The intermediate belay is an element of the safety chain when climbing . The climber (lead climber ) climbing ahead hooks the rope into an intermediate safety device to reduce the fall height. But intermediate securing is also often advantageous for the second climber , especially with cross aisles .
Intermediate backups are used both when climbing artificial climbing walls, in rock and at steep spots in the ice. Permanent fixed points such as bolts are used for intermediate securing , but also all types of fixed points that can be set up by the lead climber while climbing or climbing with mobile securing means , for example clamping wedges , clamping devices or ice screws .
In the case of intermediate securing, the connection between the rope and the anchor point is made with an express set .
A direct connection of the rope to the fixed point by means of a carabiner is disadvantageous, since the carabiner could be unhooked in the event of a fall, jammed in the hook and sheared off or loaded across the board, for which it is not designed.
Fall height and forces
The height of the fall is ideally twice the vertical distance between the climber (rope knot) and the intermediate protection. In addition, in practice there is also the length caused by rope stretching (with normal sport climbing falls approx. 17 percent), plus the length caused by the carelessness of the belaying partner (difference between direct rope guidance and current rope slack, moment of shock) and rope passage through the belay device, sliding up and stretching of the harness, giving in or being pulled up by the belaying partner. In real terms, the fall height of a sport climbing fall can be four to five times the fall potential (vertical distance between the rope knot and the deflection at the last intermediate belay).
In the event of a fall, high forces arise, which increase significantly with the distance from the intermediate safety device. It is crucial for the climber that the intermediate protection holds securely, as well as the lowest possible impact force . The forces on the intermediate safety device are significantly higher than the impact force. They depend on the fall factor , i.e. the relationship between the declared rope length and fall height, and on whether the fall is secured hard or soft.
According to the UIAA standard, intermediate securing devices should be able to withstand a force of 10 kN in the direction of the fall . However, this is not always guaranteed, especially with alpine climbing. Impairments can e.g. B. represent the strength of the area around the fixed point and the maximum holding force of the securing means.
- Pit Schubert: 'Standard testing of mountain ropes.' bergundstieg, 2003, issue 2, pp. 42–49
- Chris Semmel: 'Climbing. Fuse, equipment. ' Alpine curriculum 2A. Munich 2010, ISBN 978-3-8354-0255-3