Survival craft
Inflatable liferaft
also: life raft
An air-inflated raft in a hard canister that inflates itself after being thrown overboard.
Key facts
- Stowed in a container, it releases and inflates after being thrown overboard, or automatically when the ship sinks, thanks to the hydrostatic release unit.
- It has a canopy that protects from the weather and an emergency pack of equipment.
- The pack includes, among other things, food rations of at least 10 000 kJ (2400 kcal) and 1.5 litres of water per person the raft is approved for (part of the water may be replaced by a desalting apparatus).
- Launched by throwing overboard or by davit, depending on the ship.
- The weak link in the float-free arrangement is chosen so that it survives pulling the painter out of the container and inflating the raft, but parts before a sinking ship can drag the raft under.
Strength and release of the raft
- Time afloat
- withstands 30 days afloat in all sea conditions
- Drop into the water
- from 18 m the raft and its equipment still work properly; if stowed higher, it must pass a drop test from its stowage height
- Jumps onto the raft
- withstands repeated jumps from at least 4.5 m above its floor, with the canopy up and down
- Davit-launched raft
- under full load withstands a side impact against the ship’s side at at least 3.5 m/s and a drop into the water from at least 3 m
- Weak link
- parts at a tension of 2.2 kN with a tolerance of 0.4 kN
- Hydrostatic release unit
- releases the raft automatically at a depth of no more than 4 m
- Water and rations in the pack
- 1.5 litres of water and at least 10 000 kJ per person the raft is approved for
How this equipment is checked
- Service at an approved service station every 12 months; where proper and reasonable, the Administration may extend that period to 17 months.
- The hydrostatic release unit is checked at the same intervals. This does not apply to disposable units, which are simply replaced with new ones.
How it looks in practice
- The hydrostatic release unit is often disposable (for example the Hammar H2O type): that one is not serviced but replaced with a new one every two years, per the maker’s instructions. The date is tracked in the ship’s LSA register, next to the annual raft service dates.
From the deck: sea practice, not regulation. Details vary with the ship and the owner.
Legal basis
SOLAS III/21 and III/31; LSA Code sections 4.1 to 4.3 (construction: 4.1.1, davit-launched rafts: 4.1.4, weak link and release unit: 4.1.6, emergency pack: 4.1.5). Service: SOLAS III/20.
This is not a legal text: when in doubt, the current wording of the Convention and the LSA Code decides.