Prusiek

A prusiek is a type of friction hitch or knot used in climbing, mountaineering, caving, canyoneering, and rescue. It is used to attach a loop of cord to a rope, in such a way that the loop will hold when weighted, but can be slid along the rope when unweighted.

The prusik is typically formed using a loop of cord, which is wrapped around the main rope multiple times (usually 2-3 times, but dependent on cordage diameter and rope diameter). The ends of the loop are then attached together with a knot, such as a double fisherman's knot or a grapevine knot, forming a closed loop. When weight is applied to the loop, the wraps tighten around the rope, creating friction and preventing slippage. When the weight is released, the loop can be easily moved along the rope.

Prusiks are commonly used for ascending a rope (prusiking), creating a backup belay, rigging a haul system, or for self-rescue. The effectiveness of a prusik hitch depends on several factors, including the diameter difference between the rope and the cord, the number of wraps, and the materials of the rope and cord. Generally, the cord should be thinner than the rope. The prusik hitch is named after Austrian mountaineer Karl Prusik, who described it in his 1931 mountaineering manual.

Variations on the prusik hitch include the Bachmann hitch, Klemheist knot, and Autoblock hitch, each offering slightly different characteristics and advantages.