Hydrostatic Release Unit G-5

The G-5 Hydrostat is an automatic release device for use with Liferafts, EPIRBs and other equipment.

The Hydrostatic Release Unit G-5 is widely used for Emergency Position Indicating Radio Beacons (EPIRB). Should the vessel sink, the G-5, which is activated by increasing water pressure, will automatically release the EPIRB. On reaching the surface the EPIRB starts to emit a signal of identification and position to a satellite. Instead of the rope sling a specially developed plastic bolt secures the radio beacon and will be cut when the unit is activated.

Hydrostat G-5 is our last development in a field of hydrostatic release devices. This is a so-called collet-type device of proprietary design of the radio communication designing department former engineer Vladimir Shchegolev in agreement with Musson Marine Ltd.

Formerly he had also designed collet hydrostats for ЕВ-10 radio beacon (Saracom Ltd). COSPAS-SARSAT certificate #94 is used in EPIRB EB-20 and EB-20 SVDR Capsule (COSPAS-SARSAT certificate #128). For this СM-511 device two press mold sets are manufactured (made in Korea and Ukraine).

The similar principle of the operation is typical for hydrostats for EPIRB Samyung SEP – 406 certificate #117, SEP-500 and SEP – 500В (certificate #195).

Hydrostat principle of the operation is what the spring within hermetic package fix the collet down. At the bottom of the hydrostat there is non-leaking rubber membrane which pulls off under a pressure of water by means of what the spring constricts, collet pressure grows weaker and the collet jumps out of the case.

According to ОЕМ agreement hydrostat G-5 is used on the following products:

EPIRB M-406 (Yaroslavl radio manufacturing plant, certificate #145)
EPIRB Marlin-406 (Marlin-406 A2) (manufactured by Kolgrim-Don, certificate #161)
EPIRB PRO-5 (manufactured by Uranis, certificate #172)


- Complies with the latest SOLAS and IMO resolutions and COSPAS-SARSAT recommendations
- Compact size
- Two years service life after installing


- Weight 75g
- Operating temperature -40°C..+55°C
- Storage temperature -40°C..+65°C
- Service life after installing 2 years
- Operating deapth 2..4 meters


The G-5 needs no annual service, maintenance or spare parts.
You simply install a new one every two years and dispose of the old one.

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