Port state control: how to prepare and what gets ships detained

The legal basis and the 2025 Procedures

The right to inspect comes from the control provisions in each convention: SOLAS regulations I/19, IX/6.2, XI-1/4 and XI-2/9; article 21 of the Load Line Convention; MARPOL articles 5 and 6 and the control regulations in its Annexes; article X of STCW; the AFS and BWM Conventions; and, for labour conditions, the MLC. Ships of States that are not party to a convention get “no more favourable treatment”.

The IMO Procedures for Port State Control harmonise how inspections are done. The version in force today is the Procedures for Port State Control, 2025, resolution A.1206(34), adopted on 3 December 2025, which supersedes resolution A.1185(33). The structure of inspections did not change; the main changes are in the appendices:

• a new appendix 20 on security aspects;
• LRIT: no valid conformance test report, or a master unfamiliar with LRIT procedures, are now explicitly detainable;
• MARPOL Annex VI: missing EEXI, SEEMP or CII documentation, sulphur non-compliance and scrubber or incinerator failures are clearly listed as detainable;
• crew familiarity: inability to operate safety or pollution-prevention systems can support detention even when the hardware works;
• ISM, LRIT, STCW and Annex VI detention items moved into appendix 2, the detention guidelines.

Regional regimes

Port States cooperate through regional agreements: the Paris MoU, Tokyo MOU, Indian Ocean MOU, Mediterranean MoU, Caribbean MOU, Viña del Mar Agreement (Latin America), Abuja MoU (West and Central Africa), Black Sea MOU and Riyadh MoU (Gulf), with the United States Coast Guard running its own programme. Each publishes annual statistics, flag performance lists and concentrated inspection campaign results.

How ships are selected: the Paris MoU example

Under the Paris MoU’s inspection regime, every ship has a ship risk profile, recalculated daily from its type, age, flag, RO, company performance and inspection history: high risk, standard risk or low risk. As implemented in the UK’s 2026 port State control regulations:

“Overriding factors” listed by the MoU trigger inspection regardless of the interval; “unexpected factors” may trigger one at the inspector’s judgement. An expanded inspection is used for high-risk ships, for gas, oil and chemical tankers, bulk carriers and passenger ships over 12 years old, and for ships whose refusal of access is being lifted. A low-risk profile needs, among other things, a flag on the Paris MoU White List that has completed an IMO audit. Ships detained repeatedly are refused access for increasing periods: a first refusal can be lifted after 3 months, a second after 12 months, a third after 24 months, and a further detention after that means permanent exclusion.

The inspection step by step

1. Before boarding: an impression of maintenance from the quay: paintwork, corrosion, pitting, unrepaired damage.
2. Certificates and documents: the PSCO checks the certificates listed in appendix 12 of the Procedures. Electronic certificates are accepted if they meet the IMO guidelines and the ship has the verification instructions.
3. General walk-round: bridge, forecastle, cargo areas, engine room, pilot transfer arrangements, and whether deficiencies from the last PSC inspection were rectified.
4. Clear grounds? If certificates are valid and the general impression is good, the inspection is confined to reported or observed deficiencies. Otherwise the PSCO tells the master the clear grounds, and the master may contact the flag or RO and invite them on board.
5. More detailed inspection: using the relevant appendices, it can include drills, tests of equipment and checks of crew familiarity.
6. Decision and report: each deficiency gets an action (for example, rectify before departure, rectify within a set time, or detention), recorded in the inspection report given to the master.

Typical clear grounds listed in the Procedures include: absence of principal equipment; invalid certificates; documents not on board or falsely maintained; serious hull or structural deterioration; serious deficiencies in safety, pollution-prevention or navigation equipment; master or crew not familiar with essential operations, or such operations not carried out; key crew unable to communicate; false distress alerts not cancelled; and a report or complaint that the ship appears substandard.

When a ship is detained

The detention guidelines in appendix 2 set two tests. Timing: a ship that is unsafe to proceed to sea is detained on the first inspection, however long it will stay in port. Re-inspection: a ship is detained if the deficiencies are serious enough that the PSCO must return to be satisfied they are fixed before it sails.

The PSCO also asks whether, throughout the coming voyage, the ship and crew can:

If any answer is no, the ship should be strongly considered for detention. A combination of less serious deficiencies may also justify it. Appendix 2 then gives a non-exhaustive list of detainable deficiencies under SOLAS, the IBC and IGC Codes, Load Lines, MARPOL, STCW, the ISM Code and other instruments.

Important protections for the ship:

• Accidental damage: no detention order if the damage was reported to the flag or RO, the port State was told before arrival, and remedial action is being taken to its satisfaction.
• Next port: where deficiencies cannot be fixed in the port, the PSCO may allow the ship to proceed to another port under conditions, notifying that port and the flag.
• Appeal: the company may appeal, but the appeal does not suspend the detention.
• Undue delay: all efforts should be made to avoid undue detention or delay; a ship unduly detained is entitled to compensation.

Concentrated inspection campaigns

Each year the Paris and Tokyo MoUs run a joint concentrated inspection campaign (CIC) on one subject, from 1 September to 30 November, using a questionnaire alongside the normal inspection. Recent topics: fire safety (2023), crew wages and seafarers’ employment agreements (2024), ballast water management (2025) and cargo securing (2026). In the 2025 ballast water CIC the Tokyo MOU carried out 6,930 CIC inspections; 184 of those ships were detained (2.66%), 30 of them for CIC-related deficiencies, mostly the operation of the ballast water management system.

Preparing for PSC