What Does CHIRP Tell Ferry Crews on EV Fires?
CHIRP's 2026 ro-pax guidance says plan for consequence: treat a failing EV battery as a gas release before a fire, and never approach early signs.
To plan for consequence, not likelihood. CHIRP Maritime's guidance on electric vehicles aboard ro-ro passenger ferries, published on 22 April 2026, tells crews to treat a failing EV battery as a flammable-gas release before it is a fire. Its other instructions follow from that: stay back from early signs, choose the ventilation setting for the situation, cool the boundaries, and assume the battery can re-ignite. It works inside SOLAS, flag and SMS procedures rather than replacing them.
What the guidance is, and what it is not
It is a capability-and-preparedness document from the UK's confidential maritime incident-reporting charity, written for operational and command-level decisions on ro-pax ferries. It sets no new rules. It says plainly that it does not replace SOLAS, flag-state instructions, class rules or a company's safety management system, and that it shows where EV behaviour should change the assumptions, thresholds and timelines those frameworks already use.
Its framing line is the useful one: 'EV fire risk is different, but not inherently higher.' EV incidents on ro-pax ferries are low-frequency, high-consequence events, and 'a low probability of occurrence does not equate to low impact.' The guidance therefore asks masters to judge by consequence, escalation potential and time-dependent behaviour, rather than by how rarely EVs burn.
What crews should expect to see
Gas before flame, and often no flame at first. CHIRP describes thermal runaway as able to escalate from local heating to large-scale gas release 'sometimes before any visible fire is present', with pack temperatures above 1,000°C. The early sign may be white vapour that crews take for steam. It is flammable and toxic. The mixture includes hydrogen, carbon monoxide, hydrogen fluoride, hydrogen cyanide and more than 100 trace organics.
The cloud does not behave like smoke. Hydrogen rises; the heavier vapours and electrolyte aerosols pool at deck level, flow along the lane and gather behind obstructions, which is what makes delayed ignition and a vapour-cloud explosion possible in a semi-enclosed deck. For planning, CHIRP puts a 50–100 kWh battery at roughly 15–60 m³ of gas. It also warns that conventional gas detection may not identify all battery gases, and that crews should listen for popping, hissing or a high-pitched scream of venting gas: 'If it can be smelled, the crew and passengers are at risk.'
What it tells the crew to do first
Withdraw, confirm, then act from a distance. Section 4 opens with 'Early detection saves time — time is the Master's greatest ally' and asks for continuous monitoring by CCTV, infrared and thermal imaging, and gas detection including hydrogen-fluoride sensors. On abnormal heat or smoke, the crew alert the bridge and leave the area, confirm whether the source is isolated or spreading, and send the first situation report. 'Early indicators of battery failure do not imply that it is safe to approach.'
The activation trigger is a confirmed or suspected EV fire, or a rapid heat rise. The first actions are to sound the alarm and muster, isolate power and stop vehicle movements, and begin boundary cooling with fixed systems or monitors. Once runaway is confirmed, the instruction is to 'assume escalation until proven otherwise'. After apparent suppression, CHIRP asks for extended monitoring, conservative re-entry and continued stand-off, because individual cells can fail hours or days later.
Where it departs from car-carrier doctrine
On ventilation, fixed systems and the ramp. Car-carrier practice shuts the fans and seals the deck so CO₂ can work. CHIRP treats ventilation as 'a tactical decision, based on risk assessment rather than automatic application', and its first-action list says to consider shutting it in port and opening it to the affected deck at sea, if safe. On a ferry, the aim is to keep vapour away from passengers and escape routes, not to hold a gas-flooding concentration.
Its in-port scenario says not to rely solely on fixed systems such as CO₂ or foam, and to prioritise safe access, containment and sustained cooling. It also tells crews to consult the emergency services before closing an open bow or stern ramp, because the ramp may be their access route even as it lets toxic fumes reach the port and town. Passengers are mustered upwind with short, multilingual instructions, and plans should cover both disembarkation and shelter-in-place.
What it asks of operators before the ramp goes up
To know which vehicles are batteries, and where they are. CHIRP asks for the number and type of EVs and hybrids to be declared before loading, with locations on the loading plan where practicable. Passengers should confirm at booking that the car is undamaged and has no known battery fault, and check-in staff should look for visible damage. The information the bridge needs is the EV flag, battery kWh, state of charge, state of health, condition and position on deck. EVs should be segregated rather than mixed into stowage blocks, and there should be no charging at sea unless risk-assessed and approved.
It also asks port state control and flag administrations to check EV manifest procedures, state-of-charge policies, monitoring and containment systems, and drill records. For drills, it calls for an annual tabletop exercise across ship, port, rescue services and regulators, plus an annual live exercise that includes an EV-fire scenario. 'Preparedness must be exercised, not assumed.'
How RoRoSAFE helps
CHIRP's sequence starts with early detection, and every later decision depends on knowing which vehicle is failing and where. RoRoSAFE gives a ro-pax that location: infrared thermal and battery-vent gas sensing under each parked vehicle, alerts before visible smoke, and tiered bridge and shore alerts that name the deck and bay. It complements the ship's SOLAS detection and drencher; it does not replace them.
Pilot: one deck · installed alongside the berth · no drydock · 6 months of dashboard access
Sources
- 1. CHIRP Maritime (The CHIRP Charitable Trust) — 'Electric Vehicles on Roll-On and Roll-Off Passenger Ferries: Capability and Preparedness', published 22 April 2026 (chirp.co.uk/maritime). Read in full: purpose and scope; 'EV fire risk is different, but not inherently higher'; pack temperatures above 1,000°C; vent-gas composition (hydrogen, CO, HF, HCN, >100 trace organics); white vapour mistaken for steam; ventilation as a tactical decision; persistence and re-ignition; advance, booking and check-in declarations; ro-pax planning scenarios at sea, near harbour and alongside; Section 4 detection, activation thresholds and first actions; information management (EV flag, kWh, SoC, SoH, location; segregation; no charging at sea unless approved); PSC and flag oversight; annual tabletop and live exercises; Appendix 1 vapour-cloud formation and planning figures.
- 2. UK Maritime and Coastguard Agency — MGN 653(M) Amendment 1, 'Electric vehicles onboard passenger roll-on/roll-off (ro-ro) ferries' (August 2023): the UK administration's guidance that CHIRP's document operates alongside.
- 3. EU LASH FIRE project findings on ro-ro deck ventilation and fire intensity, as summarised in this site's post on whether car-deck fans should stop in an EV fire; SOLAS II-2/20.3.1.4 on closing ventilation from outside the space.
Questions, answered
What is CHIRP's guidance on EVs aboard ro-ro passenger ferries?+
It is a 2026 capability-and-preparedness document from CHIRP Maritime, the confidential maritime incident-reporting charity. It explains how battery-electric vehicle fires differ from petrol and diesel car fires on ro-pax ferries, especially thermal runaway and vapour-cloud explosion, and sets out detection, first actions, passenger management and pre-loading controls. It works within SOLAS, flag-state and company safety-management procedures rather than replacing them.
Should a ferry shut its car-deck fans in an EV fire?+
CHIRP treats it as a tactical decision, not an automatic one. Its first-action list says to consider shutting ventilation in port and opening it to the affected deck at sea if safe, weighing gas dispersion, flammability limits and explosion risk. That differs from car-carrier practice, where fans are stopped and the deck sealed so a CO₂ system can work.
How much gas can an EV battery release in thermal runaway?+
CHIRP's planning figure puts a 50–100 kWh battery at roughly 15–60 cubic metres of gas, more at full involvement and high state of charge. The gas mixes hydrogen, which rises, with heavier vapours and aerosols that pool and spread along the deck. In a semi-enclosed vehicle deck that volume can form a flammable atmosphere before any flame appears.
What should a ferry know about EVs before loading?+
How many EVs and hybrids are aboard, what type, and where they are stowed, ideally marked on the loading plan. CHIRP also asks for the battery's kWh, state of charge, state of health and condition, a booking declaration that the car is undamaged, visual checks at check-in, segregated stowage and no charging at sea unless risk-assessed and approved.
Continue the thread
Should Car-Deck Fans Stop in an EV Fire?
Yes — stopping the fans starves the fire and lets CO₂ work. But a sealed deck also traps battery vent gas, so when and how you reopen it matters as much.
Are Crews Trained to Fight an EV Fire?
Mostly not. STCW firefighting training is generic — and a battery in thermal runaway can't be put out by routine crew firefighting at all.
The First Ten Minutes After an EV Alarm
Detection buys time only if the crew knows what to do with it. On a vehicle carrier the decisive variable isn't the alarm — it's the rehearsed response.
Why Do Car Decks Explode During a Fire?
Most bangs on a burning car deck are tyres, struts and airbag inflators failing. The real blast risk is gas building up in a sealed deck.
Should Drivers Ever Go Back to the Car Deck?
Not without the master's consent. SOLAS bars passengers from enclosed ro-ro decks at sea, yet all 11 who died on Euroferry Olympia were drivers in cabs.
Do Ferry EV Bans Make the Car Deck Safer?
Only partly. A ferry EV ban removes the hardest fire to fight, not the most common one — and it holds only as far as check-in can spot an EV.
Should EVs Charge on a Passenger Ferry?
Denmark and operators like Havila restrict or ban EVs on passenger ferries. The real questions: onboard charging, and how low a state of charge is safe.
Can a Car-Carrier Fire Reignite a Month Later?
Yes. The Min Jiang Kou showed a deck temperature rise 32 days after CO2 contained its engine-room fire — heat that suppression never removed.