The following has been extracted from BR 827 A Seaman's Pocket-Book, June 1943 (1944 reprint, HMSO). Although the date is outside the Great War era, the terms are those which were used by the Royal Navy during World War One.
Standing rigging always stands permanently in place to support the masts and spars of a ship. The strongest steel wire rope is employed, of a type which does not bend easily. Each length of rigging wire is fitted to the exact length required with an eye spliced in each end holding a thimble or iron ring grooved on the outside to take the wire. The object of the thimble is to prevent the wire from bending round too sharply, and to protect the wire eye from chafe. These eyes can then be connected wherever required by shackles. Remember: 'Where there's a shackle there's a thimble.' A shackle is an iron 'U' formed into a 'D' by means of a bolt or pin which screws in place through the ends, or 'lugs', of the 'U'.
The wire ropes supporting a mast are called stays. The strongest stays supporting the mast athwartships are called shrouds, while those supporting it in the fore and aft direction are fore stays and back stays. These stays are shackled to the deck at the ship's side and set up taut by rigging screws.
When a mast is small enough to be made in one piece it is called a pole-mast. Otherwise a topmast will be fitted at the head of the lower mast, and if necessary, a top gallant mast at the head of the top mast. The shrouds support the lower mast at a point below its top or cap. Between this point and the cap is the lower masthead. The highest point of a mast is covered by a round wooden disc called a truck.
Yards are crossed on a mast for flag signalling purposes, or to spread wireless aerials. The weight of a yard on a mast is taken by a chain sling; the yard-arms are held up level by wire lifts and squared back athwartships by 'braces'. Signal halliards for hoisting flags are rove through small blocks along the yard; they are made of soft white hemp rope or sisal.
The gaff is the short spar which carries the ensign halliards; the lower end, at the 'throat', rides on the after-side of a mast, while it's after end, called the 'peak', is triced up at an angle. (Warships wear their ensign in peacetime at an ensign staff right aft on the quarterdeck; in harbour they also wear a union flag at a 'jack-staff' right forward 'in the eyes of the ship').
A boom is a horizontal spar, one end pivoted to the ship's side, or to a mast, the other end toped up level by a lift, or 'topping-lift'. A boom may be rigged outboard for securing ships' boats alongside clear of the ship, or to hold clear the wire of a sounding machine, etc. The ropes holding in position are called guys.
Running rigging includes all ropes, wires, etc, employed aloft which work through blocks, or which are used to shift the position of spars and other gear. Flexible steel wire rope (F. S. W. R.) is used wherever a wire rope is to bend easily round the sheave of a block, etc. Flexible wire ropes contain more hemp and less wire than a rigging wire, and, in consequence, are less strong for size.
A block was originally a block of wood with a hole in it for a rope to reeve through. To save friction the hole was enlarged to take a pully-wheel or sheave. Then the surplus wood was cut away from the outside of the block, leaving a wooden shell. This was grooved to take a rope strop spliced round the block to secure it in place as required. When the wooden shell split the block was useless. The next improvement was the 'iron-bound block' in which the strop or hook was rivetted to an iron case carrying the sheave and its pin, the wooden shell serving to stiffen the case. To-day the larger modern blocks are made of metal, and friction is further reduced by roller-bearings between the sheave and its pin.
A single whip is a rope rove through a single block overhead to hold a weight. No power is gained.
A purchase is a combination of blocks in a tackle where power is gained.
A fall is a rope rove through the blocks of a purchase.
A pendant is a flexible wire rope shackled to the moving block of a purchase to join it permanently to its work.
A tail is a rope spliced to the upper block of a purchase, by which it may be hitched temporarily to a beam or a spar, or a rope.
A double whip is the simplest form of purchase where a rope is rove through two single blocks, the end of the fall being secured to the upper block. Power gained - double. As this end of the fall does not move it is called the standing part of the fall; the other end is the hauling part. Purchases may be rigged to gain further power by making use of blocks having two or more sheaves.
Much of the power gained in a purchase is lost in friction. Power gained must not be confused with the strength of the purchase. The size of rope employed (and consequently the size of the blocks), must be chosen to suit the weight to be lifted.
The purchases or tackles commonly carried about a ship for general purposes are the luff, the jigger, and the handy billy.
A luff is used wherever a heavy pull is required - two hook blocks (one double and one single) and 2 ½ - 3 ½ inch rope. A luff can usually be recognised by the standing part, which is passed through a becket in the strop at the tail of the single block and spliced round the strop at the neck of it. Power gained 3 or 4 times.
A jigger is a smaller tackle for general use, fitted either with hook blocks as in a luff, or with a tail on the double block instead of a hook (tail jigger). The standing part of the fall is spliced into the strop of the single block.
A handy billy is a small tackle for general purposes.
'Two blocks': A purchase is said to be two blocks when both blocks are hauled up together and touching.
'Overhaul': A purchase is said to be 'overhauled' when the two blocks are separated further apart by easing out the fall.
'Round up': The opposite to 'overhaul'.
The Rigging of a Derrick
A derrick is simply a boom topped up at one end to carry the block of a whip or purchase for hoisting weights, like a crane. The lower end, or 'heel', pivots on the foot of a mast or the side of a superstructure; the upper end, or 'head', is topped up by another purchase called a 'topping lift' at any angle desired to plumb the purchase over the weight to be lifted. The head of the derrick is also prevented from being lowered too far by a 'standing topping lift', a wire permanently connected to a point higher up the mast or superstructure. The head of the derrick is hauled round sideways and steadied as required by ropes called 'guys'.
The weight to be lifted may be hooked on and hoisted either by a single whip or by a purchase; the whip or fall is led through a leading block near the heel of the derrick and can be brought to the drum of its winch or hauled by hand. The working topping lift can also be brought to a winch or hauled by hand.
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