What is an Emergency Position Indicating Radio Beacon or EPIRB?

Promoting boating safety is a shared responsibility. Discover Emergency Position Indicating Radio Beacons (EPIRBs), crucial for alerting Search and Rescue teams of your precise location in emergencies. Explore how modern AIS EPIRBs streamline Search and Rescue efforts.

The History of the EPIRB

Emergency Position Indicating Radio Beacons (EPIRBs) have been saving lives at sea for decades. Early EPIRBs, such as the large yellow Lokata beacons developed in the 1980s, provided mariners with a vital way to alert rescuers in an emergency.

The introduction of the international 406 MHz Cospas-Sarsat satellite system revolutionised maritime safety by enabling distress alerts to be detected anywhere in the world. Over time, EPIRBs evolved from large, analogue devices into compact, highly accurate beacons equipped with GNSS positioning.

Today’s most advanced EPIRBs, such as the Ocean Signal EPIRB3 series, build upon decades of innovation by incorporating AIS, Return Link Service (RLS), and smartphone connectivity via NFC—helping rescuers locate survivors faster than ever before.

What is an EPIRB?

An Emergency Position Indicating Radio Beacon (EPIRB) is a satellite distress beacon designed to alert search and rescue authorities anywhere in the world during a marine emergency. Modern EPIRBs use the international 406 MHz Cospas-Sarsat satellite network, integrated GNSS positioning, and can now include AIS and Return Link Service (RLS) technologies.

How Do They Work?

EPIRBs emit a digital 406 MHz distress signal, containing a unique 15-digit identifier, to the Cospas-Sarsat Satellite System. Depending on your vessel’s registration, this may be a serial number or its Maritime Mobile Service Identity (MMSI) number.

For EPIRBs with a serial number, Search and Rescue forces retrieve your beacon registration (also free but mandatory for all EPIRB owners). This provides ownership details and additional emergency contacts. EPIRBs with an MMSI number require the EPIRB 15 Hex ID to be added to the relevant maritime database.

EPIRBs relay your location to Search and Rescue forces either through GPS data or triangulation calculations from satellites. This information is relayed to the nearest Rescue Coordination Center, initiating your rescue mission. They utilize the EPIRB’s 121.5 MHz homing signal, AIS location signal (on newer EPIRBs), and strobe lights to pinpoint your location for a safe return.

What Happens When You Activate an EPIRB?

When activated, an EPIRB immediately begins transmitting a distress alert through the international Cospas-Sarsat satellite network, helping Search and Rescue authorities locate you anywhere in the world. Here’s what happens step-by-step:

1. EPIRB Activated
   • In an emergency, the EPIRB is activated either manually (Cat2) or automatically (Cat1) when immersed in water (depending on the model and bracket type).
     
2. GNSS Position Acquired
   • The EPIRB’s built-in GNSS receiver (GPS, Galileo, GLONASS, or BeiDou) determines your precise location, typically to within 100 metres.
     
3. 406Mhz Distress Alert Transmitted
   • The beacon transmits a digital distress signal on 406 MHz containing its unique identification number and, if available, your GNSS coordinates.
     
4. Cospas-Sarsat Satellites Receive the Signal
   • The distress message is detected by the international Cospas-Sarsat satellite system, which relays the alert to ground stations around the world.
     
5. Rescue Coordination Centre Notified
   • The nearest Rescue Coordination Centre (RCC) receives the alert, accesses your beacon registration details, and begins coordinating rescue operations.
     
6. Nearby Vessels Alerted via AIS (AIS-Enabled EPIRBs)
   • EPIRBs equipped with AIS simultaneously transmit a local AIS distress signal, allowing nearby vessels to navigate directly to your location.
     
7. Rescue Assets Home With a Direction Finder Using 121.5 MHz
   • As rescue aircraft or vessels approach, they use the EPIRB’s 121.5 MHz homing signal and visual strobe light to pinpoint your exact location and complete the rescue.

Modern EPIRBs with AIS and Return Link Service (RLS) can further improve rescue times by alerting nearby vessels and confirming that your distress message has been received by Search and Rescue authorities.

What is the range and/or location accuracy of an EPIRB?

Once activated, an EPIRB transmits your distress signal via satellite to the global Cospas-Sarsat network. EPIRBs equipped with a GNSS/GPS receiver provide location accuracy typically within 100 meters, helping rescue coordination centers determine your position quickly and precisely. For even greater precision during the final stage of rescue, AIS-enabled EPIRBs also broadcast your location via VHF to nearby AIS-equipped vessels and SAR teams — often accurate to within 10 meters Additionally, EPIRBs transmit a 121.5 MHz homing signal that rescue aircraft or boats can track. The range of this homing signal depends on factors like the height and sensitivity of the receiving antenna.

• GNSS: ~100M
• AIS: ~10M
• 121.5MHZ final homing

Do EPIRB’s Work Worldwide?

Yes. All 406 MHz EPIRBs operate worldwide via the international Cospas-Sarsat satellite network. Unlike satellite messengers and Smartphone Emergency SOS features, there are no subscription fees required to send a distress alert.

Are EPIRBs Waterproof?

Yes. All Ocean Signal EPIRBs are fully waterproof and designed to operate in harsh marine environments. They float, are submersible to at least 10 meters, and EPIRBs removed from their bracket will automatically activate when immersed in water. Built-in sensors help prevent false alarms while the beacon remains correctly installed in its bracket.

Now with AIS (Automatic Identification System)

Incorporating AIS technology into some recently approved EPIRBs enables immediate distress and location notification to nearby vessels equipped with AIS transponders upon activation. This allows for prompt rescue operations without relying solely on Search and Rescue authorities. AIS also facilitates local responders in accurately pinpointing the EPIRB’s location, presented as an AIS target on their onboard display. Vessels with onboard AIS can navigate directly to the EPIRB, thus accelerating recovery times and potentially saving lives.

In many emergencies, nearby vessels may reach a casualty significantly faster than official rescue assets. AIS-enabled EPIRBs allow those nearby vessels to navigate directly to the beacon’s location.

What Are The Advantages Of AIS ?

Switching to an AIS EPIRB offers two main benefits: (1) reducing the distress search radius to 10 meters, and (2) sending emergency alerts to all AIS-equipped vessels within VHF range. These features enhance the capability to save more boaters’ lives annually.

What Is Return Link Service or RLS?

Return Link Service (RLS) uses the Galileo satellite network to confirm that your distress alert has been received by search and rescue authorities. A flashing blue LED provides reassurance that your emergency signal and location have been successfully detected. A Return Link Service signal, transmitted via the Galileo satellite network, confirms detection of the distress message, precise beacon location, and identifiers. This reassurance that rescuers are aware of the activated EPIRB and its location helps alleviate stress in mayday situations.

When To Activate?

Activation should only be initiated in grave and imminent danger, where loss of life, limb, or valuable property is likely without emergency assistance. From a sinking vessel to a medical emergency at sea, an EPIRB is crucial for quick rescue.

How to Use an EPIRB?

EPIRBs can be deployed manually or automatically, depending on the bracket category and situation.

As discussed earlier, In an automatic Float Free Category 1 bracket, the EPIRB releases when the Hydrostatic Release Unit (HRU) is submerged in water at a depth of 1.5 – 4 meters. The release depth varies to accommodate different water temperatures, requiring HRU replacement every two years. In an emergency, the EPIRB detaches from its bracket, surfaces, and signals search and rescue teams for rapid assistance.

EPIRBs in a Category 2 bracket require manual deployment and activation. They can be installed above or below deck, shielded from external influences (e.g., water, traffic, cabin doors). Some users store their beacon in a Ditch bag, but caution is advised as EPIRBs activate upon water immersion, risking false alarms. In Australia and New Zealand, “Class 3” EPIRBs lack water activation, requiring manual activation only, ensuring their performance isn’t affected by water exposure.

What Are The Differences In Brackets?

Cat1 OR Category 1 brackets: automatically release the EPIRB in a sinking vessel scenario

• Should the vessel sink the EPIRB will automatically be released from its Hydrostatic Release Unit (HRU) when it is submerged in water at a depth of 1.5 – 4 meters and float to the surface. Contact with the water will automatically activate the EPIRB.

Cat2 or Category 2 brackets are manual release.

• When deploying the EPIRB on a deck (Or from a life raft), ensure it is vertical and clear of obstructions that might impede a clear view of the sky. If the unit is thrown into the water then it will activate automatically.

• Both bracket types include a built-in water sensor to prevent false alarms if the beacon gets wet while in the bracket.
• Manual activation of the beacon is possible in both brackets, provided the antenna faces the sky.

Where Should I Mount My EPIRB?

EPIRBs should be mounted in an accessible location on your vessel where they can be quickly reached in an emergency. For Ocean Signal EPIRBs, you have two main options:

• Manual Bracket (Cat2): Mount it in the cockpit, near the companionway, or close to the liferaft station — somewhere visible, dry, and easy to grab during an emergency.
  
• Float-Free Bracket (Cat1) (SOLAS vessels): Mount externally where the EPIRB can automatically deploy if the vessel sinks (usually on a vertical surface, clear of obstructions, and above the waterline when afloat).

Always follow the mounting instructions in the user manual, and ensure the EPIRB has a clear view of the sky when deployed.

How to Register My Beacon?

You must register your EPIRB with your local authority. Here are instances where registration is necessary:

• When purchasing a new or used 406 MHz beacon, registration with the local government is mandatory.
  
• Updating registration details (e.g., phone number, address, purchasing a new boat) requires updating the 406 MHz beacon registration.
  
• Upon selling your 406 MHz beacons, inform the local government and ensure the buyer registers the beacon personally to avoid potential contact from rescue authorities upon activation.

EPIRB registration renewal with serial numbers should occur every 2 years at least (for most recreational boats), while for other EPIRBs, it should be checked as mandated by the relevant administration. Most registrations can be conveniently updated online, enabling you to easily include a float plan or additional trip details whenever necessary.

Consider beacon Registration as an integral part of your rescue process. By providing detailed and regularly updated information, you’re equipping rescue teams with the essential details to expedite your rescue effectively.

EPIRB Registration by Country: Where to Register Your 406MHz Beacon

Registering your EPIRB is a vital part of the rescue process. When a 406 MHz distress beacon is activated, Search and Rescue authorities use registration information to identify your vessel, contact emergency contacts, and coordinate a faster rescue. Registration is typically free and should be updated whenever your contact details, vessel information, or ownership changes.

• United States 🇺🇸 – NOAA SARSAT Beacon Registration: https://beaconregistration.noaa.gov/
• Canada 🇨🇦 – Canadian Beacon Registry: https://www.cbr-rcb.ca/
• United Kingdom 🇬🇧 – UK Beacon Registry: https://www.gov.uk/register-406-beacons
• Australia 🇦🇺 – AMSA Beacon Registration: https://beacons.amsa.gov.au/
• New Zealand 🇳🇿 – RCCNZ Beacon Registry: https://beacons.org.nz/
• France 🇫🇷 – French Beacon Registry: https://registre406.cnes.fr/
• Germany 🇩🇪 – DGzRS: https://www.seenotretter.de/
• Italy 🇮🇹 – Italian Coast Guard: https://www.guardiacostiera.gov.it/
• Spain 🇪🇸 – SASEMAR: https://www.sasemar.es/
• Netherlands 🇳🇱 – Netherlands Coastguard: https://www.kustwacht.nl/
• Sweden 🇸🇪 – Swedish Maritime Administration: https://www.sjofartsverket.se/
• Norway 🇳🇴 – Norwegian Beacon Registry: https://www.brs.no/
• Denmark 🇩🇰 – Danish Maritime Authority: https://dma.dk/
• Finland 🇫🇮 – Traficom: https://www.traficom.fi/
• Japan 🇯🇵 – Japan Coast Guard: https://www.kaiho.mlit.go.jp/e/

Country not listed? Visit the official Cospas-Sarsat Beacon Registration Directory to find your national registration authority: https://cospas-sarsat.int/en/beacon-ownership/registration-system
For more information on how the international 406 MHz distress system works, visit the official Cospas-Sarsat website: https://www.cospas-sarsat.int/

Please note: Registration procedures and legal requirements vary by country. Always follow the guidance provided by your national maritime or Search and Rescue authority, and remember to update your registration whenever your vessel ownership, contact details, or emergency contacts change.

Do EPIRBs Have Subscription Fees?

In short, no. EPIRBs operate on government-funded Search and Rescue Satellites (Cospas-Sarsat), and once you own an EPIRB (or Personal Locator Beacon), there are no obligatory monthly or annual subscription fees*. In fact, EPIRBs save millions of taxpayer pounds annually by streamlining search and rescue operations.

In the event of beacon activation, rescue services are typically provided free of charge in most regions worldwide.

*Some countries do charge a radio license fee, inquiry with your national authorities.

How Often Do You Replace a Battery?

Regular maintenance of your beacon is crucial for an effective survival strategy, and replacing the EPIRB battery (and HRU, if applicable) is vital for your safety. Every beacon has a battery expiration date, and batteries should be replaced according to the interval specified by the relevant authority, or at the latest by the device’s expiry date. Some authorities mandate regular servicing, typically every 4 or 5 years, and often require battery replacement during these checks, regardless of the battery’s expiration date.

Find a Battery Replacement Center: Ocean Signal / ACR Electronics

How Do I Ensure My Beacon Is Operational?

Conduct a monthly self-test to verify your beacon’s functionality. If the test is successful, your beacon is operational. Should the self-test fail, arrange for the beacon to be serviced.

The new EPIRB2 and EPIRB3 series offer NFC (Near Field Communication) technology, enabling users to access EPIRB diagnostics via smartphones. Simply place your smartphone near the EPIRB, and the Ocean Signal Product App will open, providing access to device data. The app displays beacon status information, including current battery life, self-test and GNSS test completion, activation duration, and detailed test results. GNSS tests offer a map view pinpointing the test location, date and time, fix acquisition time, satellites used, and fix accuracy. Easy NFC connectivity ensures users can conveniently verify all beacon functions.

EPIRB Regulations

Numerous countries enforce regulations mandating EPIRB carriage on various vessel types (e.g., Fishing Vessels, Large Commercial Vessels, Passenger Vessels, etc.). Some countries also require them on recreational craft venturing beyond a specified offshore distance. The International Maritime Organization (IMO) oversees EPIRB carriage on ships trading internationally, and many countries extend these regulations to vessels in their own waters. It’s vital to review the rules and regulations applicable to your vessel (based on its registration) and ensure you possess the required safety equipment, which may include an EPIRB.

Is an EPIRB better than a PLB (Personal Locator Beacon)?

Whether an EPIRB or PLB is better depends on your type of boating. EPIRBs are designed for vessels and activate automatically in the water, making them ideal for offshore or unattended situations. PLBs, on the other hand, are smaller, manually activated, and worn by crew – perfect for personal use. For a full comparison, check out our EPIRB vs PLB guide.

EPIRB vs PLB Comparison

Feature	EPIRB	PLB
Designed for	Vessel	Person
Automatic water activation	Yes	Usually No
Float-free deployment	Cat I only	No
Typical battery life	10 years / 48 Hour Activation time	7 years / 24 Hour Activation Time
Use cases	Offshore Sailing/Cruising	Hiking, aviation, boating
Lifejacket Compatible	No	Yes (can be automatically activated upon inflation)

Survivor Stories – Real Lives Saved by EPIRBs