Vertical caving terminology and methods > SRT basic terms
A variety of techniques to help recover yourself after an equipment failure or injury, or to recover a fellow caver who has become hung up or incapacitated while on a rope. Some may involve creating a replacement sit harness, chest harness, descender or ascenders. Some may involve descending rope which the casualty is hanging on, and transferring a casualty's weight to your own equipment. Some may involve hoisting a casualty up a pitch or lowering them to the pitch base. This page does not cover the techniques or equipment used for this; attend a dedicated course for that.
However, special mention is made here of the one ascender prusik method or one knot prusik method, because they are sometimes mentioned as a prusiking system, when they really are self rescue systems that can be used to ascend a rope if only one ascender or prusik loop is available. With only a single ascender or prusik loop, it can be attached to the sit harness as a chest jammer. The down rope below it can be looped around the foot (creating a footloop in the main rope), and held up above the head, with a bight of it twisted around the up rope in a doubled version of the single hitch to get a better grip. The bight is then gripped tightly with the hands against the up rope, which acts as a top jammer. This ends up creating a very clumsy frog system, which requires a lot of hand strength. The one knot version is far harder, as it needs the rope to be gripped with just one hand while the other hand tries to move the prusik loop. This can be a little easier to do with a prusik loop that is long enough that it sits closer to head height, with the bight of rope from the foot being held against the down rope below it, to create a Texas system. While this requires more arm strength to pull the body close to the rope, it means that the down rope below the prusik loop is being actively pulled down at the time that the prusik knot needs to be slid upwards, so the hand lifting it does not need to pull the down rope at the same time to get it to feed through. Alternatively, a loop knot can be tied in the down rope as a footloop, then after standing and sitting, it can be untied and retied slightly higher.
The name "one knot prusik method" might also be used to mean an alternative approach, intended for situations when there is no ascender or prusik loop, and without any other equipment. The free end of the rope is used to thread a Prusik knot around the up rope, with the tail of the Prusik knot being tied around the body as a load bearing chest harness, or tied to the sit harnesses (if there is one). The down rope below the Prusik knot (not the part of the rope used to tie the Prusik knot) is used to make the footloop in the same way as before, but the awkward position of the Prusik knot will mean that it cannot be used for the frog system, so the single hitch and grip need to be done below it instead, which creates a barely functional Texas system. The grip needs to be done with just one hand. The actions are to stand up, and slide the Prusik knot a short distance up the rope with the other hand, before running out of strength, and collapsing back into the chest harness or sit harness, to be supported by the Prusik knot. This is repeated until there is enough slack to somehow tie a second knot so that the rope no longer needs to be gripped in one hand, or you collapse from exhaustion, whichever comes first. The worst part of this idea is that almost all Prusik knots need to be tied in a much thinner rope than the rope they are being tied around, while the one knot prusik method will use the same thickness of rope. While some may recommend the Blake's hitch instead of a standard Prusik knot because it should work with a prusik tether of the same diameter, it normally needs a much more flexible rope than the static rope used for SRT. It can be used more reliably with dynamic rope, and the 5/3 variation can be used with SRT ropes as long as it is very carefully set before and during use, but its grip is rather poor, and it is primarily designed for use with doubled rope technique, not SRT. As a result, this version of the one knot prusik method is largely a theoretical exercise rather than a real one.
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