very low speed, especially with a following wind
- Using stoves and heaters in confined, poorly ventilated spaces
- Swimming close to swim platforms while engines are running.
What to do
- Inspect your vessel to see if it is at risk. If the vessel has been modified, seek appropriate industry advice from a qualified person
- Have all engines and other appliances regularly serviced by a qualified person. Ensure that all fittings, hoses and clamps are operating properly.
- Avoid undertaking the high-risk activities listed above as much as possible
- Be aware of your surroundings – the risk may not come from your vessel, but from other vessels close by. Be particularly aware of the location of other vessels in relation to your vents and intakes
- Brief all occupants so that they are aware of the effects of CO
- Be aware that some engines (for example ‘high end’ sports boats) will have a ‘limp mode’: that is an automated system that protects the engine by limiting the RPM at which the motor can run. This is usually triggered by an oil pressure or temperature switch telling the onboard computer that something is operating outside normal ranges. The effect of this will be to restrict the boat to operating at a slow speed while you return to shore, but it will still be producing CO fumes. Be aware of the risks of fumes building up and ensure adequate ventilation
- Install CO alarms in sleeping areas and near helm positions and have them regularly inspected
- Ventilate, ventilate, ventilate. Maximise natural ventilation and seek professional advice on fans and ventilation systems.