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 shore side 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.