Tankers on AIS

Which AIS codes count as tankers

AIS codes 80 to 89 cover every ship built to carry liquid in bulk: crude oil, refined products, chemicals, vegetable oils and liquefied gas. As with cargo ships, the tens digit is the family and the units digit is a dangerous-goods qualifier: 80 is a tanker with no declaration, 81 to 84 declare hazardous-cargo categories A to D, 89 means "no additional information".

There is no separate code for an LNG carrier, an LPG carrier or a chemical tanker. The name, IMO number and dimensions tell you which kind of tanker you are looking at; the type code does not.

How to spot one on the live map

Tankers keep to the same lanes as cargo ships but gather in different places: oil terminals, refinery jetties, offshore loading buoys and ship-to-ship transfer areas, where two tankers sit side by side at sea.

Large crude carriers are slow and deep. A tanker with navigational status 4, constrained by her draught, is one that cannot leave a deep-water channel to give way, and a laden VLCC is the most common user of that status.

Open the live map → Positions there are the latest known, with their source and age.

Who has to carry AIS

Under SOLAS Chapter V, Regulation 19, AIS is mandatory on ships of 300 gross tonnage and upwards on international voyages, cargo ships of 500 gross tonnage and upwards on domestic voyages, and all passenger ships regardless of size. Those ships fit a Class A transponder, which reports navigational status and repeats its position every 2 to 10 seconds while under way.

The navigational status to expect

Ship type says what a vessel is; navigational status says what it claims to be doing. These are the statuses that normally go with tankers:

• 0 · Under way using engine
• 1 · At anchor
• 5 · Moored
• 4 · Constrained by draught

Where the type code misleads

The qualifier digit is as unreliable on tankers as on cargo ships. An 80 does not mean the tanker is empty, and the laden or ballast state is better read from the reported draught than from the type code.

Tankers are among the vessels most often discussed when AIS goes quiet. Most gaps on this site have a dull cause — the ship has sailed out of range of every shore receiver we read. Our guide to why ships go dark covers how to tell the difference.

Lights and shapes

No tanker-specific lights. A tanker constrained by her draught may show three all-round red lights in a vertical line, or a cylinder by day, under Rule 28.

Summary for orientation only. The COLREGs text is the authority; this site is not a navigation reference.

Questions

What AIS ship type is an oil tanker?

Oil tankers report a code from 80 to 89, most often 80. The same range covers product tankers, chemical tankers and gas carriers, so the code says "tanker" but not what kind.

Can you tell from AIS whether a tanker is loaded?

Not from the type code. The draught field in the static report is the better clue: a tanker sitting deep is likely laden, one sitting high is likely in ballast. Draught is also entered by hand, so it can be out of date.

Why does a tanker disappear from the map in the middle of the ocean?

On this site, almost always because it has sailed beyond VHF range of every shore-based receiver we read. AIS is line-of-sight radio, and we use no satellite reception, so mid-ocean coverage is effectively absent. It reappears when it comes within range of a coast again.

Further reading

• Why ships "go dark" — and when it means something
• AIS ship type codes explained
• Why AIS coverage is uneven — and what it means when a ship disappears from the map
• All 100 AIS ship type codes, one page each
• Port activity index