Hook Locking Part
Hook locking part is the component(s) within a hook assembly which holds the movable hook component in the closed position until activated by the operating mechanism to release the hook. This activation may be performed through other components within the hook assembly.
Source: IMO MSC.1/Circ.1392, Guidelines for evaluation and replacement of lifeboat release and retrieval systems, 27 May 2011, International Maritime Organization. Regulatory Guidance