What Does SOLAS II-2/20 Ask of a Car Carrier?

Very little. Resolution MSC.550(108), the amendment to SOLAS Chapter II-2 Regulation 20 that entered into force on 1 January 2026, is a passenger-ship regulation written out of the FIRESAFE studies and the ro-pax casualties of the 2010s. Of everything it adds — individually identifiable detection, video monitoring, weather-deck water monitors, a 2028 retrofit deadline — one paragraph binds a cargo ship, and only a cargo ship built from 2026. The vehicle-carrier rule is a separate IMO output with an entry into force of 2032 at the earliest.

Who the amendment is actually written for

Passenger ships with vehicle, special category or ro-ro spaces — and the text says so in almost every paragraph. For a passenger ship constructed on or after 1 January 2026, the amended regulation requires an individually identifiable fixed fire detection and alarm system providing smoke and heat detection throughout those spaces, with linear heat detection accepted in place of point heat detectors. Where a deluge system is fitted, detection sections must coincide with deluge sections, and the alarm interface must present the information in a way that allows a quick and correct decision.

The same ships get a fixed detection system for any weather deck carrying vehicles — with different settings permitted for loading and for voyage to reduce false alarms — plus a video monitoring system covering the whole space, high enough to see over loaded vehicles, with immediate playback and at least seven days of recording. Weather decks get fixed water monitors and drainage sized to remove no less than 125% of the combined monitor and hose-nozzle capacity. Openings are pushed a minimum of 6.0 m horizontally from accommodation and control stations and more than 12.0 m from survival craft. Internal decks a drencher cannot cover on both sides become A-30. Section signage becomes photoluminescent.

Existing passenger ships are caught too, including ships built before 1 July 2012, no later than the first survey on or after 1 January 2028: smoke and heat detection with heat detectors at smoke-detector spacing, 24 hours of video retention, and weather-deck monitors of at least 1,250 L/min each. Every one of those retroactive paragraphs — 20.4.1.6, 20.4.4, 20.6.2.3 — is scoped to passenger ships in the application clause that introduces it.

What a cargo ship actually gets

One paragraph. New paragraph 4.1.5 applies to cargo ships constructed on or after 1 January 2026 and requires a fixed fire detection and fire alarm system complying with the FSS Code in vehicle, special category and ro-ro spaces, capable of rapidly detecting the onset of fire, with detector type, spacing and location to the satisfaction of the Administration taking ventilation into account, and a post-installation test under normal ventilation conditions giving an overall response time — again to the satisfaction of the Administration. The regulation's own application text then states that cargo ships constructed before 1 January 2026 comply with the previously applicable requirements. Nothing changes on an existing PCTC.

What a cargo ship does pick up is smaller and unglamorous. Paragraph 3.1.5 on permanent openings is rewritten for cargo ships — openings in the side plating, ends or deckhead of the space must not let a cargo-space fire endanger survival-craft stowage, embarkation stations or the accommodation above. Regulation 7.5.5 rewrites accommodation and control-station detection on new cargo ships by protection method. And the option that the earlier text gave cargo ships — a sample-extraction smoke detection system in vehicle and ro-ro spaces other than special category spaces — sits in paragraph 4.2, which the resolution does not touch.

The hook that does reach a PCTC

Through the FSS Code, not through Regulation 20. Resolution MSC.555(108) amended Chapter 9 of the FSS Code to specify combined smoke-and-heat detectors and linear heat detectors for the first time, with spacing: 74 m² per combined detector, 9 m between centres, 4.5 m from a bulkhead; linear heat cables 9.0 m apart and 4.5 m from a bulkhead. Those specifications apply to ships constructed on or after 1 January 2026 — and the revised paragraph 1.1 of the chapter makes them apply wherever a fixed detection system is required under Chapter II-2, whichever ship type fitted it.

So a PCTC built from 2026 that voluntarily installs combined detectors to address its own risk is held to the 9 m grid. The Korean Register's implementation note is candid about the consequence: on such a ship the number of required detectors may increase dramatically against existing arrangements. The rule that does not require a car carrier to upgrade its detection still sets the density if it does.

The other thing 4.1.5 carries is the only performance language a cargo ship gets: "capable of rapidly detecting the onset of fire" and an installed system "tested under normal ventilation conditions" giving "an overall response time to the satisfaction of the Administration". That is a test, not a number. It does not say what counts as rapid, it does not specify the fire source, and it leaves the pass mark to the flag or its recognised organisation. A detection scheme whose response has been characterised against a defined source under the deck's real ventilation is easier to get through that clause than one that has not — which is where the argument about what to specify on a newbuild actually lives.

Where the car-carrier rule actually is

In a sub-committee, at guideline stage. The IMO output on the adequacy of fire protection, detection and extinction arrangements in vehicle, special category and ro-ro spaces for ships carrying new-energy vehicles was revised at SSE 12 in March 2026. The Sub-Committee chose to develop interim guidelines first — one set on fire safety measures for pure car and truck carriers, one on video monitoring and detection systems — before drafting SOLAS text, and sent the work to a correspondence group reporting to SSE 13 in March 2027. On that path, an amendment enters into force on 1 January 2032 at the earliest.

The interim guidelines matter more than their name suggests, because they are the first IMO instrument written for a PCTC deck rather than a ferry deck — and because the ro-pax text is the obvious template. Individually identifiable detection, smoke and heat throughout, video with playback, section numbering that coincides between detection, suppression and cameras: that is what the IMO has already decided a vehicle deck with passengers above it needs. The open question for the vehicle-carrier package is how much of it transfers to a deck with no passengers, thirteen levels of cars, and a crew of two dozen.

What it means for owners and underwriters

For a PCTC owner, the honest statement of the regulatory floor is short. An existing ship has no new detection, video or suppression obligation from MSC.550(108). A newbuild has 4.1.5, which is the pre-2026 requirement with a ventilation test attached, and the FSS Code spacing if combined detectors are chosen. "SOLAS 2026 compliant" on a car carrier's detection specification therefore describes very little, and a class fire notation or an owner's own specification is doing the real work. The ro-pax text is worth reading anyway: it is the closest published draft of where the 2032 package is likely to land, and a newbuild specified to it now is unlikely to be specified twice.

For an underwriter, the point is that the 2026 date did not move the vehicle-carrier fleet. A submission that cites the amendment as evidence of an upgraded detection standard on a PCTC should be read for what was actually installed, not for the resolution number. The controls that differentiate one car carrier from another this decade are voluntary — detection density beyond the FSS minimum, drencher zoning, the loading-time procedures the IUMI guidance describes — and the regulatory layer that will make them mandatory is, on the IMO's own timetable, six years away.

Sources

• 1. IMO Resolution MSC.550(108), adopted 23 May 2024 — Amendments to Chapters II-2 and V of SOLAS 1974; in force 1 January 2026. Regulation 20 as amended: 2.1.3 (retroactive application to passenger ships), 3.1.5 (permanent openings, cargo ships), 4.1 (application text: 4.1.1–4.1.4 passenger ships constructed on or after 1 January 2026; 4.1.5 cargo ships constructed on or after 1 January 2026; cargo ships constructed before that date comply with the previously applicable 4.1), 4.1.6 (existing passenger ships), 4.4 (video monitoring, seven days / 24 hours), 5 (structural fire protection and openings — 6.0 m, 12.0 m, 3.0 m, A-30, 5.0 L/min/m²), 6.2 (weather-deck monitors, 125% drainage, 1,250 L/min), 7 (decision-making signage). Read from the IMO resolution text directly.
• 2. IMO Resolution MSC.555(108) — Amendments to Chapters 7 and 9 of the FSS Code: combined smoke-and-heat detector spacing 74 m² / 9 m / 4.5 m; linear heat cables 9.0 m / 4.5 m; weather-deck monitor system 2.0 L/min/m² of protected area, individual monitor output not less than 1,250 L/min; smoke-detector function may be disconnected during loading on ro-ro passenger ships, heat detection may not.
• 3. Korean Register — "Amendments taking effect in 2026: SOLAS and related mandatory Codes" (technical file): the reading that existing SOLAS II-2 does not require combined or linear heat detectors on cargo ships, and that where combined detectors are voluntarily installed on a PCTC constructed on or after 1 January 2026 the revised paragraph 1.1 of FSS Code Chapter 9 applies the 9 m spacing, so "the number of required detectors may dramatically increase".
• 4. ABS Regulatory News No. 15/2025 (December 2025) — "Fire Safety Requirements for Ro-Ro, Passenger and Cargo Ships": application table by ship type and date of construction; cargo ships constructed on or after 1 January 2026 listed with detection only; cargo ships constructed before 1 January 2026 — requirements prior to MSC.550(108) remain applicable; "first survey" per MSC.1/Circ.1290.
• 5. DNV — "IMO Sub-Committee on Ship Systems and Equipment (SSE 12)", March 2026, and Riviera Maritime Media coverage of SSE 12 (9–12 March 2026): revised action plan on the adequacy of fire protection, detection and extinction arrangements for ships carrying new-energy vehicles; interim guidelines on fire safety measures for PCTCs and on video monitoring and detection systems to precede SOLAS amendments; correspondence group to SSE 13 (March 2027); entry into force 1 January 2032 at the earliest.