💡 Key Takeaways

  • An EPIRB or PLB is the single most effective way to summon rescue from anywhere on the ocean — a satellite-linked 406 MHz beacon works where a VHF, a phone, or a flare simply cannot reach
  • EPIRBs and PLBs do different, complementary jobs: the EPIRB belongs to the boat and broadcasts longest, while a PLB is a personal device carried on each life jacket so anyone who goes overboard can still signal
  • Registration is not optional paperwork — it is what tells rescuers who you are, what boat you are on, and who to call, and it turns a raw signal into an effective rescue response
  • Batteries expire, and an expired battery is the most common — and most tragic — reason a beacon fails when it is finally needed, so checking and replacing on schedule is non-negotiable
  • A modern distress setup layers the EPIRB with AIS MOB devices and PLBs for the crew, because no single device covers every scenario

Why a Distress Beacon Is the Best Safety Buy You Can Make

In the hierarchy of safety equipment, the EPIRB occupies a special place: it is the one device that works when everything else has failed, in the one place where nothing else can reach. A VHF reaches only a few dozen nautical miles and only if someone is listening; a phone dies the moment you lose a network; and a flare needs someone to see it. But an EPIRB — an Emergency Position-Indicating Radio Beacon — transmits a digitally coded distress signal up to the satellites of the international Cospas-Sarsat system, which relay your identity and position to rescue authorities anywhere on the planet, even in the middle of an ocean. It is, in the bluntest terms, the difference between a bad day and a disaster.

The technology has also become remarkably affordable and reliable. A modern 406 MHz beacon is a sealed, battery-powered unit that sits in its bracket for years, tested occasionally, and activated only in a genuine emergency — and when it is activated, it works. For a fraction of the cost of a life raft, a beacon gives a yacht the ability to be found. This guide explains how EPIRBs and their smaller cousins, PLBs, work, how they differ, and how to choose, register, and maintain them so that the one time you need yours, it performs exactly as designed. It belongs alongside the rest of your preparation, which is why it pairs so naturally with our complete safety checklist.

EPIRB vs. PLB: The Boat and the Person

The first distinction to understand is between an EPIRB and a PLB, because they solve related but different problems. An EPIRB is registered to the vessel, is larger, floats upright in the water with its antenna raised, and transmits continuously for at least 48 hours — a powerful, long-duration signal designed for the boat-level emergency of abandoning ship or the vessel itself being lost. A PLB, or Personal Locator Beacon, is a much smaller device registered to an individual, worn on a life jacket or belt, and transmits for a shorter period (typically around 24 hours). It is the personal equivalent: if a crew member is separated from the boat, the PLB ensures that individual can still be located.

The two are complementary rather than competing. A well-equipped yacht carries a registered EPIRB mounted where it can be reached and deployed in an emergency, ideally with a hydrostatic release that activates it automatically if the boat sinks, and it stows the EPIRB in the grab bag alongside the life raft. Each crew member, meanwhile, carries a PLB so that a person-overboard does not depend on the boat surviving long enough to summon help. Together they cover both the "rescue the boat" and the "rescue the person" scenarios that a single device cannot. The broader question of what else belongs in your emergency planning — from life rafts to abandon-ship drills — is covered in our safety guide, and the beacons are the communication layer that makes all of it work.

The Third Layer: AIS MOB and How the Technologies Fit Together

Alongside the 406 MHz beacons, a newer category has become an essential part of the modern toolkit: the AIS MOB device. Where an EPIRB or PLB talks to satellites to summon rescue, an AIS MOB beacon broadcasts a short-range signal on the AIS frequency that is received directly by nearby vessels and, when you are close enough, by shore stations. Its advantage is speed and precision — a nearby boat's plotter will immediately display the overboard casualty's position and bearing, allowing your own vessel or a nearby yacht to recover the person long before a satellite-coordinated rescue could arrive.

The three technologies are best understood as layers of a single distress strategy. The AIS MOB finds and recovers a person in the water quickly, using the boats already in the area; the PLB guarantees the individual can summon satellite rescue if the boat cannot; and the EPIRB ensures the vessel itself can call for help and be found even if it is lost or the crew is adrift in the raft. Each has its own strengths and limitations — AIS requires someone in range, the EPIRB is boat-bound, the PLB has a shorter transmission life — and a serious cruising yacht carries all three rather than betting on one. This kind of layered redundancy is a recurring theme in good passage planning, where the goal is never to need the last resort but always to have it.

Registration: The Step That Makes It Work

Perhaps the most important — and most skipped — step in owning a beacon is registration. When you register your EPIRB or PLB, you link its unique identification number to your name, your vessel's details, and your emergency contacts, so that when the beacon is activated, the rescue coordination center immediately knows who is in trouble, what kind of boat they are on, and who to call ashore. Without registration, the same signal still sets off the alarm, but rescuers must spend critical minutes — or hours — working out who it belongs to and whether it is genuine, and that lost time can be decisive. Registration is free in almost every country, is a legal requirement in most, and takes only a few minutes online.

Just as important is keeping the registration current. People sell boats, change addresses, and update emergency contacts, and an out-of-date registration can send rescuers to the wrong person or the wrong details exactly when it matters most. Update your registration whenever your boat, your phone number, or your shore-side contact changes, and confirm it is still correct at the start of each season. It is the same discipline of keeping paperwork and details current that underpins good insurance and documentation, and it costs nothing beyond a few minutes of attention.

Batteries, Testing, and Maintenance

A beacon is only as good as its battery, and batteries have a hard, printed expiry date. Most EPIRBs carry a lithium battery cell with a service life of roughly five to ten years, and PLB batteries typically last around five; some can be replaced by the owner, while others must go back to a service center. The expiry date is marked on the unit, and the discipline is simple and unforgiving: replace the battery before that date, and never rely on an expired beacon. An expired battery may still show a green test light but deliver a dramatically shortened transmit time — the difference between a 48-hour signal and one that dies in minutes — precisely when your life depends on it.

Routine care is minimal but important. Run the dedicated self-test on the manufacturer's schedule (most allow a periodic test that does not trigger a false distress call), keep the beacon clean and dry, and confirm the hydrostatic release mechanism on an auto-deploying EPIRB is within its service date. Stow the beacon where it is both protected and immediately accessible — a bracket in a known location, not buried in a locker. Test procedures and the discipline of checking critical safety gear regularly are exactly the habits our safety checklist reinforces, and they turn a piece of stored equipment into a system you can actually rely on when the unthinkable happens. A beacon is a promise that you will be found; the testing and maintenance are what keep that promise real.