Float-Free EPIRB (GMDSS)

medium 6 models total

Within GMDSS the EPIRB is the backup satellite alert that fires automatically if the crew never reaches the bridge to send a DSC distress call, which is why its float-free bracket, not the transmitter, is what has to work with nobody aboard to help it.

Read more — Float-Free EPIRB (GMDSS) explained ▾

Where the float-free EPIRB sits in the GMDSS chain

GMDSS is built around several independent alerting paths so that one failure does not silence the ship: DSC distress alert from the bridge radio, Inmarsat-C or another satellite terminal, NAVTEX and voice channels for coordination once contact is made, and the EPIRB as the automatic fallback. Everything else in that chain needs someone alive and able to reach the bridge. The float-free EPIRB is the one link designed to work if nobody can. Its bracket, not its transmitter electronics, is what carries that responsibility, which is why GMDSS surveyors spend as much time on the mounting as on the radio performance.

Main components

Float-free bracket

Holds the beacon in its stowage until a hydrostatic release unit fires at shallow depth, letting the beacon float clear of a sinking ship and start transmitting automatically. The bracket must be mounted where nothing above it, rigging, an overhanging deck, an awning, can trap the beacon as the hull goes down.

Manual release lever

A hand release, separate from the hydrostatic mechanism, lets the crew take the beacon with them into a liferaft or lifeboat during an orderly abandonment, rather than waiting for the ship to sink far enough to trigger the float-free release.

Remote activation point (where fitted)

Some installations add a bridge-mounted remote switch so the EPIRB can be activated without anyone going out to the bracket, useful when the bracket location is exposed or hard to reach quickly in bad weather.

Carriage by sea area

Sea area	Coverage basis	EPIRB role
A1	VHF coast station range	Still mandatory as the satellite fallback
A2	MF coast station range	Mandatory
A3	Inmarsat satellite coverage	Mandatory, backs up the satellite terminal
A4	Polar, outside Inmarsat coverage	Mandatory, often the most reliable path available

Regulations and class

SOLAS Chapter IV sets the carriage requirement across all four sea areas, and the equipment itself must meet the applicable performance standard for float-free satellite EPIRBs. The annual radio survey required for GMDSS-fitted ships includes a check of the float-free release date, the bracket's mounting and stowage, and the manual release mechanism, alongside the self-test result. A GMDSS radio log entry is expected each time the self-test is run, and shore-based radio surveyors treat a gap in that log as a finding even if the beacon itself tests fine on the day of survey.

Typical faults

Fault	Consequence
Bracket stowed under an overhang or awning added after installation	Beacon can be trapped against the hull instead of floating clear
Weekly self-test skipped and not logged	Battery or GPS fault goes unnoticed between annual surveys, and surveyors flag the missing log
Manual release seized from corrosion or paint overspray	Crew cannot free the beacon by hand during an orderly abandonment
HRU past expiry, common on a beacon that has quietly sat unused for years	Float-free release may not fire at all if the ship goes down

What to look for in a supplier

Bracket design proven compatible with the ship's actual stowage location, not a generic universal mount
Clear separation between the float-free service date and the internal battery service date, they are not always the same interval
A self-test procedure that produces a result the bridge team can log without ambiguity
Support network able to handle coding updates through the flag administration promptly