The Use of Emergency Position Indicating Radio Beacons (EPIRBs)


An Emergency Position Indicating Radio Beacon (EPIRB) is a transmitter that will send a distress signal up to a satellite system from anywhere in the World or up to aircraft if they are in range. With one, you can easily alert the emergency services in situations where you would be out of range of normal communications.

Whist useful for coastal sailors, EPIRBs could be considered to be essential for anyone contemplating an ocean crossing in a small yacht.

Register your EPIRB

They are registered to the specific boat, so if it is triggered the rescue services know exactly what they are looking for and to check that the boat is at sea (Many alerts are accidental).

Because EPIRBs are registered to the boat they must never be swapped from one vessel to another without being re-registered.

For the sailor who only occasionally needs to fit an EPIRB there are companies that will rent you one for short periods of time. In this situation it is important that the equipment is properly registered.

The authority for radio communications in the UK is OFCOM (Recently replaced The Radio Communications Agency), a registration form can be downloaded from their web site but the completed form should be sent to Falmouth Coastguard as they are the people who will deal with any incidents.

The EPIRB Registry, HM Coastguard Southern (Falmouth), Pendennis Point, Castle Drive, Falmouth, Cornwall, TR11 4WZ
Tel: 01326 211569 Fax: 01326 319264


The equipment

EPIRBs operate on 406.025GHz, this signal is received by the

COSPAS/SARSAT satellite system. These satellites are in low polar orbits this means that each time they orbit the world they cover a relatively narrow strip but because there are several and the world rotates under them, the entire surface of the Earth is covered in a few hours (NOAA EPIRBs info).

The vessel's position is worked out from the Doppler shift of the signal as the satellite passes overhead, this can result is the distressed vessel's position being know immediately or it may take a few hours. The system is not especially accurate, the position will be known to within about 3 nautical miles, not bad in the southern oceans, but not much use on a busy Saturday afternoon in the Solent!

If the satellite's foot print means that it can communicate with a ground station (Local User Terminal - LUT) when the signal from the EPIRB is first received, the signal is immediately transmitted to the ground, then to a Maritime Rescue Coordination Centre (MRCC). If the satellite is unable to communicate with an LUT, the distress signal is stored until the next time a download can be made.

Some EPIRBs also transmit on 121.5Mhz, this signal can no longer be received by the satellite as this was discontinued from Febrary 2009. The real benefit of the 121.5MHz signal is that it is an aircraft distress frequency and can be detected by airplanes and especially search and rescue helicopters. This extra signal can make "homing" in on the distressed vessel easier.

The equipment that detects the 121.5Mhz signal has been phased out on the COSPAS/SARSAT satellites, but it will remain an aircraft distress frequency


The latest generation of EPIRBs have GPS built in, this means that the position of a vessel in distress can be known to about 20m.

At present these EPIRBs are the most expensive but they will become standard in the future and the price will drop considerably.

Personal EPIRBS or locator beacons (PLB)

Some boats are fitting personal EPIRBs. These are small transmitters carried by each member of the crew, PLB detector kit.which will trigger an alarm on the yacht if the wearer falls overboard. The receiving unit then allows the operator to get a bearing back to the casualty, thus assisting greatly in the search. These EPIRBs transmit on the 121.5MHz frequency, so they are useful for a search and rescue aircraft to home in on but the equipment on the yacht can be used as a radio direction finder to work back to the casualty.

These are very useful devices, but as with all safety equipment, it needs regular practice to be useful in a real emergency. If you are often on watch alone one of these could save your life.

The state of the art equipment for PLBs is the 406Mhz with GPS from GME, it is small enough to be kept in your waterproof pocket but can reach the satellite system to indicate you are in distress.

Some amazing rescues have been possible because one of the crew was wearing a 406MHz Personal Locator Beacon.

Save money by ordering your EPIRB online. is free to use, but if you feel you would like to contribute to the running and development costs you can donate via Paypal:

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