Page 179 - J. C. Turner - History and Science of Knots

A History of Life Support Knots 169

Friction Hitches
The first friction hitches, specially the Prusik Hitch (Fig. 20) have already been
described and it was mentioned that a few European cavers experimented with
an abseil-down, prusik-up method of traversing vertical caves. This technique
has developed a lot since the War. The various ways of manipulating the slings
to ascend a rope constitute one of the major contributions by cavers to the
use of life-support ropes.
Starting in 1952, Bill Cuddington developed this system for use in Ameri-
can caves. It has since been adopted and adapted world-wide, becoming known
as the Single Rope Technique or SRT. From the 1950s on, many different knots
have been suggested as alternatives to the Prusik Hitch; Thrun [32] in 1971
described more than 25, most developed by American cavers. Novel knots
continue to be developed all over the world, by both climbers and cavers, de-
spite the introduction of mechanical devices which grip the rope and can be
used in similar ways to the Prusik Hitch. The first mechanical ascender was
invented in 1958 by two Swiss mountaineers, Jusy, a game warden, and Marti,
an engineer, and given the name Jumar [21, p. 311], so that climbing with
ascenders is sometimes known as `jumaring', though `prusiking' is also used
to describe all ways of ascending a rope using slings. Improvements and other
devices followed later. These mechanical ascenders have practically replaced
friction hitches in SRT in caving, in the use of fixed ropes in expedition moun-
taineering, and in many of the activities of full-scale rescue teams. But in
other applications, the knots are still used extensively, partly because of the
cost, weight and bulk of the ascenders, partly because of the versatility of the
knots and the ready improvisation of the equipment. Only the most popular
of the friction hitches will be mentioned below; note that many of them are
named after a person.
It must have been discovered quite early in the experience of the Prusik
Hitch that in some conditions it did not hold. Mountaineers with iced-up rope
or cavers with muddy rope could expect trouble. Cuddington is said to have
developed the Double Prusik Hitch (Fig. 38) to extract himself from a solo
trip to a muddy cave in the 1950s [21, p. 311], and the knot is now commonly
used when the ordinary Prusik Hitch slips. All the friction hitches need to
have the number of turns adjusted to suit the conditions; experience and trial
and error are needed. My drawings show the number of turns most frequently
called for.
There is a trend towards simplicity in the structure of the more successful
friction hitches; they seem easier to tie and less likely to jam. The Klemheist
Hitch (literally: clamp hoist) (Fig. 39) should have the upper loop as short as
possible. The knot is also satisfactory when tied in climbers' tape or webbing
[11, p. 36][20, p. 34][29, p. 46]. If the lower loop is half-hitched round the