By Ben Ellison
What the Heck is Navtex?
|Discovering a little-known but useful source of safety and weather information, and a great NMEA repeater as well.|
Attending the world’s largest marine equipment show in Holland last winter, I was struck by how enthusiastically European recreational boaters embrace Navtex, which I thought of as a rather obscure marine-information radio service suited mostly to commercial shipping. While numerous receiver models were available for cruisers, and everyone seemed familiar with the benefits they offered, I’d rarely seen a Navtex machine onboard an American yacht. Since then I’ve been researching and even tuning in to the broadcasts myself... and I’m still wondering why there is so much difference in Navtex use between the continents.
Well, apparently one reason is obvious if you cruise Europe extensively (some day, by golly, some day): Over there, with a coastline chopped up into so many governments and languages, VHF marine weather forecasts add up to a much less consistent and useful service than the one we’re blessed with. And one of Navtex’s main features is text forecasts, which—at least on the primary band—are in the global transportation language of English. Hence Channel-crossing Brits are particularly into Navtex, and pond-crossing Yanks are apt to pick one up pretty quickly, too. But does it have something to offer North American voyagers? Definitely, but more explanation is in order.
Welcome to the acronym zone. Navtex is part of the Global Maritime Distress and Safety System (GMDSS) that the International Maritime Organization (IMO) has been developing and regulating into existence over the last few decades. SARTs, EPIRBs, MMSIs, DSC, and AIS are a few other important, if tongue-tripping, elements of the system. You can learn more at the U.S. Coast Guard nav site (www.navcen.uscg.gov), but suffice it to say that GMDSS is a complicated, bureaucratic program, and it is targeted at commercial shipping. However, many of its parts are becoming worthwhile to regular boaters, and Navtex—thankfully just a shortening of “Navigational Telex”—is a particularly easy one to understand and use.
Navtex is the main source of Marine Safety Information (dubbed MSI, sorry) to vessels within a 200-mile coastal zone, using two medium-wave frequencies. The primary, 518 kHz, is always in English, and its messages are categorized with a strict letter code; the secondary, 490 kHz, may be in a local language and contain added small-craft information. With scores of broadcast stations worldwide, many areas are thoroughly covered. Our sea coasts are almost fully blanketed by the U.S. Coast Guard, and the Great Lakes are said to be partially served by the Canadian Coast Guard. So far only 518 kHz is in use in North America, but 490-kHz services are apparently coming on strong in Europe.
While all Navtex receivers are designed to collect MSI automatically, the final delivery method varies. There are stand-alone Navtex units that simply print out the text on a cash register-style roll of paper and PC programs that demodulate it from SSB or Ham radios to screen. Some weatherfax receivers will also bring in Navtex, a nice combination, as the more local text forecasts are complementary to the large-area fax graphics. I experienced Navtex yet another way, via the ICS Nav6plus pictured throughout the column.
This article originally appeared in the October 2003 issue of Power & Motoryacht magazine.