Prusik


Uses:


  • Used for tying a loop of rope onto a spar, or onto a thicker rope that is under tension. Can create a loop used as an ascender or decender. This "slide and grip" knot can also be handy for adding a loop to a rope when neither end of the rope is free.

Advantages:


  • The Prusik Knot grips firmly by friction when under tension, but loosens easily when un-weighted.
  • Most frequently used by climbers, cavers, and abseilers to climb up their main rope (eg to escape from a fall or a crevasse) using two or three small "Prusik loops" that can be alternately slid up the rope, then tighten when load is applied.
  • Easily-tied

Disadvantages:


  • For the best friction, the knot should be tied using cord that is smooth, supple, and no more than half the diameter of the rope that it is gripping.
  • Not suitable to take large loads.
  • Must be loaded gently and steadily. A shock load will cause it to slide down the main rope, generating sufficient heat to melt (and further lubricate) the surface of the loop.


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