Mannheim Germany Shackles-in-a-workshop-01

A shackle (or shacklebolt), also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term also applies to

handcuffs Handcuffs are Physical restraint, restraint devices designed to secure an individual's wrists in proximity to each other. They comprise two parts, linked together by a Link chain, chain, a hinge, or rigid bar. Each cuff has a rotating arm whi ...

and other similarly conceived restraint devices that function in a similar manner. Shackles are the primary connecting link in all manner of rigging systems, from boats and ships to industrial crane rigging, as they allow different rigging subsets to be connected or disconnected quickly. A shackle is also the similarly shaped piece of metal used with a locking mechanism in

padlock Padlocks are portable Lock (security device), locks with a shackle that may be passed through an opening (such as a chain, chain link, or hasp staple) to prevent wikt:use, use, theft, vandalism or harm. Naming and etymology The term '':wikt: ...

s. A

carabiner A carabiner or karabiner (), often shortened to biner or to crab, colloquially known as a (climbing) clip, is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notabl ...

is a type of shackle used in

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Types

Bow shackle

With a larger "O" shape to the loop, this shackle can take loads from many directions without developing as much side load. However, the larger shape to the loop does reduce its overall strength. Also referred to as an anchor shackle.

D-shackle

Also known as a chain shackle, D-shackles are narrow shackles shaped like a loop of chain, usually with a pin or threaded pin closure. D-shackles are very common and most other shackle types are a variation of the D-shackle. The small loop can take high loads primarily in line. Side and racking loads may twist or bend a D-shackle.

Headboard shackle

This longer version of a D-shackle is used to attach halyards to

sail A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may b ...

s, especially sails fitted with a headboard such as on

Bermuda rig Bermuda rig, Bermudian rig, or Marconi rig is a type of sailing rig that uses a triangular sail set abaft (behind) the mast. It is the typical configuration for most modern sailboats. Whilst commonly seen in sloop-rigged vessels, Bermuda rig is ...

ged boats. Headboard shackles are often stamped from flat strap stainless steel, and feature an additional pin between the top of the loop and the bottom so the headboard does not chafe the spliced eye of the halyard.

Pin shackle

A pin shackle is closed with an anchor bolt and cotter pin, in a manner similar to a

clevis A clevis fastener is a two-piece fastener system consisting of a ''clevis'' and a ''clevis pin head''. Terms The ''clevis'' is a U-shaped piece that has holes at the end of the prongs to accept the clevis pin. The ''clevis pin'' is similar to a ...

. It is for this reason they are often referred to, in industrial jargon, as ''clevises''. Pin shackles can be inconvenient to work with, at times, as the bolt will need to be secured to the shackle body to avoid its loss, usually with a split pin or seizing wire. A more secure version used in crane rigging features the combination of a securing

nut (hardware) A nut is a type of fastener with a screw thread, threaded hole. Nuts are almost always used in conjunction with a mating bolt (fastener), bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads ...

located alongside the cotter pin. Pin shackles are practical in many rigging applications where the anchor bolt is expected to experience some rotation.

Snap shackle

As the name implies, a snap shackle is a fast action fastener which can be implemented single-handedly. It uses a spring-activated locking mechanism to close a hinged shackle, and can be unfastened under load. This is a potential safety hazard, but can also be extremely useful at times. The snap shackle is not as secure as any other form of shackle, but can come in handy for temporary uses or in situations which must be moved or replaced often, such as a sailor's harness tether or to attach

spinnaker A spinnaker is a sail designed specifically for sailing off the wind on courses between a Point of sail#Reaching, reach (wind at 90° to the course) to Point of sail#Running downwind, downwind (course in the same direction as the wind). Spinna ...

sheets. Note: When this type of shackle is used to release a significant load, it will work rather poorly (hard to release) and is likely to have the pin assembly or the split ring fail.

Threaded shackle

Front of a MAN fire engine with winch and shackles

The pin is threaded and one leg of the shackle is tapped. The pin may be ''captive'', which means it is mated to the shackle, usually with a wire. The threads may

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if overtightened or have been corroding in salty air, so a liberal coating of

lanolin Lanolin (from Latin 'wool', and 'oil'), also called wool fat, wool yolk, wool wax, sheep grease, sheep yolk, or wool grease, is a wax secreted by the sebaceous glands of wool-bearing animals. Lanolin used by humans comes from domestic sheep br ...

or a heavy grease is not out of place on any and all threads. A shackle key or metal marlinspike are useful tools for loosening a tight nut. For safety, it is common to

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

a threaded shackle to keep the pin from coming loose. This is done by looping ''mousing wire'' or a nylon zip tie through the hole in the pin and around the shackle body. For pins that have a cross-hole in the threaded end a cotter pin can be used. One disadvantage of wire is that mousing can introduce

galvanic corrosion Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, different metal, when both in the prese ...

because of material differences; it is especially bad when used in places where the shackle is exposed to air and water. Nylon is not recommended for use where significant movement of the shackle is expected.

Twist shackle

A twist shackle is usually somewhat longer than the average, and features a 90° twist so the top of the loop is perpendicular to the pin. One of the uses for this shackle include attaching the jib halyard

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to the mast, or the jib halyard to the sail, to reduce twist on the luff and allow the sail

Soft shackle

Modern strong fibers such as PBO (

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

name: poly(p-phenylene-2,6-benzobisoxazole),

aramid Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated bulletproof vest, body armor cloth, fabric and ballistic composites ...

s (

Kevlar Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as ...

, Technora,

Twaron Twaron (a brand name of Teijin Aramid) is a para-aramid, high-performance yarn. It is a heat-resistant fibre, helps in ballistic protection and cut protection. Twaron was developed in the early 1970s by the Dutch company Akzo Nobel's division E ...

Vectran Vectran is a manufactured fiber, spun from a liquid-crystal polymer (LCP) created by Celanese Corporation and now manufactured by Kuraray. Chemically it is an aromatic polyester produced by the polycondensation of 4-hydroxybenzoic acid and 6 ...

carbon fibers Carbon fibers American and British English spelling differences, or carbon fibres (alternatively CF, graphite fiber or graphite fibre) are fibers about in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages: ...

ultra-high-molecular-weight polyethylene Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass typically between 2 and 6 million amu. The l ...

(UHMWPE, Dyneema, Spectra) and other

synthetic fiber Synthetic fibers or synthetic fibres (in British English; see spelling differences) are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants like cott ...

s are used to make extra strong ropes which can also be tied into lockable loops called soft shackles. According to sailmagazine.com, "a soft shackle can handle just about every function performed by a metal shackle, in many cases better. Soft shackles articulate better, don’t rattle around when not under load, don’t chew up toe rails or beat up masts and decks, don’t hurt when they whack you on the head, are easier to undo and don’t have pins that fall overboard at a critical moment". A modern rope can lift as heavy loads as a steel wire 3 times as thick and much heavier. Metal shackles may be preferred because soft shackles can be cut by sharp edges, burned, or deteriorate in some environments. One disadvantage of soft shackles made of Dyneema and other modern fibers is their susceptibility to be weakened by heat, also heat caused by friction. It is advisable to subject it to medium level loads for a while to remove any slack that may cause friction heat when loaded to its maximum. The stopping knot of a soft shackle may be a true lover's knot, a diamond knot, a double line celtic button knot or a chinese button knot (ABOK #600, ABOK #601, ABOK #603 doubled as one tail-end reverse-trails the other, emerging tail-ends preferably buried in the opposing main part as it emerges together from the knot for Chinese finger trap attachment). Another preferred stopping knot is a two rope combined wall+crown+wall+crown

knot A knot is an intentional complication in Rope, cordage which may be practical or decorative, or both. Practical knots are classified by function, including List of hitch knots, hitches, List of bend knots, bends, List of loop knots, loop knots, ...

(a two string rose knot). The latter ones with the added thickness of the returning tail ends have the advantage of less of a sharp curvature at their weakest spot, the eye around the neck of the button. File:Manille_textile_dyneema_01.jpg, Fully buried Dyneema soft shackle open, eye with ring closed File:Manille_textile_dyneema_02.jpg, Dyneema soft shackle open, eye opened using the ring File:Manille_textile_dyneema_03.jpg, Dyneema soft shackle with diamond knot head locked File:Erse_a_bouton_01.jpg, Soft shackle with diamond knot head, and Turks head collar open File:Erse_a_bouton_02.jpg, Soft shackle with diamond knot head, and Turks head collar locked File:Soft shackles.JPG, Two with diamond knot head, and buried eye with opening string, one with ends-buried-button-knot and eye adjustable by crossing sides.