Your Trusty
VHF: Don't Leave the Dock Without It
Marine VHF
radios come in two
general categories: fixed-mount and handheld. Make your first onboard
radio a fixed-mount, 25-watt (the legal limit of power output) marine
VHF, all-channel radio, factory preset for the following marine VHF
services:
•
Distress and safety
The
most important channel to monitor when
at the dock or out on the water is VHF Channel 16. This is the
international distress and calling frequency, and the best channel to
summon help in an emergency. On any sunny weekend, there may be as
many as 100 to 500 VHF radios tuned to Channel 16, standing by for
any distress call or listening in as the U.S. Coast Guard or towing
companies head out on emergency missions.
All-channel
portable handheld radios
transmit with a power output of 5 watts. Fitted with small rubber
antennas, their transmit and receive range is less than a
fixed-mount, 25-watt VHF wired to an outside white fiberglass
antenna, but they could also be a lifesaver. Some are fully
submersible, so if your daysailer turns turtle, you can call for
help. Even with a marine VHF handheld, Channel 16 is where you place
voice distress calls.
By
international maritime agreements, any
vessel from a dingy to ore-carrier must have a VHF marine radio
onboard as their primary short-range radio system before any other
type of radio can be installed. Even those mega-ton,
double-football-field-long cruise ships have marine VHF onboard. VHF
Channel 16 has the same importance to them as to the small
recreational boater putting around the harbor.
With
so many mariners using marine VHF, the
channels sometimes become crowded—even VHF Channel 16. Channel
crowding might get so severe that the skipper leans over and turns
down the volume. No more racket, but no more distress call
monitoring, either.
Improving
maritime distress and safety
communications became a priority of the International Maritime
Organization (IMO) 15 years ago when vessels were sinking within
sight of shore, yet no one knew they were heading for the bottom.
Reminds you a little bit of Titanic, doesn’t it?
Enter
DSC
In
1979, a group of radio experts drafted
the International Convention on Maritime Search and Rescue, which
detailed the development of the worldwide emergency search and rescue
plan that all boats have to comply with. This group also passed a
resolution calling for the development by IMO of a Global Maritime
Distress and Safety System (GMDSS) to provide the communications
support needed to implement the search and rescue plan. GMDSS was
officially adopted in November, 1988, and implemented some 10 years
later. Among its safeguards are an automated ship-to-shore distress
alerting system that even small recreational boats can use in case of
a life-and-death emergency. It’s called Digital Selective
Calling—DSC.
New
25-watt marine VHF radios designed to
meet the distress signaling standards are easily identified by a big
red plastic cover and a recessed white button that should only be
pressed in a life-and-death situation with the emergency message
call. In non-emergencies, however, this same button can also be used
with menu selections to place an all-ships call for safety purposes,
a ship-to-towing-company call, or a directed call to another boat.
Digital
Selective Calling is a fancy term
for a quick way to get help on your 25-watt VHF radio. Everyone
onboard should know the process of lifting the red plastic distress
button cover, pressing and holding the button in while looking at the
screen of the VHF and, if appropriate, following the screen
instructions to press the button again to confirm a life-and-death
emergency exists onboard.
What
goes out over the airwaves is a digital
burst of information on VHF Channel 70. The DSC radio automatically
knows where to send this databurst. The digital distress call not
only commands every DSC radio within range to switch over to voice
monitoring on Channel 16, but also may contain your vessel’s
latitude and longitude, along with your unique “MMSI” maritime
identity number. The latitude and longitude are coupled into your
marine VHF DSC radio by a simple three-wire connection to your Global
Positioning System (GPS) receiver.
Your
MMSI, an acronym for Maritime Mobile
Station Identification, is entered into your DSC-equipped radio by
the marine electronics dealer from whom you bought the unit. The
dealer will collect your vessel and owner information and obtain the
9-digit MMSI through an agent such as Boat US. There is usually no
fee for obtaining the MMSI, and only a nominal charge for inputting
it. Keep in mind that if you attempt to input the number yourself,
you have only two opportunities to get it right. If you accidentally
misenter the number twice in a row, you’ll have to get your radio
reset.
Once
your MMSI number is entered, the
radio’s menu provides a literal phone directory for using this
number to contact other boats or services in a non-emergency
situation. For example, say you’ve been fishing all day and there’s
not quite enough juice in the battery to turn over the engine. You
might make a direct DSC call to the local Boat US MMSI number, and
your radio will be switched automatically to their working frequency.
Or
maybe you want to find out how the action
is where a friend is fishing. If he has a DSC radio that’s turned
on, just call his phone number. It’s even possible to designate
what channel you want his radio to switch over to. Standard Horizon
has taken DSC to the next level by offering a matching color or
monochrome chart plotter that takes detailed C-Map NT cartography
linked into their marine VHF. Using DSC, you can call your other pals
who have the same equipment and actually see their position on your
LCD screen. This is called position polling.
Many
Coast Guard Auxiliary stations are
equipping themselves with this equipment for the position polling
function. In a recent Coast Guard Auxiliary test out of Los Angeles
Harbor, the base station was able to instantly see where all of their
patrol boats were by just pressing a few keys on the radio.
DSC
is also improving marine radio
signaling. In the Gulf region, for example, ships may signal ashore
for automated telephone connections. Farther from shore, the DSC
radio may signal a MariTEL station for automated phone service.
For
the foreseeable future, Channel 16 will
remain the international distress and safety channel. It is monitored
24 hours a day by the Coast Guard, and will be until the Coast Guard
is able to provide continuous DSC monitoring—and perhaps beyond.
When
transiting through large commercial
ports, listen for traffic service on VHF Channels 12 or 14. Much like
air traffic control, you will hear a vessel traffic shore station
directing big commercial ships in and out of a harbor with traffic
advisories. Tune in, but don’t transmit unless you absolutely have
to. These two port operations channels are for obtaining traffic
reports.
Single
Sideband
Beyond
the range of VHF—typically 20 miles
off shore—marine single sideband is your additional radio system
that goes in place for worldwide radio calls. Marine SSB requires FCC
licensing, and you may file for your federal radio license by
following the instructions at
www.shakespeare-marine.com/new-fcc-license-steps/index.html (all
lower case).
As
a public service for NMEA dealers and
their customers, Shakespeare offers step-by-step instructions for
electronic filing of a marine station license required for single
sideband radio equipment. You also need an FCC license if you plan to
use your marine VHF in foreign ports, too. No license is required for
your VHF if you just cruise locally in domestic waters.
The
sideband equipment consists of a big
black box that mounts out of the way, close to the battery. The small
head mounts up in your wheelhouse or NAV station, and a very flexible
wiring harness lets you position the SSB head just about anywhere you
would like.
The
sideband feeds signals into coaxial
cable that will drive an automatic antenna unit (ATU) mounted either
in the lazaret of a sailboat, or in the flying bridge of a power
boat. The job of the ATU is to take the radio energy and deliver it
into the airwaves from the insulated backstay or big white
fiberglass, non-resonant whip. The tuner is also coupled with
3-inch-wide copper foil that extends down to the bottom of your hull
to the ground plate or bronze underwater through-hulls. No extensive
grounding labyrinth of wires or copper screen is necessary. The sea
water will do it all!
On
marine SSB, there is a specific DSC
distress channel for automated calls, several long-range U.S. Coast
Guard channels, many recreational ship-to-ship and ship-to-shore
channels, plus capabilities to receive weather facsimiles. There are
also numerous SSB long-range channels for e-mail, and the hook-up
between your lap-top and new SSB radio is a smart little (and
expensive) silver box called a terminal node controller. It magically
pulls data signals out of the airwaves and puts them into readable
text on your computer screen. When you compose an e-mail message on
the screen, this same box turns it into wireless text that is
delivered onto the airwaves with your new marine SSB. While the
signaling speeds are not fast enough to handle surfing the web, you
can nonetheless pull out e-mails directed to your ship station, and
send e-mails to the gang back home telling them what a great time you
are having out at sea.
This
same terminal node controller will tie
your marine SSB into worldwide weather facsimile reception. Powerful
shore stations throughout the world transmit satellite and hand-drawn
weather facsimile charts, and the terminal node controller faithfully
reads your sideband reception of the signals and turns them into
crystal-clear charts.
Pumping
Up your Cell Phone
Not
going out as far as SSB long-range
reception, but you need to squeak a few more miles out of your little
cell phone? Several manufacturers offer white fiberglass marine
cellular phone antenna systems that boost the gain of your cellular
signal well beyond what you might experience with just the little
cellular stubby antenna on your phone. The range-boosting antenna
clears up dropped cellular calls so hardly a word is missed when
you’re at the extreme of at-sea cellular coverage. The antenna
manufacturers offer a variety of phone pick-up cables so almost any
type of cell phone may be adapted to their marine cell antenna
set-up.
But
all of this SSB and cellular radio
range, plus long-range capabilities of satellite phone systems, are
secondary to the local coverage you can obtain with a marine VHF. If
you’re within 20 miles of shore, using sideband, satellite, or
cellular to call for help only confuses matters. For local calls for
assistance, marine VHF is the intended radio system.
Work
with your local marine electronics
specialist to help plan a new or upgraded DSC VHF radio system. Get
that GPS tie-in and double check that your MMSI information is
current. Then brief everyone onboard how to place a distress call,
and go cruising with confidence that anyone, anytime knows how to
lift the red protective cover and press the button for immediate
assistance.
About
the Author
Gordon
West joined the NMEA in 1969 while
working as a licensed Certified Marine Electronics Technician. A
frequent contributor to the Journal, West also writes several monthly
columns about marine electronics and is the author of the General
Radio Operator License Study Book in Preparation for the FCC Element
1, 3 and Radar Element 8 License.
Author: Gordon West
|