Nearly all new EPIRBs feature an internal GPS receiver, a big advantage in an emergency. Once satellites are acquired, these units will send a lat/long fix as well as enable position tracking via Doppler shift. ACR offers a dual GPS unit that eliminates the lag time in position reporting caused by delays during initial satellite signal acquisition. The EPIRB is interfaced with the onboard GPS, keeping the beacon aware of the current position, and allowing the first emergency signal burst to carry an accurate lat/long.
Bottom line: In an emergency, a GPS-equipped EPIRB is well worth its capital outlay. Be aware that the batteries for some older models are very expensive or have been discontinued, so units that use these batteries might not be the bargain they appear to be.
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