EPIRB (Emergency Position Indicating Radio Beacon)

An Emergency Position Indicating Radio Beacon (EPIRB) is a core safety component of the Global Maritime Distress and Safety System (GMDSS). Unlike a Personal Locator Beacon (PLB), which is registered to an individual, an EPIRB is officially coded to a specific vessel using its Maritime Mobile Service Identity (MMSI) or serial number.

Upon deployment, the beacon transmits a 406 MHz distress alert to Cospas-Sarsat satellites alongside a low-power 121.5 MHz homing signal for local search vessels. Understanding how GPS works demonstrates how GNSS-enabled EPIRBs shrink the search radius from 5 kilometers (2.7 nautical miles) down to within 100 meters (328 feet).

EPIRBs fall into two operational categories. Category 1 utilizes a Hydrostatic Release Unit (HRU) that automatically frees and activates the beacon when submerged to a depth between 1.5 and 4 meters (4.9 to 13.1 feet). Category 2 requires manual release. International standards specify a minimum battery operating life of 48 hours at -20°C (-4°F). When sourcing safety yacht equipment, skippers must rigorously monitor HRU expiration dates (typically 2 years) and battery service intervals (5–10 years). The swift loss of vessels like the superyacht Bayesian emphasizes the life-saving role of accessible distress beacons during sudden sinkings.