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
sails, especially sails fitted with a
headboard such as on
Bermuda rigged 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. 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) 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 to a line. 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 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 -based
fire engine with two mounted threaded shackles and a
winch 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
gall if overtightened or have been corroding in salty air, so a liberal coating of
lanolin 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 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 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
block 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 name: poly(p-phenylene-2,6-benzobisoxazole),
aramids (
Kevlar,
Technora,
Twaron),
Vectran,
carbon fibers,
ultra-high-molecular-weight polyethylene (UHMWPE, Dyneema, Spectra) and other
synthetic fibers 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
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. File:2025-05-31 Soft shackle Musée Maritime Rouen 123212464.jpg|Rope shackle, probably made for the museum exhibition. == References ==