2.5 Occupant Safety During Launch
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.616 – Evaluation of Free-Fall Lifeboat Launch Performance – (22 June 1993) - Annex – Evaluation of Free-Fall Lifeboat Launch Performance - Section 2 - 2.5 Occupant Safety During Launch

2.5 Occupant Safety During Launch

  2.5.1 The final objective of the free-fall tests is the evaluation of occupant safety during launches from the free-fall certification height. Safe transportation of the occupants during the free-fall and subsequent water entry is a primary design consideration. When the lifeboat enters the water, the acceleration forces exerted upon the occupants are significant. Through proper design, water entry attitude, and seat orientation, the magnitude of these forces can be limited so that they are not injurious to the occupants.

  2.5.2 The allowable limits for acceleration forces experienced by the occupants are presented in Resolution A.689(17) of the International Maritime Organization. These limits represent the acceleration forces that a human can tolerate with minimum potential for suffering adverse effects. If these limits are greatly exceeded, the occupant could become disoriented, loose consciousness, or suffer other physiological damage. Along with protection of the occupant from injury is an implicit requirement that all objects in the cabin must be well secured. If an object were to become loose during the free-fall and water entry, it could impact an occupant and potentially cause serious injury.

  2.5.3 Included with occupant safety is the strength of the seats in the lifeboat. For the occupant to be protected, the seat must be strong enough to support a person with a reasonable margin of safety. A margin of safety is demonstrated by overloading critical seats when conducting the free-fall strength test. During this test, the overloaded seats should not break away from the supports or become fractured. Seat flexibility is acceptable unless it causes fittings to become loose and fly around the cabin during water entry, causes a loaded seat to impact an occupant in another seat, or causes excessive acceleration forces on the occupants.

  2.5.4 Another consideration of occupant safety is the harness assembly at each seat location. The harness should be easy to use. It should be of adequate strength and design to fully restrain a person during free-fall and water entry. In this sense, the lap belt portion of the assembly should fit low across the abdomen and should not "ride up" as the shoulder harness is tightened. The harness assembly should be adjustable so that persons of varying size and weight can use it with efficacy.

Parent topic: Section 2
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