Appendix III to Part 1918 - The Mechanics of Conventional Cargo Gear (Non-mandatory)
29:7.1.1.1.7.10.6.7.9 : Appendix III
Appendix III to Part 1918 - The Mechanics of Conventional Cargo
Gear (Non-mandatory) Note:
This appendix is non-mandatory and provides an explanation of
the mechanics in the correct spotting of cargo handling gear.
Although the most prevalent method of cargo handling is
accomplished through the use of modern shoreside container gantry
cranes, there are occasions when break-bulk cargo is handled with
conventional ship's cargo gear. This appendix provides a reference
for those unfamiliar with such cargo gear.
Sections 1918.52, 1918.53, and 1918.54 all address the subject
of rigging and operating vessel's cargo handling gear. It is
important to understand that under the Burton System of cargo
handling (conventional gear consisting of two cargo derricks with
married falls), the midships or up-and-down boom should be spotted
as close to the fore and aft centerline of the hatch as
operationally possible. Such spotting of the up-and-down boom will
allow the most effective leads for the guy(s) and preventer(s) to
safely support the lateral stresses generated in the boom(s) by the
married falls. As the lead of the guy(s) and preventer(s)
approaches the vertical, in supporting the boom(s) head, the total
stress in the guy(s) increases rapidly due to the increased
vertical force that is generated in the guy(s) in order to
counteract any particular horizontal or lateral force exerted on
the boom(s) head. The appreciable vertical forces that are
generated in this process are transmitted, in substantial part, to
the boom(s) and topping lift(s), causing proportionate compressive
stresses in the boom(s) and tension stresses in the topping
lift(s).
In general, guys and preventers must be located so that enough
vertical resistance is developed so as to prohibit the boom(s) from
jackknifing as cargo passes across the deck. Special care must be
exercised in the proper placement of guys and preventers associated
with the Burton or yard boom. Preventers, when used, must parallel
as closely as possible the guys that they support. Guys and
preventers must not be attached to the same fitting.
While under a load, the cargo falls (running rigging) must not
be permitted to chafe on any standing or other running gear.
Special attention must be paid to ensure that cargo runners work
freely through the heel block, without chafing the cheek of the
block. Also, bobbing chains and heel block preventers must be
attached so as to not interfere with the movement of the cargo
runners.