Inspections

Port state control and detentions

Published 20 August 2026 · updated 17 October 2026

A ship that is detained cannot do its job. Detention is not a simple off-hire period (time when the charterer stops paying hire). The ship is held at the berth, not sailing, while its laycan (the agreed loading window) runs out. Port state control is the only regular, public, worldwide record of how well a ship is kept. That makes it the cheapest information a broker has about a ship they have never seen.

What port state control is

The flag state (the country where the ship is registered) is responsible for the ship’s condition. Flag states differ greatly in how seriously they take this, and some have almost no inspectors. Port state control is the second check: the country where the ship calls inspects foreign ships in its ports. It checks them against the international conventions the ship is certified under: SOLAS, MARPOL, Load Lines, STCW and the Maritime Labour Convention. It also checks that the certificates on board describe the ship the inspector is standing on.

It is not a survey, and it is not class (the technical standard a classification society sets). A PSC officer looks for proof that the safety management system really works: whether the fire dampers close, whether the lifeboat engine starts, whether the oil record book matches the equipment, and whether the crew can find the muster list and read it. Most findings are small, but a few of them stop the ship.

The regional MoUs

Port state control is organised into regional Memoranda of Understanding (MoUs). In each one, a group of coastal states agrees a common inspection system and shares results:

• Paris MoU, Europe and the North Atlantic.
• Tokyo MoU, Asia and the Pacific.
• Indian Ocean MoU, Mediterranean MoU, Black Sea MoU, Riyadh MoU for the Gulf states.
• Viña del Mar Agreement for Latin America, Abuja MoU for West and Central Africa, Caribbean MoU.

The United States is outside all of them, and the US Coast Guard runs its own programme. This matters when you compare numbers, and it is the first reason not to read the table below as a ranking.

The important business point is that the regions share information. A detention in one region is visible in the others, and it counts towards the published performance of the flag state and the class society. Under the Paris MoU, repeated detentions can lead to a ban from the whole region. A bad inspection in Rotterdam is seen in the other regions too. If an owner tells you otherwise, that has not been true for decades.

What an inspection produces

An inspection produces a report that lists deficiencies (faults). Each fault has a code and is grouped by area: fire safety, life-saving equipment, structure, pollution prevention, certificates and documents, ISM, and working and living conditions. Each fault also has an action code. These range from fix at the next port, through fix before leaving, up to detainable.

Detention is the serious result. The ship cannot sail until the faults are fixed and, usually, inspected again. A detention can last one day or several weeks, depending on whether the fix needs a spare part, a class surveyor or a shipyard. An inspection with zero faults is common, and a few minor faults is the normal state of a working ship. On its own, that says almost nothing.

What the record actually looks like

Neptune Atlas holds an inspection history from a data vendor. It covers 364,256 inspections across 44,764 hulls, from 22 March 2017 to 21 August 2026. Across that whole set:

By authority, and how not to read it

These are the twelve authorities with the most inspections on file, and what each one recorded.

This table does not rank how strict each country is. It shows what each authority recorded and what reached this dataset. At least three things affect a row more than strictness does. The first is traffic mix. A port that mostly sees young, well-run ships will detain fewer ships than a port that sees forty-year-old coasters, whatever its inspectors are like. The second is targeting. An authority that inspects only the ships its risk model flags will show a higher rate than one that inspects widely, because it divides by a different number. The third is reporting practice. What counts as a detention, what is filed and what is published all vary.

The narrow spread is the important result. Every authority above is between about two and four per cent, which is far too close to be measuring twelve different inspection cultures. An earlier extract of the same dataset showed the same authorities ranging from under one per cent to over six. The vendor has since corrected them. Neither version measures strictness. Both measure what a commercial data supplier could collect and standardise. That the numbers moved this much between two downloads is the strongest reason not to read a ranking into them.

Use the table to understand what your data contains. Do not use it to decide that a call in one country is riskier than a call in another.

Targeting: why some ships get inspected constantly

Nobody inspects every ship at every call. The main systems give each ship a risk profile, which decides how often and how closely it is checked. The inputs are broadly the same across MoUs:

• Age and type. Older ships and higher-risk types are checked more.
• Flag. The flag state’s own detention record is published as a list. It feeds directly into the profile of every ship under that flag.
• Recognised organisation. The class society’s record feeds in the same way.
• Company. The record of the ISM manager (the company responsible for safety management) across its whole fleet. This is one of several reasons to identify the technical manager.
• The ship’s own history. Deficiencies and detentions over a recent rolling period.

This creates a loop that works both ways. A clean record lowers the profile, which means fewer inspections, further apart, and fewer chances to find something. A detention raises the profile, and the ship is then checked more closely for years. The record therefore measures partly the ship and partly how much attention it has had, and a ship with many inspections is not automatically a worse ship.

How to read a history

A pattern matters more than one incident. One detention is an event. A detention every couple of years, in different regions, with different inspectors, is a way of working. Do not reject a ship for one bad inspection, and do not excuse a series of them as bad luck.

Recent records matter more than old ones. Ships change owners, managers and crews, so a detention eight years ago, under a manager who no longer holds the DOC (the ISM safety certificate), describes a company that no longer runs the ship. What has happened since the last change of manager is what tells you about the future.

The same kind of fault again. The most useful sign is the same category coming back: fire safety at three calls in a row, or ISM findings that keep returning after they were supposedly closed. A repeated category means the safety management system is not correcting itself, and that points to a habit of poor maintenance, not an accident.

Read the deficiencies, not only the detentions. Detention is so rare that most ships have none, and the average inspection records 4.51 deficiencies, so the useful detail is in the list of deficiencies, not in the detention count.

Most attempts to check a ship's record fail on this last point. The IMO number is permanent and the name is not, so a PSC record can only be trusted when it is linked by IMO number. The IMO number checker confirms that a number is valid before you search on it. A ship with a poor record, a new name and a new flag looks like a ship with a clean record in any system that matches on the name. A clean record is often the whole reason for the change.

References

• IMO, Port State Control. The regional Memoranda of Understanding and the United States programme. imo.org
• Paris MoU, Annual Report 2025. parismou.org
• Paris MoU, Performance Lists, the white, grey and black list. parismou.org
• Paris MoU, Current Banning. Ships refused access to the whole region. parismou.org
• Tokyo MoU, New Inspection Regime. The ship risk profile and how targeting is calculated. tokyo-mou.org
• Tokyo MoU, Annual Report on Port State Control in the Asia-Pacific Region 2024. tokyo-mou.org

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