Maritime glossary · Going Dark
AIS Gap
A period when a vessel stops transmitting AIS, sometimes innocent, sometimes a sign of evasion.
Definition
An AIS gap is a stretch of time when a ship’s AIS signal disappears. It can be innocent, such as poor satellite coverage in a remote area or genuine equipment failure, or deliberate, when a crew switches off the transponder to hide a position. Going dark near sanctioned load ports or before a ship-to-ship transfer is a recognised evasion pattern. The length, location, and timing of a gap are what separate a routine dropout from a red flag.
How Vessel Hunter uses AIS Gap
Vessel Hunter records AIS gaps against each hull and weighs them in the risk score, so an unexplained dark period stands out.
Related terms
- AISAutomatic Identification System
The VHF radio system every commercial vessel uses to broadcast its position, course, and identity.
- AIS Spoofing
The transmission of false AIS data to disguise a vessel’s true position, identity, or movements.
- Ship-to-Ship TransferSTS
The transfer of cargo directly between two vessels at sea, routine in trade but also used to obscure origin.
- Sanctioned Vessel
A ship designated under a sanctions regime, or trading in breach of one, which is barred from much of the market.
The bigger picture
AIS Gap is one piece of the commercial maritime picture Vessel Hunter pulls together for shipyards, suppliers, service providers, and port agents. Every vessel record bundles AIS, ownership, inspections, dry-dock history, casualty record, classification status, and a verified contact for the operator decision-maker behind the ship, so the team that reaches out first wins the work.
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