Thar she blows!
Two incidents involving fires onboard vessels highlight the dangers of failing to ventilate a vessel adequately.
Dad, Mum and the two girls intended to go boating for a few days on their fibreglass flybridge cruiser. Prior to setting out they took on fuel (petrol) at a marina. On completion of refuelling the owner went to pay for the fuel before retuning to his vessel.
The owner went to the flybridge and operated the bilge blowers for a period of time to remove any petrol fumes before inserting the ignition key and attempting to start the vessels engines.
Instantaneously he heard and felt a massive explosion towards the bow of the vessel and saw the windscreen of the vessel explode outwards followed by flames.
As a result of the explosion his wife and daughters were thrown from the vessel into the water. His wife suffered significant burn injuries to her lower legs while the two children suffered singed hair and minor burns. All three had been in the cockpit prior to the explosion. The vessel was totally destroyed and the marina wharf sustained considerable fire damage.
The investigation found that the vessel had been loaded with provisions in such a way that the boat took on a bow down attitude (known as being ‘trimmed by the head’). The petrol fumes from refuelling were trapped in the forward bilge after refuelling due to the trim and were not expelled after blowers were activated because no hatches were opened forwards in the vessel to allow ventilation.
The cause of the explosion and subsequent fire was due to this build-up of fumes which exploded after the ignition key was turned to start the engines.
The Water Police called Tim the owner and let him know that his vessel (another fibreglass flybridge cruiser) looked to be low in the water so he rowed out to the mooring to investigate.
The vessel carried a large amount of anchor chain in the bow which normally gave the vessel a slight trim by the head. As he rowed out, Tim noticed that this was more obvious than usual, presumably because of the water ingress.
Tim entered the vessel and went to the forward part where the bilge pump was located in a hatch under the deck. The vessel was fitted with blowers and gas detection equipment, but he didn’t use these, nor did he open any hatches forwards to create a flow of air through the boat.
While Tim was inspecting the bilge pump and float switch, he inadvertently caused a spark which ignited petrol fumes. The resultant explosion seriously damaged the vessel and Tim spent many months in hospital undergoing skin graft operations.
- Always be aware of the danger of petrol fumes on boats. Fumes are heavier than air and will accumulate in the lowest part of the vessel.
- Prior to operating any other equipment, ventilate by opening hatches at each end of the vessel.
- Install blowers and gas detectors and make sure that they are used prior to operating any other equipment.