More details about the The Prusik Knot or Triple Sliding Hitch
History: The Prusik knot was developed in 1931 by Dr.Karl Prusik (sometime president of the Austrian Mountaineering Club and often misspelled "Prussik".) It appears to be identical in structure to a knot described by Ashley for hoisting a spar. (ABOK # 1763, p 300), but Ashley did not expressley describe the slide and grip feature.
Structure: The knot requires a "Prusik Loop" which is constructed by joining the two ends of a length of rope using a Double Fisherman's or a Triple Fisherman's.
Uses: Its principal use is allowing a rope to be climbed. Two Prusik loops are alternately slid up the static rope: a long Prusik loop allows the climber to lift himself using leg power, and a second short Prusik loop is attached to the harness. In rescue work, if a climber has to be pulled up, a Prusik loop could be used to attach a pulley block purchase system to a climbing rope.
Slide and Grip Knots: The Prusik is a slide and grip knot: symmetrical, it is useful if a load might need to be applied in either direction. For loads which are always applied in the same direction other knots are preferred such as the Klemheist (see picture on left) or the Bachmann (see picture on left)