PLB or EPIRB?
PLBs were designed to give people in trouble a good chance of being rescued, whether they get lost or hurt in the backcountry, fall overboard, or their vessel sinks from under them. However, like all emergency equipment, they must be used correctly and within the limits of their performance.
A PLB is not a substitute for an EPIRB aboard an offshore vessel, largely because PLBs have a battery life in the neighborhood of only 24 hours. While your approximate location may be determined by the satellite-signaling 406Mhz beacon, it is the 121.5Mhz homing beacon that will bring a rescuer close to you. If you are well offshore, it could be far longer than 24 hours before a surface vessel can reach you. Furthermore, PLBs were designed to be carried by an individual; they lack the robust construction and permanent-mounting capability of a full-sized EPIRB.
For mariners, we believe that a PLB is a great device for two purposes.
First, its short-range 121.5Mhz homing signal is highly useful as an overboard recovery device — if have on board a radio direction finder that receives 121.5Mhz.
Second, a PLB can be a life-saver for near-shore fishermen, sea kayakers, and others who do not travel far from shore.
For offshore vessels, our strong advice is to stick to a rugged, vessel-mounted, long-lived EPIRB for the ultimate fall-back safety device for your vessel. Equip yourself and each crew member with a good auto-inflatable vest, a tether, and jacklines — and use them. If you want the additional security of a homing device for locating crew overboard, make sure your vessel is also equipped with a suitable RDF.