EPIRBs, PLBs and SARTs
The EPIRB (Emergency Position Indicating Radio Beacon) is a small radio transmitter that sends out a coded signal on a special frequency used internationally for distress purposes. The signals are picked up by a network of satellites that can locate the approximate position of the EPIRB and then relay this information down to a rescue co-ordination center. Every EPIRB that operates on this 406 Mhz satellite frequency must be registered with your national coast guard authority and therefore as soon as they receive a distress signal they will be able to identify who the vessel is, its approximate locaton, and who its shore based contacts are.