Belay

Belaying refers to a variety of techniques climbers use to exert tension on a climbing rope so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing.

The term "belay" also means the place where the belayer is anchored; this is typically a ledge, but may be a hanging belay, where the belayer is suspended from protection in the rock.

In a typical climbing situation, one end of the rope is fixed to the harness of the climber, using either a Rewoven Figure Eight, bowline, or double bowline knot. The rope then passes through climbing protection, which is fixed into the rock. Attachment to the rocks may be via bolts that are permanently fixed into the rock, or by traditional protection that the climber places and later removes without altering the rock.

The rope runs through the protection to a second person called the belayer. The belayer wears a harness that has a belay device attached. The rope threads through the belay device. By altering the position of the end of the rope, the belayer can vary the amount of tension on the rope. In one position, the rope runs freely through the belay device. In another position, it can easily be held without moving, because the tension on the rope is so great. This is called 'locking off' the rope.

If the climber climbs three feet higher than the last piece of protection in the rock, and then falls, the rope allows him to fall the three feet to the protection, and another three feet below that. If they fall any further, rope is pulled upwards through the protection from the belayer below. Because the belayer generally keeps the rope locked off, the climber's fall should be arrested and they are left suspended, but safe, somewhere below the protection.

A dynamic rope, which has some stretch in it, is often used so that the climber is not brought to a sudden jarring stop. Some climbers choose static ropes for abseiling/rapelling because it's more easy to use.

As the climber continues to ascend, they clip the rope into higher and higher metal loops fixed into the rock, so that in the event of a fall they don't fall further than the "unclipped" length of rope allows. While the task of belaying is typically assigned to a companion who stays at the bottom, self-belaying is also possible as an advanced technical climbing technique.

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Wikipedia