Launching and embarkation
Launching and embarkation
Davits and release gear put the survival craft in the water; the ladders are for people to board.
Key facts
- A davit with a winch lowers the boat or raft to the water from under the embarkation deck.
- All the downward motion comes from gravity or stored mechanical energy. Launching must not depend on the ship’s power sources, because in that situation the ship may already be dead.
- The lowering rate is held by the winch brake. Manual brakes are built to stay applied on their own: the boat goes down only while the operator holds the lever in the off position, and lets go the moment something goes wrong.
- The on-load release gear frees the craft at the right moment.
- A raft floats free differently: the hydrostatic release unit frees the container at a depth of up to 4 m, and the weak link parts at a tension of 2.2 kN with a tolerance of 0.4 kN, so a sinking ship cannot drag the inflated raft under.
- A free-fall lifeboat is not lowered: it slides down a ramp and enters the water. It must move clear of the ship immediately after entering the water, even with the ship trimmed up to 10 degrees and listed up to 20 degrees either way.
- The launching stations have embarkation ladders and lighting, and large ships have marine evacuation systems.
How this equipment is checked
- The crew inspects the launching appliances weekly together with the survival craft and checks the on-load release mechanisms.
- Annually the launching appliances go through a thorough examination, and the winch brakes a dynamic test with the mass of the craft without persons on board; at least once every 5 years the test is run with a load of 110% of the fully equipped and manned craft.
- Qualified personnel periodically examines the falls and renews them no less often than every 5 years.
- The marine evacuation system is deployed from the ship at intervals set by the Administration, no less often than once every 6 years.
Legal basis
SOLAS III/11, III/12, III/13, III/16; LSA Code chapter VI (launching power: 6.1.1.3, brakes: 6.1.2.12), raft release unit and weak link: 4.1.6, free-fall boat: 4.7.3.1. Inspections: SOLAS III/20.
This is not a legal text: when in doubt, the current wording of the Convention and the LSA Code decides.