The engine room detains the ship: what 52,000 port state control inspections in 2025 reveal

Every year the two big port state control regimes publish their annual reports, and every year most of the industry reads the flag lists and moves on. This year we read the deficiency tables instead — all of them, from both reports. Together the Tokyo MoU and Paris MoU recorded 52,020 inspections, 141,965 deficiencies and 1,943 detentions in 2025.

The headline finding is simple, and it is not about paperwork: the deficiencies that most often stop a ship live in the engine room.

The list that should worry technical managers

The Tokyo MoU’s 2025 report ranks the deficiencies that most frequently led to detention (Figure 8, p. 17). Read it as a chief engineer would. Teal bars mark items that are found in — or are primarily proven through — the engine room and its maintenance regime:

Count them. Fixed fire-extinguishing installations — the CO₂ system protecting the machinery space. Fire pumps. Fire detection. The remote controls that shut down fuel pumps and ventilation from outside the engine room. Fire dampers. The “maintenance of ship and equipment” ISM item. The oily water separator. Seven of the ten most frequent detainable deficiencies either live below deck or are proven — or disproven — by the engine-room maintenance file. An eighth, the ISM system itself, is where those maintenance failures get written up as a system failure.

This is not our editorial framing stretched over the data. The Tokyo MoU says it in its own words: deficiencies related to propulsion and auxiliary machinery (along with structure, watertight integrity and emergency systems) have “constantly increased in recent years”, which the report treats as evidence of a “lacking of effective maintenance” on board (p. 12). The organisation has gone further than commentary — at its 2025 committee meeting it adopted new PSCO guidelines for enhanced inspections of machinery and maintenance conditions and runs a dedicated working group on machinery maintenance. The engine room is not incidentally on the radar. It is the radar.

Both regimes, same direction

The volumes behind the ranking are worth a minute. The Tokyo MoU ran a record 35,546 inspections in 2025 and found 90,168 deficiencies; 65.4% of inspections found at least one deficiency — the highest share in eleven years of data. Detentions: 1,255, a rate of 3.53%.

The Paris MoU inspected less — 16,474 inspections, 14,554 individual ships — but detained harder: its annual report shows 688 detentions, a 4.18% detention rate, the third consecutive annual rise (3.86% in 2023, 4.03% in 2024). Nineteen ships were banned from the region. Total deficiencies climbed for the third year running to 51,797, with 4,744 of them serious enough to be detainable.

One honesty note, because the data deserves it: the Paris MoU states that its deficiency analysis does not point to a single area as the primary cause of the rate increase. What it identifies instead are recurring areas of concern — fire safety (SOLAS II-2) at 16.8% of deficiencies, structural and electrical elements at 11.6%, and crew health and welfare under MLC at 10.0%. The engine-room ranking above is the Tokyo MoU’s detainable-deficiency data; the Paris data is consistent with it (fire safety is its largest category, and much of a cargo ship’s fire-safety hardware protects the machinery space) but the Paris report does not itself run that analysis. We put the two side by side; we do not blend them.

The Paris report adds one more theme that will sound familiar to anyone watching sanctions trades: it warns of being “increasingly confronted by shipping operating outside legitimate oversight” — ships that transit the region without port calls and therefore sit outside the risk-based inspection system entirely — alongside concerns about false flags and fraudulent certification.

Ship types: general cargo is the exposed flank

Detention risk is not evenly distributed. In the Tokyo MoU’s 2025 figures, two ship types are detained at roughly twice the regional average:

Gas carriers are a small, heavily scrutinised population (2.87% of inspections). General cargo is not: it is the workhorse segment — 15% of all Tokyo MoU inspections — typically older, smaller-crewed and running the shortest port stays, which is exactly the operating profile where planned maintenance quietly becomes breakdown maintenance. If you operate general cargo tonnage, the 2025 message is blunt: your segment is detained at nearly twice the average, and the deficiencies doing the detaining are overwhelmingly the ones a maintenance file answers.

A chief engineer’s read: every item on that list is a routine

Here is the uncomfortable part, reviewed by our chief engineer: nothing in the Tokyo top ten is exotic. Each item maps to a known routine —

None of this is news to a working superintendent. What the 2025 data changes is the economics of proving it. When both regimes are inspecting more, finding more, and — in Europe — detaining at the highest sustained rates in a decade, the maintenance record stops being an internal document and becomes the difference between a six-hour port call and a three-day detention with an off-hire clause attached. Evidence discipline — dated, signed, retrievable — is now a revenue protection measure.

If you want to pressure-test where your fleet stands before an inspector does it for you, start with our PSC deficiency checklist, run the fleet risk self-assessment for the honest weak-point view, and put the findings into a structured weekly report so the office sees the trend before the port state does. For the broader context of what inspectors focus on below deck, see our guide to common engine-room inspection risks.

Methodology

All figures are taken directly from the two primary documents: the Tokyo MoU Annual Report 2025 (published May 2026; inspection, deficiency and detention figures pp. 10–18, Figures 4–11) and the Paris MoU Annual Report 2025 (published 1 July 2026; statistical annex pp. 14–15, narrative pp. 4–10; data cut-off 12 February 2026). The Paris 2025 detention count of 688 is stated in the organisation’s press release and is consistent with the published rate (4.18% of 16,474 inspections). Combined totals (52,020 / 141,965 / 1,943) are simple sums of the two regimes and are ours, not the MoUs’. The engine-room classification of detainable items in the chart is our editorial mapping and is shown in full so you can disagree with it.