In climbing, belaying is the technique of controlling the rope so that a falling climber does not fall very far. This task is assigned to a belayer. (Self-belaying is possible as well, but as it is an advanced technical climbing technique, the description is beyond the scope of this article.) The term belay is also used to mean the place where the belayer is anchored; this would typically be a ledge, but may instead be a hanging belay, where the belayer is suspended from anchors in the rock.
Control of the rope is achieved through applying friction, which allows control of the speed at which the rope slides past the belayer. This friction is generally achieved by forcing the rope through tight bends and past rough surfaces. Usually either one thick rope (about 11mm) or two thinner ropes (about 9mm) in parallel are used; both systems have their advantages in different situations.
The person climbing is said to be on belay when one of these belaying methods is being used. Belaying is a critical part of the climbing system. By using a correct belaying method, the belayer can hold the entire weight of the climber by using relatively little force, and can easily arrest even a long fall. By using a mixture of belaying angle and hand-grip on the rope, a climber can be lowered gently by the belayer to a safe point where climbing can be resumed.
As the climber moves on the climb, the belayer must remove the slack from the rope by paying out or pulling in excess rope. If the climber falls, then they will free-fall the distance of the slack or unprotected rope before friction applied by the belayer will start to slow their descent. It is extremely important for the belayer to concentrate on the climbers situation, as they literally have the climbers life in their hands. Most belay methods also require an action by the belayer in order to arrest a fall, hence they must be alert and ready to perform this action at a moments notice.
Communication is also extremely important in belaying.
Climbers should wait for a verbal confirmation from the belayer that they are ready to begin. Usually the belayer will say "On Belay" or "Climb Ready". This is usually acknowledged by the climber saying "Climbing"
During the climb, the climber may ask the belayer for "Slack", "Tension", warn of a "Rock!" or that they are about to be "Falling!".
At the top of the climb, the climber may elect to climb back down, be lowered, down walk back down, set up a new belay point for another pitch. Whatever they choose to do, it must be made clear to the belayer. When the climber is in a safe position independent of the belay they will call "Off belay".
Silent belay communication is possible via tugging the rope. Though it is much more difficult, it may be necessary in storm weather.
Except in situations where the belayer is of similar or heavier weight than the climber, and is standing on the ground, an anchor will be required to hold the belayer in place. In the event of a fall, the belayer may be jerked or hoisted, and without an anchor, may be placed in a dangerous situation themselves.
The anchor should be positioned below the belayers harness since an upward force will be transferred to it from the climbing rope.
Climbers now almost exclusively use a Belay Device to achieve controllable rope friction. Before the invention of these devices, climbers used other belay methods, which are still useful in emergencies.
A belay device is a piece of climbing equipment that improves belay safety for the climber by allowing the belayer to manage their duties with minimal physical effort. Belay devices are designed to allow a weak person to easily arrest a climbers fall with maximum control, whilst avoiding twisting, heating or severely bending the rope.
A munter hitch is a method of belaying which creates a friction brake by tying a special knot around an appropriate carabiner. This type of belay however causes the rope to become twisted, and cannot be used on double ropes
Historically, belaying in climbing meant simply that the belayer would take a wrap of rope around his or her waist; friction between rope and the belayer's body was used to arrest a fall. This technique, known as the hip belay, is still sometimes used by climbers needing to move quickly on low-angle terrain, but on vertical rock it is no longer used as it is less reliable and more apt to injure the belayer stopping a long fall.