Single-rope technique

The single-rope techniques (SRT) are a set of methods used to descend and ascend on the same single rope. Single-rope techniques are used in caving, potholing, rock climbing, canyoning, roped access for building maintenance, and by arborists for tree climbing, although to avoid confusion in the tree climbing community, many have taken to calling them "stationary" rope techniques.

Single-rope techniques are used in contrast to double-rope techniques (DRT), also known as the moving-rope techniques.

In the 1930s, as caving became increasingly popular in France, several clubs in the Alps made vertical cave exploration an outdoor sport. During World War II, a team composed of Pierre Chevalier, Fernand Petzl, Charles Petit-Didier, and others explored the Dent de Crolles cave system near Grenoble, France, which became the deepest explored cave in the world (–658m) at that time. The lack of available equipment during the war forced Pierre Chevalier and the rest of the team to develop their own equipment, leading to technical innovation. The first use of single-rope techniques with prusik and mechanical rope ascenders (Henri Brenot's "monkeys", first used by Chevalier and Brenot in a cave in 1934) can be directly traced back to the exploration of the Dent de Crolles cave system. American caver Bill Cuddington, known as "Vertical Bill", developed single-rope techniques in the U.S. in the late 1950s. In 1958, two Swiss alpinists, Juesi and Marti, teamed together, creating the first commercially available rope ascender known as the Jumar. In 1968, Bruno Dressler asked Petzl, who worked as a metals machinist, to build a rope-ascending tool, today known as the Petzl Croll, that he had developed by adapting the Jumar for pit caving. Petzl started a small caving equipment manufacturing company, Petzl, which manufactures equipment for caving, climbing, mountaineering and at-height safety in civil engineering. The rappel rack was developed in the late 1960s by cavers in the Huntsville, Alabama, caving club to facilitate long descents. The evolution of mechanical ascension systems helped extend the practice and safety of pit exploration.

For ascent (prusiking or "jugging"), cammed devices (ascenders, Jumar, Petzl Croll) are used that can be pushed up the rope but lock and hold the user's weight when a downward force is applied; these must also be easily removable from the rope without being detached from the user. Knots such as the prusik, Bachmann, and Klemheist are used to ascend ropes in emergencies in climbing and mountaineering; they have ceased to be the primary ascent method in single-rope techniques because they are slow in use, and ice or mud greatly reduce their efficiency.

Numerous prusik systems have been devised. Popular systems are:

Modern single-rope techniques use specialized devices for both descent and ascent, and low-stretch kernmantel rope of 8-11 mm diameter. Descent (abseiling or rappelling) uses various types of descenders to control speed. The most commonly used are the Petzl Stop (self-locking) and Bobbin, and rappel racks. For safe single-rope technique, especially on drops with complex rigging with intermediate belays, it is essential that the abseiling device can be removed from the rope without being unclipped from the harness. This is a problem with the simplest device, the single-piece figure eight. These also twist the rope, which is a problem if there is a rebelay below so the rope cannot untwist itself. Figure eights and racks do have the advantage of being able to be used on a doubled rope. Other essential items of a personal single-rope technique set are a sit harness and one or more safety cords ("cow's tails") terminated in carabiners, for temporary attachment to safety ropes at the heads of drops and used in maneuvers at intermediate rope belays. To pass intermediate belays on a descent, the ascending devices may also be required.

How the rope is sent down a shaft has great bearing on the type of single-rope technique used. In general, while rope-walking techniques may be very effective for climbing long, unobstructed pitches, they prove less versatile in cases of awkward passages and complex rope rigging with re-belays used to avoid hazards such as loose rocks, waterfalls, and rope damage from rub points.

Rigging in the United States is typically done using a single anchor point, and pitches are rigged as a single long drop, often in excess of 100 meters. The rope is usually a thick, abrasion-resistant type, which allows the rope to go over the lip of a shaft in contact with the rock. This is sometimes pejoratively called the Indestructible Rope Technique. To descend such large drops on a bobbin-type descender would be difficult owing to the thickness and stiffness of the rope, and the resulting descent would be slow and jerky. The bobbin-descender could also overheat and melt the surface of the rope. Racks are preferred as they have a much larger heat-sink capacity and offer a much smoother descent on such pitches. Using the frog system to ascend long pitches is time consuming, so rope-walking systems are preferred.