EPIRB (Emergency Position Indicating Radio Beacons) and PLB (Personal Locator Beacons) are a fast effective way of distress alerting for any kind of vessel.

A 406MHz beacon enables the SAR (Search and Rescue) agencies to quickly and accurately identify and locate a casualty so that they can effect a successful rescue.

Do I need an EPIRB?

Put quite simply an EPIRB could mean the difference between surviving an incident at sea and losing your life. This could be because you are in a communications “hole” or because your boat has lost its VHF communications (through for example losing the VHF antenna e.g. in a dismasting, electrical failure or sinking); you don’t necessarily need to be hundreds of miles off shore and miles away from other vessels to be thankful of an EPIRB.

An EPIRB does not rely on there being a vessel within VHF range to hear your Mayday call, nor does it rely on somebody spotting your flares; it simply relies on the beacon being activated and functioning correctly.

For vessels regularly cruising outside reliable VHF range, a 406MHz beacon should be considered an essential piece of equipment, rather than a desirable extra, particularly for long-range cruising boats. The RYA recommends that small craft which cruise outside VHF range carry a beacon.

For occasional trips further afield than your regular cruising ground or offshore you could consider hiring an EPIRB if you don’t want to own one or if the cost of doing so is prohibitive.

What should I buy?

EPIRBs and PLBs on the market today are dual frequency; the distress alert is transmitted on 406MHz and advises the SAR authorities of an incident and the 121.5MHz frequency is used as an effective homing frequency, once SAR is near to the casualty.  NB satellite processing of 121.5/243 MHz transmissions ceased as of 1st February 2009 and beacons which operate only on this frequency should no longer be relied on for distress alerting.


EPIRB manufacturers normally offer two types of fixing brackets for the EPIRB - manual or automatic.  With a manual bracket human intervention is required to remove the EPIRB from its bracket before its activation. The automatic bracket is designed to automatically release the EPIRB from its housing as the vessel sinks; once in contact with salt water, the EPIRB should start to transmit its emergency signal without you having to do a thing. 

The location of the EPIRB needs to be carefully thought through, especially if you decide on an automatic bracket, in which case the EPIRB must be in a position that enables it to be freely released should your boat founder, but which also affords it protection from accidental damage by crew or from being accidentally wet (or worse still washed overboard) and prevents it from being removed or stolen when the boat is unattended. A manually activated beacon is usually either clipped on the bulkhead, just inside the companionway or is kept in the life raft grab bag.


As an alternative a 406 MHz Personal Locator Beacon (PLB) could be considered. This is in essence a personal EPIRB. A PLB is registered to a person rather than to a vessel and it is always manually activated. It is again available with or without an integral GPS and once activated it sends the same signal via the same route as an EPIRB to the same destination. Due to a shorter battery life of around 24 hours, the signal will cease transmission sooner than would be the case with the EPIRB.

PLB can be used offshore, but are more likely to be the choice for users of smaller boats, RIB and personal watercraft (PWC). Carrying a PLB on your person could also be of advantage if you find yourself unexpectedly in the water either through the boat sinking rapidly or in the event that you have gone overboard.

The key considerations when choosing between an EPIRB and PLB are:

  • the type of boating you do and the size of the boat
  • the size of the equipment and how it will be stowed / carried
  • with or without integral GPS (this significantly shortens the time it takes the beacon to alert the rescue service)
  • the battery life (how long the beacon will transmit the signal for after it is activated)
  • the operational temperature range
  • manual or automatic (on contact with water) activation

There is nothing to stop you registering more than one beacon per vessel or person.

How do they work?

The frequencies in the band 406.0 - 406.1 MHz are reserved for the exclusive use of distress beacons operating with satellite systems and it is on this 406 MHz frequency a distress radio beacons transmits if activated.

  1. the signal it transmits is detected by instruments on board satellites in the COSPAS-SARSAT International Satellite System for Search and Rescue.
  2. Local Users Terminals which are the ground receiving stations receive and process the satellite downlink signal, thereby generating distress alerts.
  3. the distress alerts are passed to a Mission Control Centre which
  4. relays them to the search and rescue point of contact. For a UK registered beacon this would be the Joint Rescue Co-ordination Centre at Fareham.

The signal transmitted by the distress radio beacon includes a digital message which allows the transmission of encoded data such as the unique identifier for the beacon that transmitted the alert and if the beacon has an integral GPS, the beacon’s position.  Otherwise the beacon’s signal may need to be detected by two or three satellites before its position can be sufficiently estimated, therefore it may take longer for SAR to be initiated.

The unique identifier links the beacon to the data held by the UK 406 MHz Beacon Registry about the vessel or person. This database is available 24/7 and gives the Rescue Co-ordination Centre critical information, such as what type of vessel is in distress.  They need to know whether they are dealing with a cruise ship carrying thousands of people, a container ship or tanker, a fishing boat or a yacht, to know what response is needed. 

406 beacon poster

What are the laws surrounding EPIRB?

Under the Merchant Shipping (EPIRB Registration) Regulations 2000 it is mandatory to register 406 MHz beacons (EPIRB or PLB) with the competent authority - HM Coastguard. Changes to registered particulars must also be notified and it is an offence by the owner and/or the operator not to follow these requirements.

Your EPIRB or PLB must therefore be licensed on your Ship Radio Licence (or Ship Portable Radio Licence as applicable) and registered with the UK Beacon Registry.

New beacon registrations and updates to registrations can both be completed online.  Contact the UK Beacon Registry for help with registering. Registrations and updates are free in the UK.

The UK Beacon Registry: contact details

Full details of your obligations can be found in MSN 1816.

EPIRBs are elements of the Global Maritime Distress and Safety System (GMDSS), which aims to be a complete global distress and communications system for the mariner. In addition, the GMDSS incorporates satellite communications, NAVTEX and Digital Selective Calling. 

Related page

Personal Emergency Radio Devices: https://www.gov.uk/government/publications/personal-emergency-radio-devices-leaflet