A Comprehensive Guide to EPIRB: What It Is and Why It Matters

When venturing out to sea, whether for commercial or recreational purposes, safety should always be the top priority. One piece of equipment that plays a crucial role in maritime safety is the Emergency Position Indicating Radio Beacon, or EPIRB. This guide will delve into what an EPIRB is, how it works, and why it's an essential piece of safety equipment for any sea voyage.

What is an EPIRB?

An EPIRB is a device that is designed to transmit a distress signal if a vessel is in trouble. Once activated, it sends out a signal that can be detected by satellites and used to locate the vessel in distress, facilitating a faster and more accurate response from rescue services.

How Does an EPIRB Work?

When activated, an EPIRB transmits a signal at 406 MHz, a frequency monitored by the Cospas-Sarsat satellite system, an international search and rescue operation. This signal contains a unique identification code and, if the EPIRB is equipped with a GPS, the precise location of the beacon. The signal is relayed to the nearest Rescue Coordination Center, which then initiates the rescue operation.

EPIRBs — Marine Safety Services Alaska Marine Safety
EPIRB Signal Chart

Manual and Automatic EPIRBs

Technically, all EPIRBs are manual as they require manual activation to send a distress signal. However, EPIRBs are often categorized as 'manual' or 'automatic', based on their mounting and deployment systems.

Manual EPIRBs are typically placed in a bracket that prevents them from being accidentally activated. In an emergency, a person must physically retrieve the EPIRB from its bracket and activate it.

Automatic EPIRBs are housed in a specially designed bracket equipped with a Hydrostatic Release Unit (HRU). If the vessel sinks, the increasing water pressure triggers the HRU, which releases the EPIRB. Upon contact with water, the EPIRB automatically activates and starts transmitting the distress signal.

The Role of the Automatic Identification System (AIS)

In addition to the main 406 MHz signal, some modern EPIRBs also transmit an AIS signal. The Automatic Identification System is a tracking system used on ships and by vessel traffic services for identifying and locating vessels by electronically exchanging data with other nearby ships and AIS Base stations. AIS complements the EPIRB by providing another layer of safety, allowing nearby vessels to quickly locate and assist a vessel in distress.

Why EPIRB Matters

In an emergency situation, time is of the essence. Being able to accurately locate a vessel in distress can make the difference between a successful rescue and a tragedy. That's where the EPIRB comes in.

With its ability to send a distress signal with precise location information to a global search and rescue system, an EPIRB significantly increases the chances of a successful rescue. It provides an effective means of calling for help even when other communication systems fail or are out of range.


Whether you're embarking on a commercial fishing trip, or a recreational voyage, an EPIRB is an essential piece of safety equipment. It's a small investment that can make a big difference when it matters most. Remember, the sea can be unpredictable, but with an EPIRB, you can be prepared for any eventuality.

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