EPIRBs, Beacons and Safety Equipment

Every other system on this site earns its value continuously. A distress beacon earns its entire value in a single moment, possibly never.

That asymmetry changes how it should be treated. The correct approach is not to buy the most expensive unit — it is to make sure that the unit aboard is registered, accessible, in date, and understood by every person on board.

#How a 406 MHz beacon actually works

A modern EPIRB or PLB transmits a digitally coded distress signal on 406 MHz to the Cospas-Sarsat satellite system, along with a 121.5 MHz homing signal for final localisation by rescue aircraft and vessels.

The coded message contains the beacon's unique identity. That identity is the reason registration matters: it is the key that connects the alert to a registered vessel, its description, its normal operating area and the contacts who can confirm whether the boat is genuinely at sea.

Modern beacons commonly include an internal GNSS receiver, which allows the alert to carry a position from the first transmission rather than relying on satellite Doppler localisation. Some also support return-link service, indicating to the user that the alert has been received.

In Australia, AMSA operates the Joint Rescue Coordination Centre and the national beacon registration service. Registration is free.

#Beacon types and what each one solves

These are layers, not alternatives. An offshore boat typically wants:

1. DSC VHF for immediate local alerting, with the correct MMSI programmed and position available to the radio
2. EPIRB as the dedicated satellite distress path for the vessel
3. PLBs for crew on watch, particularly at night and shorthanded
4. AIS MOB devices on lifejackets so the boat can find a person in the water
5. A satellite messenger for independent two-way communication that survives a vessel electrical failure
6. A charged handheld VHF in the grab bag

The satellite communications guide covers why broadband belongs in that list for convenience but not as the emergency path.

#Registration, expiry and testing

Three administrative facts sink more beacons than hardware failure.

Registration currency. A beacon registered to a boat sold three years ago sends rescuers to the wrong vessel and the wrong contacts. Update registration on purchase, sale, change of contact details, and when the vessel's normal operating area changes significantly.

Battery expiry. Beacon batteries have a defined service life and a printed expiry date. An expired beacon may still transmit, or may not — and its certification no longer holds. Check the date as part of pre-passage preparation, and diarise replacement well ahead.

Self-test discipline. Beacons have a self-test function that confirms basic health without transmitting a distress alert. Use it at the manufacturer's recommended interval. Never activate a beacon to "see if it works" — that generates a real alert and consumes real rescue resources.

Store the beacon where it can be reached by a person in a hurry, wearing gloves, in the dark, possibly at an extreme angle of heel. Then tell the crew where it is. A beacon locked in a locker only the skipper can find has failed its design brief.

#Person overboard: the electronics side

Recovery of a person overboard is a manoeuvring and equipment problem, but the electronics contribute materially.

The MOB button. Every chartplotter has one. Know which button it is, on which display, without looking. Pressing it marks the position and — depending on the system — starts a bearing and range to that mark. The mark is where the person was, not where they are; drift and current move them.

AIS MOB devices integrated into lifejackets transmit the person's own position to your AIS, which is dramatically better than a static mark because it updates. This is the single most effective electronic MOB aid for a shorthanded boat.

Autopilot behaviour. Know what your autopilot does when you take manual control in a hurry, and how to disengage it instantly.

Crew briefing. The person who does not fall overboard has to do all the work. Everyone aboard should have pressed the MOB button at least once in calm conditions.

#State and territory equipment requirements

Australia does not have one national recreational safety equipment list. Requirements are set by each state and territory maritime authority, and typically scale with distance from shore — enclosed waters, open waters, and beyond a specified distance offshore.

As an illustration of the pattern rather than a statement of law: New South Wales requires a chart and compass on open waters, and explicitly notes that a compass is still required where satellite navigation is carried. It requires marine radio for relevant operations two nautical miles or more from shore, along with other specified safety equipment.

Two lessons generalise.

First, the redundancy principle is regulated, not merely recommended. The requirement to carry a compass alongside GPS is precisely the navigation redundancy argument written into a rulebook.

Second, requirements differ and change. Before relying on any list — including this page — confirm the current requirements with:

• AMSA for beacons, MMSI and national safety guidance
• your state or territory maritime authority for recreational equipment requirements
• ACMA for radio licensing

#Building a grab bag that works

A grab bag is the physical expression of the redundancy argument. A workable offshore version:

• registered EPIRB (or a second beacon if the primary is float-free mounted)
• PLB per crew member where carried
• charged handheld VHF, ideally with spare batteries
• satellite messenger on an active plan
• handheld GNSS or a charged phone with offline charts
• torch with spare batteries
• water, high-energy food, thermal protection
• copies of vessel and crew documentation, and the beacon registration details
• first aid supplies and any essential medication

Then do the part that is always skipped: check it. Batteries flatten, subscriptions lapse, charts were never downloaded, and the bag ends up under six months of spare warps.

#Pre-passage safety checklist

• beacon registration current and details correct
• beacon battery expiry in date, self-test passed
• lifejackets serviced, AIS MOB devices tested and in date
• DSC MMSI programmed and position available to the radio
• handheld VHF charged and in the grab bag
• satellite messenger charged and on an active plan
• flares in date where carried, and stowed accessibly
• liferaft service in date, hydrostatic release checked where fitted
• crew briefed on locations and operation of every item above
• equipment checked against the current requirements for the waters concerned
• shore contact holds the passage plan and knows when to escalate

#Bottom line

Buy a good beacon, register it properly, keep it in date, stow it where a frightened person can find it, and make sure everyone aboard knows how to use it. Then keep the other distress layers — DSC VHF, AIS MOB, satellite messenger, handheld VHF — genuinely independent of each other, because the scenario that takes out one should not take out all of them.