So, time for the guilty admission: it is the exception, rather than the rule to belay someone performing SRT in a cave. There’s a few reasons for this, but first note that in the case of club-run SRT, a belay either means a bottom belay or a self-belay; top rope belays are almost entirely unsuitable for club-run SRT (see Note 1 though).
- Many pitches are unstable or have loose debris on them, and the belayer risks being hit by debris knocked loose by the abseiler
- Most caving descenders offer excellent control of your descent via friction, and an experienced caver will know several ways of adding more friction to their descender while abseiling
- A lot of the time you will not have a clear line of sight to the abseiler, and thus a belay is difficult to run
- Many pitches are either very long, or have rebelays in them. On long pitches the degree of rope stretch can make a belay impossible to establish. When there is a rebelay below an abseiler, it is impossible to belay them
- Most self belay options have issues of their own and are difficult to operate safely in a cave environment
The first person down a pitch will will likely abseil without a belay, and is usually the most experienced SRT caver for that reason. If they feel that a belay is necessary, they will use an autolocking descender, of which the most common is the Petzl Stop. A Stop is not a beginner’s piece of equipment, as misuse of their braking capacity has been the cause of several nasty accidents overseas.
Instead, a beginner will be given a bottom belay (or fireman’s belay). It is standard in caving for beginners to be given a bottom belay, or for all to be given a bottom belay if the nature of the pitch dictates that (eg, loose rock). For a fireman’s belay, the belayer holds the rope with both hands, and attentively watches the abseiler. Once help is required, the belayer firmly holds the rope and rapidly moves away from the pitch, pulling the rope tight. This increases the friction in the descender and should halt their descent enough for the abseiler to regain control of their abseil. If they’re unconscious, the belayer should carefully lower them to the ground. Of course, there are some caveats:
- The belayer needs to stand close to, but not directly under the pitch, so that they’re not exposed to falling debris
- It it takes very little pressure for a belayer to hold a stationary abseiler. However, if the abseiler is already out of control, it does take significantly more pressure, so practise belaying FIRST in a safe and controlled environment (obviously, please don’t simulate a complete free-fall unless you really, really know what you’re doing!)
- Generally, don’t anchor the rope to the belayer, as the belay system should be a setup that the belayer can easily eascape
- If there is a lot of stretch in the rope, the belay can be less secure. In this instance, more elaborate forms of belay than the fireman’s belay can be necessary, such as tying off the belay to a belayer’s belay belt or harness, and routing the rope through a karabiner (or inverted pulley) secured to an anchor at the bottom of the pitch
Note 1: as always, there are exceptions to this, when there are potential dangers on pitch to the abseiler that may require rapid extraction (eg, foul air), although arguably, there are still better alternatives to a top belay