DSC - Your VHF Radio is Smarter than You Think

Digital Selective Calling is a radio technology that has come of age.  If you've bought a VHF (or SSB) in the last five years, it is probably DSC capable.  All that is required is a little bit of set-up, and your VHF will become a very powerful digital communications tool that can add dramatically to the safety and comfort of your yachting.  We at YachtPals feel that it is incredibly important to the safety of life at sea that you properly install your DSC radio, so we're going to walk you through a basic installation overview of a DSC VHF radio on a private boat.

DSC VHF sets are cheap, reliable, and robust.  In the US and many other nations, DSC has been required on all new mounted radios for some time, so you probably already have one.  If you have a red "DISTRESS" button on the front, your radio is DSC-capable.  If you don't, consider the small investment in safety well spent - go out and buy one, and keep those old stained foulies for another season.  We'll wait right here until you get back.

OK, assuming you've got a DSC VHF, step one is to get an MMSI number.  An MMSI (Maritime Mobile Service Identity) number is a unique nine digit number that identifies a particular ship or shore station, it's something like a telephone number.  It is unique to your boat, and thus requires a registration so that numbers don't overlap.  Many organizations all over the world allow you to register your MMSI number online (see list below), and it is often included in an operator's license. You will generally be asked your name, the vessel name, home port, description, secondary contact info and the like.  This will be kept available in a global database in case of the need for a coordinated search and rescue.

Step two is to mount your radio.  We cannot stress this enough:  use quality antenna cable, and put anti-corrosive dielectric grease in the coax connections.  Ask your chandler if you don't know what this means.  Radios are only worthwhile if the antenna works, and many boats (even expensive luxury yachts) are built with cheap cables installed by untrained hands.  If in doubt, replace it all.  Cut corners elsewhere, never on your boat safety equipment.

You will notice that there are extra wires coming out of the back of your DSC radio (or an extra connector on some models).  These are used to connect your radio to your GPS, which is absolutely critical in using DSC to its full potential.  Depending on your current GPS system, you may want to connect to your main GPS, or buy a secondary GPS for this which can also serve as your backup.  Refer to your radio and GPS manuals for connection instructions.  It's just two wires, and it's fairly easy to connect these electronics.  An added benefit is that most radios will display your lat/lon when properly connected, giving you an extra GPS display.

Now you need to program your radio.  Check the manual, and you'll find instructions for adding your MMSI number.  Do it now.  Don't put it off, it's not hard, and it's very important.  Once you've finished, your DSC radio is ready to use.  Now, if you were to push the red distress button on the front of your radio, a digital MAYDAY signal would be sent out to all DSC stations with your position and your MMSI (and thus your boat's description is available to authorities).  It's like a very inexpensive localized EPIRB that provides two-way communication.  Make sure everyone on your boat knows that, in an emergency, they need to hit that button.

NOTE:  The DSC alert does not necessarily replace a voice call on the radio. It will alert all DSC-equipped stations in your area (including all large commercial vessels) to your emergency, but they have no information about the specifics (fire, sinking, etc.). Whether or not there is immediate response after hitting the distress button, mariners are advised to make a traditional (voice) MAYDAY call - including information about your location, the boat description, and the nature of the emergency - to help rescuers reach you and your boat more effectively.

Done!  Wasn't that easy?  Now you are ready to look into the fun side of DSC.  Go convince a friend (within radio range) to read this and set up their own radio properly.  Then get their MMSI number, and give them yours.  You are both going to enter these numbers into something like a speed dialer.  Again, check your radio manual for specific instructions.  Once you're done, ring up your friend.  That's right, the radio will ring like a telephone, and he or she can hit a button and immediately the radio will switch to a working frequency of your choice.  No hailing, no tying up emergency channels, and no "switch and answer," just push a couple of buttons and you're talking.

Finally, there is one more DSC feature that allows the DSC VHF radio to act as a sort of transponder.  If you organize or participate in local races and regattas, it is possible to have local, real-time location plotting of all the DSC-equipped boats in your fleet, without the added expense of buying and installing purpose-built transponders.  This is outside the scope of this basic guide, but if you want more detailed information and instruction on this feature called "polling," contact YachtPals and we'll do what we can to help you make your race safer.  Like everything else to do with DSC, the benefits are high, and the costs are low.  So no excuses!

- Brad Hampton exclusively for YachtPals.com

Where to find information or register for a new MMSI number for your DSC VHF Radio:
U.S. - boatus.com/mmsi
U.K. - http://www.ofcom.org.uk/licensing/olc/  
AUSTRALIA - http://www.amsa.gov.au/Search_and_rescue/Distress_and_Safety_Communications/Maritime_Mobile_Service_Identity/
CANADA - http://sd.ic.gc.ca/pls/engdoc_anon/sd_pages.mmsi_forms

If your nation (or your vessel's flag nation) is not listed above, contact your national radio licensing office for more information.

Read more: 

• Could DSC have Prevented the Lightship Race Tragedy?
• EPIRB Alert - News and Rescue Videos
• Weatherfax - Make Your Own
• What's a GRIB?
• Boating How-to (all Boating How-to's)