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fire on board

by RICHARD BROWN

Of all the horrors that may afflict the small boat sailor, fire at sea must be one of the worst. The progressive changes in the materials from which boats are made and equipped has gradually increased the potential for a serious fire to the point where a modern yacht could be regarded as a floating incendiary bomb. That view may seem melodramatic, but plastic hulls and liners with wooden trim are readily flammable and they are then filled with plastic foam cushions, synthetic fabrics, liquid petroleum gas (LPG), fireworks (flares), petrol or diesel fuels, perhaps paraffin for cooking, heating or lighting, paints and solvents, and an ever growing range of electrical equipment.

Possible sources of ignition are the engine, the electrics, cooking and heating with naked flames, gas refrigerators, and smoking. Additionally, there are the natural phenomena of lightning and static electricity.

The potential for a fire is very real, but fortunately they are fairly infrequent, which is undoubtedly due to both good management by skippers and crews, and good luck.

Fire prevention - installations

Fire prevention must begin with the builders of the vessel, for they are responsible for the installation of the engine, fuel tank and pipework, the electrical systems including wiring, and the cooking and heating arrangements. It is interesting to reflect that unsinkability is now being made a selling feature for yachts, but fire resistance (apart from hull materials like metal or ferrocrete) is never advertised. Yet the risk of fire is probably greater than that of being seriously holed.

Details of correct installation of the above facilities would take up several articles, but the following points should be considered:

Fuel

Petrol has a much lower flash-point than diesel, but if it is kept in secure, leak-proof tanks with on-off taps it cannot catch fire. Because diesel does not ignite as readily as petrol, it is tempting to regard it as safe and become careless, but remember, once ignited diesel burns fiercely.

The fuel tank should be situated well away from the engine and exhaust pipe. The tank must have a vent pipe which exhausts on deck or overboard to ensure that any fuel vapour is discharged safely. Metal exhaust pipes must be well lagged, particularly where they pass through bulkheads and if the exhaust pipe has to pass near the fuel tank, fire proof thermal insulation should be used to prevent heating of the fuel. The fuel feed pipe to the engine will be subject to considerable vibration which could fracture it in time. The pipe must be of adequate material and well secured. Plastic tubing should not be used for flexible fuel lines as it will rapidly melt and feed an engine compartment fire with fuel. Special purpose flexible pipes are readily obtainable.

A drip tray placed under the engine and gearbox will prevent leaking oil and fuel from accumulating in the bilges and is easily wiped clean at regular intervals.

Gas

The gas bottle should be located in a separate compartment well away from the engine, electrics and fuel. This compartment should have a drain through the side of the hull (above the waterline), so that any leakage from the on-off valve or regulator will drain safely overboard. The gas supply line should be correctly installed to minimise the possibility of damage. Any flexible connection to the cooker, especially if the cooker is gimballed, should be inspected very regularly for signs of damage, slack connections or wear. British Standard BS 5482 Part 3 is a Code of Practice for Domestic Butane and Propane gas burning installations in boats, yachts and other vessels.

Electrics

The electrical supply systems should have isolating switches at the batteries. The wiring should be properly insulated and of more than adequate current carrying capacity for each circuit. Every circuit should be separately fused with a fuse of the correct rating for the normal current taken by the connected equipment.

All installations should be thoroughly checked at every opportunity for signs of damage: dents; cracks; chafing; etc. Do not forget to inspect the stove mountings, more than one stove has been known to come adrift in a rough seaway.

Fire prevention - good housekeeping

Fuels and bottled gases are safe if handled correctly. Follow a set drill for refuelling: Stop the engine. No smoking. Turn off the cooker, heater and any gas pilot lights. Switch off all electrics. Watch the fuel delivery pump gauge to check that the amount being supplied to the boat's tank does not exceed the available tank capacity. In warm weather allow space in the tank for the expansion of cold fuel.

After refuelling allow time for fumes to disperse and ventilate where possible before restarting the engine or relighting pilot lights etc. Gas leaks frequently occur after connecting a fresh cylinder, so it is advisable to regularly change the sealing washer between the bottle and regulator.

Gas connections can be tested with soapy water. If a regulator develops a fault, do not attempt repairs. Leave it to the experts.

It is very sensible to install a gas 'sniffer' alarm as LPG is heavier than air and if spilt from a cooker or a faulty connector, it will descend into the bilges. Modern diaphragm bilge pumps are also very effective air pumps and they can be used to pump gas or fuel fumes out of the bilges. Daily pumping of the bilges, even if dry, is thus a sensible routine. Modern gas stoves have low flame 'clicks' and flame blowout sensor/cutouts to reduce the possibilities of gas getting into the bilges.

For lighting gas cookers I much prefer a good quality piezo-electric lighter. Mine has been very reliable, it does not need batteries and unlike matches can be used one handed, leaving the other hand free to control the gas tap or to hang on with if conditions are rough.

The gas supply should always be turned off at the bottle when it is not going tobe used for a while and when leaving the boat unattended.

The hazards of smoking are well known. If possible do not permit smoking other than on deck and certainly do not allow lighted cigarettes to be left unattended or permit smoking by a crew member who is lying in a berth.

Never refill paraffin heaters while they are hot. It is better to have the inconvenience of a short wait while they cool than risk the new fuel flaring up in your face.

The deep fat frying of chips is hazard enough in the home, let alone on a yacht. This skipper has to frequent ports with good chip shops to avoid this risk (and mutiny by the junior crew).

Spare cans of fuel should be stored in similar compartments to that of the gas bottles. The cans should be in good condition and it is advisable to check that the filler caps are sealing properly before stowing them. The new plastic cans complying with SI 1982/630 seem ideal for marine use, as they are light and won't rust.

Extinguishing a fire

On board a yacht the range of fire fighting equipment is usually limited to a couple of extinguishers, buckets of water and perhaps a small fire blanket. Each can be extremely quick and efficient if used correctly, but it should also be remembered that a fire can be stopped by removing the source of fuel (e.g. turning off the petrol), providing that the necessary tap or switch can be reached without further endangering life.

Fire extinguishers. There are many types on sale, but those recommended for small craft are filled either with dry powder or a liquid halon (BCF or BCM).

Dry powder is effective on all types of fires, but has the drawback of being very messy to clear up afterwards, its use being like an explosion in a talcum powder factory. Through checking the contents of the dry powder extinguishers fitted to my own boat, I have found that the powder has a tendency to agglomerate into soft lumps, which I am worried might severely impair the performance of the extinguisher, even if they did not block the discharge nozzle. These lumps have been found to begin forming in as little as a couple of months afloat and I am now rather dubious about the suitability of dry powder extinguishers for use on small craft, unless checked or serviced at least every season.

BCF (bromchlorodifluoromethane), or the less common BTM (bromotrifluoro methane) can also be used on all types of fires and is astonishingly effective. Since BCF evaporates it leaves no mess, but it does have the disadvantage that the fumes are toxic and should not be inhaled. This could be a problem in a confined space, but the fumes are heavier than air and will sink to the bilges, whence they can be pumped out. BCF is ideal for flooding an engine compartment fire, but remember to switch off the exhaust fan, if one is fitted.

Water can be applied from an extinguisher, a pump or a bucket. Water filled extinguishers, while very effective, are large and heavy and therefore not very suitable for stowage and use in small craft. It is unusual to find a yacht with a pump rigged for fire fighting, although it would be very easy to do, using a modern bilge pump in reverse. This could give a discharge of about 8-10 gallons per minute, which would probably match the performance of a bucket wielded by a desperate yachtsman.
Water must NEVER be used on a fire involving petrol, diesel, paraffin or oil, because not only will it not extinguish the fire, but it will increase its severity several fold. Having seen it demonstrated on several occasions, I can assure you the effect is spectacular and frightening, with the height of the flames increasing instantly by four to five times. There is a high risk of electrocution if water is used on electrical fires of mains voltage or higher, until the electricity is switched off, but at the 12 volts used on most yachts (unless connected to a marina mains supply), there is little danger. Water is probably best used as a back up to the fire extinguishers and to cool down the burnt area when the flames have been put out.

Fire blankets are ideal for smothering blazing frying pans. Small glassfibre blankets are now available for under 10 and are well worth installing in the galley area.

The Department of Trade(UK) recommend that a minimum of two 1.4kg (31b) extinguishers are carried on small vessels (up to 9 metres) with auxiliary engines. Extinguishers should be sited within easy reach at any time, preferably with one close to the main hatch where it can be reached from inside or outside the cabin, one close to the engine, and one at each either hatch or cabin. No individual extinguisher should have a capacity of less than 1kg.

If you ever have to use an extinguisher, remove the safety devices, then aim the discharge nozzle at the seat of the fire from as close a range as possible before pulling the trigger. Do not aim over the fire, but try and put the fire out from front to back. The sizes of extinguisher recommended can be used in one hand with the arm fully extended and if necessary the other arm can be used to shield the face from the heat of the fire. Attack the fire from a direction which will leave a safe escape route if you are not successful in putting out the fire. Continue using the extinguisher until well after the visible fire has gone in case the residual heat re-ignites it. The residual heat can be totally removed by damping down with water.

Fire extinguishers have a very short discharge time (10-15 secs) and it is well worth practising with one on a controlled fire. This would also ensure that they are tested and refilled from time to time, say every 3 or 4 years.


Action in the event of fire
  • Treat any fire very seriously no matter how small. Any fire can get out of hand very rapidly.
     
  • Alert all on board and tell them to get on deck. Count heads.
     
  • Attack the fire at once with an extinguisher.
     
  • If fuels or electrics are involved, detail one crew member to turn them off at source, if possible.
     
  • Close fore hatches and ventilators to reduce through draughts. Shut off engine compartment ventilation fans.
     
  • If you can transmit either by radio or visually, inform the nearest Coastguard station or other vessel of your problem. (An alarm call can always be cancelled, but there might be only once chance to send it.)
     
  • Prepare to launch the dinghy or life raft with lifejackets and emergency survival kit ready i.e. flares, water, etc.
     
  • If possible get the crew to alter course or stop the vessel to prevent the wind fanning the fire.
     
  • Think about your own possible reactions to fire on board. Make sure you and your crew read and learn the operating instructions for your extinguishers. Keep all equipment in good order. A few minutes planning and practising your fire drill could save life and your vessel when every second counts.