Satellite Messenger vs PLB vs EPIRB: Which Emergency Device Should You Carry?

• Small lakes and rivers within cell range and sight of others: a VHF or phone in a waterproof case may be enough, but a PLB on your life jacket is cheap insurance if you fish alone.
• Big lakes, coastal and nearshore: carry a VHF with DSC and a PLB for each person who might end up in the water. A messenger is a great add-on for texting family and calling for non-emergency help.
• Offshore: an EPIRB for the boat (Category I float-free is best, because it activates itself if the boat sinks) plus a PLB worn by each crew member, a VHF with DSC, and ideally a messenger or satellite phone for two-way contact.
• Solo boating, paddling, PWC: a PLB or messenger worn on your body. A device left on the boat drifts away with it.

• A PLB is manual only (NOAA): if you are unconscious, it won't send.
• An EPIRB on a float-free bracket activates automatically, but NOAA notes the beacon must sink to about 3 meters first; mount it where it can float free.
• A messenger needs a charged battery and active plan. It may also need a clear view of the sky to send.
• Once switched on, a beacon runs on its sealed battery for a limited time: NOAA lists at least 24 hours for a PLB and at least 48 hours for an EPIRB. Leave it on and don't keep turning it off to "save" it.
• A phone with satellite emergency texting is a useful backup, but it is not a PLB. Ocean Signal points out that it needs a charged, working phone with an intact screen, a clear view of the sky, and you able to operate it, which can be hard when you are cold, wet or injured.
• Very old beacons that send only on 121.5 MHz are obsolete for this purpose: NOAA notes the satellites stopped listening for 121.5 MHz in 2009. Replace one if you find it in a used boat.
• None of them guarantee an instant helicopter. Practical Sailor notes that the vast majority of beacon alerts are false, and rescue centers call your registered contacts to confirm, so accurate contact info speeds things up.

Register each PLB and EPIRB free with NOAA. Online registrations are active right away; NOAA asks owners to renew every 2 years and reminds you by email or letter. For a PLB used on a boat, fill in the vessel fields (name, MMSI, home port). Update the registration when you sell or replace a beacon; NOAA notes that not registering can result in penalties. BoatUS reports that after more than 700 false EPIRB alerts in one year, the Coast Guard could reach only 163 of the owners, and that the FCC can fine owners of unregistered beacons that go off by accident. Full details are in EPIRB and PLB registration.

Two more things owners trip over: a beacon bought from a seller in another country must be programmed with the US country code or NOAA can't accept the registration, and an old beacon you retire should be taken out of service (Ocean Signal suggests removing the battery) and its registration closed, so it can't send a false alert from a dumpster. NOAA's advice for disposal is to make the beacon inoperable (remove the battery and, if possible, return it to the maker); if you ship one back with the battery still in, wrap it in aluminum foil so it can't transmit on the way. Update the NOAA registration when you sell or dispose of it.

Activate the plan before the trip, not at the ramp. Add emergency contacts who know your plans and will answer the phone, and enter boat details in your profile notes. Check what the plan includes (SOS, number of messages, tracking interval) and whether it auto-renews. If you pause the plan in winter, put a reminder in BoatMend to restart it.

• PLB and EPIRB: sealed batteries with a replacement date on the label. ACR, for example, lists a 5-year battery replacement interval for its ResQLink PLBs (or after emergency use). Replacement is usually done by the maker or an authorized service center.
• Messenger: rechargeable. Charge before every trip, keep a power bank aboard, and learn how long it lasts with tracking on.

Write the battery date in BoatMend.

• PLB/EPIRB: NOAA says to test only with the beacon's self-test function or at an authorized facility, following the manufacturer's instructions. The test button is not the ON switch. NOAA explains that a self-test sends a specially coded test burst that ground stations know to ignore, so no approval is needed; any other "live" activation counts as a real distress call. Makers limit how many self-tests and GPS tests a battery allows, so follow the schedule in your manual.
• Messenger: most can send a test message or check-in through the normal messaging menu. Never press SOS to test.

Read the manual at home. For a PLB, that usually means deploying the antenna and pressing an ON button under a cover; for a messenger, lifting a cap and holding SOS. Practice the motions with the device off. In cold water with shaking hands, you'll be glad you did.

Clip the PLB or messenger to your life jacket or belt, or use a PFD with a beacon pocket. Some PLBs do not float, so a lanyard matters. Keep the EPIRB in its bracket or grab bag where it can float free or be grabbed fast. NOAA lists a badly mounted automatic beacon that falls out of its bracket after a bump as a common source of false alerts, so make sure the bracket is secure and nothing knocks it.

Some newer PLBs add an AIS man-overboard signal. Boating Magazine describes an ACR model that sends an AIS MOB alert on the DSC frequency so nearby boats can respond, alongside the Cospas-Sarsat alert. Personal AIS devices alone alert only nearby boats with AIS, not the Coast Guard's satellite system. See AIS setup and man-overboard recovery gear.

Leave the device on and pointed at the sky, stay with the boat if it floats, and keep trying VHF 16. With a messenger, answer the response center's messages with your situation, number of people and injuries. Some newer PLBs offer a Return Link confirmation: ACR's RLS models show a light when the satellite system has received your alert, but ACR notes that confirmation does not by itself mean rescuers have launched.

Tell someone ashore where you're going, who's aboard, and when you'll be back. A messenger's tracking map is a great complement, but a float plan with a trusted person is still the backup when electronics fail.