On-board petrol leak puts skipper and vessel in danger
Lookout! Issue 30, December 2013
The incident occurred when the man, on his own in a 7 metre motor boat in heavy seas about 3 nautical miles offshore, sat down without thinking on a flexible petrol tank. The tote tank, holding 20 litres of emergency fuel, had been installed in the central cabin after an earlier incident in which sediment contaminated the underfloor fuel tanks, causing engine failure. The tote tank allows the fuel supply to be quickly isolated, if needed.
As the skipper sat down in order to brace and close a wiring cover hatch that had fallen open, the tank’s seals broke and petrol was forced out. The petrol soaked the man’s trousers, a bag of spare clothes resting on top of the tank and the carpet.
Earlier in the day the anchor winch rope grabber had failed, so the skipper was unable to anchor to safely deal with the contamination. After trying without success to contact his shore base, he decided to reduce the risk of sparking a fire by not operating any more switches until he was close enough to shore to swim if he needed to.
The windows had to be kept closed because water from the 2 to 3 metre swells was breaking across the wheelhouse, and the skipper vomited twice from inhaling the petrol fumes.
Keeping his spot beacon in his jacket pocket and wearing a personal flotation device (PFD), he steamed closer to shore, where shallower waters and shelter enabled him to shift the contaminated carpet and tank onto the deck, and rinse the petrol off himself. Once the petrol smell had gone from the wheelhouse, he immediately felt better.
The man began the homeward journey naked from the waist down, to reduce the risk of hydrocarbons from the contaminated clothing causing a rash or hypersensitivity. Eventually, however, recognising that he was developing symptoms of hypothermia, he put on wet shorts and his wet weather gear over the top. In the heavy conditions, the journey, normally a two-hour trip, took four and a half hours.
- Petrol contamination is both a fire hazard and a risk to people’s health. In this situation the skipper could have been exposed to serious injury from inhalation and, had the petrol ignited, lost his vessel and/or his life.
- The petrol leakage was caused by the tank seals of the flexible plastic tank failing when they were subjected to a man’s weight and the force applied as he braced the hatch. Had it been covered by rigid boxing, the tank would not have been able to be sat on directly and its seals would not have given way.
- Normally the tank was kept inside a fish tub to contain any potential leak, but on this day the tub was being used on deck for another purpose and was not in place to prevent the carpet becoming contaminated.
- The man’s lack of attention contributed to the incident. He hadn’t considered that leaving the bag of spare clothes on the tank put it at risk of becoming saturated or igniting in the event of a leak.
- He didn’t notice that he’d sat down on the tank rather than the adjacent bunk, where he usually sat while securing the hatch. It is vital to remain aware of any possible risks to safety at all times on board a vessel, especially when operators are on their own at sea.
- After the contamination occurred, the skipper took sensible precautions to reduce the risks to himself and the vessel by not operating on-board switches and steaming to more sheltered waters where he could anchor and rinse some of the petrol off, as well as wearing a PFD and keeping his spot beacon on him. When the skipper realised he was becoming chilled, he put some clothing back on despite it being wet and uncomfortable.
- MNZ investigators said the man had learned a valuable lesson from his unpleasant and scary experience, and had resolved to maintain a better standard of housekeeping on board to ensure the vessel’s operating environment remained safe at all times.