A merchant ship generally cannot trade without protection and indemnity cover. Ports require it, coastal states require it, and the reason is pollution: P&I is the insurance that answers the question of who pays for a spill.
The established P&I market consists of mutual associations with published rules, published membership and known reinsurance arrangements. Cover from one of them can be confirmed by asking. Opaque marine insurance is the practice of satisfying the requirement with something that cannot.
How it works
The requirement is documentary. A vessel presents a certificate of entry or a blue card showing it is covered, and the port or authority accepts it. What is verified in practice is that a document exists, not that a claim would be paid.
Three patterns appear in the published material.
The unidentifiable insurer. Cover is written by an entity whose corporate existence, capitalisation and reinsurance cannot be established. It may be registered somewhere and have a website, and there may be no way to determine whether it has ever paid a claim.
Cover that is denied. A certificate is presented naming a real insurer for a period or voyage that the insurer does not confirm. This is the maritime equivalent of an impersonated end user.
Cover that lapses in practice. A policy exists but has been rendered ineffective — by non- disclosure of the trade actually undertaken, by exclusions that apply to that trade, or by non-payment — while the certificate remains in circulation.
The document that addresses this directly is the 2023 Price Cap Coalition advisory, not the 2020 global advisory. Its first recommendation is to require appropriately capitalised protection and indemnity cover, and it states the problem precisely: the shadow trade involves ships that may rely on unknown, untested, sporadic or fraudulent insurance1 . It asks industry to require continuous and appropriate cover for the entirety of a voyage2 , and where an insurer is unfamiliar, to review its financial soundness, track record, regulatory record and ownership structure2 .
The 2020 advisory’s contribution is narrower and worth stating accurately: it suggests that a party asked to insure or finance a vessel request documentation on the vessel’s ultimate beneficial owner3 . That is an ownership check performed by an insurer, not a check on the insurer.
Why it travels with the other maritime techniques
Insurance sits at the junction of every other maritime indicator. Recognised insurers underwrite by reference to the vessel’s age, condition, ownership, flag and trade, and they decline vessels whose answers to those questions are unsatisfactory.
A vessel that loses mainstream cover therefore has to find something else, and the something else is typically found alongside a change of flag, a change of registered owner and a change in trading pattern. The insurance is not the cause of the sequence; it is the point at which the sequence becomes visible to a port state that would otherwise have no view of the vessel’s ownership at all.
How it is caught
Direct confirmation. The named insurer is asked whether cover exists for the period stated. The established clubs answer this routinely and the answer is dispositive, which is why the advisory frames the requirement as continuous cover for the whole voyage4 rather than a certificate held at one moment.
Solvency and existence checks. Where an insurer is unfamiliar, the advisory’s own list is the starting point: financial soundness, track record, regulatory record, ownership structure2 . A related signal is a vessel that has shifted away from an industry- standard classification society5 , since classification is what insurers and port states rely on to judge seaworthiness.
Correlation with the rest of the picture. Unverifiable cover appearing at the same moment as a flag change and an ownership change is a sequence, and the sequence is the finding.
Port state action. Port state control inspection is where the certificate meets a person entitled to question it, and detentions on the basis of unverifiable cover are recorded. Those per-vessel inspection records are kept on the sister vessels site.
The signals travel together
The Multilateral Sanctions Monitoring Team, reporting in 2025 on vessels carrying arms between North Korea and Russia, found that they lacked recorded protection and indemnity cover, had operated with tracking systems off for months at a time, and had no recorded inspections for three years6 . Its summary of that combination is the phrase the industry uses: this behaviour is commonly described as deceptive shipping practices7 .
Three independent absences — no verifiable insurer, no transponder, no inspection record — on the same hulls. That is the clustering described above, observed rather than predicted.