When a ship “goes grey,” it doesn’t disappear.
It slips into a world where names change and paperwork turns to smoke. Yet the people aboard still wake to the same seas, navigating under rules that no longer protect them.
Shadow-fleet tactics are a market response to sanctions, the ships are a symptom, not the whole story.
“Shadow-fleet” tankers span a wide range of ages and types, from older hulls sold into opaque ownership chains to newly built tankers and are often reflagged, renamed and run mid-ocean ship-to-ship transfers (STS) and AIS dark periods to move Russian crude outside Western channels and the G7 price cap.
The G7 price cap is not a ban on buyers, it is a limit on the price at which coalition-based insurers, shippers and financial services may support Russian-origin cargoes. The cap works by restricting services (insurance, broking, financing), not by outlawing purchase and when the rails are cut, trade often shifts into harder-to-verify channels.
European states have intensified inspections and seizures for three overlapping reasons:
(1) these ships are used to evade sanctions and price caps,
(2) investigations link some to unsafe operations and pollution, and
(3) intelligence alleges a few have been used for hostile activities, including reconnaissance and drone launches.
Those pressures give coastal states both legal and political grounds to intervene.
UNCLOS’s rule of innocent passage still applies, but it does not protect conduct “prejudicial to peace, good order or security,” nor does it bar lawful port-state safety inspections when domestic law is triggered (UNCLOS Arts. 17–19).
What actually happens at sea (the short technical picture)
When western banks, brokers and insurers withdraw from a cargo, the entire commercial chain collapses.
Normally, the buyer’s bank issues a letter of credit and the ship sails with Hull & Machinery (H&M) insurance and Protection & Indemnity (P&I) cover for crew, pollution and other third-party claims. Ports, bunker suppliers and charterers rely on those guarantees before they provide services.
Remove those warranties and operators fall back on a practical playbook ie. split the paperwork with STS transfers, create “dark” windows by switching off or spoofing AIS, rename hulls, rotate managers and use shadow registries or present alternative, hard-to-verify insurance papers. Industry trackers and blacklists document the pattern across vessels of many ages.
TankerTrackers’ public list counted 1,271 blacklisted tankers (9 Oct 2025), including recent builds, showing that both old and new ships can be drawn into the network.
Three Real Cases – Safety, Security, and the Grey Between
Boracay (ex-Pushpa) French boarding and drone allegation
In early October 2025 French forces boarded a vessel reported as the Boracay near Saint-Nazaire after tracking it as part of a list of suspect ships. Two people were detained amid claims of nearby drone activity. What began as a commercial inspection turned into a national-security probe.
Eventin – Germany seizes an adrift tanker
IIn January 2025 German authorities secured and seized the Panama-flagged Eventin found adrift off Rügen. Officials called it a navigational and environmental hazard linked to sanctioned traffic patterns, a safety intervention that became a sanctions case.
Eagle S – Subsea cable damage and legal complexity
The Eagle S was detained after reports that its anchor damaged undersea cables in the Gulf of Finland (Dec 2024). Finnish prosecutors charged senior officers, but courts later dismissed parts of the case showing how infrastructure incidents can spiral into jurisdictional traps for crews.
These cases matters because together they show the full spectrum of security allegations (Boracay), safety risk (Eventin), and infrastructure impact with messy prosecutions (Eagle S). Each case justifies vigilance, none justifies turning every opaque ship into a default criminal.
The human cost
When headlines fade, those who pay the price are not owners, they are crews left aboard.
- Detention and loss of wages. Crews can be held aboard for weeks or months while authorities sort ownership, manifests and legal claims, repatriation and wages are often delayed.
- Criminal or civil investigations. Masters and senior officers can be interviewed, detained for questioning, or face criminal/civil charges if paperwork suggests deliberate deception, sanctions evasion, pollution, or infrastructure damage, even where intent is disputed. Legal proceedings are often slow and jurisdictionally complex. (See: Eagle S; Boracay reporting.)
- Insurance gaps and owner abandonment. IInsurers deny claims if forgery or sanction-busting is alleged; owners walk away from stranded ships.
- Direct safety exposure. Older, poorly maintained tankers pose increased physical risks like leaks, fires, structural failure particularly where operators cut corners to avoid scrutiny. This is a seafarer safety issue distinct from legal risk.
Passports and seafarer documents are often retained & hardship is immediate.
BIMCO has introduced contractual clauses and guidance, but these remain small steps compared with the scale of harm.
Why policymakers feel compelled to act
Estimates vary by data and definition. Brookings identified about 343 tankers it classifies in one “shadow-fleet” dataset (Apr 2025) while TankerTrackers’ continuously updated blacklist lists a broader 1,271 vessels (9 Oct 2025).
Differences reflect methodology and thresholds but both datasets show the activity is not anecdotal and that enforcement faces a shipping-scale problem. Port State Control activity has risen accordingly: the Paris MoU reported a 2024 detention rate of 4.03%, up from 3.81% in 2023.
The Captain’s Priorities. Always seaworthiness, crew safety, cargo integrity
If a ship’s class, certificates, safety and firefighting systems, or cargo system pose an immediate danger, authorities must act. PSC, class surveys and SIRE inspections exist for that very reason.
But there is a critical distinctionbetween technical deficiency and commercial opacity. Painting over a funnel, a non-Western insurer, or a name change are red flags, they merit investigation but they are not proof of criminality.
The Root Cause is not criminality at sea, but geopolitics
Put plainly, the shadow fleet is a symptom, not the disease.
Sanctions, the price cap, banking restrictions and insurer withdrawals altered the economics of moving certain cargoes. When the trusted service rails that let tankers call ports and receive bunkers and repairs are cut, commercial actors find alternative routes.
If buyers in India, China or elsewhere insist on importing, they can but only if they accept alternative payment rails, insurers and port arrangements. Criminalising the vessels on which such choices are imposed is not a durable answer.
Technically, these are sanctions imposed by one part of the world, not by international law.
What is illegal under G7 or EU measures can remain perfectly lawful for others, including major importers in Asia and the Middle East.
This disconnect fuels the grey market, a trade that exists not because the sea has changed, but because law and legitimacy now depend on geography.
What a sensible policy should do
- Target the enablers, not only ships. Sanction and prosecute brokers, insurers and payment intermediaries who enable concealment.
- Fast interoperable insurance verification. Build a technical mechanism for ports to verify non-Western insurer solvency quickly and reliably.
- Neutral third-party inspection hubs. Acceptable independent inspection at agreed hubs would let buyers prove cargo origin without mid-ocean secrecy.
- Require admissible technical evidence for security interdictions. Intelligence must be paired with radar, imagery, telemetry or debris that will hold up in court. (See: Boracay.)
- Codify crew protections. Any detention protocol should mandate immediate welfare, consular/legal access and a presumption of non-complicity for seafarers unless evidence shows otherwise.
Common Objections and Why They Miss the Point
- “You’re allowing evasion.”
No. Prosecute culpable owners and intermediaries. Removing commercial incentives is more effective than only detaining ships. - “If a ship hides, it’s suspicious.”
Hiding is a red flag and must be investigated, circumstantial signs (paint, non-Western insurer) are not proof and must lead to evidence-based action. - “Security concerns justify immediate interdiction.”
If credible technical evidence exists, act immediately but if not, be proportionate to avoid destroying livelihoods on suspicion alone.
Judge every ship first by three checks ie. seaworthiness, crew safety and cargo integrity – then by the politics.
Change market incentives, target demand and intermediaries, create verifiable alternatives, and detain only where admissible technical evidence exists. Protect crews.
Do that, and the sea will look less grey because the market and the law finally line up.
References
Brookings, The Shadow Fleet (dataset and analysis), 2025 (scale and sanctions data).
Windward, Illuminating Russia’s Shadow Fleet, 2024–2025 (operational indicators and AIS-based analysis).
Reuters, reporting on Boracay, Eventin, Eagle S, and alternative payment rails, 2024–2025 (live cases and timeline).
Paris Memorandum of Understanding on Port State Control, Annual Report 2024, 2025 (detention statistics).
C4ADS, Unmasked: Vessel Identity Laundering, 2021 (identity laundering playbook).
OCIMF, SIRE 2.0 programme and guidance, 2023–2024 (inspection standards and operational risk).
BIMCO, Russian oil price-cap clause and sanctions guidance, 2023–2025 (contractual tools and time-charter wording).
United Nations, UNCLOS Articles 17–19 (innocent passage) (legal baseline).
London Market Association, guidance on sanctions and insurance market practice, 2023–2024 (insurance and reinsurance context).
Thomson Reuters Foundation, reporting on seafarer welfare and abandonment, 2024–2025 (human-cost evidence).
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