Instruction manual

PROFICIENCY IN SURVIVAL CRAFT AND RESCUE BOATS OTHER THAN
FAST RESCUE BOATS
6 8
6.1.4 Automatic release hook for davit-launching liferaft
Fig. 6.6 Release hook
The automatic release hook is for use with liferafts or small boats where a
quick simple and automatic disengagement of the craft from the lowering gear is
required.The hook itself is a basically of the “ fail safe” or off load release type,
which means that it cannot be released whilst laden, but it has an automatic
device which releases as soon as the craft is waterborne.
The “fail safe “ characteristic is achieved by the geometry of the hook,
which is so shaped that in order to release the craft before it is waterborne the
entire weight of the craft would have to be lifted, this is due to the peculiar curve
of the bill of the hook. As is no force to swivel the hook, it is clearly impossible to
effect a release until the craft is settled on the water.
All the working parts are contained between the two side plates, which are
permanently riveted together. The hook and latch rotate on shafts through the
plates which are held in position by circlips visible on the outer surfaces of the
side plates. The pawl is retained by the pawl pin which is retained by the
instruction plates secured by screws to the side plates. As the latch and pawl are
approximately half the thickness of the hook, the latch shaft and the pawl pin
have spacers fitted each side of these components, holding them centrally
between the side plates. Only the nut (not shown) and bolt may be removed
when the tab washers are opened back. As the bolt is withdrawn, the two cones
are released. When the hook is in the Safe Position it is locked closed by a step
on the hook which bears against a corresponding step on the latch.