Last reviewed 20 April 2021

Two people, who had spent the previous evening in the city centre socialising, were found dead after spending the night on board a motor cruiser moored on the River Ouse in York in December 2019.

An investigation by the Marine Accident Investigation Branch (MAIB) discovered that both men had been poisoned after carbon monoxide leaked into the cabin from the boat’s diesel-fuelled cabin heater exhaust.

“The cabin heater’s exhaust silencer was not designed for marine use: its connection to the exhaust pipe system was not gas tight, the installation had not been checked by a professional heater installer, and it had not been serviced,” the MAIB report highlighted.

It recommends that owners should read a safety bulletin highlighting the importance of installing carbon monoxide alarms on boats with enclosed accommodation spaces, which was published after the incident in York.

The Chief Inspector of Marine Accidents, Andrew Moll, pointed out that this is the fifth fatal marine accident investigated since 2014, where a functioning carbon monoxide alarm could have saved lives.

It is commonplace for marine engines, generators, cookers and heaters to produce carbon monoxide during normal operation, he explained, and amateur installation and unserviced appliances can introduce the risk of boat users inhaling lethal levels of this toxic gas.