Ship-to-Ship Transfer (STS)
The transfer of cargo directly between two vessels moored alongside, often at anchor or offshore rather than at a terminal.
- Category
- Cargo and Operations
- Abbreviation
- STS
- Last reviewed
How it works
A ship-to-ship (STS) transfer moves cargo (typically crude, products, LNG or LPG) from one vessel to another lying alongside, using fenders and hoses, instead of going through a shore terminal. It is used for lightering large tankers into smaller ones, for offshore loading, and to consolidate or break bulk parcels.
STS is a legitimate, routine operation, but it is also a recurring tactic for obscuring the origin of sanctioned or "dark-fleet" cargoes, especially when paired with AIS gaps, so STS activity is closely watched in compliance screening.
Where it shows up on The Maritime
Also known as: STS, ship to ship transfer, lightering.
Related terms
Dark Fleet
The population of ageing, opaquely owned and often uninsured tankers that move sanctioned oil while disguising their movements.
Automatic Identification System (AIS)
A VHF transponder system that broadcasts a ship’s identity, position, course and speed for collision avoidance and tracking.
Sanctions
Government measures restricting trade or dealings with designated entities, vessels, cargoes or jurisdictions.
Bill of Lading (B/L)
The document that acts as receipt for cargo, evidence of the contract of carriage, and (when negotiable) document of title.
More cargo and operations terms
A plain-English reference definition: our own explanation of a standard shipping concept, not a licensed source or legal advice. See the full glossary or the broader maritime dictionary.
Last reviewed: .