EPIRB and PLB for Boats: The Complete 2026 Safety Guide

An EPIRB or a PLB is the single piece of equipment on your boat that exists for one moment: the moment everything else has failed and you need someone to come find you in open water. This guide explains how an EPIRB works, how a PLB differs from it, and how the whole 406 MHz beacon system talks to the satellites overhead. If you have been trying to settle the epirb vs plb question, sort out epirb registration, or figure out what a 406 mhz beacon actually does when you press the button, you are in the right place. I have spent years teaching crews how to rig, register, and trust these devices, and I want you to leave here able to choose one, mount it, and register it correctly.

A beacon is not a gadget you buy and forget. It has a battery with an expiry date, a registration record that has to match reality, and a mounting position that decides whether it saves your life or floats away without you. Get those three things right and a 406 MHz beacon is the most reliable rescue tool ever put on a small boat. Get them wrong and you are carrying an expensive paperweight. Let us make sure yours works.

What an EPIRB actually is

EPIRB stands for Emergency Position Indicating Radio Beacon. It is a self-contained distress transmitter that belongs to the vessel. When it is switched on, it sends a coded digital burst on 406 MHz that is picked up by a network of satellites, and it holds a battery large enough to keep transmitting for at least 48 hours in cold water. That endurance requirement, 48 hours minimum at minus 20 degrees Celsius, is one of the main things that separates an EPIRB from a smaller personal beacon. The device is registered to a specific boat, and the distress message it sends carries a unique identity code so that rescue services know exactly whose beacon is calling before they even reach you.

The physical unit is usually the size of a large water bottle. It is bright orange or yellow so it is visible in the water, it floats, and it has a strobe or high-intensity LED so a helicopter or lifeboat can spot it at night once they are in the area. Every modern EPIRB sold today is a 406 MHz beacon with a built-in GPS receiver, and most new models also carry a second, low-power 121.5 MHz transmitter used only for close-range homing. We will get to why both frequencies matter.

What a PLB is, and how it differs

PLB stands for Personal Locator Beacon. It uses the same 406 MHz satellite system and sends the same kind of coded distress message, but it is designed to be carried by a person rather than fixed to a boat. It is smaller, it clips into a pocket or a life-jacket, and it is registered to an individual instead of a vessel. That difference in registration is not a technicality. If you fall overboard wearing a PLB, the alert is tied to your name and your emergency contacts, and it goes with you no matter which boat you are on.

The trade-off is endurance and buoyancy. A PLB is only required to transmit for 24 hours instead of 48, its battery is smaller, and many PLBs do not float on their own unless you buy a flotation pouch. Some models float, many do not, so read the specification before you assume. A PLB also has to be switched on by hand. It will never activate itself, which brings us to the most important practical difference of all: automatic activation, a feature only an EPIRB offers.

How the system works: 406 MHz, Cospas-Sarsat, and 121.5 homing

The satellite side of all this is a program called Cospas-Sarsat, an international system run jointly by the United States, Russia, Canada, and France, now supported by dozens of participating nations. It has two layers. The older layer rides on satellites in low earth orbit and medium earth orbit. The newer and now dominant layer, called MEOSAR, uses receivers hosted on the GPS, Galileo, and GLONASS navigation satellites, which means a huge constellation is always overhead. In practical terms, when you activate a 406 mhz beacon today, the signal is very often detected within a minute or two because so many satellites can hear it at once.

The 406 MHz burst carries a digital identity called a hex ID, sometimes written as the UIN or 15 hex ID. That code is what links the beacon to your registration record. The satellites relay the burst to ground stations, the ground stations decode the identity and the position, and the alert is passed to the rescue coordination center responsible for your region. In the United States that means the alert reaches the US Mission Control Center at NOAA, which forwards it to the Coast Guard or to the appropriate authority inland.

Position comes from two sources working together. First, the beacon's own GPS receiver puts your latitude and longitude directly into the digital message, usually accurate to within about 100 meters. Second, the MEOSAR satellites can independently calculate your position from the signal itself using Doppler and time-difference measurements, which gives rescuers a backup fix even if the internal GPS never got a lock. Together these usually produce a confirmed position within minutes.

The old 121.5 MHz frequency is no longer monitored by satellites, and it has not been since 2009, so do not buy a 121.5-only beacon. It survives on modern beacons only as a short-range homing signal. Once a search aircraft, a helicopter, or a lifeboat is roughly in your area, its direction-finding gear locks onto that weak 121.5 tone and walks straight to you. The 406 signal gets rescuers to the right patch of ocean, and the 121.5 homer gets them the final mile to your hull. Newer beacons add a third layer on top of both.

GPS-equipped and AIS-equipped beacons

Two features are worth paying for on any beacon you buy in 2026. The first is GPS, and at this point it is effectively standard. Skip any beacon that lacks it. The internal GPS is what turns a rough satellite fix into a precise one, and it shortens the time between activation and a confirmed location.

The second feature is AIS. An AIS-equipped beacon also transmits a local Automatic Identification System distress signal, the same technology commercial ships and many yachts use to see each other on a chart plotter. This does nothing for the satellites, but it does something the satellites cannot: it lets any AIS-equipped vessel within a few miles see your exact position pop up on their own screen immediately. In a crowded coastal area or on a boat where crew went overboard, that local alert can bring help faster than the satellite chain, because the nearest rescuer is often another boat, not a helicopter an hour away. Ocean Signal, ACR, and McMurdo all sell AIS-equipped models now, and for coastal crews I recommend them strongly.

Category 1 versus category 2 EPIRBs

When you shop for an EPIRB you will see it described as Category 1 or Category 2. This is one of the most misunderstood choices in marine safety, and it is genuinely important, so read this section twice.

A Category 1 EPIRB is mounted in a bracket fitted with a hydrostatic release. A hydrostatic release is a small pressure-sensitive device that lets go of the beacon automatically once it is submerged to a depth of roughly one to four meters. If your boat sinks fast, if it rolls and goes down before anyone can reach the beacon, the hydrostatic release cuts the beacon free, it floats to the surface on its own, and because Category 1 units are set to activate when they float upright in water, they begin transmitting without a single human hand touching them. This is the whole point. In the worst sinkings, nobody has time to grab anything.

A Category 2 EPIRB is mounted in a simple bracket with no hydrostatic release. It only activates when a person takes it out of the bracket and switches it on, or in some models when it is manually placed in water. It is cheaper, it is smaller, and it is perfectly acceptable for a boat where you can reasonably expect someone to reach it and deploy it by hand, such as a day boat that stays close to shore.

The hydrostatic release itself is a serviceable, dated part. It carries an expiry, typically two years from manufacture, and it must be replaced on schedule or the automatic function is void. People forget this constantly. They buy a Category 1 unit, congratulate themselves on the auto-deploy feature, and then let the hydrostatic release lapse so that in a real sinking the bracket never releases the beacon. Put the release expiry on your calendar the day you install it.

Category 1 versus Category 2 EPIRB

Feature	Category 1	Category 2
Deployment	Automatic float-free plus manual	Manual only
Bracket type	Hydrostatic release housing	Fixed non-release bracket
Activates in a sinking without a person	Yes, floats free and self-activates	No, someone must remove and switch on
Extra dated part to service	Hydrostatic release, replace about every 2 years	None beyond the beacon battery
Typical 2026 cost	Around 550 to 850 US dollars	Around 350 to 600 US dollars
Best for	Offshore, overnight, single-handed, fast-sinking risk	Coastal day boats with crew who can deploy by hand

My blunt advice: if you go offshore, sail short-handed, or ever leave the helm unattended overnight, buy Category 1. The cost difference is a rounding error against the scenario it is designed for. If you stay within a few miles of a busy shore and always have hands aboard, Category 2 is a defensible choice.

Registration: NOAA in the US and national databases everywhere else

This is the step people skip, and skipping it is the difference between a fast rescue and a slow one. Every 406 MHz beacon must be registered before it goes on the water, and epirb registration is free everywhere it is required. The registration links your beacon's hex ID to a record that tells rescuers who you are, what your boat looks like, and who to call to confirm you are actually missing.

In the United States, EPIRBs and PLBs are registered with NOAA through the online registration site at the National Oceanic and Atmospheric Administration. You enter the beacon's unique hex ID, your name and phone number, your emergency contacts, and a description of the vessel or, for a PLB, of you and your typical activities. NOAA registration is free, it takes about fifteen minutes, and it must be renewed every two years. NOAA will email you a reminder, but do not rely on that. Set your own reminder.

Outside the United States, you register with your own country's beacon registry, not with NOAA. In the United Kingdom that is the Maritime and Coastguard Agency. In Canada it is the Canadian Beacon Registry. In Australia it is the Australian Maritime Safety Authority. In every case the principle is identical: the registry is national, the registration is free, and the beacon's country code, coded into the hex ID at the factory, tells the satellite system which national database to query. This is why you should buy a beacon coded for the country where the boat is actually based.

Two registration mistakes cause real harm. The first is never registering at all, which turns a precise position report into an anonymous alert that rescuers must treat with more caution and slower confirmation. The second is letting the record go stale. If you sell the boat, change your phone number, or update your emergency contacts, log in and fix the record the same week. When a beacon fires at three in the morning, the rescue center's first move is to phone your emergency contacts to confirm you are at sea and not sitting in a marina with a faulty unit. A dead phone number breaks that chain.

Battery replacement intervals and servicing

A beacon battery is not a rechargeable pack you top up. It is a sealed lithium battery pack with a fixed shelf life, and it is designed to sit unused for years and then deliver full power the one time you need it. Because of that design, replacement is by calendar date, not by usage.

Most EPIRB batteries carry a replace-by date of ten years, some brands specify five to seven, and the exact figure is printed on the beacon housing and stored in your registration paperwork. When that date arrives, the beacon must go back to an authorized service agent to have the battery pack replaced. You cannot buy a battery and swap it at the kitchen table, because opening the sealed housing compromises the waterproof integrity and the unit has to be pressure-tested and recertified afterward. Battery replacement plus service typically runs 150 to 300 US dollars in 2026, which is why some owners simply replace the whole beacon when the battery expires if a newer AIS model has come out in the meantime.

PLB batteries follow the same logic on a shorter clock. Many PLBs are rated for a five to six year battery life, and some manufacturers treat the PLB as effectively disposable at end of battery life, replacing the whole unit rather than servicing it. Check the model before you buy so you know which path you are committing to.

Separate from the battery, there is a periodic function test you should run yourself. Every 406 MHz beacon has a self-test button that checks the electronics, the battery voltage, and the GPS without sending a real distress signal. Run the self-test monthly and log it. Do the extended GPS self-test the manufacturer describes a few times a year, ideally with a clear view of the sky. And remember the Category 1 hydrostatic release is on its own two-year clock, independent of the ten-year battery. Two dated parts, two calendar entries.

Mounting: where the beacon lives decides whether it works

A Category 1 EPIRB must be mounted outside, in the open, where nothing overhead can trap it when the boat goes down. Mount it on the cockpit coaming, on the aft rail, or on the exterior of the wheelhouse, high and clear, with unobstructed water above it so the hydrostatic release can float the beacon straight to the surface. If you bolt a float-free EPIRB inside a locker or under a hard bimini, you have defeated the entire mechanism. The beacon releases, rises, and slams into the underside of a deck it can never get past.

A Category 2 EPIRB can live inside, but it should be somewhere obvious and reachable in seconds, not buried in the bottom of a lazarette under the fenders. The best place is on a bulkhead near the companionway or the helm, on the escape route you would take when abandoning ship, so grabbing it is part of the same motion as getting out.

Whatever the category, keep the mounting bracket free of corrosion, check that the release mechanism moves freely, and make sure the beacon has a clear view of the sky from where it sits, because the internal GPS needs that view to get a fast lock. Never store a beacon where it bakes in direct engine heat or gets doused in fuel. And rig your grab bag so a PLB or a handheld backup goes into the life raft with you regardless of what the EPIRB does.

When a beacon is legally required versus recommended

The legal picture depends on where you are, what you do, and how big your boat is. For most recreational boaters in the United States, an EPIRB is not federally mandated. There is no general rule that a private pleasure boat must carry one. That surprises people, and it should not be read as permission to skip it. The absence of a law does not lower the risk of the water.

Requirements do bite in specific cases. Commercial vessels, uninspected commercial fishing boats operating beyond certain distances offshore, and passenger-carrying vessels face EPIRB mandates under Coast Guard and SOLAS rules depending on size and route. Many offshore races and rallies require a registered EPIRB as a condition of entry, and their safety inspectors will check the registration and the battery date, not just that a beacon is bolted to the rail. Charter operations and yachts working under a flag-state safety code often must carry a Category 1 unit. If you operate commercially or race offshore, treat the beacon as required and confirm the exact rule for your flag and category.

For everyone else, the honest framing is this: an EPIRB is recommended anywhere you can go beyond swimming distance of help, and it becomes close to essential the moment you go offshore, sail overnight, or cruise anywhere a phone has no signal and other boats are scarce. A PLB clipped to each crew member's life-jacket is the strongest recommendation I make to anyone who spends time on deck in rough water, whether the law requires it or not.

EPIRB versus PLB versus satellite messenger

This is where a lot of buyers get stuck, because the market now sells three overlapping things: EPIRBs, PLBs, and satellite messengers like the Garmin inReach or the ACR Bivy Stick. They are not the same, and the differences matter in an emergency.

An EPIRB and a PLB both talk to the Cospas-Sarsat rescue satellites on 406 MHz, they are both regulated distress beacons, and pressing the button connects you directly to government search and rescue with a coded, guaranteed-priority alert. A satellite messenger talks instead to a commercial satellite network, usually Iridium, and routes an SOS through a private monitoring company that then contacts rescue authorities on your behalf. The messenger's huge advantage is two-way text: you can tell the responders what is wrong, and they can tell you help is coming. Its disadvantages are that it depends on a paid subscription staying active, it depends on a commercial relay staying online, and its transmit power is far lower than a 406 beacon's, so it can struggle to punch a signal out under heavy cloud or a poor sky view.

My recommendation for anyone going offshore is not to choose between them. Carry a registered EPIRB as the primary, guaranteed distress beacon fixed to the boat, and carry a satellite messenger as well for two-way communication and for the reassurance of knowing your family can see you moving. If budget forces one device for a person on deck, a PLB is the safer single choice, because it needs no subscription and it connects straight to rescue services with full 406 power.

EPIRB versus PLB versus satellite messenger

Attribute	EPIRB	PLB	Satellite messenger
Registered to	The vessel	A person	A user account
Distress network	Cospas-Sarsat 406 MHz	Cospas-Sarsat 406 MHz	Commercial (usually Iridium)
Subscription needed	No	No	Yes, ongoing fee
Automatic activation	Yes on Category 1	No, manual only	No, manual only
Battery transmit time	48 hours minimum	24 hours minimum	Days on standby, varies
Two-way messaging	No	No	Yes
Floats on its own	Yes	Often no, needs pouch	Usually no
Typical 2026 cost	350 to 850 US dollars	250 to 400 US dollars	200 to 450 plus subscription

Real brands worth knowing in 2026

Three names dominate the beacon market, and all three make reliable, fully certified equipment. Knowing them helps you shop without getting lost.

ACR Electronics is the best-known name in the United States and makes the GlobalFix series of EPIRBs and the ResQLink series of PLBs. The GlobalFix V5 is a common Category 1 and Category 2 choice for offshore boats, and the ResQLink series is a popular buoyant PLB for crew. ACR also makes the AISLink beacons that add the local AIS distress feature described earlier.

Ocean Signal, a British brand now part of the same group as ACR, makes the compact rescueME EPIRB1 and the very small rescueME PLB1, which is one of the smallest full-power PLBs on the market and fits a life-jacket pocket easily. Ocean Signal's EPIRB3 adds AIS and near-field Bluetooth for testing from a phone app, a genuinely useful feature for logging your self-tests.

McMurdo is a long-established maritime brand strong in the commercial and professional market, making the SmartFind range of EPIRBs and the FastFind PLBs. McMurdo units are common on charter yachts and commercial vessels where a flag-state code applies.

Whichever brand you choose, the buying rules are the same. Insist on 406 MHz with built-in GPS, choose AIS if you cruise coastal or crewed waters, choose Category 1 if you go offshore, buy a unit coded for the country the boat is based in, and check the battery and, where relevant, the hydrostatic release dates before money changes hands.

False alerts and how to prevent them

Rescue coordination centers deal with a steady stream of false 406 MHz alerts, and most of them come from a small set of avoidable mistakes. Understanding them protects rescue resources and, just as important, keeps you from the embarrassing and sometimes costly experience of sending a lifeboat to an empty berth.

The most common cause is accidental activation during handling, storage, or transport. A beacon knocked loose in a locker, packed into luggage on a flight, or bumped during installation can switch itself on. If you ever suspect your beacon has activated by accident, do not just switch it off and hope. Contact the rescue coordination center or the Coast Guard immediately, tell them the beacon hex ID, and confirm it was a false alarm. They would far rather get that call than launch a search.

The second common cause is improper disposal. When a beacon reaches end of life, the battery still holds charge and the electronics still work, so a unit thrown in a skip can activate in a compactor. Dispose of an old beacon properly: deregister it, then return it to a dealer or follow the manufacturer's disposal instructions, which usually involve disabling the battery.

The third cause is stale registration acting like a false alert. If a beacon fires for real but the registry lists a disconnected phone and a boat sold three years ago, rescuers waste precious time confirming it is genuine. Keeping your record current is as much a part of false-alert prevention as it is of real-rescue speed.

Finally, only ever activate a beacon in a genuine grave-and-imminent-danger situation. A 406 beacon is not for a flat battery or a fouled prop. Use your radio, your phone, or your satellite messenger for anything short of a true emergency, and save the beacon for the day a life is actually at risk.

Putting it together: a simple ownership routine

Owning a beacon well is a short checklist you repeat forever. Register it the day it arrives and renew every two years. Run the self-test monthly and log the date. Watch two calendar dates, the battery replace-by and, on Category 1 units, the hydrostatic release expiry. Mount a float-free EPIRB outside with clear sky above it, and keep a Category 2 unit on your abandon-ship route. Add a PLB to each life-jacket if your budget reaches. Carry a satellite messenger for two-way contact offshore. Update the registration the same week anything changes. That is the whole discipline, and it takes an hour a year.

A beacon rewards that hour more than any other equipment on your boat. Radar, autopilot, and chart plotters make good days easier. The beacon is the one device that only earns its keep on the worst day of your life, and on that day it does not care how expensive it was or how good it looks. It cares whether the battery is in date, whether it is mounted where it can float free, and whether the satellites can find your name in a database. Handle those three things and you have done the single most valuable piece of safety preparation available to a small-boat sailor.

For a fuller picture of how a beacon fits alongside the rest of your safety kit, read our companion guides below, and use the free tools on Yacht Service Network to line up the dealers and service agents who keep all of it in date.

Related reading on YSN

• Life raft guide: selection and servicing
• Boat safety equipment guide and requirements
• Marine weather and passage planning guide

Frequently asked questions

Is an EPIRB legally required on a private boat?

For most recreational boats in the United States there is no federal requirement to carry an EPIRB. Requirements apply to many commercial vessels, some offshore fishing boats, passenger vessels, and race entries under safety codes. Even where it is not required, an EPIRB is strongly recommended for any boat that goes offshore or beyond quick reach of help.

What is the real difference between epirb vs plb?

Both use the same 406 MHz Cospas-Sarsat rescue system. An EPIRB is registered to the vessel, is larger, floats, transmits for at least 48 hours, and in Category 1 form can activate automatically if the boat sinks. A PLB is registered to a person, is small enough to clip to a life-jacket, transmits for at least 24 hours, and only ever activates by hand. Many offshore boats carry both.

How does epirb registration work and does it cost anything?

Registration links your beacon's unique hex ID to a record of who you are, your emergency contacts, and your vessel. In the United States you register free with NOAA online and renew every two years. Other countries use their own national registries, such as the Maritime and Coastguard Agency in the UK or the Canadian Beacon Registry. Registration is free everywhere it is required, and an unregistered beacon slows down your rescue.

How often does a 406 mhz beacon need a new battery?

Beacon batteries are sealed and replaced by date, not by use. EPIRB batteries commonly last five to ten years depending on brand, then must go to an authorized service agent for a battery pack replacement and pressure test, typically 150 to 300 US dollars. PLB batteries often last five to six years and some units are simply replaced whole at end of life. Run the built-in self-test monthly regardless.

Should I buy an EPIRB or a satellite messenger like inReach?

They do different jobs. An EPIRB connects directly to government search and rescue on high-power 406 MHz with no subscription. A satellite messenger routes an SOS through a paid commercial service and adds two-way text messaging. For offshore work the best answer is both: an EPIRB as the guaranteed distress beacon and a messenger for two-way contact. If you can only carry one small personal device, a PLB is the safer single choice because it needs no subscription.

What is a hydrostatic release and why does it expire?

A hydrostatic release is the pressure-sensitive device on a Category 1 EPIRB bracket that frees the beacon once it is submerged a meter or more, letting it float up and self-activate in a sinking. It is a dated part, usually valid about two years, and it must be replaced on schedule or the automatic float-free function will not work when you need it. Keep its expiry on your calendar separately from the ten-year battery date.

What happens if my beacon goes off by accident?

Do not simply switch it off and hope no one noticed. Contact the Coast Guard or your rescue coordination center at once, give them the beacon hex ID, and confirm it is a false alarm. False alerts most often come from mishandling, poor storage, or improper disposal of an old unit, all of which are avoidable with careful mounting, transport, and end-of-life deregistration.