Cargo gear and rigging

46 CFR §28.885

§ 28.885 § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear shall be marked on the heel of each cargo boom, crane, or derrick. These letters and figures are to be in contrasting colors to the background and at least one inch in height. The SWL is construed to be the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire rope, chains, rings, hooks, links, shackles, swivels, blocks, and any other loose gear used or intended to be used in cargo loading or unloading must be commensurable with the SWL rating in paragraph (a) of this section. This gear shall be visually inspected by the vessel's captain or his designee at frequent intervals, and in any event not less than once in each operating month. (c) In addition to the inspection…

NAVEDTRA 14343 §8-2

NAVEDTRA 14343 §8-2 — Blocks and tackle — mechanical advantage A block is a pulley in a frame; a tackle (pronounced "taykle") is an assembly of blocks and rope (the fall) used to gain a mechanical advantage or to change the direction of pull. A block's parts are the shell (frame), the sheave (grooved wheel), the pin (axle), and the strap or hook/shackle by which it is secured; a swallow admits the rope and the becket is a fixed eye for making the standing part fast. The theoretical mechanical advantage of a tackle equals the number of parts of the fall supporting the moving (load) block. A single whip (one fixed block) gives no advantage, only a change of direction; a gun tackle (two single blocks) gives an advantage of two or three depending on which block moves; a luff tackle (a double …

NAVEDTRA 14343 §8-4

NAVEDTRA 14343 §8-4 — Safe working load, breaking strength, and safety factor Every piece of lifting and rigging gear has a breaking strength (BS, the load at which it fails) and a safe working load (SWL, also called working load limit), the maximum load it may carry in service. The safety factor (design factor) is the ratio of breaking strength to safe working load; it provides a margin for shock loading, wear, and uncertainty. For general rigging the factor is commonly about five to one, and higher — six, eight, or ten to one — for gear that lifts personnel or that is subject to severe dynamic loading. A rough field estimate of a fiber or wire rope's breaking strength can be made from formulas based on diameter, but the manufacturer's certificate governs. SWL is reduced by the angle of …

NAVEDTRA 14343 §9-1

NAVEDTRA 14343 §9-1 — Cargo booms and rig components A cargo boom is a spar (the derrick's load arm) stepped at its heel to a mast or kingpost and supported at its head by a topping lift that sets its angle. The boom's principal rigging: the heel is secured by a gooseneck fitting that lets the boom swing and top; the topping lift (a wire and tackle, often led to a topping-lift winch or secured to a cleat/ bull-wire) raises and lowers the boom head; the cargo runner (whip) reeves over a head block at the boom head and a heel block and leads to the cargo winch to hoist the load; and the guys (preventer guys and working/slewing guys) control the boom's swing athwartships and hold it against the load's side pull. The kingpost (or samson post) and the mast take the compression from the boom an…

NAVEDTRA 14343 §9-2

NAVEDTRA 14343 §9-2 — Single swinging boom rig In the single swinging (single-whip or single-purchase) boom rig, one boom lifts the load, is slewed over the side or the hatch by its guys, and lowers the load to or from the pier or hold. The sequence: the load is hooked on over the hatch or pier, the cargo runner heaves it up clear by the cargo winch, the boom is swung by slacking one guy and heaving the other (or by a slewing winch) to position the load over its landing spot, and the runner lowers it. The rig is flexible — the boom can spot a load anywhere within its swing — but it is slow because the boom must be slewed for every lift, and it demands careful guy tending because a load hanging off the boom head puts a heavy side load into the guys. A single boom can be given greater lifti…

NAVEDTRA 14343 §9-3

NAVEDTRA 14343 §9-3 — Yard-and-stay (burton) rig The yard-and-stay rig, also called burtoning or married falls, uses two fixed booms to move cargo quickly between the hold and the pier without slewing either boom for each lift. One boom (the hatch or "yard" boom) is topped and guyed to plumb the hatch; the other (the stay or "burton" boom) is topped and guyed to plumb over the ship's side and the pier. The two cargo runners are shackled together at a single cargo hook (the falls are "married"). To move a load: the hatch boom's winch heaves the load up out of the hold while the ship-side boom's runner is slack; when the load is high enough, the ship-side winch heaves and the hatch winch slacks in coordination, so the load transfers across and swings out over the pier, then is lowered by th…