EPIRB is an acronym for "Emergency Position Indicating Radio Beacon", and it
just may be your last chance for help when all else fails. An EPIRB is a portable, self
contained, battery-operated radio transmitter designed to summon help in the event of a
disaster (i.e. offshore sinking). It is a MAYDAY tool designed to be used only in life
On August 11, 1992, the 121 ft. "lady Anna" went to the bottom in just 10
minutes. Thanks to its EPIRB, the Coast Guard found and recovered the crew 10 hours later,
80 miles out in the Atlantic.
Properly mounted, a full-featured EPIRB is designed to float free from a sinking
vessel and activate when either a trip switch is thrown or by hydrostatic release (when
water pressure reaches a certain level as the vessel sinks). In either case. the modem 406
MHz EPIRB immediately goes to work to summon help in two ways.
First, a 406 EPIRB is a dual-frequency radio transmitter. When you purchase one, you
register it with the National Oceanic and Atmospheric Administration (NOAA) and describe
the unique characteristics of your vessel, along with your name, address, homeport, and so
on. When the unit is activated, it broadcasts a signal that's unique to your EPIRB, which
will be picked up shortly by an orbiting satellite. From there, the signal is relayed to a
ground receiving ("listening) station where it is received and processed. The receipt
or the MAYDAY signal is then passed along to personnel at the nearest mission control
center, who dispatch search and rescue (SAR teams. At this point. The SAR team knows your
approximate position (within a few miles), and help is on the way.
While the EPIRB is broadcasting on 406 MHz, it summons help a second way by simultaneously
broadcasting on 121.5 MHz. Knowing your approximate location, the SAR team can use the
short range 121.5 MHz signal to home in on your exact position, and BINGO! You've been
Found; and either a U.S. Coast Guard cutter or helicopter will be on scene shortly to
handle the situation.
FEATURES AND FUNCTIONS
The unit just described is a top-of the-line, Category 1406 EPIRB. It's the best you can
get thanks to its satellite and homing Frequency transmissions, along with its automatic
deployment and activation features. Here are several different types of EPIRB from which
1.) CATEGORY I 406 - Transmits on both 406 and 121.5 MHz. Automatic float-free deployment.
Activated either manually or by hydrotalic release. Built in strobe light.
2.) CATEGORY II406 - Transmits on both 406 and 121.5 MHz. Must be deployed and activated
manually. Built-in strobe.
3.) CLASS A--Transmits on 121.5 and 243.0 MHz only. Signals are received by over flying
aircraft and SAR SAT satellites. Automatic float-free and activation.
4.) CLASS B--Transmits on 121.5 and 243.0 MHz only. Must be deployed and activated
manually. Available in a mini-size for attachment to a personal flotation device (PFD).
An EPIRB is one of those items you never think about until you really need one. Maybe
now's a good time to think again.
(unknown origin, if you know, let me know)