NAVTEX: what it is, how it works and today’s warnings live

Published on 28 September 2026 · By Ricard Prehn, yachtmaster, master of yachts up to 200 GT (STCW), professional recreational skipper (PPER) and sailing instructor for more than 27 years

What is NAVTEX?

NAVTEX is a GMDSS radio service that broadcasts navigational, weather and search-and-rescue warnings as text. The boat’s receiver listens on its own and prints them or shows them on screen as they arrive, with nobody having to monitor the radio.

It is the “hear without listening” part of the boat’s radio. The VHF is for talking and for sending a DSC alert (see how to make a MAYDAY call); NAVTEX brings you, in writing and without you doing anything, what has changed in your area: a buoy unlit, a container adrift, a military exercise or a gale warning.

Which frequencies does NAVTEX use?

On 518 kHz, the international service, always in English; and on 490 kHz, the national service, in the country’s language (Spanish, in Spain). A dual-channel receiver listens to both at once.

All stations share the same frequency and take turns: each has its own minutes, six times a day, every four hours. That way they don’t overlap, and the receiver just keeps listening. Range is several hundred miles, more than enough to cover the coast and well offshore.

How do you read a NAVTEX message?

It starts with ZCZC and four characters, B1B2B3B4: B1 is the station letter, B2 the message type and B3B4 its number. Then comes the text, ending in NNNN. “ZCZC XA12” is navigational warning number 12 from station X (Cabo la Nao, on 518 kHz).

ZCZC XA12        ← station X, type A, no. 12
(warning text: where, what,
 position and since when)
NNNN             ← end of message

This is an example of the format, not a real warning.

The message types (B2) you will see most:

A detail people forget: number 00 (for example “XA00”) is reserved for urgent warnings, which the receiver always prints, even if received before.

Which NAVTEX stations are there in Spain?

Four, run by Salvamento Marítimo: A Coruña (D on 518 kHz, W on 490 kHz), Tarifa (G and T), Cabo la Nao (X and M) and Las Palmas (I and A). For the Catalan coast and the Balearics the one that matters is Cabo la Nao.

Each station repeats every four hours. Times from the list of NAVTEX stations; before a passage, check them in the official list of radio signals.

Can you filter messages on the receiver?

Yes: you choose which stations and message types to receive. But navigational warnings (A and L), weather warnings (B) and search and rescue (D) cannot be switched off. And the receiver does not print again a message it has already received correctly.

In practice you select the stations for the area you are sailing and let all message types in. If you cross to the Balearics, Cabo la Nao covers the whole passage; if you head down to the Strait, add Tarifa.

What warnings come up on the Catalan coast?

Look at the viewer above: there is almost always one. The most common are buoys and beacons unlit or off station (in September 2026, for example, the buoy on the Besòs sewage outfall, off Barcelona), objects adrift (containers, tanks, boats), harbour works, military and rescue exercises and cable ships at work, which need a wide berth.

Read them before you leave. An unlit buoy at the entrance of your destination harbour, at night, changes your landfall. For the weather, besides NAVTEX, see Mediterranean weather. If you are fitting radio equipment aboard, remember that on Spanish-flagged boats the installation must be certified by an approved installer (more here, in Spanish).

Source of the warnings: Salvamento Marítimo radio warnings, the Spanish national coordinator of the coastal warnings broadcast by NAVTEX. The viewer is a study tool: for navigation always use your NAVTEX receiver and official information.