15 reference articles
Maritime intelligence guides
Long-form reference articles on container shipping geography, AIS data, IMO classifications, port operations, and the public datasets behind PortWatch.
How AIS vessel tracking works (and what its limits are)
An end-to-end walkthrough of the Automatic Identification System — what AIS broadcasts contain, who receives them, how they get aggregated into the public maps you see online, and where the system breaks down.
What is an IMO number, and why does it matter?
The seven-digit identifier issued by the International Maritime Organization that follows a vessel for the rest of its working life — and the difference between IMO numbers, MMSI numbers, and call signs.
Understanding UN/LOCODE — the world’s port identifier system
The five-character UN/LOCODE is the lingua franca of international shipping documentation. This guide explains how the system works, who maintains it, and how to read a code.
Container ship size classes — Feeder, Panamax, Neo-Panamax, ULCV
The vocabulary of container vessel sizes — Feeder, Feedermax, Panamax, Post-Panamax, New Panamax / Neo-Panamax, ULCV — and the canal and port constraints that define each tier.
Dry bulk carrier classes — Handysize, Supramax, Panamax, Capesize
The size classification of dry bulk carriers, from Handysize through Capesize and VLOC, and what each size class is typically used for.
Tanker vessel types — Crude, Product, Chemical, LNG, LPG
A guide to the distinct families of tanker tonnage, what each carries, and the different terminal infrastructure each requires.
Ro-Ro shipping and Pure Car & Truck Carriers (PCTC)
How ro-ro vessels differ from container ships, why automotive supply chains rely on them, and what to look for in port calls of car carriers.
MMSI vs IMO vs call sign — the three vessel identifiers
A short reference page on the three identifiers attached to every commercial vessel and how to use them in research.
How to track cargo ship arrivals at any port
A practical guide to using PortWatch and complementary tools to find out which cargo vessels are due at any given port and when.
Querying Wikidata for ports — a SPARQL cookbook
Worked examples of SPARQL queries against the Wikidata endpoint to retrieve port data, with notes on common pitfalls.
What is a bill of lading, and how do UN/LOCODEs appear on it?
An overview of the bill of lading — the central document of international ocean shipping — with focus on how port identifiers appear in the load and discharge fields.
The world’s busiest container ports by annual throughput
An overview of the top global container ports by TEU throughput and what their dominance reflects about world trade patterns.
LNG export terminals around the world
A geographic survey of the world’s major LNG export terminals — where the gas is liquefied, who buys it, and how the trade has grown since 2000.
How freight vessel ETAs are calculated and why they slip
ETAs reported in AIS data and on shipping line schedules are estimates that change throughout a voyage. This guide explains where the numbers come from and what makes them move.
Port state control — the inspection regime that polices global shipping
An overview of the regional port state control agreements (Paris MoU, Tokyo MoU, USCG and others) that inspect foreign vessels visiting their ports.