What Is an LNG Tanker? Types, Size and How to Track One
In this article 9 sections
An LNG tanker is a ship built to carry natural gas in liquid form, cooled to roughly -162°C rather than squeezed under pressure the way a propane bottle is. That single engineering choice explains almost everything else about the ship. The round tanks bulging above deck on older vessels, the double hull, the price tag running into the hundreds of millions, and why a live map shows one differently from an oil tanker heading the same direction all trace back to keeping gas cold. LNG carriers move a growing share of the world’s energy trade, and MarineRadar users search for them constantly, usually after a headline about an attack near Hormuz or a new terminal opening in Texas. This guide covers what the ship actually is, the size classes that matter, how it differs from an LPG carrier, and how to find one live on a map once you know its name.
What Is an LNG Tanker, Exactly?
Strip away the engineering and an LNG tanker is a very large thermos flask with a hull wrapped around it. Natural gas takes up about 600 times less space as a liquid than as a gas. That is the entire reason anyone bothers to cool it down before putting it on a ship. Pipelines move gas across land well enough, but reaching a buyer with no pipeline connection means shrinking the cargo first, carrying it cold, and turning it back into gas on arrival. Doing that safely requires insulated cargo tanks capable of holding a liquid colder than almost anything else shipped commercially. It also requires a containment system that can flex as the hull works in a seaway without cracking, plus enough redundancy that a single tank failure does not become a catastrophe. Classification societies rank LNG carriers among the most heavily regulated ship types afloat. It is also, technically, not a cargo ship at all in the sense our guide to cargo ship types covers. AIS and the shipping industry both file tankers under a separate category from the container ships and bulk carriers that make up most dry cargo traffic.
How Does an LNG Tanker Keep Gas Liquid for Three Weeks at Sea?
Two containment designs dominate the current fleet, and you can tell them apart from a distance. The older one, called Moss type after the Norwegian engineering firm that patented it, uses four or five freestanding spherical tanks that sit mostly above the main deck, giving the ship its unmistakable row of silver domes. The newer one, membrane type, lines the inside of the hull with a thin corrugated steel or invar membrane backed by insulation, which keeps the deck flat and the cargo space roughly 40 percent larger for the same hull length. Most LNG carriers built in the last two decades are membrane type, because yards can build them cheaper and owners get more cargo per dollar of steel.
Neither design actually stops the cargo from warming up; they just slow it down. A small amount of LNG boils off every day regardless of insulation quality, and rather than vent it, modern ships burn that boil-off gas in their own engines or re-liquefy it and pump it back into the tanks. A ship loaded in Qatar and bound for Japan loses a measurable but manageable fraction of its cargo to boil-off over a three-week voyage, and the fuel system is designed around using that loss rather than fighting it.
How Big Are LNG Tankers?
Capacity is measured in cubic metres of LNG rather than deadweight tonnes, because the cargo is so much lighter than oil or dry bulk that tonnage figures would be misleading. A conventional LNG carrier holds somewhere around 150,000 to 180,000 cubic metres, which has become the industry’s default size for a new ship ordered today. At the top end sit Qatar’s Q-Flex and Q-Max classes, built specifically to move gas from the giant North Field. Q-Max ships run close to 266,000 cubic metres on a length near 345 metres, longer than most container ships and too large to transit the original Panama Canal locks.
Why Size Classes Exist at All
Route and port draught decide the ceiling more than ambition does. A Q-Max makes sense loading at a purpose-built Qatari terminal and discharging at a deep-water regasification terminal in Japan or South Korea, but the same ship cannot call at a shallower or narrower terminal built for a smaller class. Plenty of mid-size ships remain in service for exactly that reason, even though the largest carriers get most of the press.
How to Tell an LNG Tanker Apart From an Oil Tanker
From a distance, the silhouette gives it away faster than any paperwork. Three profiles cover almost everything you will see labelled tanker on a live map:
- Moss-type LNG carrier: four or five large spheres rising above the deck like a row of oversized golf balls, a shape no other commercial ship type shares.
- Membrane-type LNG carrier: flat-decked and closer in profile to a large container ship, with a reliquefaction plant amidships rather than anything visible on the skyline.
- Oil tanker: a flat deck over a honeycomb of tanks, with little visible above deck beyond piping and a few vent masts.
An LPG carrier splits the difference, with smaller pressurised or refrigerated tanks that bulge only slightly. Spotting the type correctly matters because the risks, the ports each can call at, and the cargo each carries are all different, even though all of them get lumped under the word tanker in everyday conversation.
What AIS Ship Type Code Does an LNG Tanker Broadcast?
Every LNG carrier identifies itself the same way any other large commercial ship does, through the Automatic Identification System. Its AIS message carries a ship type code in the 80 to 89 range, the band reserved for tankers generally. That groups oil, chemical and gas carriers together rather than giving LNG its own number. Our guide to AIS ship type categories covers how that two-digit system works across every vessel class. An LNG tanker also sets a hazard cargo indicator flagging it as carrying gas, a detail a tracker can surface even when the type code alone would not distinguish it from an oil tanker.
A generic tanker search on a live map returns oil, chemical and gas carriers side by side, all sharing that same code. Narrowing to a specific ship by name, MMSI or IMO number is the faster route once you know which vessel you are after. The underlying broadcast works identically regardless of cargo, since AIS was built to prevent collisions, not to describe what is in the tanks.
LNG Tanker vs LPG Tanker: What Is the Difference?
LNG and LPG sound interchangeable and are not. LNG is methane, cooled to a liquid at atmospheric pressure. LPG is propane or butane, which liquefies far more easily and is typically carried either refrigerated, under moderate pressure, or a mix of both, depending on the ship. An LPG tanker’s tanks are smaller as a result, often cylindrical rather than spherical. The ship as a whole tends to be a fraction of an LNG carrier’s size, because the cargo is denser and the market moves smaller parcels.
| LNG Tanker | LPG Tanker | Oil Tanker | |
|---|---|---|---|
| Cargo | Methane (natural gas) | Propane or butane | Crude oil or refined products |
| Storage | Cryogenic, about -162°C | Refrigerated and/or pressurised | Ambient temperature |
| Typical capacity | 150,000-266,000 m³ | 20,000-85,000 m³ | Up to roughly 320,000 DWT (VLCC) |
| Visible deck feature | Spheres (Moss type) or flat deck (membrane type) | Smaller pressure vessels, often cylindrical | Flat deck, minimal superstructure above cargo area |
Neither ship type is interchangeable with the other, and a terminal built to handle one generally cannot load the other without a separate berth and separate safety systems. If you are tracking a specific tanker and want the oil-carrying side of the picture, our tanker tracker guide walks through following any oil tanker live by name or IMO number.
How Is LNG Transported Internationally?
Gas leaves the ground and moves by pipeline to a coastal liquefaction plant, where it is cooled until it shrinks into a liquid small enough to load. From that point the chain is entirely maritime until it reaches a buyer with no pipeline connection of its own. The LNG tanker carries it across open ocean to a regasification terminal, where it is warmed back into gas and injected into a local pipeline network, often within hours of the ship coming alongside.
LNG trade concentrates heavily around a handful of chokepoints as a result. Qatari and UAE cargoes transit the Strait of Hormuz. Australian and increasingly American cargoes route past Southeast Asia’s straits. A large share of global LNG tonnage never goes near the Suez or Panama canals at all, because the ships are simply too big for them. No overland alternative exists once gas has been liquefied, so a disruption at any one chokepoint shows up in LNG ship traffic faster than in almost any other cargo trade.
How to Track an LNG Tanker Live
Once you have a ship name, following it works exactly like tracking any other large commercial vessel by AIS.
Step 1: Get the Ship’s Name or IMO Number
News coverage, a terminal’s arrival schedule, or a shipping line’s fleet list will usually name the vessel. The IMO number is the safer identifier if two ships share a similar name, since it never changes for the life of the hull.
Step 2: Search It on MarineRadar
Open the app or the web map and search by name or IMO number rather than by ship type, since a generic tanker search returns every oil, chemical and gas carrier currently transmitting.
Step 3: Read Position, Speed and Destination
The ship’s page shows live position, course, speed and the destination and ETA its crew has entered, along with route history showing where it has been over recent days.
Step 4: Set a Zone Alert for a Chokepoint
If you care about one strait or one terminal more than the ship’s whole voyage, draw a zone around it and get notified the moment the vessel enters or leaves, rather than checking the map repeatedly.
What a Live Map Will and Will Not Tell You
A live map built on AIS is honest about what it actually knows, and an LNG tanker’s page shows:
- Position, speed and course, refreshed as new AIS messages arrive
- Destination and ETA, as entered by the crew
- Draught, the closest proxy available for whether the ship is laden or in ballast
It will not show how full the tanks are, who bought the cargo, or what price was paid, because none of that rides in the AIS broadcast. Our guide to how AIS transponders work covers exactly what gets transmitted and what never does. A laden LNG carrier sits noticeably deeper than one running in ballast after discharging, so a quick draught comparison against the ship’s known specifications is usually the best read you will get on cargo state from a tracker alone.
Where LNG Tankers Actually Sail
Qatar’s Ras Laffan terminal anchors one of the busiest LNG export routes on the planet, feeding buyers across Asia and increasingly Europe. The US Gulf Coast has grown into a major exporter in its own right over the past decade, with terminals at Sabine Pass and Calcasieu Pass loading cargoes bound mostly for Europe and Asia. Australia’s Gorgon and Wheatstone projects supply Japan, China and South Korea from the west coast, and newer African and Mediterranean export projects are adding routes that did not exist a few years ago. None of these routes are fixed the way a liner shipping schedule is; LNG cargoes are frequently sold and resold mid-voyage, so a ship’s destination field can change more than once before it actually discharges.
Conclusion
An LNG tanker is defined by one fact above all the others: the cargo is a gas held liquid by deep cold rather than high pressure, and every other feature of the ship follows from managing that cold safely across an ocean crossing. Spheres or a flat membrane deck tell you the containment type. The AIS tanker code tells you it shares a broadcast category with oil and chemical carriers despite carrying neither. And once you have its name, tracking one live works the same as tracking any other large commercial ship.
MarineRadar is free to start on Android and iPhone. Search the name from a news report or a terminal’s schedule and you will have it moving on the map within seconds.
FAQs
What is LNG fuel?
Methane cooled to about -162°C until it turns liquid, used both as a shipped energy cargo and, increasingly, as fuel burned directly in ship engines.
What is a LPG tanker ship?
An LPG tanker carries propane or butane, kept liquid by refrigeration, moderate pressure, or a mix of both depending on the ship. It is a different vessel from an LNG tanker: smaller, often with cylindrical rather than spherical tanks, and built for a denser cargo that does not need the extreme cold methane does.
What are the different types of LNG tankers?
The two containment designs that matter are Moss type, with freestanding spherical tanks rising above deck, and membrane type, which lines the hull with an insulated flat membrane. Membrane ships dominate current newbuilding because they carry more cargo on the same hull length. Size further splits the fleet into conventional ships around 150,000-180,000 cubic metres and the larger Q-Flex and Q-Max classes built for Qatar’s exports.
How is gas transported internationally?
Pipeline to a coastal liquefaction plant, LNG tanker across the ocean, then regasification and injection into a local pipeline network at the other end. The maritime leg exists to reach buyers with no physical pipeline connection to the gas field.
How big are LNG tankers?
Most carry 150,000-180,000 cubic metres; Qatar’s Q-Max class, the largest in service, runs close to 266,000.
Can I track an LNG tanker on MarineRadar?
Yes, by name or IMO number, the same as any other large commercial ship.
Are LNG tankers dangerous?
They carry a genuinely hazardous cargo and are built and regulated accordingly, with double hulls, redundant containment systems and some of the strictest classification standards of any commercial ship type. That design has given the global LNG fleet a strong safety record over decades of operation, though like any tanker it faces added risk when transiting contested waters.
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