An improvised exhaust and silencer system on the boat's generator may have caused the mother and daughter deaths

Early findings into an investigation into the deaths of a mother and daughter on a motor cruiser confirm that carbon monoxide poisoning was the cause.

It is believed that the boat generator’s improvised exhaust had become detached and deadly fumes had filled the aft cabin where the victims slept.

The Marine Accident Investigation Branch (MAIB) has issued a safety bulletin following the double tragedy, which occurred on the Bayliner 285 motor cruiser Arniston, on Lake Windermere, Cumbria, on 1 April 2013.

The MAIB preliminary report findings indicate that the mother and her 10-year-old daughter died from carbon monoxide poisoning, while staying on board the 11-year-old boat during the Easter bank holiday weekend.

Initial findings

A ‘suitcase’ type portable petrol-driven generator (Figure 1) had been installed in the motor cruiser’s engine bay to supply the boat with 240v power.

The generator had been fitted with an improvised exhaust and silencer system which had become detached from both the generator and the outlet on the vessel’s side (Figures 2 and 3).

As a result, the generator’s exhaust fumes filled the engine bay and spread through gaps in an internal bulkhead into the aft cabin where the mother and daughter were asleep.

When the owner of the boat awoke in the boat’s forward cabin, he was suffering from carbon monoxide poisoning but was able to raise the alarm. The mother and daughter could not be revived.

The boat’s carbon monoxide sensor system did not alarm because it was not connected to a power supply.

Safety issues

1.   Portable air-cooled petrol generators are readily available and inexpensive, but they are usually intended for use in the open air.

The use or permanent installation of these engines on boats, particularly in enclosed spaces or below decks, increases the risk of carbon monoxide poisoning.

2.   It is essential that engine exhaust systems are fitted and maintained to direct poisonous fumes outside the vessel clear of ventilation intakes and accommodation spaces.

Work on these systems should therefore only be undertaken by suitably qualified marine service engineers using approved parts and following the equipment manufacturer’s instructions for marine installations.

3.   Carbon monoxide is a lethal gas, which has no smell, no taste, is colourless and is extremely difficult for human senses to detect.

All boaters need to be vigilant and recognise the signs of carbon monoxide poisoning, which can include: headaches, dizziness, nausea, vomiting, tiredness, confusion, stomach pain and shortage of breath.

4.   Carbon monoxide is a silent killer that is just as lethal afloat as it is ashore. The correct positioning and the regular testing of any carbon monoxide sensors, whether powered by a boat’s electrical supply or self-contained, is essential.

Carbon monoxide sensor alarms that do not work correctly should be replaced.

When selecting a carbon monoxide alarm preference should be given to those marked as meeting safety standard EN 50291-2:2010 which are intended for use in a marine environment.

Click here for more advice on how to avoid carbon monoxide poisoning on boats and more detail about carbon monoxide alarms.

Read the report online here.