REPORT ISSUED INTO THE DEATH OF TWO MEN ONBOARD THE MOTOR VESSEL DIVERSION
The MAIB has released its report on the carbon monoxide poisoning aboard the motor cruiser Diversion that killed two men. At about 2000 on 4 December 2019, the bodies of two men were discovered in the cabin of the privately owned motor cruiser Diversion, which was moored to a quay in the centre of York, England. The bodies were those of the boat owner and his friend, who had spent the previous evening in the city centre socialising with former work colleagues and were spending the night on board.
and the exhaust gases containing CO and carbon dioxide (CO2
Both men had died as a result of carbon monoxide poisoning. The carbon monoxide had leaked into the cabin from the boat’s diesel-fuelled cabin heater exhaust.
Safety Issues
The heater’s exhaust lagging was removed to enable closer inspection of the system, which comprised of a Webasto exhaust silencer, connected to the heater and boat’s side via flexible pipes. The Eberspächer heater exhaust port had a 24mm outside diameter stub pipe, but the Webasto silencer inlet had a 22mm outside diameter stub pipe. This meant that the two sizes were incompatible, and the flexible exhaust that connected the heater to the silencer was loose, and leaked exhaust gas. In addition, the silencer had spot welded seams and a condensate drain hole, which also leaked exhaust gas when the heater ran (Figure 4).
- 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.
Exhaust silencer as found Exhaust silencer removed ) were discharged outside via a silencer
connected to a through-hull fitting on the starboard side. The exhaust system was fully insulated with heat proof fibreglass and covered by foil tape.
The manufacturer’s installation instructions, available via the internet, provided guidance regarding the requirements of the heater’s fuel system, exhaust, combustion air, electrical connection and circulating air. It is unknown if the owner read the instructions before he installed the heater and there was no record to indicate the installation was checked by an approved Eberspächer agent, or of the heater being serviced since it was fitted.
Gas leak path from condensate drain and riveted seam
Exhaust gas leakage path from loose inlet pipe connection
Figure 4: Gas leak path from condensate drain and spot welded seam
Statement from the IIMS Chief Executive Officer: “Too often we have seen carbon monoxide as the cause of deaths onboard boats. Such incidents are avoidable, and the installation of an inexpensive carbon monoxide alarm would most likely save lives. I urge marine surveyors the world over to implement a duty of care and if, when surveying a vessel and no carbon monoxide alarm is installed, they make a recommendation to the owner to fit one as a matter of urgency.”
Access the report at
https://bit.ly/3mQFiTu.
The most well-known brands of diesel-fuelled heaters are Webasto and Eberspächer. These are commonly installed into lorries, earth moving machinery, caravans and boats. Diversion’s Webasto silencer was not designed to be fitted in marine installations because it was not gas tight and it was incompatible with the exhaust piping. As a result, the leaking exhaust gas was drawn into the heater’s circulating air inlet and then blown into the main cabin (Figure 5).
The heater would often be left running while the owners were ashore when using Diversion on cold days. On one occasion in October 2019, the owner and his wife experienced nausea and sickness after sleeping on board with the cabin heater running.
The Report • June 2021 • Issue 96 | 19
Safety Briefings
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