Chuck Husick: Techno-Talk, January 2007 BoatUS Magazine -
When You Need It
Would you spend $200 to save your life? That’s the cost of
a VHF/DSC radio, the most effective emergency communication device
you can put on your boat. I believe you owe a duty to yourself and
to everyone on your boat to install a DSC radio, connect it to your
GPS and learn how to use it.
recently virtually all radio communications began with a voice hailing
call on channel 16, the international calling and distress channel.
Hailing on channel 16 works fairly well, except when a call is blocked
by other callers. Although inconvenienced, we repeat the call, adding
to the congestion and blocking other calls. However, a distress
call that is blocked or made incomprehensible doesn’t just
cause temporary inconvenience. Lives can be lost if the message
does not get through immediately.
DSC system avoids the major deficiencies of channel 16 voice hailing
for both distress and routine calling by substituting a digital
message, similar to the text messages used on cell phones, for the
channel 16 hailing voice hailing call. The brief, typically 1/3rd
of a second, messages are sent on channel 70, which is reserved
exclusively for DSC signals. There are no voice calls on channel
70 and the brevity of the digital call virtually eliminates interference
from other users. DSC calling, combined with the Coast Guard’s
DSC-based Rescue 21 system and the DSC radios on virtually all Coast
Guard boats and on tens of thousands of your fellow recreational
mariners vessels will create an incredibly valuable safety net.
addition to its value for emergency signaling DSC hailing also makes
routine communication as easy as making a telephone call. To call
a vessel or shore station simply select a working channel, enter
the Maritime Mobile Station Identity (MMSI) of the station you want
to call and press the enter button. Your DSC call tells the station
you are calling who you are (your MMSI) the working channel you
wish to use and your position (position can be optional for routine
can buy a Class D DSC radio, the type with two separate receivers,
one permanently tuned to channel 70, the DSC hailing channel for
the price of a dinner for four at a nice restaurant. The Maritime
Mobile Service Identity number (MMSI) registration number you need
to be identified on channel 70 is available at no cost by phone
or on line from BoatUS (At last count BoatUS has issued more than
obtain the most value from your DSC radio for emergency signaling
and routine signaling it must be connected to your boat’s
GPS or Loran C receiver. Be sure that your radio is properly connected
to the boat’s GPS or Loran C receiver. Making the connections
is not difficult, you need connect only two wires from the GPS to
two wires from the radio. Whether you make the connections yourself
or have someone do it for you be sure to verify that the position
information is transmitted in your DSC hailing calls. Remember,
in an emergency five minutes saved can save a life.
calling has obvious value in the hand-held radios many boat owners
carry as back-up for their fixed mount sets and when on their yacht’s
tender, a canoe or kayak. At present there are very few hand-held
radios that offer DSC capability. However, today’s GPS receivers
are tiny, require little power and are cheap enough to make including
them in a hand-held a practical option. It’s virtually certain
that the safety value of DSC will make a distress button available
in many if not all newly designed hand held radios.
boaters routinely verify the operation of their radios by making
a “radio check” call. To perform the test with a DSC
radio select a working channel (not channel 16), enter the MMSI
of a friend’s radio or that of a marina or yacht club and
press the “enter” button to send the DSC hailing message.
If the called station receives your call it will usually respond
with a digital acknowledgment message that will appear on your radio’s
LCD screen and then switch to the working channel you selected for
voice communication. Under no circumstance use the distress key
to make the radio check call.
to www.boatus.com/mmsi for information about obtaining your MMSI.
Click on the DSC Radio Tutorial to view “Can You Hear Me Now”
a BoatUS Foundation / U.S. Coast Guard radio communication briefing
for the recreational mariner.