Everything About Life Raft, HRU and Requirements.


Life rafts are provided in addition to lifeboats on all the ships. They can be launched manually or even automatically when submerged in water with the help of HRU (hydrostatic release unit). Life rafts are stored in a fiberglass container, incorporated with a high-pressure gas used for inflating life raft at the time of emergency.


  1. Liferafts should be stowed in such so as to permit the manual release of one raft or container at a time from the securing arrangements.
  2. All liferaft provided on ships should be stowed with its painter permanently attached to strong point on the ship.
  3. Liferaft should inflate automatically when the ship sinks. (we will talk about this later in this post)
  4. Liferafts intended for throw-overboard launching should be stowed so as to be readily transferable for launching on either side of the ship.
  5. Liferafts shall be so constructed so that it can withstand nature for 30 days in all sea conditions.
  6. Liferafts shall be constructed so that it can be droped from a min height of 18m and works satisfatory. Maximum height depends on the place it is stowed.
  7. It shall be provided by means of maunting SART at a height at least 1m above sea level.

What is Hydrostatic release unit (HRU)

What is Hydrostatic release unit (HRU) .

The black cylinder in the above image is a HRU. When HRU is submerged in water by 4 m it will automatically cut the rope and liferaft is free to float clear to the surface.

IMUNOTES.IN What is Hydrostatic release unit (HRU)

HRUs may be either of the disposable type, in which case they are replaced every 2-4 years, or they can be of the type that has an unlimited life provided they are serviced and tested.


On a 399.98m long container vessel, We had 12 liferafts –

  • 2 Each Side Forward of accomodation.
  • 2 Each Side on boat deck.
  • 2 Each Side Aft of accomodation.

Read more about HRU source –

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