EPIRB vs. PLB: What’s the Difference?

There are two important satellite distress beacons to understand. They are the Emergency Position-Indicating Radio Beacon (EPIRB) and the Personal Locator Beacon (PLB).

Both transmit a 406 MHz distress signal through the Cospas-Sarsat satellite network, helping search-and-rescue authorities identify your beacon and locate you. However, EPIRBs and PLBs are designed for different purposes.

What Is an EPIRB?

An EPIRB is a maritime distress beacon registered to a vessel. Its registration typically includes information such as the vessel’s name, description, emergency contacts, and other details that may help rescuers respond more effectively.

When activated, an EPIRB transmits a unique identification code and, when equipped with integrated GPS or another satellite-navigation system, its location.

EPIRBs are designed to float upright and transmit while in the water. They must provide at least 48 hours of transmission after activation.

There are two common EPIRB configurations:

Category I EPIRBs are installed in float-free brackets with hydrostatic release units. If the vessel sinks, the beacon can automatically release, float to the surface, and activate.

Category II EPIRBs are stored in manually releasable brackets and must be removed and activated by a crew member. This type of EPIRB is best stored by the helm or in an easily accessible ditch bag.

EPIRBs are required aboard most commercial vessels. When an EPIRB is legally required, a PLB cannot be used as a substitute.

What Is a PLB?

A PLB is a compact distress beacon registered to an individual rather than a specific vessel. It can be attached to a life jacket, carried in a pocket, or secured to clothing.

Like an EPIRB, a PLB transmits a 406 MHz distress alert and may include GPS positioning. However, PLBs must be manually activated and typically provide at least 24 hours of transmission.

PLBs are useful for:

• Crew members who may become separated from the vessel

• Kayakers and personal-watercraft operators

• Solo boaters

• Hikers, hunters, and other outdoor travelers

A PLB adds an important layer of personal protection, but it does not replace a properly installed EPIRB.

Key Differences:

Purpose: An EPIRB is intended for vessel-wide emergencies. A PLB protects the person carrying it. 

Registration: EPIRBs are registered with vessel information. PLBs are registered to individuals.

Activation: Category I EPIRBs may release and activate automatically. PLBs require manual activation.

Transmission time: EPIRBs transmit for at least 48 hours. PLBs transmit for at least 24 hours.

Size: EPIRBs are larger and normally mounted aboard a vessel. Most PLBs are designed to be small enough to be kept on the person it is registered to, whereas an EPIRB is much larger and is typically mounted or stored in a ditch bag on the vessel. 

Flotation: EPIRBs are designed to float and transmit in the water. PLB flotation capabilities vary by model. The antenna must be out of the water and pointed upward in order for a signal to be transmitted and received. 

Regulations: EPIRBs are mandatory for certain vessels and operations. PLBs are generally optional. If your vessel is required to carry an EPIRB, a PLD cannot be used as a substitute. 

Should You Carry Both?

For offshore boating, carrying both an EPIRB and a PLB provides the strongest protection.

The EPIRB serves as the vessel’s primary satellite distress beacon. A PLB provides backup protection if someone falls overboard or becomes separated from the boat, life raft, or EPIRB.

Even when an EPIRB is not legally required, recreational boaters should consider carrying one when operating offshore or beyond reliable cellular and VHF radio coverage.

Register and Maintain Your Beacon

In the United States, 406 MHz EPIRBs and PLBs must be registered with NOAA. Registration is free and can be completed through the NOAA 406 MHz Beacon Registration Database. Registrations must be renewed every two years and updated whenever ownership, contact information, vessel details, or intended use changes.

Owners should also regularly check battery-expiration dates, perform manufacturer-approved self-tests, inspect mounting brackets and hydrostatic releases, and replace the battery after an emergency activation.

A distress beacon is only effective when it is properly registered, maintained, accessible, and ready to use.

EPIRBs available at Life Raft Professionals

• ACR GlobalFix V5 Cat 1 GPS AIS EPIRB — An advanced model that transmits via satellite GPS and over AIS. Also has a Return Link Service for confirmation.
• ACR GlobalFix V5 Cat 2 GPS AIS EPIRB — An advanced model that transmits via satellite GPS and over AIS. Also has a Return Link Service for confirmation.
  
• View all EPIRBs for more options.

PLBs available at Life Raft Professionals

• ACR ResQLink 410 RLS PLB — buoyant and GPS-enabled, with Return Link Service confirmation.
• ACR ResQLink AIS PLB 450 — integrates AIS alerts for local rescue with global PLB signaling.
  
• View all PLBs for more choices.

Best practice: using both together

For offshore safety, experts recommend carrying both an EPIRB and a PLB. The EPIRB covers the vessel as a whole, while the PLB protects individuals who may become separated from the vessel. This redundancy ensures the fastest possible rescue response in different scenarios. Combining both devices provides the strongest safety net.

FAQ

Can a PLB replace an EPIRB on my boat?

No. PLBs do not meet mandatory carriage requirements. They are designed as personal devices, not vessel beacons.

Do EPIRBs and PLBs require subscriptions?

No. Both operate on the free COSPAS-SARSAT satellite system. Registration is required, but there are no subscription fees.

How do I register my beacon?

In the U.S., register with NOAA. Other countries have their own national authorities. Registration is free and can be completed through the NOAA 406 MHz Beacon Registration Database. Registrations must be renewed every two years and updated whenever ownership, contact information, vessel details, or intended use changes.

How long do the batteries last?

EPIRB batteries usually last five to ten years in storage, with at least 48 hours of transmission when activated. PLB batteries last five to seven years, with at least 24 hours of transmission when activated.

Which should I buy first?

If you own a vessel and plan offshore trips, start with an EPIRB. Add PLBs for each crew member to provide personal protection as well.