Great Circle Hydrostatic Release Unit (H.R.U.)


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Hydrostatic Release Units (HRUs) are a quick release system to allow your life raft to inflate automatically in an emergency situation without you having to do anything.

Designed and fabricated from tough non-corrosive materials, the SeamateTM HRU represents innovative thinking and real cost-saving benefits in automatic Hydrostatic Release Units (HRU).

At a depth of 1.5 to 4 metres, water pressure alone is sufficient to operate the release mechanism to free life rafts and emergency beacons for deployment, without any human input.

This offers considerable advantages both in reliability and performance as the releasing system does not depend on a pyrotechnic device or a battery to release the life raft or emergency beacon.

SeamateTM HRU’s meet all international regulations and each unit is individually tested to ensure that it is the most reliable HRU in an emergency situation.

At a depth of between 1.5 to four metres, water pressure depresses an internal diaphragm within the device. This operates the cutting mechanism within the release housing that secures the raft container to its cradle or mounting position.

The life raft will then float free of the sinking vessel and rise towards the surface with the raft’s painter line paying out as the vessel continues to sink.

When all the free length of painter line is paid out, the inflation mechanism of the life raft is activated, the life raft inflates and continues to rise towards the surface.

At this point of inflation, the weak link on the HRU breaks and allows the life raft, now unattached to the vessel, to continue to float to the surface, ready for boarding.

Seamate HRU Features

  • Suitable for life rafts from 4 to 150 persons – maximum load 10kN (2250 lbs).
  • Fabricated from non-corrosive, long-lasting, quality components.
  • Highly reliable release mechanism – does not depend on pyrotechnic device or battery.
  • The service life of three years – no maintenance required. Realise 50% more active service compared with the usual two-year in-service period offered by other popular brands.
  • Complies with SOLAS and IMO regulations, DNV, Wheelmark Certified, US Coast Guard approved.


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