Senior Marine Service Advisor & NMEA Electronics Specialist // 35,000 Miles
“USCG Licensed Captain and NMEA-certified technician with 22 years of experience in powerboat diagnostics and offshore communication systems.”
Continue your journey with these curated navigation guides.
Confused by the alphabet soup of marine AIS? We explain the technical differences between Class A, Class B, CSTDMA, and SOTDMA so you understand exactly how commercial ships see your yacht.
A practical RYA Yachtmaster's guide to jacklines, tethers, and harness systems. Learn the critical rigging errors that turn your safety equipment into a liability — and how to configure it correctly for offshore passages.
A practical guide to choosing the right life raft for your sailing. We break down coastal vs offshore standards, SOLAS pack specifications, hydrostatic release, and the service interval trap that leaves sailors dangerously exposed.
Three years ago, halfway across the Bay of Biscay in a steady 30-knot gale, we engaged in a full-scale man overboard (MOB) drill. We threw a weighted dummy over the transom. Despite having a dedicated spotter, within 45 seconds the dummy was completely hidden behind the 4-meter Atlantic swell. It’s in these exact moments—when visual contact is lost and panic sets in—that the theoretical differences between maritime survival beacons become brutally practical.
Are you prepared to signal for help if your boat goes down? What if you, as an individual, go over the lifelines while the boat sails on under autopilot?
Every week, I am asked by coastal cruisers and aspiring ocean crossers: "I'm setting up my safety ditch bag. Do I buy an EPIRB or a PLB?"
Here is the direct answer: An EPIRB (Emergency Position Indicating Radio Beacon) is registered to a vessel, designed to float upright, and automatically deploy if the boat sinks. A PLB (Personal Locator Beacon) is registered to an individual, must be manually activated, and is designed to be worn physically on your lifejacket. If you're going offshore, the boat needs an EPIRB, and the watchkeeping crew needs PLBs. They are not interchangeable.
This guide breaks down exactly how these systems operate on the COSPAS-SARSAT network, where sailors make critical registration mistakes, and which beacon configuration you actually need for your specific cruising grounds.
How we evaluated these beacons: As an NMEA-certified marine electronics installer and RYA Yachtmaster, I have installed, programmed, and maintained over 150 EPIRBs and PLBs for offshore cruising yachts and racing syndicates. The data and recommendations below draw from scheduled deployment tests during Sea Survival drills, battery lifecycle tracking, and direct liaison with coastguard rescue coordination centers regarding COSPAS-SARSAT operational realities. Editorial independence: Captain Jack has no commercial relationship with Ocean Signal, McMurdo, ACR, or Garmin. No units were provided free of charge for this review.
While both beacons transmit a 406 MHz digital distress signal to the international search and rescue satellite system (COSPAS-SARSAT) and a 121.5 MHz homing signal for local rescue aircraft, their engineering and intended use cases are vastly different.
| Feature | EPIRB (Emergency Position Indicating Radio Beacon) | PLB (Personal Locator Beacon) |
|---|---|---|
| Primary Purpose | Vessel abandonment / Sinking | Individual Man Overboard (MOB) / Remote land use |
| Registered To | The Vessel (MMSI) | The Individual Person |
| Battery Life (Active Transmission) | Minimum 48 hours | Minimum 24 hours |
| Buoyancy | Floats upright independently with antenna clear | Most float, but require manual support to keep antenna pointing at the sky |
| Activation | Manual or Automatic (Water activation / Hydrostatic Release) | Strictly Manual |
| Strobe Light | High-intensity LED strobe | Smaller LED strobe |
| Average Cost (2026) | $500 – $900 | $350 – $550 |
An EPIRB is the ultimate "abandon ship" device. It is engineered to summon a multinational rescue effort to the last known position of your vessel. When activated, it transmits your boat's identity, the country of registration, and an exact GPS location to rescue coordination centers worldwide.
If you are buying an EPIRB, you will immediately face a choice between mounting categories. Understanding this difference is critical, as installing the wrong one in the wrong place can be fatal.
What Most Sailors Miss: I frequently audit recreational yachts where the owner has proudly installed a Category I auto-deploy EPIRB... inside the main salon. If the boat sinks, the EPIRB will deploy inside the cabin, float to the ceiling, and become trapped under the deck. A Category I EPIRB must be mounted externally on a bulkhead or stern rail, completely clear of rigging and overhangs.
A PLB is small enough to clip onto the waist strap of a Spinlock Deckvest or slip into foul-weather gear. It is registered to you personally, meaning you can take it from your sailboat, onto a friend’s charter catamaran, or even on a backcountry hiking trip.
While PLBs operate on the same 406 MHz satellite frequency as an EPIRB, their operational constraints are stricter. Because they have vastly smaller batteries, they only transmit for 24 hours. Furthermore, while most modern PLBs are inherently buoyant, they do not reliably float upright. In a steep sea state, a PLB bouncing in the water will severely degrade the satellite transmission. You must physically hold the beacon, keeping the antenna pointed roughly straight up toward the sky.
For decades, the fatal flaw of a standard PLB was that it alerted rescue authorities in another country, but it did absolutely nothing to alert the boat you just fell off. If you went overboard at night, the crew might not know until morning.
The current pinnacle of safety equipment—devices like the Ocean Signal PLB3 or McMurdo FastFind ReturnLink—has solved this. These units combine the 406 MHz satellite transmission with local AIS (Automatic Identification System) MOB alerting.
Experience Signal: During an MOB drill off the Fastnet rock in a Force 6, we triggered an AIS-equipped PLB. Within 15 seconds, the B&G chartplotter at our helm erupted with an ear-piercing alarm, drawing a big red circle on the screen marking the exact GPS location of the "casualty." Instead of waiting an hour for the Coastguard to coordinate a helicopter, we simply tacked the boat and sailed straight down the bearing line on the plotter. If you sail short-handed, you must invest in an AIS-integrated PLB.
Many sailors mistakenly believe that triggering a beacon opens a direct line to the local Coast Guard. In reality, it triggers a sequence via the MEOSAR (Medium Earth Orbit Search and Rescue) satellite network:
The RLS Update (Return Link Service): Modern EPIRBs and PLBs now feature Galileo RLS. In the past, activating a beacon felt like dropping a message in a bottle; you had no idea if anyone heard it. RLS-enabled beacons contain a small blue receiver LED. When the rescue coordination center receives your SOS, they send a ping back to your beacon, lighting up the blue LED to confirm: "We see you, help is on the way." The psychological impact of this feature when sitting in a liferaft cannot be overstated.
Purchasing the hardware is only 50% of the job. As an electronics technician, I see these massive failures every season:
Your safety inventory should scale precisely with your passage planning.
If the budget only allows for one device, and you sail primarily with family on a small cruising yacht? Buy the EPIRB first. It protects the whole vessel, operates hands-free once in the water, and has double the battery life required for offshore rescue coordination.
For decades, activating a 406 MHz beacon felt like shouting into a void. You hoped the satellite heard you, but you had no confirmation.
Modern beacons (like the ACR GlobalFix V5) utilize the European Galileo satellite constellation, which features a unique two-way communication link.
If you opt for a Category I EPIRB, you are relying on a tiny piece of engineering called the Hydrostatic Release Unit (HRU), typically a Hammar H20.
The HRU is a pressure-sensitive device. Inside, a stainless steel spring is held back by a plastic bolt.
HRUs have a strict 2-year expiration date. Because they are exposed to UV rays, salt spray, and extreme temperatures, the internal components degrade.
If you have to abandon ship, you need a "Ditch Bag"—a waterproof, floating bag that contains your secondary survival equipment.
Distress beacons aren't "set and forget" devices. They are complex pieces of radio engineering that require active management. By understanding the COSPAS-SARSAT network, the benefits of RLS confirmation, and the nuances of HRU maintenance, you are turning a piece of plastic into a guaranteed lifeline.
I'll see you at the ramp!