Deck seamanship means the rigging, operation, and maintenance of all the ship's equipment located on deck or aloft. A person versed in deck seamanship must know the purpose of everything topside, how it is rigged out for operation, how it is operated properly and safely, how it is rigged in and secured for sea, and how it is kept in proper working order. Every outside area of the ship, from jackstaff to flagstaff and from truck to waterline, must be readily accessible to a deck seaman.
Rigging, in general, is a large phase of deck seamanship. The ship's rigging consists of the lines and wires supporting the masts, stacks, yards, etc. (called standing rigging), and those used in hoisting and lowering heavy weights or in positioning and operating the ship's movable deck gear (called running rigging). The process of setting up apparatus containing rigging is itself called rigging, as rigging boat booms, rigging cargo gear, rigging stages.
The block and tackle, or just plain tackle, is an important element in almost any type of running rigging.
A block consists essentially of a wood or metal frame (or shell) containing one or more rotating pulleys called sheaves. When a line or wire (the fall) is rove (threaded) through a block or a pair of blocks, the whole arrangement becomes a tackle (or purchase). Usually, the purpose of a tackle is to multiply the force applied on the hauling part of the fall. The number of times it is multiplied (disregarding friction) is the mechanical advantage of the tackle.
With two exceptions every tackle contains a fixed block, attached to some solid support, and a movable block, attached to the load. The force applied at the hauling part is multiplied (excluding friction) as many times as there are parts of the fall at the movable block.
A block ordinarily is referred to by the number of sheaves it contains; for example, single-sheave, two-sheave, three-sheave, etc. Its size is designated by the length of its frame in inches. The frame is the main body of the block, and contains the metal strap supporting the pin on which rotates the sheave(s). Multiple-sheave blocks usually have both inner and outer straps. The closed upper end of the strap on a wooden block holds the hook or shackle; the other end accommodates the becket (if the block has one) for securing the dead end ofthe fall.
To take apart such a block for overhauling, first the keeper is pried off and the pin is driven out from the opposite end, allowing the sheave to drop out. Then the becket bolt is removed, and the strap is driven out from the bottom upward. Wood blocks must be overhauled frequently, their pins lubricated with graphite grease, and their other metal parts chipped, wire brushed, and painted with a primer paint. Wood blocks of this type are used exclusively with line; they are never used with wire. Blocks for wire normally are all-steel, heavy-duty, roller bearing blocks, either self-lubricating or equipped with fittings for grease guns. It is seldom necessary to overhaul one of these blocks.
A snatch block is a single-sheave block, a part of whose strap opens on a hinge so that a line whose end is unavailable may be rove on the block. Fairleading (causing a line or wire to lead angularly around an obstruction and then straight to some desired point) is the usual purpose of a snatch block. A tail block is a single-sheave block to which a length of line is spliced, usually for the purpose of securing the block aloft.
Standing rigging, usually of 6X 19 galvanized high-grade plow steel wire rope, is used to support the masts. The fore-and-aft supports are caned stays; the supports running athwartships, shrouds. Stays and shrouds are set up at the lower end with turnbuckles, and those in the line of fire of the guns are also fitted with pelican hooks so that they may be moved quickly. Vibration often causes turnbuckles to back off; keepers are installed on most turnbuckles in standing rigging to prevent this.
The effectiveness of shrouds and stays is reduced considerably if they are allowed to become slack. To forestall this condition, standing rigging should be inspected periodically and tightened if necessary.
All metallic standing rigging is wormed, parceled, and served wherever chafing is likely. Elsewhere they are left bare, except for a coating of lubricant.
Insulators should present clean surfaces. They should not be painted, tarred, varnished, or coated m any way.
All electrical grounds on standing rigging should be inspected periodically for excessive deterioration at points of contact between dissimilar metals. The connections should be cleaned thoroughly and new parceling and serving applied.
