Tracking Sanctions Evasion & Dark Tankers at Sea

MMSI changes are a core flag-hopping / identity-laundering signal: a vessel adopting a new maritime radio identity, often alongside a flag or name change, to break the trail between its past and current activity. It's a classic sanctions-evasion tactic: a tanker already flagged or designated under one identity re-emerges with a new MMSI (and often a new flag) to trade as if it were a different, "clean" vessel, resetting its risk profile in commercial and regulatory systems that key off self-reported identifiers rather than the permanent IMO number.

A fraudulent flagged tanker falsely claims to be flagged by an international ship registry that is not recognized by that country's maritime administration. This is distinct from tankers that may falsely claim to be flagged by legitimate open registries but whose maritime administration confirm that ship is not registered with them. This is a separate phenomenon and not included in this count.

The pace of sanctions designation growth has accelerated since 2023 when the EU and UK changed their regulations so that they could designate or proscribe a vessel by its IMO number, in a similar way to the US Office of Foreign Asset Control (OFAC). Each line tracks the number of distinct tankers first designated on or after 1 September 2023 by USA, EU or UK.

Windward's designation outlines which sanctions compliance program a vessel is affiliated with. A vessel already carrying a formal sanctions designation is tagged to that program directly. Where a vessel isn't formally designated, Windward still assigns it a risk based on its behavior (the pattern of activity itself) and associates it with the country that behavior is linked to. A single vessel can be cited under more than one program at once, so citations exceed the number of vessels: this is a count of citations, not a headcount of vessels.

GNSS spoofing occurs when a vessel broadcasts a false or altered position to hide its true location and activity. It's one of the fastest-growing deceptive shipping practices, clustering around chokepoints and conflict zones. Tracking it matters because it's often the first signal of a vessel preparing to circumvent sanctions, conduct an unauthorised or subterfuge ship-to-ship transfer, or operate outside the reach of maritime law.

"Going dark" is when a vessel switches off or loses AIS transmission for an extended stretch, distinct from GNSS spoofing (broadcasting a false position) since there's no signal at all. Clusters of dark activity concentrate where vessels have the most to hide: areas where subterfuge ship-to-ship transfers are known to occur, loitering near sanctioned ports, or transiting waters they'd rather not be tracked in. Shown in heatmap by default to surface the hubs; switch to Scatter for individual episodes.