What is New in VHF Radios?
By John TarboxIf you have an older VHF radio, you may find you could benefit greatly by giving your system a tune-up and perhaps a new radio. "But you may counter, my old radio works just fine." That may be true, but there is more to consider.
How Can Digital Selective Calling (DSC) Help Boaters be Safer?
Many new VHF radios incorporate Digital Selective Calling or DSC for short. The primary feature you will notice on the front of a new DSC radio is a button you can push when you have an emergency. When you press this button, the radio begins automatically transmitting a mayday call. Given that these new radios are often available for less than $150, this feature alone may justify the cost of replacing your old radio.
Before you run out and install your new DSC radio, you need to consider a couple of things. Just as before, when you call the Coast Guard for help they are going to want to know:
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Who are you?
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Where are you?
How DSC Radios Help You to Answer the "Who" and "Where" Questions Quickly
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First, Digitally encode a unique number assigned to your boat called a MMSI number. More on this later.
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Second, If connected by a wire to your GPS, getting the position from the GPS.
If your GPS has a NMEA output connecter, which most all modern GPS units do, it is a simple matter to connect it by cable to your new DSC radio. If your new radio does not come with the cable, make sure the store that sells you the radio also sells you the proper cable. Installation is simply a matter of plugging each end of the cable into the GPS and radio.
Since 1996 recreational boaters who operate solely in US waters do not need a license from the FCC for their VHF radios. If you are planning on staying close to home and not going to foreign countries, you probably have no reason to get a FCC license which would cost you $156 for 10 years.
If you do not have a FCC license for your radio, you can get a MMSI number for free from BoatUS (http://www.boatus.com/mmsi ) Once you get your MMSI number you can program it into your radio through the keys on the front panel. This is an important step and failure to enter your MMSI number may mean you don't get the help you need in an emergency!
If you may enter foreign waters, including Canada, there is a compelling reason to get a FCC License. This is because when you apply for an FCC license you can get a MMSI number from the FCC at no additional cost. MMSI numbers issued by the FCC differ from those issued by BoatUS in that FCC assigned MMSI data is shared with search and rescue (SAR) agencies in foreign countries. This is important because if you push the distress button on the radio in foreign waters, the SAR station will take the number they receive and attempt to look it up in their MMSI database. If the number is from the FCC, they will have the information they need about your boat. If however the number is from BoatUS, they may be unable to find any data on your vessel. Needless to say, in an emergency you do not want to do anything to impede a speedy rescue.
Tips on Selecting a DSC Radio for Your Boat
When selecting a new DSC radio, you need to be aware that not all DSC radios are made to the same standards. The highest level is Class A is what is required on large ships. A step down, but perfectly adequate for recreational boaters is a Class D radio. For a description of the classes and their capabilities see http://www.navcen.uscg.gov/marcomms/gmdss/dsc.htm Without going into details, you are probably best off not buying a radio that is not either Class A or D.
Most boaters do not realize that more than half of the power put out by their radio may be lost before it ever reaches the antenna! This is because the coax cable used to connect the radio to the antenna is often of dubious origin and quality. Further even the best coax will degrade with age, especially if water is ever allowed to get into the cable. For a sailboat with the antenna at the top of the mast, the cable may be quite long and the power loss substantial.
And Don't Forget When Replacing an Older Radio...
When installing your new radio, why not replace the coax cable as well? Now there is a big difference between low quality cable often seen in marine stores and top quality cable from a reputable manufacturer such as Belden. An excellent choice would be Belden 9913F7 cable which is available on the internet for about $1.50 per foot or less. Equally important are the connectors on the ends of the cable which screw into the radio and antenna. Ideally these should be silver plated and soldered on. Crimp on and screw on types are not nearly as reliable. Often you can purchase the cable with the connectors already installed on the ends. This is definitely the way to go unless you need to fish the cable through holes that are too small for the connectors to pass through.
You should also be aware that coax connectors are not waterproof and you are advised to coat the connectors with a waterproof sealer such as Scotchkote? electrical coating.
Finally now that you have your new radio installed and operational, take a few minutes to insure that everyone in your crew understands how to use the radio to call for help if something should happen to you.
John Tarbox, co-creator of www.boatmaine.us, can be found on his 38' LeComte Sloop with his friend Carolyn Smith. In his day job he owns and operates Symdak Analytics, an internet consultancy firm specializing in helping businesses get the most out of the internet.