EPIRB vs. PLB: Which Emergency Beacon Do You Need?

Last reviewed May 2026 · Reviewed by the West Marine Technical Team — offshore safety specialists with hands-on experience specifying emergency beacons for coastal, offshore, and bluewater applications across vessel types and operating environments.

An EPIRB and a PLB both transmit a 406 MHz distress signal to the COSPAS-SARSAT satellite system and alert the Coast Guard to your position in an emergency. The difference between them — vessel registration vs. personal registration, automatic vs. manual activation, float-free mounting vs. carried on the body — determines which device is right for your situation and in some cases which one is required. This guide covers how each device works, where each falls short, the registration and carriage requirements for each, and which one to choose based on how and where you boat. For visual distress signals including flares and VHF DSC, see the visual distress signals guide.

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How EPIRBs and PLBs Work

The 406 MHz COSPAS-SARSAT system

Both EPIRBs and PLBs transmit on 406 MHz — the international distress frequency monitored by the COSPAS-SARSAT satellite network operated by the U.S., Russia, Canada, and France. When a beacon activates, the signal is received by low-earth-orbit and geostationary satellites and relayed to a ground station, which identifies the beacon's registered owner from a global database and forwards the alert to the appropriate rescue coordination center. A 406 MHz beacon alert typically reaches the Coast Guard within minutes of activation. Both devices also transmit a 121.5 MHz homing signal that allows search and rescue aircraft and vessels to home in on the beacon's location during the final approach.

GPS and position accuracy

All current EPIRBs and PLBs include an integrated GPS receiver that encodes the beacon's precise coordinates into the 406 MHz transmission. A GPS-equipped beacon can provide position accuracy within 100 meters to the rescue coordination center — dramatically reducing the search area compared to older non-GPS beacons that required satellites to calculate position by Doppler shift, a process that could take up to 90 minutes and produce position accuracy of only 2 to 5 kilometers. When purchasing a new beacon, GPS integration is standard — confirm it is present on any used or older device before relying on it offshore.

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EPIRB: What It Is and Who Needs One

What an EPIRB is

An EPIRB — Emergency Position Indicating Radio Beacon — is a vessel-registered distress beacon designed to be mounted on the boat and to activate automatically if the vessel sinks. Category I EPIRBs are mounted in a float-free bracket on deck: when submerged to a depth of 1.5 to 4 meters, a hydrostatic release automatically frees the EPIRB from its bracket and it floats to the surface and activates. Category II EPIRBs require manual activation or manual release from the bracket before water activation. The float-free automatic activation of a Category I EPIRB is its defining advantage — it alerts rescuers even if the crew is incapacitated, swept overboard, or unable to activate a device manually before the vessel sinks.

EPIRB registration

An EPIRB is registered to a specific vessel through NOAA's 406 MHz Beacon Registration Database. The registration links the beacon's unique 15-digit hex ID to the vessel name, type, size, color, home port, owner contact information, and emergency contacts. When the beacon activates, this information is immediately available to the rescue coordination center — the Coast Guard knows what they are looking for before they launch. EPIRB registration is free, mandatory under FCC regulations, and must be renewed every two years. An unregistered EPIRB is a liability: a false activation from an unregistered beacon cannot be quickly verified and diverts rescue resources from real emergencies.

Who needs an EPIRB

An EPIRB is the appropriate distress beacon for any vessel that operates offshore, makes extended coastal passages, or goes far enough from shore that crew survival time in the water could exceed the battery life of a PLB. Offshore fishing boats, bluewater cruising sailboats, and any vessel making overnight passages are the core EPIRB use cases. The float-free automatic activation of a Category I EPIRB provides a level of protection that no other distress device offers — the vessel itself triggers the alert even if no crew member is able to do so.

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PLB: What It Is and Who Needs One

What a PLB is

A PLB — Personal Locator Beacon — is a person-registered distress beacon designed to be carried on the body. It transmits the same 406 MHz distress signal as an EPIRB and is detected by the same COSPAS-SARSAT satellite network, but it is smaller, lighter, and worn or carried by an individual rather than mounted on the vessel. PLBs are manually activated — there is no automatic float-free function. The user must deploy the antenna, press and hold the activation button, and hold the beacon with a clear view of the sky for GPS acquisition. PLBs are registered to a person rather than a vessel, which means the same beacon provides protection on any boat, any kayak, or any other activity the owner undertakes.

PLB battery and signal duration

PLBs are required to transmit for a minimum of 24 hours after activation. EPIRBs are required to transmit for a minimum of 48 hours. In an extended offshore search scenario where rescue may be delayed by weather or distance, the additional 24 hours of EPIRB transmission time is a meaningful survival margin. PLB battery life is adequate for most coastal and inland emergencies where rescue response times are measured in hours rather than days. Both devices require battery replacement or factory servicing at the end of their rated battery life — typically five years for the main 406 MHz battery.

Who needs a PLB

A PLB is the appropriate distress beacon for individual boaters, kayakers, anglers, and anyone who wants personal distress alerting capability that travels with them regardless of which vessel they are on. A PLB is also the right choice for crew members on offshore vessels who want individual backup distress capability separate from the vessel's EPIRB — if a crew member goes overboard, their PLB activates their personal distress signal independently of anything happening on the vessel. For vessels operating in coastal waters where response times are short and the crew is conscious and capable of manual activation, a PLB provides 406 MHz distress alerting at a lower cost and smaller footprint than an EPIRB.

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EPIRB vs. PLB: Key Differences

Side-by-side comparison

Registration: EPIRBs are registered to a vessel. PLBs are registered to a person. An EPIRB alert tells the Coast Guard the vessel name, type, and description. A PLB alert tells them the owner's name and emergency contacts — they do not know which vessel the person is on unless the owner has noted it in the registration record.

Activation: Category I EPIRBs activate automatically when submerged — float-free hydrostatic release triggers activation without any crew action. PLBs require manual activation by the user. In a scenario where crew are incapacitated or the vessel sinks rapidly, only an EPIRB provides automatic alerting.

Signal duration: EPIRBs transmit for a minimum of 48 hours. PLBs transmit for a minimum of 24 hours. For extended offshore emergencies, the EPIRB's longer transmission window is a survival advantage.

Size and portability: PLBs are significantly smaller and lighter than EPIRBs — most PLBs fit in a jacket pocket or clip to a PFD. EPIRBs are larger and are mounted in a bracket on the vessel. A PLB travels with the person; an EPIRB stays with the boat.

Cost: PLBs are generally less expensive than EPIRBs. Entry-level GPS PLBs start around $250–$300. GPS EPIRBs start around $400–$600 for Category II and higher for Category I with float-free brackets.

Regulatory requirement: EPIRBs are required by the FCC on certain vessel classes — primarily SOLAS vessels and vessels on international voyages. There is no federal requirement for recreational vessels to carry either an EPIRB or a PLB, though both are strongly recommended for offshore and extended coastal use.

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Registration and Carriage Requirements

Federal registration requirements

All 406 MHz beacons — both EPIRBs and PLBs — must be registered with NOAA under FCC regulations. Registration is free and is completed through the NOAA 406 MHz Beacon Registration Database at beaconregistration.noaa.gov. An unregistered beacon transmitting a distress signal cannot be immediately linked to an owner, vessel, or location by rescue coordinators — this delays response and can divert resources from real emergencies. Register the beacon immediately upon purchase, update the registration any time your vessel, contact information, or emergency contacts change, and renew every two years.

Carriage requirements for recreational vessels

There is no federal USCG regulation requiring recreational vessels to carry an EPIRB or PLB. The USCG strongly recommends both for offshore and extended coastal use, but carriage is voluntary for recreational boaters. Vessels documented under the FCC Ship Station License operating on international voyages and certain commercial vessel classes have mandatory EPIRB requirements — recreational boaters on domestic waters do not. The absence of a legal requirement does not change the practical calculus: beyond VHF radio range, a 406 MHz beacon is the only distress alerting device that can reliably notify the Coast Guard of your position.

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Which One to Choose

Choose an EPIRB if:

You make offshore passages, overnight trips, or bluewater voyages where the vessel could be lost or the crew incapacitated before anyone can activate a distress device manually. The float-free automatic activation of a Category I EPIRB is the single feature that justifies its cost for any vessel going far offshore — it alerts rescuers regardless of what happens to the crew. Choose a Category I EPIRB with GPS for offshore use. Choose Category II if you want manual activation capability at lower cost for coastal use and are comfortable with the trade-off of no automatic activation.

Choose a PLB if:

You want personal distress alerting capability that travels with you across multiple vessels and activities. A PLB is the right choice for crew members on offshore vessels as a personal backup to the vessel's EPIRB, for coastal boaters who want 406 MHz alerting without the cost and mounting requirements of an EPIRB, and for anglers and paddlers who want individual coverage regardless of vessel type. A PLB registered to you covers you on any vessel, any kayak, or any other activity — one device, registered once, provides coverage everywhere.

Consider both if:

You operate offshore and want both vessel-level automatic alerting and individual crew coverage. The combination of a Category I EPIRB mounted on the vessel and a PLB on each crew member provides the most complete distress alerting capability available to recreational boaters — the EPIRB alerts if the vessel sinks, and each crew member's PLB alerts if they go overboard. For offshore racing, bluewater cruising, and any extended passage where crew overboard is a realistic scenario, carrying both is the professional standard.

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Frequently Asked Questions

What is the difference between an EPIRB and a PLB?

An EPIRB is registered to a vessel, mounted on the boat, and can activate automatically via a float-free hydrostatic release if the vessel sinks. A PLB is registered to a person, carried on the body, and requires manual activation. Both transmit a 406 MHz GPS distress signal to the COSPAS-SARSAT satellite network. EPIRBs transmit for a minimum of 48 hours; PLBs for a minimum of 24 hours. An EPIRB is the better choice for offshore vessels where automatic activation is critical. A PLB is the better choice for individual coverage across multiple vessels and activities.

Am I required to carry an EPIRB or PLB on my recreational boat?

No federal regulation requires recreational vessels to carry an EPIRB or PLB. The USCG strongly recommends both for offshore and extended coastal use, but carriage is voluntary for recreational boaters on domestic waters. For any boating beyond VHF radio range — typically 20 to 25 miles offshore — a 406 MHz beacon is the only device that can reliably alert the Coast Guard to your position if you cannot reach them by radio.

What is the best EPIRB for a small boat?

For a small boat operating offshore or on extended coastal passages, a Category II GPS EPIRB provides 406 MHz automatic distress alerting at a lower cost than a Category I and without the float-free bracket requirement. Category II EPIRBs can be manually activated or activated by water immersion when removed from their bracket — they do not automatically float free if the vessel sinks. For small offshore vessels where the crew is likely to be able to activate the beacon manually, a Category II GPS EPIRB is a practical and cost-effective choice. If budget allows and the vessel goes well offshore, a Category I with float-free bracket is the safer long-term investment.

How do I register my EPIRB or PLB?

Register any 406 MHz beacon — EPIRB or PLB — through the NOAA 406 MHz Beacon Registration Database at beaconregistration.noaa.gov. Registration is free and takes approximately five minutes. You will need the beacon's 15-digit hex ID, found on the label. For EPIRBs, provide vessel name, documentation or registration number, vessel type, size, and color. For PLBs, provide owner name and contact information. Update your registration any time your vessel or contact information changes, and renew every two years as required by the FCC.

Should I carry an EPIRB or a PLB for offshore fishing?

For offshore fishing, the strongest recommendation is a Category I EPIRB mounted on the vessel plus a PLB on each crew member. The EPIRB provides vessel-level automatic alerting if the boat is lost; the PLB provides individual coverage for crew overboard situations. If budget requires choosing one, a Category I EPIRB on the vessel provides automatic float-free activation that a PLB cannot replicate — in a rapid sinking or crew incapacitation scenario, the EPIRB alerts without any action from the crew. A PLB alone requires a conscious, capable person to activate it.

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