ACR has developed the next generation of safety locators by creating an EPIRB interfaced with a GPS receiver. EPIRBs, or Emergency Positioning Indicating Radio Beacons, use a network of satellites, aircraft and land stations. They are essentially small transmitters that broadcast signals on internationally recognized distress frequencies. Through the past decade global weather and mapping satellites have joined in monitoring signals from EPIRBS. These satellites relay any distress signal from a stricken vessel to ground stations which in turn relay the information to international rescue agencies. The satellites compute a fix on the signal so rescue agencies can divert ships or aircraft to attempt a rescue. EPIRBS are designed for Mayday type emergencies in which either the boat is in danger of sinking, or an on-board medical emergency exists.
The RapidFix 406 EPIRB with GPS interface broadcasts the vessel's precise position over the 406 MHz frequency. This frequency has been internationally designated for distress use only. Using a network of both polar orbiting (COSPAS-SARSAT) satellites, and GEOSAR, or high altitude stationary satellites, the unit broadcasts a digitally coded signal identifying the user, the vessel, and its position. According to the manufacturer, the ability to broadcast the vessel's position has improved response time by an average of 46 minutes. Previously, a satellite was able to calculate the position of the sender to about a two-mile radius. The GPS interface however provides a position accurate to 100 meters. Connecting the GPS to the RapidFix is via a NMEA 0183 data output cable. By interfacing the GPS with the EPIRB, a cold start intialization period, or the time a GPS receiver needs to find itself without the benefit of being setup prior to its first use, is avoided. The set up process can consume a great deal of precious time when minutes may make the difference. The results are a faster relay without the wait for satellites to pass overhead. NOAA estimates a 5-minute period between notification and receiving the signal.
The GPS interface is an important advancement. While several geo-stationary satellites are capable of detecting 406 MHz signals and re-transmitting them to ground stations, they have not been able to locate the signal since they don't move relative to the transmitter. However, with the position included in the distress signals, geostationary satellites can relay a distress signal to ground and rescue stations worldwide. By being interfaced with a battery powered, handheld GPS, the vessel's position is continually updated every twenty minutes through a data cable. When activated the unit broadcasts the owner's unique, registered, digitally coded 406 MHz search and rescue homing frequency and position. Rather than wait for further weather satellites to pick up your broadcast, rescuers have an accurate fix from which to better plan search and recovery efforts. Additionally the unit broadcasts a homing signal on the 121.5 MHz search and rescue frequency aiding aircraft and ships in recovery.
Like previous ACR 406 EPIRBs there is a single, three-position switch for easy test and operation. The unit is encased in shock resistant plastic and is manually activated, although an automatically deployable unit is also available. ACR provides a limited 5-year warranty. The built-in strobe light is designed to aid in poor visibility and the bright yellow case uses a polycarbonate blend which is UV and chemical resistant. A lithium battery provides power with a 5-year replacement life and 11-year storage life. The minimum operating life is 48 hours to -40 Fahrenheit, though the 2-lb. unit will operate longer in milder climates. The RapidFix is sold alone or in a package with a handheld GPS.
When venturing offshore, an EPIRB may be your only link to rescuers and represents an important safety consideration. Hopefully the majority of offshore and near coastal sailors will never have to use it, but a well prepared boat is one that takes worst case scenarios into route planning. EPIRBS are a critical part of a worldwide system letting others know of your plight. While the RapidFix 406 is more expensive, at less than $200 more than existing 406 EPIRBs, its speed and accuracy are worth it. In short, the RapidFix 406 EPIRB with GPS represents the best kind of EPIRB your money can buy.