What Ship Is That? Identify a Vessel by Name or MMSI
In this article 10 sections
Spotted a ship and can’t stop wondering what it is? Here’s how to get a name, a flag and a destination in about a minute. This guide is from the MarineRadar team and takes about 8 minutes to read.
You’re on a sea wall, or leaning on a ferry rail, and a huge ship slides along the horizon. Somebody says it out loud: what ship is that? Not long ago the honest answer was a shrug. Now it’s usually a one-minute job, as long as you know which clue to start with.
There are three ways in. You can search by the ship’s name, by its nine-digit MMSI, or by its seven-digit IMO number. Which one you pick depends on what you’re holding. If you have no name and no number, just a silhouette and a rough memory of the time, there’s a fallback for that as well. We’ll go through all four, then look at what a vessel profile tells you once you’ve found the ship. The searching happens on the MarineRadar live vessel map, which is free to start on iOS and Android.
Start with what your eyes can tell you
Before you touch your phone, spend ten seconds being a detective. Jot down the time, because every AIS position carries one, and a ship making 20 knots covers about 6 km in ten minutes. Note where you were standing and which way the ship was heading. Then look at the ship itself.
Shape says more than you’d think. A long flat deck piled with coloured boxes is a container ship. A low hull with pipework running down the middle is usually a tanker. A tall white block with rows of balconies is a cruise ship, and a stubby boat with a net drum and a cloud of gulls is most likely fishing. Hull and funnel colours help too, since shipping lines are fond of their liveries. If you’re not sure what category you’re looking at, our guide to ship types and AIS categories lays them out.
The best clue, though, is written on the ship. The name is painted on the bow and again on the stern. The stern also shows the port of registry, which is the ship’s home port on paper, not where it’s sailing today. A phone zoomed in on the stern can give you the name from a surprising distance. Found a name? Keep the rest of your notes handy, because names aren’t always unique.
Route one: search by name
Open MarineRadar, tap into the vessel search and type what you read. A name is the quickest way in, and also the likeliest to trip you up. Shipping companies name their vessels in series, and whole classes of container ships carry near-identical names, so a search can return several hulls when only one is the ship you saw.
When that happens, don’t just tap the first result. Compare the type, flag and position against your notes. A tanker sitting 3,000 km from where you stood isn’t your ship, however nice the name looks. If the search returns nothing at all, read why a ship isn’t found by name. The causes run from a spelling variant to a vessel that has gone quiet.
Route two: search by MMSI
An MMSI is a nine-digit number tied to a ship’s radio and its AIS unit. You may have one from a photo caption, a shipping record, a news report or an AIS receiver on your own boat. Type all nine digits into the same search bar, and if the ship is broadcasting, its live position comes up.
The digits split 3 + 6. The first three are the MID, which shows the country that issued the number. For example, 366 to 369 is the United States and 232 to 235 is the United Kingdom. The remaining six are a serial number handed out by the national authority. Treat the MID as a clue about paperwork rather than geography, because a ship can spend its whole career without visiting the country in its own MMSI. For the long version, read our MMSI lookup guide or the shorter walkthrough on how to find a ship’s MMSI number and track it.
Route three: search by IMO number
The IMO number is the ship’s fingerprint. It has seven digits, it belongs to the hull, and it doesn’t change when the ship is renamed, sold or moved to another flag. That makes it the safest identifier when names clash, or when you’ve read that a vessel was “formerly” something else. Larger ships often have it permanently marked on the hull, so it’s worth a squint through your zoom lens. We explain the details in why the IMO number matters for ship tracking. A simple habit saves a lot of grief: use the name to get started, and use the IMO to be sure.
No name and no number? Let the map do the work
Plenty of sightings come with neither. Start from where you were instead. Ships Near Me shows actual ships inside a 50 nautical mile radius of wherever your phone puts you, so you can scan the candidates for the time you noted. Narrow them by type, and look for one whose size and heading make sense for what you remember.
Turning on vessel labels speeds this up. The map can print a ship’s name, identifiers, type or speed beside each icon, which saves you tapping them one by one. If you took a picture, other users’ photos can help you check your guess too, and the guide on image upload and ship identification shows how that works. Unsure what a marker means? How to read ship symbols, icons and colours decodes them.
You found it. What is the profile telling you?
A vessel profile packs a lot into a small screen, and a few fields mean less than they seem to. For a field-by-field tour, see how to read vessel details on MarineRadar.
Type is the category the ship broadcasts, such as cargo, tanker, passenger, fishing or tug. It’s a broad label chosen on board, not a full spec, and you can browse the vessel types to see the groups. Flag is the country the ship is registered in. It isn’t the owner’s nationality or the ship’s destination. Panama, Liberia and the Marshall Islands are common among big merchant ships, and each has a flag state page.
Speed is how fast the ship is moving, in knots, and near zero usually means anchored or moored. What ship speed means covers the rest. Course is the direction the ship is travelling, but wind and current can push a ship sideways, so its heading and its course may differ.
Destination is where the crew says the ship is going. It’s typed in by hand, so it can be blank or oddly abbreviated. See destination unknown. ETA is the estimated arrival time, and it’s only an estimate because it moves with speed, weather and routing. Read about ETA tracking. Last update shows how old the newest signal is, and an old timestamp means you’re looking at where the ship was, not where it is.
When the ship you saw isn’t on the map
It happens, and it doesn’t always mean you did something wrong. AIS only shows ships that broadcast, and a few groups often don’t.
Navies mostly keep warship transponders off, and our piece on navy ship tracking explains what you can and can’t see. Some fishing crews switch AIS off to protect a good spot, and here’s why some fishing crews go dark. Many small leisure craft carry no transponder, and cheaper units behave differently from the gear on big ships. Class A vs Class B AIS spells out the gap.
Far from shore, a ship depends on satellite coverage, so updates arrive less often than near a busy coast, and MarineRadar describes its satellite positions as arriving about every five minutes. If the timestamp is old, the dot is a memory. How often AIS updates positions explains why.
If nothing matches, check the timestamp, widen your time window and try again a little later. If you’re curious how any of this data gets onto a map in the first place, what an AIS transponder is is a good place to start.
Keep following it
Once you know what you’re looking at, you don’t need to keep searching for it. Save the vessel to follow it, and set vessel alerts for arrivals and departures. You can also share a ship’s live location with whoever was standing next to you asking the question.
Want to see what else is out there? Browse the vessel directory, jump to cargo, tanker, passenger or fishing vessels, or check the ports directory to see where your mystery ship might be heading. For a wider introduction, try how to track any ship online in 2026, or browse everything in the MarineRadar Resource Hub.
So next time someone on the sea wall asks what ship that is, you’ll have an answer before the ship has left the frame.
See your own waters
Search a vessel by name, MMSI or IMO and follow it live on the map. MarineRadar is free to start, and available on iOS and Android: App Store, Google Play, or all download options.
FAQs
How can I find out what ship that is?
Write down the time and place, then read the name painted on the bow or stern. Type it into the vessel search on MarineRadar and check the result’s type, flag and position against what you saw. No name? Use Ships Near Me to list vessels around your location.
Can I identify a ship by its MMSI number?
Yes. Enter all nine digits into the search bar. If the ship has transmitted AIS recently, its profile and live position appear. Our MMSI lookup guide covers what the digits mean and why a search can come back empty.
Why can’t I find a ship by name?
Common causes are a spelling variant, several ships sharing a similar name, or a vessel that isn’t broadcasting right now. Try the IMO or MMSI instead, and read why a ship is not found by name for the full list.
Can I identify a ship from a photo?
IMO number from the hull, then search for it. Photos uploaded by other users can also help you confirm a match.
Why doesn’t every ship show up on the map?
AIS only shows vessels that broadcast. Many warships stay dark, some fishing boats switch AIS off, and small craft may carry no transponder at all. Far offshore, positions also update less often. See navy ship tracking for one example.
Track the ships behind the story
MarineRadar follows 112,000+ vessels with satellite positions every 5 minutes. Search by name, MMSI or IMO — free on iOS and Android.
