The MAIB (Marine Accident Investigation Branch) have this week released an Accident Investigation Report on the two fatalities on-board the motor cruiser, Diversion, on 4 December 2019. The report details the cause of death of the two occupants on-board as carbon monoxide (CO) poisoning due to a gas leak from the boat’s diesel-fuelled cabin heater exhaust into the cabin. 

Following an inspection, the MAIB found that the Diversion did not have a CO alarm fitted at the time of the accident or when it was last presented for a Boating Safety Scheme (BSS) examination in February 2019. The owner was not present at the BSS examination and was therefore not advised that from the 1st April 2019 a CO alarm would be required on all boats in scope of the BSS that have accommodation spaces.

The key safety issues highlighted in the report were:

  • 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 cabin ventilation system did not meet the requirements of the Boat Safety Scheme and this might have increased the rate at which the carbon monoxide accumulated in the boat’s cabin space.
  • the owner and his friend were not alerted to the danger because a carbon monoxide alarm had not been fitted.

Statement from the Chief Inspector of Marine Accidents:

“The MAIB investigation into this tragic loss of lives once again highlights the importance of installing carbon monoxide alarms on boats with enclosed accommodation spaces. This is the fifth fatal marine accident investigated since 2014, where a functioning carbon monoxide alarm could have saved lives. Carbon monoxide alarms suitable for the marine environment are readily available, inexpensive and simple to fit, and I urge boat owners to invest in one as soon as possible.

“It is commonplace for marine engines, generators, cookers and heaters to produce carbon monoxide during normal operation; amateur installation and un-serviced appliances can introduce the risk of boat users inhaling lethal levels of this toxic gas. The importance of checking the installation and routine servicing of all such devices by a professional cannot be overstated.”

Stuart Carruthers, RYA Cruising Manager wished to remind all boaters that CO is a highly poisonous gas that cannot be seen, smelt, tasted or felt by humans; therefore, it is essential that CO alarms are fitted in areas of a vessel where it could accumulate particularly those with accommodation.

The symptoms of CO poisoning include headaches, tiredness, nausea and dizziness. The greater the amount of CO the more severe the symptoms will get, leading to weakness, loss of balance and memory. High levels can also cause collapse, unconsciousness and death.

For more information on CO and how to avoid a carbon monoxide related incident, visit the advice page on the RYA Safety hub.

You can find further information on CO alarms for boats here.

Photo credit: MAIB