AIS Vessel Tracking Signals

AIS (Automatic Identification System) is a maritime safety transponder that most large commercial ships broadcast continuously, reporting their position, speed and heading for collision avoidance. Satellite and coastal receivers pick this up globally, and data vendors aggregate it into a live feed of where the world's tankers, bulk carriers and container ships actually are — which turns out to be useful for predicting commodity flows before they show up in official statistics.

The core signal is simple: if crude tankers are visibly loading at a major export terminal and heading toward a specific region, that region's crude imports are going to rise weeks before the customs data confirms it. Traders use draft changes (how low a ship sits in the water, indicating cargo weight), port dwell times, and route changes to infer oil, iron ore, or grain shipments in near-real time, well ahead of officially reported trade statistics that lag by weeks or months.

The data has real gaps worth knowing before relying on it: AIS transponders can be legally turned off or spoofed (notably by vessels wanting to obscure sanctioned trade), coverage is worse in areas with sparse satellite passes, and inferring cargo type and volume from a ship's movement alone (rather than its actual bill of lading) is an estimate, not a direct measurement.