What are lifeboat release mechanism/ what is ON load and OFF load release mechanism as per SOLAS ?

1. Launching by falls
1.1 Principle requirements

Every lifeboat to be launched by a fall or falls, except a free-fall lifeboat, shall be fitted with a release mechanism complying with the following requirements subject to 1.1.9: (LSA 4.4.7.6)

1.1.1 The mechanism shall be so arranged that all hooks are released simultaneously.
1.1.2 The mechanism shall have two release capabilities: (LSA 4.4.7.6.2)

  • normal (off-load) release capability.
  • an on-load release capability

1.1.2.1 The normal (off-load) release capability shall release the lifeboat when it is waterborne or when there is no load on the hooks, and not require manual separation on the lifting ring or shackle from the jaw of the hook.

1.1.2.2 The on-load release capability shall release the lifeboat with a load on the hooks. This release shall be arranged as to release the lifeboat under any conditions of loading from no load with the lifeboat waterborne to a load of 1.1 times the total mass of the lifeboat when loaded with its full complement of persons and equipment. This release capability shall be adequately protected against accidental or premature use. Adequate protection shall include special mechanical protection not normally required for off load release, in addition to a danger sign. To prevent a premature on-load release, on-load operation of the release mechanism shall require a deliberate and sustained action by the operator.

1.1.3 Prevent an accidental release during recovery of the boat, unless the hook is completely reset, either the hook shall not be able to support any load, or the handle or safety pins shall not be able to be returned to the reset (closed) position without excessive force. Additional danger signs shall be posted at each hook station to alert crew members to the proper method of resetting. (LSA 4.4.7.6.3)

1.1.4 The release mechanism shall be designed and installed that crew members from inside the lifeboats can clearly determine when the system is ready for lifting by: (LSA 4.4.7.6.4)

1.1.4.1 directly observing that the movable hook portion or the hook portion that locks the movable hook portion in place is properly and completely reset at each hook, or

1.1.4.2 observing a non-adjustable indicator that confirms that the mechanism that locks the movable hook position in place is properly and completely reset at each hook, or

1.1.4.3 easily operating a mechanical indicator that confirms that the mechanism that locks the movable hook in place is properly and completely reset at each hook.

1.1.5 Clear operation instructions shall be provided with a suitably worded warning notice using colour coding, pictograms, and/or symbols as necessary for clarity. If colour coding is used, green shall indicate a properly reset hook and red shall indicate danger or improper or incorrect setting. (LSA 4.4.7.6.5)

1.1.6 The release control shall be clearly marked in a colour that contrasts with its surroundings. (LSA 4.4.7.6.6)

1.1.7 Means shall be provided for hanging-off the lifeboat to free the release mechanism for maintenance.

1.1.8 The fixed structural connections of the release mechanism in the lifeboat shall be designed with a calculated factor of safety of 6 based on the ultimate strength of the materials used and the mass of the lifeboat when loaded with its full complement of persons, fuel and equipment, assuming the mass of the lifeboat is equally distributed between the falls, except that the factor of safety for the hanging-off arrangement may be based upon the mass of the lifeboat when loaded with its full complement of fuel and equipment plus 1000 kg. (LSA 4.4.7.6.8)

1.1.9 Where a single fall and hook system is used for launching a lifeboat or rescue boat in combination with a suitable painter, the requirements of 1.1.2.2 and 1.1.3 need not be applicable; in such an arrangement a single capability to release the lifeboat or rescue boat, only when it is fully waterborne, will be adequate. (LSA 4.4.7.6.9).

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