|“Just the Fax Ma’am”
Boaters have long relied on a weather fax to stay abreast of meteorological developments. Now they can opt for digital reception.
|By Frank Lanier
Chesapeake Bay Magazine 2003
Offshore Magazine 2003
“When sheep begin to breed late, it’s a sign of fair weather to come. So also when an ox lies on his left side and a dog does the same.”
These were among the weather indicators recorded over 2000 years ago by Theophrastus of Athens, a student of Aristotle. While many homespun weather rhymes and observations make sense when you think about them (old salts will tell you, for example, that seabirds head inland before a storm), the modern options for gathering weather information give sailors the best chance to not only predict bad weather, but avoid it altogether. Of these, the marine weather facsimile transmission (weather fax) is hard to beat for a clear, comprehensive look at current and future weather forecasts.
Although viewed as a modern invention by most, the first broadcast of weather maps via radio facsimile actually occurred during a 1926 demonstration for the Navy by Charles Jenkins (inventor of the motion picture). The process became readily available to commercial and pleasure boaters in the 1950s and hasn¹t really changed much since.
Weather fax transmissions are similar to home and office faxes, except they¹re broadcast over marine single sideband radio (SSB), not “narrow cast” over phone lines. The radio fax transmitter scans the weather chart and converts it into a series of tones, which the receiving unit decodes and prints out. Each black and white chart covers various time periods (current weather, 12-hour, 24-hour, and so on up to 96-hour forecasts) and provides graphic information on high and low pressure centers, tropical cyclone positions, wind direction and strength, isobars, fronts and cloud cover, as well as observations from ships at sea.
The weather charts for U.S. waters and adjacent high seas areas are compiled by divisions of the National Weather Service (NWS). The NWS transfers them to the Coast Guard for broadcast from one of five stations scattered along the coastal U.S. from Massachusetts to Alaska and another in Hawaii. Each station follows a daily broadcast schedule using numerous channels simultaneously, to increase the likelihood that at least one frequency can be received from anywhere in the area. Broadcast schedules for each station can be found on the internet at www.mpc.ncep.noaa.gov/radiofax/.
Weather fax is commonly received through either a dedicated SSB receiver-printer unit or receiver-and-laptop computer combination. Receipt via e-mail is also possible, although accessibility to the internet is not currently a viable option for most vessels. The receiver-printer units were first on the weather fax scene, and while still common, they do have some distinct disadvantages when compared to the SSB/laptop setup, one being the need to carry a supply of fax paper. Worse, they print exactly what they receive from the airwaves, complete with “snow” or static.
Downloading the signal to a computer with the appropriate weather fax software not only lets you save and file the data received, it also allows you to clean up and enhance the images before viewing them. Add a basic printer, and the laptop option also lets you print – and only the reports you want, without the need for specialized paper (dedicated units sometimes require thermal or other special paper).
Dedicated weather fax units start out at around $2,000, and a simple SSB-laptop setup can be had for not much more<considerably less if you already own a laptop. Add to that the other benefits of having an SSB onboard, and the latter option is even better.
An alternative for vessels that already have an SSB onboard is installation of a weather facsimile signal processor, such as the SEAFAX 4000 by SEA Marine. Essentially it¹s a digital modem that, when attached to your existing SSB and a printer, allows you to receive weather faxes without a computer or dedicated unit. It¹s a cheaper alternative to either of the previous options, and it shares some of the shortcomings of the dedicated unit, mainly the inability to enhance the image you receive.
Whichever system you choose, having weather fax information onboard makes good sense from both a safety and comfort standpoint. Who wants to get beaten to death on a rough passage when a little foresight can generate smooth sailing? Put technology to work for you now and enjoy fair winds and following seas on your next outing.
Contact National Weather Service Marine and Coastal Weather Services at www.nws.noaa.gov.
Frank Lanier is an FCC licensed Coast Guard eletronics technician and owner of Captain F. K. Lanier & Associates, LLC, Marine Surveyors and Consultants of Chesapeake, Va.