Maritime News

MAIB Safety Digest 2 / 23 Published

The latest Safety Digest from the Marine Accident Investigation Branch in the UK tells the story of a recently refurbished sailing vessel which caught fire and burnt to the waterline before sinking. The skipper had placed a laptop and two mobile phones on charge in the vessel’s saloon and the fire started in this area. The speed with which the fire spread and the ferocity of the flames gave very little time for firefighting.

Recognising the severity of the situation and the immediate threat to the crew, the skipper gave the order to abandon ship into the vessel’s tender over the windward side. The vessel was lost but the crew saved due to the quick thinking and preparedness of the skipper.

Lithium-ion batteries can be found in thousands of battery powered devices these days. From the smallest battery in a hearing aid to the largest multi-cell power packs in an electric vehicle. The design and technology has been around since the 1980s and there are now 6 main variations on the theme. Those most likely to be found in the maritime environment are lithium iron phosphate (LiFePo₄) for battery banks and lithium cobalt oxide (LiCoO₂) batteries in laptops, tablets and smartphones. Lithium-ion batteries are an understandably popular choice in many applications but are also increasingly in the news due to EV and mobile phones batteries catching fire or exploding.

Edition 1 of Boat Chat looked at the fire on board the bulk car carrier MV ‘Fremantle Highway’ earlier this year. Whilst the cause of the fire has yet to be reported, the presence of the EVs on board which also caught fire complicated the situation and made fighting the fire more difficult and dangerous than a ‘traditional’ vehicle fire. In the end the crew abandoned ship, many jumping into the sea and an Indian crew member tragically lost their life fighting the fire.

Boat Maintenance Tips

Fire on board any boat is a very serious incident which puts the vessel and crew in real danger. The presence of lithium-ion batteries therefore needs to be considered in this scenario by the conscientious skipper. Whilst the probability of a lithium battery fire is very low, the risk it poses to vessel and crew is very high. Thermal runaway of lithium-ion batteries is a phenomenon which can be caused by damage to the battery, over charging and using defective chargers. The London Fire Brigade offers the following safety advice:

• Always use the genuine charger / cable that came with your device.

• Always avoid using counterfeit chargers and cables.

• Avoid storing, using or charging batteries at very high or low temperatures.

• Protect batteries against being crushed, punctured or immersed in water.

• Don’t leave items on charge after the charge cycle is complete.

• Devices, cable and adapters get warm when charging, never cover them.

• Don't overload your sockets – as true on a boat as it is at home.

It would also be worth adding: When charging devices, place them on the least combustible surface available.

Fire safety on boats is a broad topic which encompasses many threats and demands many considerations. The wide range of different materials and the multitude of different fuels and oils found on board, and the presence of many enclosed spaces make detailed fire planning an essential activity for any vessel. For private vessels not bound by any mandatory periodic operations or equipment inspections, this is even more important.

It goes without saying that the time interval between a battery starting to fail and detection is critical and what happens in those first few seconds and minutes can make the difference between you and your vessel surviving the situation.

There are now known to be four stages in a typical lithium-ion battery failure:

1. Damage – Impact, immersion, over charging, over temperature

2. Off-gassing – The emission of several gasses, many of them toxic, as the battery structure degrades and heats up (carbon monoxide, methane, ethane, ethylene followed by hydrogen chloride, hydrogen fluoride and hydrogen)

3. Smoke – As the battery nears ignition the off gassing continues and smoke generation begins

4. Ignition – Often accompanied by an explosion of the gasses given off earlier.

There are great advances being made in better understanding the off-gassing phase and the by-products of battery degradation. Particle detectors are coming online which can sense the presence of typical off-gasses and alarm when concentrations reach pre-determined levels. Currently aimed at larger battery installations used for grid storage, it is only a matter of time before small units similar to conventional smoke alarms are developed.

Once ignition has occurred, the modular nature of many lithium-ion battery packs makes extinguishing the fire very difficult, especially in larger packs. The exothermic, self-sustaining nature of these fires only respond to cooling and ideally the exclusion of oxygen. However, some good news is that fire extinguishers continue to evolve to meet emerging threats.

Water additive mist extinguishers are now able to tackle almost all fire types including live electrical equipment up to 1000V, oil and fat fires and lithium-ion battery fires. These offer the ability to rapidly cool the battery but may lack the ‘stamina’ to keep it extinguished. A 2 litre extinguisher will easily fit inside most small craft.

It also comes in a stainless steel version:

Moving beyond the capability of water additive mist extinguishers are the new breed of AVD (Aqueous Vermiculite Dispersion) extinguishers which spray a 4:1 liquid solution of water and vermiculite with the colour and consistency of a runny chocolate sauce. The solution both rapidly cools the battery through evaporation but also forms a film around the battery, greatly reducing the availability of oxygen and effectively smothering it. This is a patented technology available through AVD Fire Ltd in Stoke-On-Trent.

There is a link to a YouTube video of an AVD extinguisher in action in Further Reading.

Surveyor’s Top Tips

As lithium-ion battery packs become more common, surveyors need to stay abreast of developments in relevant fire detection and firefighting technologies. Only then can they provide their Clients with the best advice based on good observations leading to well reasoned recommendations.

When considering the battery installation on any vessel key questions that should be considered are:

• Are the batteries sufficiently secure with no more than 10mm of travel in any direction?

• Does the battery box have a fixed cover?

• Is the battery box airtight?

• Is the battery box watertight?

• Is the battery box made from combustible materials?

• What is the distance to the nearest combustible surface?

•  Where is the nearest smoke detector?

• Are the terminals protected from accidental shorting?

• Are the cable connections in good condition and tight?

• Is the battery compartment well ventilated?

•  Is the outlet vent at the top to allow hydrogen gasses to escape?

• Could the battery compartment be made airtight?

•  Is there a fixed fire extinguisher in the battery compartment?

With the answers to these questions in mind, the suitability of any given battery installation can be assessed and recommendations made to the Client to improve the overall safety of the batteries. It should also prompt thought as to what type of fire detection and firefighting capabilities are best suited to the type of batteries installed and the layout of the vessel.

More Great Kit Ideas

For more great kit ideas for your boat, bookshelf, surveyor’s toolbox or Christmas Wish List have a look at our page on Kit.Co

Boaty Terminology

Fire Ship – Deliberately loading a ship with flammable material and explosives with a view to sailing it into an enemy port, setting it alight and then abandoning it prior to collision with, and hopefully destruction of, enemy ships.

Links To Further Reading

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