Shackle

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.

A shackle is also the similarly shaped piece of metal used with a locking mechanism in padlocks.

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

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.

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.

[4] A modern rope can lift as heavy loads as a steel wire 3 times as thick and much heavier.

[5] 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.