# The Fishing Vessels (Safety Provisions) Rules 1975, Paragraph 8


Blocks.
(a) All blocks used in the operation of hoisting and lowering of lifeboats, Class C boats or other boats shall be of a design that affords an adequate factor of safety. Lower blocks, when fitted, shall be non-toppling and in the case of emergency lifeboats, provision shall be made to prevent the falls from cabling. The size of blocks shall be commensurate with the size of the falls.
(b) A metal block shall be capable of withstanding a proof load test of not less than 2½ times the maximum load it is intended to carry in service. The clearance between the sheaves and the block cheeks of metal blocks in which wire rope is used shall be kept to a practical minimum that will prevent the rope from overriding the rim of the sheave of any block or lead sheave. Component parts of blocks other than their sheaves shall be of ductile material.
(c) A wood block shall be capable of withstanding a proof load of not less than 2½ times the load on the block. The width between the cheeks shall be 10 millimetres greater than the diameter of new cordage ropes when those ropes are 95 millimetres in circumference, and less in proportion to the circumference of the ropes when they are smaller.

---
Source: https://www.legislation.gov.uk/uksi/1975/330/schedule/15/paragraph/8 (the official version)
Page: https://openlegislation.uk/fishing-vessels-safety-provisions-rules-1975/schedule-15/paragraph-8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.