“Prusik” is a word that describes a knot and the action of ascending a rope using a “Prusik System”. Named after it’s inventor, Dr. Karl Prusik, the Prusik Knot is a friction hitch that allows a climber to ascend a standing line.
The Prusik is tied by wrapping a cord around the standing rope a number of times (usually 3-5 ), and then back through itself. This forms a barrel around the rope with a tail hanging out the middle. When the tail is weighted, the turns tighten and make a bend in the rope, securing the knot into place and allowing the climber to place his/her weight on the knot. When weight is removed, the loop can be moved up or down the rope by placing a hand on the barrel and pushing. Breaking the Prusik free from the rope after it has been weighted can be difficult and is easiest done by pushing on the “bar”. This unwinds the wrap to loosen the grip of the hitch, and allows the climber to move the knot.
A basic “Prusik System” is two knots. One knot which the climber attaches to his/her harness. This lets the climber “sit” on the standing rope. The second knot is placed above the first knot. The climber places his/her foot into the tail on this knot and uses it to “push” his/her weight up the standing line. The process is a “leapfrog” affair where the climber “steps” up on the “foot knot”…pulls up on the “sit knot”….sits on the “sit knot” and pushes the “step knot” further up the rope.