Vertical caving terminology and methods > Rigging methods and equipment
An alternative to Alpine rigging, used in some areas, particularly parts of the USA. These are especially the southeast and midwest USA. Ropes are routinely treated as disposable, and thicker ropes are used to allow more damage from rub points before the rope has to be disposed of. This may be 11 mm, 12 mm, or even 12.5 mm (approximately half inch) rope. Ropes are usually made from harder wearing polyester, to make them more resistant to the damage that they will inevitably receive from rub points. Naturals are generally preferred over anchors, particularly a single natural that is considered particularly indestructible ("bombproof"). The rope is often connected to the natural using a tensionless hitch. The tail of the tensionless hitch is normally clipped to the loaded rope using a single carabiner, but it is also common for a bowline to be threaded around the loaded rope instead to avoid carabiners altogether. The rope is then hung over the edge of the pitch, and it takes whatever route gravity causes it to take down the pitch, using rope rub protectors as needed because of all the rub points that will be encountered on the way.
The theory is that rigging takes less time, and less rope is needed since the rope can go directly from the pitch head to the pitch base. However, extra rope is needed to reach that perfect indestructible natural, and loop the rope around it several times. This approach is used to avoid having to use traverses, rebelays and deviations, which provides simplicity, and removes some of the risks associated with performing manoeuvres. While indestructible rope technique avoids having to modify the cave by adding anchors, it could easily be argued that the cave gets damaged more by all of the rub points, and footprints down the walls. Deep grooves are often visible at rub points where ropes have rubbed for many years (many of these in Britain are from the use of ladders and lifelines). The main benefit of the tensionless hitch, that it preserves the full breaking strength of the rope, is entirely unnecessary, since a knotted rope is already strong enough to allow more than 10 cavers to actively bounce around on the rope at the same time, and is far stronger than any descender or ascender, or the caver that they are attached to. The benefit is immediately wasted by bending the rope over the lip of the pitch, which is often far more severe than a knot, and the motion can also cause it to rub there. Fewer carabiners are needed but more rope rub protectors are needed. According to "Vertical" by Al Warild, the thicker rope and extra length used for reaching and attaching to naturals, means that on average, indestructible rope technique requires nearly twice as much weight of equipment as Alpine rigging. Trips take about the same length of time and energy as with Alpine rigging, but larger teams may be needed to carry the extra equipment.
Hazards on pitches can only be avoided if the rope happens to miss them during the descent, and there are many cases where hazards such as loose boulders and waterfalls simply cannot be avoided. This adds significant risk, and also means that cavers may have to carry around the extra weight of water in their clothing. At least it washes the ropes, and avoids burning them with hot descenders. Since there are no knots to pass, and there is often a very heavy rope below, cavers may prefer to use a rack for abseiling and rope walking for prusiking. The effect of bounce is significantly higher, due to big pitches not being broken up into shorter hangs, and the rope being made even longer by the distance needed to reach naturals. This is counteracted slightly by the thicker ropes, and counteracted even more by selecting ropes with far less stretch and far less shock absorbing capabilities than the European rope standards would allow, and using prusiking systems that produce minimal bounce, such as step systems like rope walking. Even on a long pitch, only one caver at a time can abseil, which adds to the time spent waiting. With prusiking, the only way to allow more than one caver at a time on the rope is to use tandem prusiking, but this makes it far harder to get past a rub point.
Getting over the lip of a pitch is the most difficult part, and deaths have occurred from exhausted cavers being unable to lift a heavy rope up enough to get their ascenders past the lip of a big pitch. This is particularly problematic on tall pitches where there is a lot of rope, or on wet pitches which make the rope heavier, or when using the thick and heavy ropes which are normally used for indestructible rope technique, or when tandem prusiking, or on pitches where there are no rock ledges to stand on while passing the lip. As a result, techniques such as a tail might be used, or an etrier made from a prusik loop connected to the rope just above the lip, with its loop hanging below the lip, giving something to stand on. Many cavers will carry an additional ascender with a footloop that they can attach to the rope above a lip, to provide a foothold exactly when they need it. By having a safety cord attached to it, making it a quick attachment safety, it allows other ascenders to be detatched one by one to get past the lip while maintaining a good number of safe connections to the rope. This problem can be avoided by using Alpine rigging.
While it may be popular in parts of the USA, indestructible rope technique was not originally created there. It is, in essence, the lack of an advance in rigging, beyond the basics that were developed in the very early days of SRT. It is how SRT started. In 1944, French caver Henry P. Guérin depicted only the overhand on a bight knot (and the Prusik knot, chain sinnet, and a variation of the butterfly coil), and although it is not explicitly stated if it was used for rigging, it is almost certainly the knot that was used for that purpose, and presumably had been used by French cavers Henri "Kiki" Brenot and Pierre Chevalier in 1934. Once SRT started to be used in the USA, there were some developments that originated there, such as thicker ropes, harder wearing rope materials, better rope rub protection materials, and the tensionless hitch used for naturals. The tensionless hitch was mentioned by American sailor Clifford Warren Ashley in the Ashley Book Of Knots (#2047) in 1944, using a clove hitch as the final knot. It was used by rope manufacturing companies as a way to test the maximum strength of their ropes. It was not in use by cavers in 1962, and probably started to be used in the 1970s. In 1977, it was shown in an SRT manual by Australian caver Neil R. Montgomery (which discussed Alpine rigging), using a figure of 8 on a bight as the final knot. It was described in 1983 in Nylon Highway as being the "conventional way" in America, and had become well established by then. Some of the rope rub protection developments came in response to serious incidents, such as three separate incidents where a rope snapped while passing over the unprotected sharp lip of Dante's Descent in the USA, presumably in the mid to late 1950s, one of which ended with a caver suffering severe injuries. Another incident that inspired use of better naturals was in 1974 when a large boulder that was used as a natural decided to follow a caver down a pitch in Tennessee, USA, injuring him significantly when it hit him (a similar incident happened in 1981). Another incident which may have inspired the tensionless hitch occurred some time before 1977 when a caver in Puerto Rico was mildly injured when the rope came untied from its only natural as she tried to prusik past the awkward lip of a pitch.
This history section only covers indestructible rope technique. This article also has a detailed history of many of the other devices and techniques that are used for vertical caving.
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