SOLAS II-2/7: Fixed Detection vs IR

IMO's work on container-ship fire safety includes a draft new SOLAS regulation II-2/7.11 requiring at least two portable infrared thermal imagers, suitable for screening and detecting hot areas, on every ship designed to carry containers on or above the weather deck. For a container ship it is a sensible measure: crew can walk the lashing bridges and scan the stacks. On an enclosed vehicle deck the same idea runs into access, line of sight and time.

What does the draft II-2/7.11 require?

Two imagers, kept ready, on container ships. As progressed at the Sub-Committee on Ship Systems and Equipment in February 2025 (SSE 11), the draft requires at least two portable infrared thermal imagers meeting standards acceptable to IMO, stored in a readily accessible and clearly marked location, and subject to monthly testing, with servicing and calibration to the maker's instructions. It sits within a wider package on detecting and controlling fires in container holds and on deck. It does not apply to vehicle carriers.

Where does portable imaging work?

Where a person can see the cargo from a walkway and has time to look. Container stacks on deck are scanned from lashing bridges and gangways, and a warm reefer or a hot box stands out against its neighbours. Portable imagers are also useful on any ship for checking a known location: confirming a fire boundary is cooling, checking a bulkhead after an alarm, or surveying hot surfaces in an engine room, where MAIB has shown a spot thermometer can miss a hot manifold that a thermal camera finds at once.

Why does it fail on a vehicle deck?

Because most of the cargo cannot be seen. Cars are stowed bumper to bumper with little walking space, a PCC deck has about 1.7 metres of clearance, and the likely origin of a fault is under a vehicle or inside its engine bay or battery pack, which a hand-held imager pointed from an aisle cannot see. A scan is also a snapshot: a crew member covers a deck of several hundred cars in a round, and the battery that starts to fail an hour later is not being looked at.

• Access: bumper-to-bumper stowage leaves most vehicle surfaces out of reach.
• Line of sight: the underbody and battery pack face the deck, not the aisle.
• Time: a round is periodic, and a failure can start between rounds.
• Safety: sending crew into a closed vehicle deck to scan a suspected event is what fixed-first doctrine tries to avoid.

What should a vehicle carrier use instead?

Fixed, continuous detection that watches each vehicle, with a portable imager as a verification tool. SOLAS II-2/20 already requires fixed detection in vehicle spaces, and IUMI's 2025 guidance asks for detection and verification to be treated as one step. A portable imager is still worth carrying, to confirm a boundary temperature or check a vehicle at the ramp, but it cannot be the detection layer on a car deck.

Sources

• 1. IMO Sub-Committee on Ship Systems and Equipment, 11th session (SSE 11), 24–28 February 2025 — draft amendments to SOLAS chapter II-2 and the FSS Code on detection and control of fires in cargo holds and on the cargo deck of container ships, including draft new regulation II-2/7.11 on portable infrared thermal imagers. Summaries by DNV, Lloyd's Register, ABS and LISCR.
• 2. SOLAS II-2/20 — fixed fire detection in vehicle, special category and ro-ro spaces, as amended by MSC.550(108).
• 3. IUMI — 'Risk mitigation for the safe ocean and short-sea carriage of electric vehicles', September 2025: detection and verification as one step; manual firefighting a last resort.
• 4. MAIB — Stena Europe engine-room fire: spot thermometer versus thermal camera. As analysed in 'Stena Europe: The Hot Spot Nobody Found'.