Satellite view of two vessels moored alongside each other in a ship-to-ship transfer detected on the Theia map

Maritime Capability

Ship-to-Ship Transfer Detection

Detect vessel proximity events used to transfer cargo covertly, evade sanctions, or obscure origin, from satellite, whether or not AIS is broadcasting.

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Explore the Platform

The Problem

When cargo changes hands at sea.

Ship-to-ship transfers move cargo, typically crude oil or refined products, between vessels at sea without docking. Some operations are legitimate, but the practice has become the primary mechanism for sanctions evasion in maritime trade.

A sanctioned vessel transfers its cargo to a “clean” vessel at sea, which then proceeds to port as if the cargo came from a non-sanctioned source. The participants typically go dark or spoof their positions. When one or both disable AIS, conventional platforms see nothing.

Ship-to-ship transfer near a refinery mapped by satellite

How Theia Detects

Detection that works regardless of AIS status.

01 / Optical

Optical STS Detection

Satellite imagery identifies vessel proximity events: two vessels alongside or in close formation, regardless of AIS status.

02 / Correlate

AIS-Correlated Detection

When both vessels broadcast AIS, Theia correlates position data to identify the event, its timing, duration, and participants.

03 / Dark

Dark STS Detection

When one or both vessels disable AIS during a transfer, satellite-based detection identifies the event through imagery alone.

04 / Classify

Transfer Classification

Theia separates legitimate bunkering from potentially illicit transfers using location, participant profiles, and sanctions status.

By the Numbers

STS activity, quantified.

143,401

Optical STS events detected

331,227

AIS STS events detected

Global

Coverage of STS hotspots and open-ocean transfer zones

Use Cases

Where STS detection matters.

Sanctions Enforcement

Detect and document illicit cargo transfers used to circumvent oil sanctions, price caps, and trade restrictions.

Insurance Claims Investigation

Identify STS events that affect cargo provenance, coverage validity, or claims integrity.

Commodity Trading Verification

Verify cargo origin and transfer history for crude oil, LNG, and refined product trades.

Environmental Monitoring

Detect illegal bunkering and at-sea fuel transfers that pose environmental risk.

Related Capabilities

STS rarely happens in isolation.

Dark Fleet

Dark Vessel Detection

Many STS operations involve vessels that have gone dark.

Signal Integrity

AIS Spoofing Detection

Spoofing is often used to disguise STS activity.

Identity

Vessel Attribution

Put a name to each participant in a covert transfer.

Ship-to-ship transfers connect directly to the deception tactics Theia tracks across the maritime domain.

Get Started

Monitor STS activity in real time.

Request a demonstration and see how Theia detects transfers that AIS-dependent platforms miss.

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