A shackle, 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 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 padlocks.
A carabiner is a variety of shackle used in mountaineering.
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 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 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 sheets. Note: When this
type of shackle is used to release a significant load, it will work rather
poorly and is likely to have the pin assembly or the split ring fail.
= Threaded shackle= 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 to
set better. References
^ Shackles "Alternative Terminology of Shackle"
^ Admiralty Manual of Seamanship. 1995. pp. 3–80.
Edwards, Fred. Sailing as a Second Language. Camden, ME: International
Marine Publishing. ISBN 0-87742-965-0. Hiscock, Eric C.. Cruising Under Sail.
Oxford University Press. ISBN 0-19-217599-8.
Marino, Emiliano. The Sailmaker's Apprentice: A guide for the self-reliant
sailor. Camden, ME: International Marine Publishing. ISBN 0-07-157980-X.
Simply Circus Shackles Page