Single rope technique
The single rope technique , also called SRT (from English "single rope technique"), is used in cave exploration for driving mainly vertical routes such as shafts . Since many places in caves are difficult to climb in the classic style, also due to moisture and clay - and safety is the top priority in the cave - these are overcome with the best possible technical aids. In addition, cave exploration is not about reaching any destination on the most difficult path possible, as is the case with sport climbing , but rather about reaching a destination as time-saving as possible and, above all, as safely as possible.
development
Up until the 1970s it was common to negotiate shafts using wire rope ladders. Despite the lightest possible construction - only as narrow as a mountain shoe, aluminum rungs - the disadvantage of being heavy and voluminous and therefore represents a considerable transport problem, especially in caves that are kilometers long. Apart from that, climbing on such a wire rope ladder requires some practice and is very exhausting. Above all, dismounting is laborious: when climbing onto the lower rung of the wire rope ladder, if it is freely suspended, it has the tendency to evade. If it lies against the rock, it must first be pushed away from the rock somehow. This not only requires strength, but also represents a safety risk. It is also common to secure the person ascending or descending with a rope. This makes so-called shaft posts necessary, which secure the last man when dismounting and then have to wait - possibly for days - until the first man comes up again.
Thus, the single rope technique originally developed in France was a revolution in cave exploration, which now made it possible to master even the most difficult shaft caves and extremely deep descents with significantly reduced material costs and, above all, greatly reduced risk.
equipment
The basic single rope technique equipment consists of a seat and chest harness , a descender , several ascenders with ankle loop and a safety set, the so-called cowtail . The equipment for the frog technique consists of:
- The Speleo sit harness is very similar to a climbing harness. However, the belt material is often wider so that you can sit in the belt for a longer period of time, and areas that are subject to heavy use are reinforced with PVC . The rope point is more immobile than with a climbing harness and is close to the body to make it easier to climb the rope. A half-round screw link serves as the central attachment point.
- The Speleo chest strap is used to fix the chest ascender to the body and usually has no safety function.
- The (chest) ascender is attached directly to the half-round screw link.
- The hand ascender is an ascender with a handle to which a foot loop is attached.
- The cowtail consists of a short and a long safety loop with a screw carabiner at the end.
- The descender has two or more fixed pulleys around which the rope is wrapped. The friction between the rope and the pulley is large enough to control the descent speed with the hands holding the rope underneath the descender. In addition, a safety clamp can be used, which, if the person leaving passes out and can no longer hold the rope, stops the descent.
Other pieces of equipment are required for other techniques. For example, another hand ascender with a foot loop is used for the caterpillar technique. Foot ascenders or hand ascenders with a pulley system are also or optionally used.
technology
There are various ascent methods, including the frog and the caterpillar technique, which also differ in terms of equipment. The frog technique is the most widespread technique in Europe.
Ascending is done with the ascenders. These can be pushed upwards if they are not stressed; when loaded, they clamp securely to the rope. One method is to attach foot slings to both ascenders, one of which is also hung in the chest strap. You now alternately push one and the other clamp up and climb higher step by step.
Another possibility is to attach one clamp to the chest strap and the other to both feet so that you can work your way up with caterpillar-like movements. This means that the strength of both legs is available at the same time for the actual climbing process.
In the early days of the single rope technique, the ropes known from sport climbing were used, which have a high elongation (full ropes maximum 10%) in order to slow down a fall into the rope as gently as possible. This had the disadvantage that you first had to climb a few meters from the bottom of the shaft. Only after the stretching had been overcome according to the weight of the person ascending did the actual ascent begin. The rope industry has reacted to this and developed so-called Speleo ropes, which have a reduced elongation (maximum 5%). Nowadays, ropes are available by the meter so that greater shaft depths can be overcome with a single rope.
literature
- Georges Marbach, Bernard Tourte: Alpine Caving Techniques. A Guide to Safe and Efficient Caving. Speleo Projects, Allschwil 2002, ISBN 3908495105 (translated from French)