Fire in the Lithium-Ion Battery Space
You are master of an 18 m motor yacht on passage 12 nm south-west of a harbour, with four persons on board. At 14:10 the smoke detector in the engine space sounds. You see thin grey smoke from the engine-room vents; the space contains a lithium-ion battery bank, two diesel engines and a fixed clean-agent extinguisher that was last serviced 13 months ago. The vessel is making 14 kn; wind is north-east 20 kn, sea 1.5 m, water temperature 12°C. One crew member has asthma and has begun coughing. The extinguisher's remote release is accessible at the helm. You have a liferaft for six, an EPIRB, VHF DSC and a hand-held VHF. The nearest coastguard helicopter is 35 minutes away; a fishing vessel is 4 nm away. The engine space temperature gauge is rising. The batteries are not yet involved, but you cannot see the source.
1. State your immediate actions and decide whether to release the fixed extinguisher. Justify your decision using the information available.
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Immediate actions: sound the general alarm, muster the crew, lifejackets, close all engine-space vents and doors, shut down the engines and isolate the battery bank if the isolation is outside the space. Reduce speed and head into the wind to keep smoke aft if that does not worsen the fire. Make a Pan-Pan or Mayday - with smoke from a lithium-ion battery space and an asthmatic casualty, I would go to Mayday: 'Mayday, Mayday, Mayday, this is [name], position 12 nm SW of [harbour], fire in engine space, four persons on board, one asthma casualty, over.' Keep a hand-held VHF away from the space.
Should I release the fixed clean-agent system? The space is closed and the release is accessible at the helm; the system was serviced 13 months ago, which may be outside its annual service interval, so its reliability is uncertain. If I can confirm the space is not occupied, I would release it, because a clean agent can knock down a diesel or electrical fire and buys time. But I would not assume it will solve a lithium-ion battery fire: clean agents may not cool the cells, and a battery fire can reignite. I would not open the space to look. I would boundary-cool from outside if possible, keep the space closed, and prepare to abandon if smoke spreads or the temperature continues to rise. The asthma casualty is a strong reason to move people to fresh air and plan for evacuation early.
2. How would you manage the asthma casualty and the decision to abandon? What are your criteria and what transmissions would you make?
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Casualty management: move the asthmatic to the least smoky place, preferably on deck upwind, sit them upright, give oxygen if carried, and use their own reliever inhaler. Do not send anyone into the engine space. Monitor breathing and keep them warm; if breathing deteriorates, that is a medical emergency and raises the priority of evacuation.
Abandon criteria: fire not knocked down within a few minutes; smoke or heat entering the accommodation; visible flames; risk of battery thermal runaway; loss of steering or flooding; or the asthma casualty needing oxygen we cannot sustain. I would not abandon while the yacht is still a safe platform and the fire is contained; a liferaft in 1.5 m seas and 12°C water has its own risks. But I would prepare: liferaft on deck, EPIRB and hand-held VHF in the grab bag, flares, water, medication, warm clothes, and a headcount.
Transmissions: Mayday with position, nature (fire), POB, casualties, vessel description, and intentions. If the fishing vessel is closer, ask it to stand by. Tell the coastguard clearly: 'We are preparing to abandon; request immediate assistance; one asthma casualty.' Update if the situation changes. A Pan-Pan is not enough once abandonment is being considered.
3. If the fishing vessel arrives before the helicopter, what do you ask it to do, and what are the risks of transferring crew in 1.5 m seas?
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If the fishing vessel arrives first, I would ask it to stand by to windward and not come alongside until asked. In 1.5 m seas, two vessels rolling differently can crush a person between them. The safest transfer is usually from my lee side into a small boat or liferaft, one person at a time, with lifejackets and a line. I would ask the fishing vessel to:
- keep a radio watch on Ch 16 and a hand-held on the agreed working channel;
- approach from downwind and lie stopped, showing a lee;
- rig fenders, heaving lines and a scramble net or pilot ladder if it can be done safely;
- be ready to recover a person from the water, not just from my deck.
Risks: propeller contact, a person trapped between hulls, hypothermia, and the asthma casualty deteriorating during transfer. I would transfer the casualty first if the helicopter is delayed, but only if the transfer itself is safer than staying. If the sea state worsens, I would keep everyone aboard, stay with the liferaft and EPIRB, and wait for the helicopter rather than attempt a risky alongside transfer. The decision is a comparison of risks, not a reflex to get off the yacht.