Selecting an EPIRB


What they do
An EPIRB (Emergency Position Indicating Radio Beacon) is one of the most critical pieces of last–resort lifesaving gear on your boat when you are out of range of a VHF radio, cell phone or other means of communication. EPIRBs are small radio transmitters, connected to a global satellite network, which is used worldwide to alert Search and Rescue agencies in the event of a dire emergency. Used only when all other means of rescue or communication have failed, these emergency beacons can be activated if your boat is in danger of sinking, or if you have a life–threatening accident or medical emergency. Activating an EPIRB starts a chain of responses, beginning when your signal is received by the COSPAS–SARSAT international satellite system, relayed rapidly to ground stations, forwarded to a regional Rescue Coordination Center and ending when a helicopter, boat, rescue swimmer or other type of emergency response team makes contact with you.

An EPIRB does not allow you to send or receive voice or text messages. If you can reach rescue agencies with an Iridium, INMARSAT or Globalstar satellite phone, Single Sideband radio or cell phone, you can better communicate the important details of your emergency. EPIRBs work when all of these means have failed, such as if your boat is sinking on the high seas and you have no electrical power. Since 1982 EPIRBs have saved about 20,300 people worldwide. In 2006, of the 105 incidents in the US, 272 people are alive, thanks to the COSPAS-SARSAT system.

How they work
EPIRBs transmit using internationally recognized distress frequencies, monitored by LEOSAR (low earth orbit) satellites moving from pole to pole above the earth’s surface, and GEOSAR (geostationary) satellites in high stationary orbit. LEOSAR satellites, because they are in motion, use Doppler shift processing (the perceived frequency change caused by the relative movement of the receiver and the source) to calculate the location of the distress beacon. They cover the entire globe, orbiting once about every 100 minutes. GEOSAR provides instantaneous alerting, but no position locating. Signals from both types are relayed to automated Local User Terminal (LUT) ground stations worldwide, which forward them to Mission Control Centers (MCC). The MCC (which in the U.S. is the NOAA office near DC) tracks the signal, attempts to identify the transmitting vessel using the database of registered EPIRBs, and notifies a regional Rescue Control Center (RCC), operated in the U.S. by the Coast Guard or the Air Force.

A Search and Rescue operation is launched, sometimes involving international communication, substantial costs, lots of planes, helicopters or ships, and rescuers who risk their lives. Unfortunately, some EPIRB transmissions are false alarms. Curious onboard guests or painters may remove an EPIRB from its cradle, causing accidental activation. Some false alarms are hoaxes, and deliberate misuse of emergency beacons may result in substantial fines, restitution and/or prison. If you accidentally trigger your EPIRB, call the U.S. Coast Guard HQ Command Center at 1–800–323–7233 immediately. You will keep valuable resources from being mobilized, unable to deal with an actual emergency, and possibly prevent a SAR team from converging on the trunk of your car. .

What to look for:
Class A & B EPIRBs: These older types were in use from 1970 to the end of 2006 and have saved many lives, but they also lacked accuracy, could trigger false alarms and are now obsolete compared to newer technology. As of January 1, 2007 the U.S. Coast Guard prohibits the use of Class A and B EPIRBs. As of February 1, 2009 all satellite processing of distress signals from all 121.5/243MHz beacons by the international COSPAS-SARSAT System will terminate (this does not apply to Crew Overboard devices with a base station like the Vecta2 and Mini B 300). Boaters wishing to have an emergency beacon now must use only a 406 MHz EPIRB.

406 MHz EPIRBs: Modern EPIRBs transmit digitally on 406.025 and 406.028 MHz (so they are called “406 EPIRBs”). Their signal has an embedded code containing a unique identification number, allowing rescue agencies to look up your emergency information (including name, phone number, vessel type, emergency contact, etc.), in a database, but only if you have registered your EPIRB. When your EPIRB transmits, rescuers know who you are, a huge improvement over Class A and B technology, and can phone your emergency contacts to verify your itinerary. Another advance over older EPIRBs is that satellites can store and rebroadcast your 406 emergency message, so the LEOSAR satellite does not need to be in direct contact between you and a ground station. A 406 MHz signal also allows the satellite to calculate the position of the sender to less than a 2-nm radius (instead of 12 nm with the older Class A and B EPIRBs), resulting in a faster and less costly rescue response. 406 EPIRBs also transmit with 5W of power (compared to 0.1W for the Class A and B beacons) so they function better in poor weather conditions. The average time to notification of RCCs via 406 MHz EPIRBs is approximately one hour worldwide.

Category I and II: By rule, all EPIRBs must be able to activate and transmit when they are removed from their brackets and immersed. Category I brackets will automatically deploy the beacon when submerged between 3′ and 14′, while Category II brackets need to have the beacon released manually. Both types can be manually activated either in or out of their brackets.

GPS/EPIRB Combinations: Two types of EPIRBs now include the ability to transmit GPS coordinates along with the rest of the digital distress message. Some units can interface with an external GPS and if the receiver is turned on will transmit coordinates within seconds of activation. Other EPIRBs contain their own receiver and take longer to acquire their location, but keep transmitting while the EPIRB is operating, without remaining connected to an external GPS with an interface cable. Using the stationary GEOSAR satellites, these transmitters do not need to wait for a LEOSAR to pass overhead and fix a Doppler bearing, and reduce the time–to–notification to as little as four minutes. Like other GPS receivers, their position accuracy is 100yd. (instead of 2nm without GPS).

Personal Locator Beacons: EPIRBS are intended strictly for marine use, but Personal Locator Beacons (PLBs), their smaller cousins, can be carried with you just about anywhere. They provide the same worldwide coverage as 406MHz EPIRBs, and can rescue hikers, kayakers, backpackers, climbers, pilots, river rafters and hunters (among others) as well as boaters. PLBs were extensively tested in Alaska beginning in 1994 before FCC approval for general U.S. use in July, 2003, and saved 400 lives there during that time period. Pocket-sized and weighing less than a pound, PLBs are different than EPIRBs in some important ways. Their battery life (24hr. minimum transmit time) is half that of an EPIRB. PLBs do not have a strobe light, are not required to float (but most do), and are manually deployed and activated.

Like 406 EPIRBS, PLBs have an additional 121.5MHz homing signal to help planes, helicopters and other searchers find you. They also have a Morse code encryption for PLB attached to their digital signal. Manufacturers are marketing PLB versions intended for marine, backcountry and aeronautical use, like ACR’s AquaFix, TerraFix and AeroFix, and all three types often appear virtually identical (ACR’s products, for example, have the same specs).

We believe that EPIRBs are for your boat, and a PLB is a “personal” beacon. A PLB is also great insurance while exploring away from the mothership in your dinghy, and is a less-bulky EPIRB alternative for any small boat. The ability to be carried with you and to be used anywhere, with a group of hikers, on a snowmobile, in a canoe or in a backpack makes a PLB a valuable and versatile lifesaving tool.

Register your 406 EPIRB or PLB!
It is mandatory that you register your 406 EPIRB/PLB with NOAA SARSAT, yet only 80% of our customers register their new beacons. In the U.S. you can register online at or in Canada at http: U.S. registration can also be completed by mail or by downloading the registration form and faxing it to NOAA SARSAT at 301–568–8649. It is free, no license is required and it is critical in making your EPIRB perform as intended. When filling out the registration form, carefully select the emergency contacts NOAA or the Coast Guard should call in case your beacon goes off. These should be individuals who are familiar with your plans, and who are most likely to be available.

Failure to properly register your beacon will most likely delay the launch of a rescue mission. Also, the Coast Guard says that 94% of EPIRBs alerts are false and that registration data has enabled them to resolve 65% of the alerts prior to launching SAR operations.

Can I lend my EPIRB or PLB to another boater?
Yes, you can lend your EPIRB or PLB to your friends. The problem, of course, is that if you lend your 406 to a boater with a different boat description or different land contacts, you are likely to send the Coast Guard on a wild goose chase. The key to this is alerting NOAA of the change of information, even if only for a week or two. If you have previously registered your 406 MHz beacon with NOAA but have not accessed your registration information via their online registration site, you can access your beacon (just be sure you have your 15-digit Unique ID at hand) and view/update your registration. The online registration site contains a section for “Additional Information”. Use this section like a float plan, and let rescuers know how many passengers are aboard and your plans for the trip. This information can be updated on a daily basis.

You can also fax another registration form documenting the new information, and the approximate time that this will be in effect, to the MCC at 1-301-568-8649.

A 406 EPIRB will dramatically improve your chances and your boat’s chances of survival in an emergency. A Personal Locator Beacon provides almost the same level of protection, in a pocket-sized package, to an individual on land or water. If you own an older Class A or B EPIRB, which will soon cease to be monitored by COSPAS/SARSAT, you should upgrade to a Category I or II 406MHz EPIRB. Linked to an internal or interfaced GPS receiver, 406 EPIRBs and PLBs allow instant notification of your identity and an accurate fix on your position, speeding the launch of a full-scale search and rescue effort. One thing is for sure, however: You must do your part in registering your EPIRB/PLB and keeping the emergency contact information up to date, so rescuers can validate the authenticity of the distress signal.



4 responses to “Selecting an EPIRB

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