Knot List: Purcell Prusik Loop ‐ Step-by-Step
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Purcell Prusik TyingLay the rope out to form two loops with the ends ovelapping. Use the overlapping section to tie a Figure 8 knot. Twist the long loop to form a pair of three-turn coils. Position these coils to form a tube. Pass the short loop and the Figure 8 Knot through the tube. Tighten the tube and adjust the length.
Purcell Prusik Details
Purcell Prusik Loop is an adjustable loop suitable for making the components of the Purcell Prusik System and an adjustable tether. - The Purcell Prusik System is standard personal protective equipment for many rescue personnel operating in technical Search and Rescue settings.
Uses: This system is utilized for a wide range of applications including: adjustable attendant/patient tethers, load releases/transfers, or friction hitches/rope grabs.
The Purcell Prusik System comprises three components: a long foot Purcell Prusik, a short foot PurcellPrusik, and a harnesss or waist Prusik. The top of the Figure of Eight loop on the long one should reach the chest/nipple height of the rescuer; the top of the Figure of Eight loop on the short one should reach the rescuer's iliac crest (top of hip bone.) The Harness Prusik should reach from the chest/ nipple line to a height about 4 inches above the helmet. See the measuring guide below.
The Purcell Prusik Adjustable Tether uses a Purcell Prusik Loop. It must be used with the small loop at the bottom. Then, if the climber grabs the Figure 8 Knot, it holds instead if slipping.
Measuring Guide: Typically constructed with 6 or 7 mm cord with the following overall lengths: 1.5-2.0 meters (Harness); 3.5 meters (Short); and, 4.5 meters (Long). The picture (right) shows the usual length for the small loop and for the overlap.
To tailor the overall lengths more accurately for an individual, the tables below show suggested lengths. These tables are derived from data originally shown on the The Swiftwater Rescue Website:
Tying the Purcell Prusik: The animation shows the two coils forming in the long loop as if by magic. The practical method to form the two coils is by wrapping the line around the finger and thumb. Then join the finger and thumb together to arrange the coils neatly as shown.
Advantages: The Purcell Prusik Loop provides an excellent system for ascent/descent and also makes a safe adjustable tether.
Disadvantages: Some climbers report finding the system somewhat bulky.
Disclaimer: Any activity that involves ropes is potentially hazardous. Lives may be at risk - possibly your own. Considerable attention and effort have been made to ensure that these descriptions are accurate. However, many critical factors cannot be controlled, including: the choice of materials; the age, size, and condition of ropes; and the accuracy with which these descriptions have been followed. No responsibility is accepted for incidents arising from the use of this material.