Maritime Safety Information (MSI)


Her Majesty's Coastguard (HMCG) is responsible in the UK for the broadcast of Maritime Safety Information (MSI) on VHF, MF and NAVTEX and for the provision of Radio Medical Link Calls (MEDILINK) Service.


Its network of remote radio sites around the coast of the UK provides VHF and MF coverage out to 30 miles and 150 miles respectively, with NAVTEX coverage out to 270 miles.


HM Coastguard’s co-ordination centres make MSI Broadcasts every 4 hours. The broadcast times shown in the schedules are UTC.


MSI is broadcast on VHF Channels 10, 23, 73, 84 or 86 and exceptionally on VHF Channel 67. This prevents mutual interference and allows one operator to broadcast simultaneously on 2 or more aerials. This is important when some broadcasts are in excess of 20 minutes.


Navigational Warnings are provided by the NAVAREA ONE co-ordinator at the UK Hydrographic Office, Taunton. The primary means of disseminating this information is by NAVTEX and INMARSAT SAFETYNET. However, WZ navigational warnings are also broadcast on VHF and MF on selected aerials, on receipt and at four hourly intervals (see broadcast schedules).

Negative Tidal Surge Warnings are issued as a WZ on receipt, and at hourly intervals until absorbed into the next regular broadcast.


Meteorological Warnings are broadcast at four hourly intervals and include Local Inshore Forecasts and Gale Warnings. Area forecasts are broadcast twice daily. Strong wind warnings will be broadcast if significantly different from the inshore forecast. Users are encouraged to listen to these broadcasts as an alternative to calling co-ordination centres for meteorological information outside these times.


Maritime Safety Information will be broadcast by co-ordination centres either on VHF Channels 10, 23, 73, 84 or 86, and exceptionally channel 67, following an initial announcement on Channel 16. The initial announcement will indicate the working channel the mariner should return to. 


A Navtex set automatically receives Maritime Safety Information (MSI) 

There are two NAVTEX frequencies. All transmissions on NAVTEX 518 kHz the international channel should be in English. Wherever you are at sea in the world, a set receiving NAVTEX 518 kHz should provide you with relevant weather forecasts, severe weather warnings and navigation warnings such as obstructions or buoys off station. Depending on your location other information options may be available such as ice warnings for high latitude sailing. 

The 490 kHz national NAVTEX service may be transmitted in the local language. In the UK full use is made of this second frequency including useful information for smaller craft, such as the inshore waters forecast and actual weather observations from weather stations around the coast.

Dual frequency NAVTEX sets are available to allow yachtsmen to take advantage of both services, and some such sets will monitor both frequencies at the same time.  

Once you have programmed your receiver it will automatically receive and (print or) store information until you want to access it.  A NAVTEX receiver can be set up to ensure that it collects the information you are interested in and rejects that which you do not want, such as information from transmitters further afield or subject matter not applicable to small craft. It may not be possible to switch some transmissions off such as transmissions classed as warnings.

Text ©

Adobe Acrobat Document 274.2 KB
NAVTEX abbreviations
Adobe Acrobat Document 476.1 KB