The advantages of 406 EPIRBs are worldwide coverage, position location accuracy, a reliable transmitted signal, an encoded message that identifies the vessel in distress, and faster response time. For long offshore trips, a 406 EPIRB is the way to go.

The frequency stability of a 406 MHz EPIRB, which directly affects position accuracy, is about 10 times greater than a homing-type 121.5 MHz EPIRB. Satellites can detect the 121.5 signal, but the location information they transmit is not as accurate, and there is no encoding information to identify you and your vessel. The location of a transmitting 406 beacon can be determined within approximately three miles by the first satellite pass, and to within one mile after three satellite passes. For a homing EPIRB, position accuracy is only 12 miles. It’s the difference between a 144 sq. mile search area vs. as little as one square mile. This is why the 406 EPIRBs are so much more expensive.

The homing-type EPIRB transmitting on 121.5/243 MHz relies on an earth station being within range of the transmitted signal. In addition, commercial and military aircraft are required by law to listen for these signals. In the Northern hemisphere there are plenty of earth receiving stations; not so in the Southern hemisphere. Using the COSPAS/SARSAT system of polar orbiting satellites gives you worldwide coverage.

406 EPIRBs also have a much greater power output - five watts compared to 25-125 milliwatts for homing EPIRBs. And noise interference is much less, which means that the 406 can be more reliably detected over greater distances than most homing 121.5 EPIRBs.

Once registered, the unique, encoded digital message received by the satellite and transmitted back to ground-based search and rescue authorities provides them with information to assist in the search - who you are, your boat type and size, where you are (within three miles), and other important data, including emergency contact information. The encoded signal also performs the important function of circumventing false alarms, which are the vast majority of transmissions from 121.5 EPIRBs.

If you would like to rent instead of buy a 406 EPIRB for your next offshore trip, click here for rental information from BoatUS.