The phrase “shadow fleet” gets used constantly in coverage of Russian oil sanctions, Iranian shipping, and now the fight over the Strait of Hormuz. It sounds sinister and specific. What it actually describes is a set of practical workarounds — ordinary tankers made deliberately hard to identify — that undermine the ordinary system by which the maritime industry is regulated and insured.

Here is what makes a fleet a “shadow” fleet, why the workarounds work, and why breaking them is harder than it looks.

What normally holds shipping accountable

Under the ordinary system, a merchant vessel has a flag state (the country in whose registry it is listed), a beneficial owner, an operator, an insurer, and a classification society that certifies its seaworthiness. Each of those parties is subject to law and to commercial pressure. If a Greek-owned tanker under a Norwegian flag, insured by a major P&I club and classed by Lloyd’s Register, spills oil off Denmark, there are half a dozen phone numbers a Danish official can call the same day.

The shadow fleet exists to remove those phone numbers.

The workarounds

Flag hopping. Sanctioned or high-risk ships change their flag frequently, moving between “open registries” — states that will register almost any vessel for a fee. Common shadow-fleet flags include Panama, Liberia, the Marshall Islands, Cameroon, Gabon and San Marino. The paperwork changes; the ship does not.

Shell ownership. Beneficial ownership is routed through shell companies in permissive jurisdictions, often two or three deep, so that identifying who actually profits from a voyage requires investigative work no regulator has time for at scale.

Alternative insurance. The major maritime insurers — the P&I clubs that cover pollution and liability — will not insure sanctioned cargoes. Shadow-fleet vessels use domestic Russian or Iranian insurers instead, whose claims-paying capacity in a large casualty is untested and probably inadequate.

AIS manipulation. Every commercial ship broadcasts its position via the Automatic Identification System. Shadow-fleet vessels routinely switch AIS off when they do not want to be tracked, and sometimes broadcast false positions to disguise where they have been. The tanker at the centre of the current Arabian Sea oil spill had done exactly this.

Ship-to-ship transfers. Cargo is moved at sea, often in international waters, between a sanctioned vessel and a “clean” one, so the eventual delivery vessel can arrive without an obvious paper trail back to origin. This is how much sanctioned Russian and Iranian crude actually reaches its buyers.

Why breaking it is difficult

The shadow fleet is not a single organisation. It is an emergent structure — hundreds of ageing vessels, dozens of shell companies, several sympathetic flag registries — held together by the profit margin between sanctioned oil and non-sanctioned oil. Removing any one component does not collapse the system; another substitutes for it.

Ships identified and blacklisted change names and flags. Registries that lose international standing are replaced by more obscure ones. Insurance that gets sanctioned is replaced by domestic providers. Even seizure — the mechanism the EU has recently authorised, at the centre of Putin’s threat to seize European ships in return — captures individual vessels while the fleet as a whole continues operating.

The pollution problem

The single most concrete cost of the shadow fleet is safety. These ships are older on average, less well maintained, insured by parties who may not pay out, and crewed under contracts that do not always meet international standards. When one of them has an accident — a fire, a collision, a grounding — the compensation and cleanup framework that ordinarily kicks in either does not engage or is refused engagement.

The Arabian Sea slick is one example. The Baltic and North Sea have seen several suspicious incidents involving anchors dragging across seabed cables. None of these events is what sanctions were designed to prevent. All of them are what a shadow fleet, by design, makes more likely.

Sources

Kpler ship-tracking data and analysis; European Council sanctions documentation; International Maritime Organization guidance on flag state responsibility; industry reporting by TradeWinds, Lloyd’s List and Reuters.