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.
Ascent 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: • Sit-stand systems (also known as frog systems)—one ascender is at chest level attached to the sit harness, and a second is held in the hand with a long loop of rope for the feet. Movement up the rope is by repeated moving of the foot loop ascender up the rope, pushing up with both feet together, and sitting, supported by the chest ascender. This motion appears like a
frog kick. • Rope-walking systems—one ascender is attached directly to one foot, and the second connected to the other foot by a rope, with the ascender higher up to avoid clashing. Movement up the rope is by alternate stepping movements with the feet.
Descent 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. ==Rigging==