Choosing a safety beacon.

Three kinds of beacon

The Coast Guard describes three kinds of 406 MHz beacon, all of which alert rescuers through the SARSAT satellite system: the personal locator beacon (PLB), carried by a person; the EPIRB, mounted on a vessel, larger and more powerful; and the ELT, installed in aircraft. An AIS man-overboard (MOB) device is a different thing. Ocean Signal, a beacon maker, explains that it alerts nearby boats and plotters that have AIS, rather than satellites.

PLBs

A 2015 Coast Guard SARSAT presentation says a PLB is switched on by hand, may or may not float, must be held out of the water to transmit, and transmits for at least 24 hours. Seas of Solutions, which sells these devices, adds an important point: a PLB alert goes to a Rescue Coordination Centre, and nearby boats hear nothing until shore authorities contact them.

EPIRBs

The same presentation says a Category I EPIRB sits in a bracket with a hydrostatic release that frees and switches on the beacon at 1.5 to 4.0 m depth, while a Category II must be taken out of its bracket and switched on by hand. It also said the hydrostatic release must be replaced every two years from installation or four years from manufacture. That presentation dates from 2015, and we did not find a current Coast Guard or NOAA statement on service intervals, so follow the manufacturer's instructions.

The Coast Guard also recommends carrying an EPIRB alongside a DSC radio, since receiving both alerts helps confirm a real emergency. See handheld VHF.

AIS MOB devices

Seas of Solutions stresses that an AIS MOB device is not part of the COSPAS-SARSAT network, so it should not be called a PLB. Instead, it shows nearby AIS-equipped boats and plotters where the person in the water is. US Sailing's Safety at Sea Committee calls personal AIS the best way for a nearby boat to find someone overboard, and says night tests relocated casualties well beyond visual range. It recommends AIS for night sailing, very fast boats, wavy conditions and all shorthanded boats.

Range claims differ. Ocean Signal gives a typical range of 1 to 2 miles for its unit; Seas of Solutions gives about 4 miles for a unit it sells. Both are claims about their own products.

Registration

These are the US rules as the Coast Guard and NOAA state them. Other countries run their own registers, so check with your national authority.

• Required. The Coast Guard says every 406 MHz beacon must be registered, and anyone who buys a new or used US-coded beacon must register it with NOAA. NOAA says this is required by law, and a Coast Guard brochure says it is required by federal regulation (47 CFR).
• Free. The Coast Guard brochure says registration is free, and that failing to register, or to report a change of owner, can lead to penalties or fines.
• Renew every two years. NOAA says registrations expire after two years and must be renewed. Owners update them online using the beacon's 15-digit Unique ID, or by mailing or faxing a paper form.
• Selling or buying used. The Coast Guard says the seller must notify NOAA and the buyer must re-register, or rescuers may call the seller when the beacon goes off.

Registration also helps rescuers sort out accidental activations without launching a mission, according to the Coast Guard brochure. A Coast Guard DSC article says 98% of EPIRB, ELT and PLB activations are false alerts.

AIS MOB devices are not 406 MHz beacons, and our sources do not describe a NOAA registration for them.

Racing requirements

World Sailing's Offshore Special Regulations were amended for 2026-2027, including the EPIRB and communications sections, according to an April 2026 Irish Sailing notice. We could not find the new wording. If you race offshore, check the current regulations and your Notice of Race before you buy.

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