When undertaking longer voyages, especially going outside the range of the Coastguard VHF MSI or abroad, fitting NAVTEX should be seriously considered.
As part of the Global Maritime Distress and Safety System (GMDSS), there are criteria for NAVTEX set by the International Maritime Organisation (IMO). NAVTEX stations must have a transmitting range of 250M and must provide a weather forecast covering that 250M radius. In reality this may be as much as 400M, but this range is "out to sea". Difficulty is often experienced when trying to receive NAVTEX transmissions on vessels that are in close proximity to land, in estuaries, inlets, ports or marinas, as NAVTEX is not designed for this, its intended use is by vessels which are underway at sea.
Transmissions are made by a dedicated network of transmitters around the world, with the power of the different transmissions controlled to minimise interference. In the UK there are three NAVTEX transmitters, NITON, CULLERCOATS and PORTPATRICK. The Maritime and Coastugard Agency (MCA) publishes a Maritime Safety Information (MSI) leaflet which provides information on the timings and content of NAVTEX transmissions relevant to UK waters.
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. It is good practice to tune your NAVTEX to receive broadcasts for the area you are in and the area you are sailing to.
Use of abbreviations in NAVTEX weather broadcasts
Abbreviations are the best way to reduce the length of messages, however for NAVTEX it is important that these are standardised and controlled. These standardised abbreviations have been published by the MCA in MGN 375.
NAVTEX is an element of the Global Maritime Distress and Safety System (GMDSS), which aims to be a complete global distress and communications system for the mariner. In addition, the GMDSS incorporates and satellite communications, EPIRB and Digital Selective Calling.
Maritime Safety: weather and navigation: https://www.gov.uk/maritime-safety-weather-and-navigation