Fire on Board
PART 1
Marine
am certain that all members watched with horror the Fire on board many boats, in the Aberdeen Typhoon Shelter, in June and our thoughts go out to members who lost property and boats during the fire. No doubt the HKSAR Government will issue a report on the fire in due course. Fires on boats are nothing new here in HK with the most famous being the RMS Queen Elisabeth, as it was converted into a floating university, catching fire, under “unexplained circumstances”, in the harbour. There have been fires on pleasure boats at HK Marina, HHYC, Causeway Bay, Shau Kei Wan, Kwun Tung and Aberdeen Typhoon Shelters. To quote from an Article from Club Marine in Australia:
“Fire on a boat can be the most terrifying and potentially lethal situation you can face on the water.” How the fire started in Aberdeen we do not know at this time; and we may never know. Boat US statistics show there are six specific areas that lead to most boat fires: 1 26% of fires are due to “Off-the-boat” sources: Over a quarter of the time, a Boat US member’s boat burned when something else goes up in flames – the boat next to theirs or the marina. 2 20% of fires are due to “Engine Electrical”: For boats older than 25 years, old wiring harnesses take a disproportionate chunk of the blame here. 3 15% of fires are due to “Other DC Electrical”: The most common cause of battery-related fires is faulty installation of batteries. 4 12% of fires are due to “AC Electrical”: Most AC electrical fires start between the shore power pedestal and the boat’s shore power inlet. 5 9% of fires are due to “Other Engine”: This one is all about when an engine overheats due to blocked raw water intake or mangled impeller. 6 8% of fires are due to “Batteries”: This fire fact is for the outboard folks to pay attention to. On older outboards, by far the most common cause of fires is the voltage regulator. At 10 years of age, failure rates on these important electrical components begin to climb. Once the boat reaches 15 years old, it is time to replace.
There are lots of other soft furnishing on a boat, bedding, seats, curtains etc. etc. to get a small fire started. So that’s how fires can begin but fibreglass is a heat insulator, so why does it burn? Well, fiberglass is not flammable but, like practically anything else, it will disintegrate with enough heat. It’s the resins and other composites that give it that oh so nice burn to the waterline potential. The polyester resin, that binds fibreglass together to make it strong, will start melting at about 60 degrees Celsius and becomes significantly weaker as it melts. Once the resin, and other additives used in laying up fibreglass boats, in fiberglass starts to combust, it reaches incredibly high temperatures, emits a thick, toxic black smoke and burns at an alarmingly fast rate. You definitely don’t want to breathe the toxic smoke in. Fibreglass fires radiate this high burning heat and this is why boats beside the burning boat catch fire easily. Fires within a marina, or on tightly packed moorings, are especially difficult because they can rapidly hop from one boat to the next. Some resins are more fire retardant than others. Ease and rate of burn will depend on many factors, e.g. type of resin or if the laminate is resin rich, but the main one is if any fire retardant additives are present. These are included in mainstream resins such as Isophthalic or orthopaedic polyester, vinyl ester or epoxies. Of course these are a lot more expensive. I am lead to believe that most of the boats in Aberdeen were built with polyester resin. Once a boat catches fire there are other hazards that come in to play apart from setting fire to the boat moored close by. Cooking gas tanks are highly inflammable and when the temperature rises high enough they will explode, sometimes taking off like a rocket. This is another way in which fires can spread. Petrol in outboards, jet skis, spare cans will all burn fiercely and may explode in some circumstances. To put the very real dangers of explosion into perspective, consider this: one cupful of vaporised petrol in a small space such as an engine compartment, has the explosive power of 15 sticks of dynamite ! Remember both cooking gas and petrol vapour will sink to the lowest position on a boat, the bilge. Next month we will advise on how to mitigate fire on board. Safe boating. SEPTEMBER 2021 AHOY! |
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