Page 180 - J. C. Turner - History and Science of Knots

170 History and Science of Knots

upper in a sort of Sheetbend configuration, the knot is less likely to jam and
easier to loosen [32]. The French Prusik Hitch (Fig. 40) is the only knot in this
series that is readily released under load [29, p. 481]. Indeed, Shepherd [29] in
particular uses this knot in many applications, including as a safety rope for
abseiling, providing emergency braking or ready passage past a knot, or as a
safety backup when hauling on a rope.

Fig. 38. Double Fig. 39. Klemheist Fig. 40. French Fig. 41. Wend Fig. 42. Tucked
Prusik Hitch Coil Hitch Prusik Hitch Prusik Hitch Coil Hitch
Sometimes people wanted to tie a friction hitch with a single rope rather
than a sling. Perhaps they had no sling and either too short a rope or in-
sufficient time to make one; or perhaps they wished to attach the other end
to somewhere special; or perhaps there was a need to adjust the friction very
delicately. If an ordinary Prusik Hitch was simply tied in a single rope, making
the Wend Prusik Hitch (Fig. 41) taking the load on one of the ends, it was
found that with repeated load-unload-move cycles the wend (running end)
worked back through the knot. Even making an Overhand in the end will not
always prevent this, though making the Overhand round the standing part
(Fig. 41) will usually work. With this knot, there is the choice of having more
or fewer coils above or below the ends, and of taking the load on the upper
or the lower rope. Unfortunately, authorities disagree on how these choices
should be made. Someone needs to do some careful tests if the knot is to be
used with confidence and efficiency. Possibly the most adaptable of the single-
rope friction hitches is the Tucked Coil Hitch (Fig. 42), developed by Prohaska
[22]. This shows minimal tendency to work the end through the knot, and a
simple Overhand in the end will prevent it. Prohaska says that if the knot
slips because the cord is too stiff, then more coils should be added to the lower
part, but if it slips because the load is too big, the extra coils should go to the
upper part.