Figure eight

A standard figure eight descender (left) and a variant with additional deflection options to vary the rope friction (right)

The figure eight is a descender and belay device that is mainly used for climbing , but also for other activities that involve abseiling. In its most common form, it consists of an approximately 15 to 20 cm tall figure eight made of drop-forged aluminum . There are also numerous special shapes, the shape of which is optimized for specific purposes.

Rappelling

Rope course with normal use (left) and as a "quick eight" with less braking effect (right). In both cases, the brake cable is the end of the cable running to the bottom right out of the picture.

Climb

The climbing rope is guided around the figure eight and through its large eyelet in such a way that the friction of the rope is sufficient to brake the climber in such a way that a safe abseil is possible. The figure eight is attached to the climbing harness with its small eyelet with a screw carabiner .

Abseiling with the figure of eight is now considered universal and safe Abseilmethode and has older techniques such as the dülfersitz displaced.

Canyoning

The figure eight is also used for abseiling during canyoning . However, the braking effect is significantly greater with a wet rope. This is compensated for by the fact that the rope is placed around the figure eight in a different way in order to generate less friction. The loop drawn through the large ring is not placed around the middle bar, but hung in the carabiner in which the figure eight itself is hanging. This technique, which is also referred to as “quick eight”, also prevents the rope from turning into the anchor point and thus preventing the rope from jamming unintentionally.

Climbing protection

In addition to being used for abseiling, the figure eight was also widely used as a belay device, especially in sport climbing . The friction of the rope in and on the figure eight is used to reduce the fall energy and the resulting forces. Although it is increasingly being replaced by the more modern tubes and semi-automatic belay devices such as the Grigri , it can still be found quite often, depending on the region.

General problem

Despite its widespread use, there are some limitations and criticisms when using the descender as a belay device:

In order for the figure eight to achieve its maximum braking force, the brake and load cables must run out of the large eye of the figure eight in opposite directions. Even in this case, the figure eight has a low braking effect of 2.0 to 2.5 kN compared to other belay devices . In comparison, the half-mast safety device (HMS) develops 2.7 kN braking force with the same rope route. This means that the belayer needs more hand strength to achieve the same braking force on the figure eight, which is why children and inexperienced climbers are not advised to belay with the figure eight.

If both strands of rope run out of the figure eight in the same direction, the braking force is only 1.3 to 1.5 kN (3.5 kN with the HMS in the same configuration). This situation can occur in two cases when using the figure eight in multi-pitch routes :

If the figure eight is used by the lead climber to secure a second climber from above, the safety rope runs into the figure eight from below and the brake cable out again downwards. In this way, the forces of 1.6 to 2.0 kN, which can arise if the second climber falls, may no longer be able to be held. The course of the rope in the figure eight, which is necessary for greater braking power, could theoretically be established by holding the brake rope upwards. However, this posture contradicts the human reflexes in such a situation and would also be difficult to maintain under a fall load. For this reason, the figure eight should not be used to secure a second climber .
The same situation occurs with a factor 2 fall of the lead climber directly into the stand protection , as the lead climber falls down past the stand. This case is much more dangerous than the fall of a second climber, as the forces that occur are significantly greater and such a fall is almost impossible to brake with the figure eight.

The two situations mentioned when belaying in multi-pitch routes can be avoided by the belayer hooking the safety rope into an intermediate belay above the figure eight - a so-called dummy runner - which prevents the figure eight from being subjected to downward pull. However, since this is not always possible and forgetting this additional intermediate belay creates a further source of danger, the figure eight is rather unsuitable as a belay device for multi-pitch routes.

In addition to these problems, the figure eight can cause kinking as the only belay device besides the half-mast cast safety device . In addition, handling with two ropes when using half or twin ropes can be very strenuous, which means that optimal dynamic belaying is no longer guaranteed. This use is also not recommended.

For the reasons mentioned, the figure eight as a belay device is only a sensible option for (advanced) climbers who belay from the ground. Despite the criticism, the figure eight is classified by modern textbooks as suitable overall as a device for securing the body (the device is attached to the climber's harness) for securing on single-pitch routes.

Application error

In addition to the general problems, there are - as with all backup devices - typical application errors. The eighth are:

When braking, the braking hand is not below the device as required. As a result, the device cannot develop the normal braking force, which is already low in comparison.
While the rope is being pulled in, the braking hand grips both strands of the rope instead of remaining on the brake rope alone. This has the effect that the braking hand remains up under load and the braking effect decreases accordingly.
The figure eight tilts on the snapper of the snap hook and acts as a lever in the event of a load, which destroys the locking mechanism of the snap hook. This allows the carabiner to open and the figure eight to unhook. This danger can be averted if the figure eight is prepared with a rubber band or a strip of tape so that it has no freedom of movement in the carabiner. Alternatively, a carabiner can also be used to prevent the figure eight from tilting on the locking device. This is the case with the DMM Belay Master, for example.
The screw carabiner rotates in the rope loop of the climbing harness and is loaded crosswise. This creates an increased risk of the carabiner breaking. This source of danger can also be switched off by a tape that is stretched across the screw carabiner and prevents the carabiner from turning in the rope loop. Alternatively, carabiners with additional anti-twist protection can be used. In most cases, a wire catch at one end of the carabiner holds the rope loop tight so that the carabiner automatically rotates into the correct longitudinal position when loaded.

A large study in German climbing halls showed that the figure eight, with an operator error rate of 40%, fared significantly worse than the next-best devices Grigri and Tube with 28.6%.

literature

Walter Britschgi: Understandable. Sport climbing safety. Manual for beginners, advanced, instructors . Self-published, Sarnen 2004.
Dieter Elsner, Jochen Haase: Mountain sports manual . Rowohlt, Reinbek 2000, ISBN 3-499-61002-7 .
Walter Fimml, Michael Larcher: Energy is power times way. Security theory basics . In: Mountaineering . Part 2, No. 4/2000 , 2000, pp. 15–18 ( bergundstieg.at [PDF; 913 kB ]).
Michael Larcher: Old and New Belay Devices (2) . In: Mountaineering . No. 2/1999 , 1999, p. 14–16 ( bergundstieg.at [PDF; 397 kB ]).
Wolfgang Pohl, Christoph Schellhammer, Georg Sojer: rope and safety technology. The practical book for beginners and advanced users . Bruckmann Verlag, Munich 2008, ISBN 978-3-7654-4742-6 .
Chris Semmel, Dieter Stopper: Secure safely . In: DAV Panorama . No. 4/2003 , 2003, p. 58–60 ( 3-leg logic ( memento from February 1, 2013 in the Internet Archive ) [PDF; 1000 kB ]).
Sonja Schade: Security technology up to date . May 9, 2007 ( uni-bielefeld.de [PDF; 26 kB ]).
Pauli Trinklwalder, Martin Schwiersch, Jan Mersch, Dieter Stopper: Indoor climbing . In: Mountaineering . Part 2: Factors influencing behavior errors , No. 2/2005 , 2005, p. 52–57 ( bergundstieg.at [PDF; 3.6 MB ]).

Web links

Commons : Figure eight abseil - collection of images

Wikibooks: Overview of different types of abseilers - learning and teaching materials

Wikibooks: Securing with the figure eight - learning and teaching materials

Wikibooks: Figure eight for abseiling - learning and teaching materials

Wiktionary: figure eight descenders - explanations of meanings, word origins, synonyms, translations

Figure eight with Prusik - video instructions on Kletterlaune.de

Individual evidence

↑ ^a ^b Walter Fimml, Michael Larcher: Energy is power times way. Security theory basics . In: mountaineering . Part 2, No. 4 , 2000, pp. 15 ( bergundstieg.at [PDF; 900 kB ; accessed on March 20, 2008]).
↑ Sonja Schade: Security technology up to date . May 9, 2007, p. 3 ( uni-bielefeld.de [PDF; 25 kB ; accessed on March 21, 2008]).
↑ ^a ^b ^c ^d Michael Larcher: Old and New Belay Devices (2) . In: Mountaineering . No. 2 , 1999, p. 14 ( bergundstieg.at [PDF; 390 kB ; accessed on March 21, 2008]).
^ ^A ^b Klaus Berghold: Belay devices. In: berghold-online.de/Sicherungstechnik.htm. January 9, 2002, accessed August 17, 2008 .
^ ^A ^b Wolfgang Pohl, Christoph Schellhammer, Georg Sojer: rope and safety technology. The practical book for beginners and advanced users . Bruckmann Verlag, Munich 2008, ISBN 978-3-7654-4742-6 , p. 107 f .
↑ ^a ^b ^c Walter Britschgi: Understandable. Sport climbing safety. Manual for beginners, advanced, instructors . Self-published, Sarnen 2004, p. 85 f .
↑ Dieter Elsner, Jochen Haase: Bergsport Handbuch . Rowohlt, Reinbek 2000, ISBN 3-499-61002-7 , pp. 94 .
↑ Chris Semmel and Dieter Stopper: Safely secure . In: DAV Panorama . No. 4/2003 , 2003, p. 58–60 ( 3-leg logic ( memento from February 1, 2013 in the Internet Archive ) [PDF; 1000 kB ; accessed on March 21, 2008]).
↑ Trenkwalder, Pauli et al .: Indoor climbing. Part 2. Factors influencing behavior failure . In: Mountaineering . No. 2/2005 , 2005, p. 55 ( bergundstieg.at [PDF; 2.3 MB ; accessed on April 11, 2015]).

[Fimml-1] Walter Fimml, Michael Larcher: Energy is power times way. Security theory basics . In: mountaineering . Part 2, No. 4 , 2000, pp. 15 ( bergundstieg.at [PDF; 900 kB ; accessed on March 20, 2008]).

[2] Sonja Schade: Security technology up to date . May 9, 2007, p. 3 ( uni-bielefeld.de [PDF; 25 kB ; accessed on March 21, 2008]).

[Larcher-3] Michael Larcher: Old and New Belay Devices (2) . In: Mountaineering . No. 2 , 1999, p. 14 ( bergundstieg.at [PDF; 390 kB ; accessed on March 21, 2008]).

[Berghold-4] A ^b Klaus Berghold: Belay devices. In: berghold-online.de/Sicherungstechnik.htm. January 9, 2002, accessed August 17, 2008 .

[Pohl-5] A ^b Wolfgang Pohl, Christoph Schellhammer, Georg Sojer: rope and safety technology. The practical book for beginners and advanced users . Bruckmann Verlag, Munich 2008, ISBN 978-3-7654-4742-6 , p. 107 f .

[Britschgi-6] Walter Britschgi: Understandable. Sport climbing safety. Manual for beginners, advanced, instructors . Self-published, Sarnen 2004, p. 85 f .

[Elsner-7] Dieter Elsner, Jochen Haase: Bergsport Handbuch . Rowohlt, Reinbek 2000, ISBN 3-499-61002-7 , pp. 94 .

[Semmel-8] Chris Semmel and Dieter Stopper: Safely secure . In: DAV Panorama . No. 4/2003 , 2003, p. 58–60 ( 3-leg logic ( memento from February 1, 2013 in the Internet Archive ) [PDF; 1000 kB ; accessed on March 21, 2008]).

[9] Trenkwalder, Pauli et al .: Indoor climbing. Part 2. Factors influencing behavior failure . In: Mountaineering . No. 2/2005 , 2005, p. 55 ( bergundstieg.at [PDF; 2.3 MB ; accessed on April 11, 2015]).