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EPIRBs

EPIRBs - You Bet Your Life

This week's tip is going to focus on "Life Insurance." Most everyone has some sort of "life insurance," right? You pay every month or it is deducted from your check. Well, I submit that the policy you pay for is not life insurance at all, it is "death insurance." You get no benefit from it until you are no longer alive! Real life insurance comes from the money you spend on things like VHF radios, life rafts, first aid equipment, navigation equipment and, what I want to focus on this week, the Emergency Position Indicating Radio Beacon (EPIRB).

An EPIRB is a small battery-powered transmitting device that is carried on board.. As the name implies, it is used only in case of emergency and usually only as a last resort when your marine radio is inoperable or out of range.

There are several types of EPIRBs. If disaster strikes, some float free and automatically activate; others must be activated manually. All EPIRBs float and will send out a continual signal for 48 hours. Since EPIRB signals are primarily detected by satellites that pass overhead, occasionally there may be a delay in detection (perhaps an hour) because there is no satellite currently in the area to pick up the signal. Once activated, the EPIRB should be left on to make sure the signal is available for detection by the satellite and for purposes of homing in on your location.

EPIRBs that operate on 121.5/243 MHz (category II) are the least expensive and least capable. They may cost around $400.00. These were designed in the 1970's to alert aircraft flying by. They are not well suited for satellite detection because of the problem of distinguishing them from other signals on the same frequency. Often, multiple passes of the satellites are required to identify the signal, which can definitely delay the rescue.

The one you want is the 406 MHz EPIRB (category I) which includes a 121.5 MHz signal which is mainly used for homing. This one is more expensive but what is your life worth? Response time to the 406 EPIRB is dramatically reduced and the position information it provides is much more accurate. Additionally, the 406 EPIRB's signals are coded, allowing non-EPIRB signals to be filtered out. They also provide other valuable information which will help the search and rescue efforts. At the time of purchase you can register your EPIRB and part of the coded signal will include your name, address, phone number, vessel description, and an emergency contact shoreside who will know of your plans and capabilities. Once the satellite picks up the signal and transmits it back, the search and rescue team knows where you are and who you are.

The 406 EPIRB is carried on all U.S. flag merchant vessels and is required on commercial fishing vessels operating beyond three miles from shore (unless they do not have a galley and sleeping facilities). EPIRB's are also required to be licensed by the Federal Communications Commission. They should be listed on your ships station license. Although EPIRBs are not required on recreational vessels, the U.S.C.G. strongly recommends them and strongly suggests that the choice be the Category I, 406 MHz model. Its long-reaching, long-lasting signal can make a significant difference in the speed and effectiveness of rescue efforts.

In a recent test of the 406 MHz model, a Naval Academy midshipman found out how effective it was. The test signal was identified within four minutes and pinpointed within 15 minutes. If that is not enough to convince you, the comparison chart below may help you make up your mind whether or not you want to "bet your life" to save a little money.

Category I, 406 MHz model Category II, 121.5/243 MHz model
Global detection - Regional satellite
earth station not needed
Regional earth station needed - not
available in many ocean areas.
Potential for detection by overflying
aircraft.
Reliable beacon with low false alarms
and high probability of detection.
Beacons often incompatible with satellites.
Designed for detection by aircraft. High
number of false alarms is typical.
Beacon signal coding and exclusive
international use of the 406 MHz
frequency band for distress beacons
assures a signal received is from an
EPIRB - no problem with false alerts
from non-beacon sources
High false alert rate due to alerts
generated by other transmitters within
the 121.5 MHz
1.5 nautical mile accuracy and a
second signal provided to use for
homing.
10-20 nautical miles accuracy. Search
and rescue forces can home on the
primary signal.
Beacon is coded with owners name,
address, phone, vessel type etc.
No way to know whether signal is from
an EPIRB, similar aviation beacon, or
non-beacon source. No coded information
with signal.
Good ambiguity resolution, i.e. can
promptly launch rescue unit to a
known position with an alert from
a single satellite pass.
Hard to know which of two separate
positions calculated with first satellite pass
is the beacon location. Usually must wait
for a second satellite pass to resolve.

Related Articles:
EPIRBs - Safety at Sea

 

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