The register, and what AIS adds to it

What is recorded against each vessel, and how far the movement data actually reaches.

A ship has several identities at once. The IMO number is welded to the hull and never changes. The MMSI is a radio licence and changes when the vessel changes flag. The name changes on sale. A register that keys on the wrong one of those will quietly merge two ships or split one in half.

This register keys on the IMO number. Names and MMSIs are recorded against it as they are observed, which is why searching an old name often still works, and why the address of a vessel page carries both the name and the number.

What is recorded

Emissions come from the EU MRV returns and cover 24,129 vessels. Particulars come from Wikidata. Sanctions listings come from the OFAC register, inspections from the United States Coast Guard. Each vessel page names its own sources at the bottom.

What AIS adds, and where it stops

Automatic Identification System transponders broadcast a vessel's position continuously. The Norwegian Coastal Administration publishes its recording of those broadcasts as open data, and that recording is the movement layer here.

Two limits matter, and neither is small. It is regional. The extract covers Norwegian waters, so a ship trading exclusively between Singapore and Rotterdam will show nothing at all. It is historical. The window runs from July 2025 to July 2026; this is not a live tracking service and is not intended to become one.

The raw extract also carries no identity: it records an MMSI and a position, with no name, IMO number or ship type attached. Linking a track to a hull therefore depends on a separate identity source, and where that link is ambiguous, no track is shown rather than a track on the wrong ship.

Of the 24,129 vessels with a page, 1,228 have been observed in that window and carry a movement section. The rest have not been seen in Norwegian waters, which says nothing whatever about where else they sailed.

The company side: LEI

Every identifier here describes a hull. None of them describes a company. The equivalent on the corporate side is the Legal Entity Identifier, a twenty character code issued under ISO 17442 that identifies the legal person rather than the asset, and which is what financial regulators use to know who is actually party to a transaction.

The two systems answer different questions and neither substitutes for the other. A vessel keeps its IMO number through sale; the operating company keeps its LEI through renaming and reflagging of its fleet. Where an operator page here names a company, it links to a search in the LEI register so the corporate identity can be resolved properly, with jurisdiction, legal form and parent structure.

We do not attempt to match operator names to specific legal entities automatically. Tested against the GLEIF name index, shipping company names are ambiguous enough that automatic matching returns the wrong subsidiary or nothing at all, and a confident wrong answer about who operates a ship is worse than a search box.

Reading a gap

An empty month in a vessel's activity chart means the ship was not recorded in the covered area during that month. It is not evidence that the vessel was idle, and it is certainly not evidence that a transponder was switched off. Both of those are real phenomena worth reporting on, and neither can be established from a regional extract.