Vertical caving terminology and methods
The most hazardous part of any caving trip is the part before it where you cross a street, or the parts where you drive to and from the cave. That is not to say that vertical caving is not hazardous, but hopefully it should help to put things into perspective. As humans, we are quite poor at judging danger, and tend to think of things as dangerous just because we are unfamiliar with them. In reality, the hazards of daily life far outweigh the hazards of cave exploration. At least with vertical caving, we put a lot of effort into minimising the hazards, far more than we do with most other sports or common daily activities.
With vertical caving, there are many of the same potential hazards as in regular caving, but there are a several that are unique to the vertical nature of the cave, which must be avoided by rigging the ropes or ladders away from the hazards, or providing protection. This section is not intended to be an exhaustive list (this page is about terminology, after all), but this shows why the approaches and equipment described on this page are used.
Many hazards can be avoided by good rigging. The heights and slippery surfaces can result in falls, and need protection. The dropzone for shrapnel and equipment from cavers, idiot tourists and streams, needs to be avoided where possible, to protect both cavers and the equipment. Falling sheep can sometimes happen with surface shafts! Rigged routes should avoid loose debris where possible, as well as birds' nests in surface shafts. Waterfalls are a common hazard which can make breathing difficult and rapidly reduce body temperature if not avoided. Fast flowing water at the head or base of a pitch is a hazard of its own. Deep water, such as sumps or lakes, does occur at the bottom of pitches in some caves, and rigged routes should not normally land in it. Spikes of rock, or pointed stalagmites sometimes occur at the bottom of pitches, and these need to be avoided. Rub points can rapidly cause severe damage and even cut through a rope, which can be avoided with Alpine rigging, or reduced using rope rub protection. Confusing rigging can cause cavers to make mistakes, such as getting hung up, accidentally abseiling off the short end of a rope, or following the wrong rope when a pitch has ropes rigged over each other. Selecting a good rope diameter and pre-shrinking it or wetting it before use prevents it from being so fast that someone might lose control of their speed while abseiling. Preparing the rope correctly can also prevent some other hazards. Packing the rope correctly prevents the rigger from having to contend with spaghetti. A safety knot prevents a caver from abseiling off the end of the rope.
Some environmental hazards can happen in spite of good rigging. Fear of heights can be a significant risk if it causes someone to act irrationally, forget their training, or shake so much that they cannot use their equipment. Cold can be excessive, due to the amount of time spent waiting for rigging while in a wet and draughty cave, without anywhere to go to warm up. Sitting in a sit harness for too long without moving can cause suspension syncope, which can happen while waiting for a rigger without having anywhere good to stand, or can happen to an incapacitated casualty. Loud sounds from water and big hangs can make communication challenging or cause confusion, but whistle calls can help with this to some extent, and walkie talkies can help a little more. Flooding is something that can happen particularly quickly in many potholes. Very narrow pitches can prove challenging, particularly given the movements required for prusiking.
Training can help avoid a lot of hazards. Failing to use the equipment correctly, or follow the right procedures, can have serious consequences, so training is essential. Sit harness buckles and carabiners should be checked to make sure they are closed. Failing to connect to a rope correctly can result in a fall. When abseiling, it is very easy to forget to look down and watch out for hazards which can cause injury or snagging of equipment. With long hangs, where the weight of the rope changes the friction during the descent, additional friction might need to be added part way down the hang to avoid losing control. Body parts could be entangled in equipment which is not used correctly. Hair can be abseiled into a descender, and may need to be cut free, using a knife next to the rope while unable to see it.
A great deal of effort is made to make sure there is redundancy, such as almost always having two points of contact with the rope, which mitigates a lot of potential hazards and mistakes. The exceptions are that a single descender is normally used (though climbers are sometimes seen using a shunt or prusik loop as a safety brake), a single sit harness is used (though these do have minimal redundancy), a single D-ring is used, and a single rope is normally used; if one of these fails, there is normally nothing left, so they are typically over-engineered.
Extra challenges are presented by the existence of caving and SRT gear, and selection of approapriate equipment can help avoid this. Swimming across pools while wearing SRT gear is challenging, and needs additional buoyancy. Carbide lighting (where still in use), is not only environmentally questionable (hello pile of spent carbide) and unintentionally vandalising with its pervasive soot marks, it is also a significant fire risk, since there is a flame dancing around on your head right next to a rope, and you cannot see where it is pointing.
Equipment can be damaged or fail. Anchors, naturals, tat and knots can fail, resulting in shock loading as other equipment takes over, impacting the floor or a ledge, or a fall if there is no suitable backup. Even if they do not result in a fall, an accidental pendulum may result in impacting a wall. Passing cavers could dislodge a sling that has been looped around a natural (particuarly common with deviations), exposing the caver to whatever hazard the rope had been set up to avoid. Equipment can become worn out or fail, and needs regular inspections before and after each use to ensure that it is still safe. Weak or fractured rock could break, dislodging an anchor which was placed in that piece of rock. For all of these reasons, rigging normally includes multiple backups and Y-hangs, configured to reduce shock loading.
Ropes exposed to heat or UV from sunshine, or many types of cleaning chemicals, deteriorate relatively quickly (this applies to slings and sit harnesses too). Ropes left dangling in a waterfall for several weeks or months can become damaged because of the constant movement, expecially if they frequently make contact with rock. Unused ropes eventually deteriorate over time (though nothing like as fast as previous maintenance schedules would suggest). General use of a rope slowly wears it out. Mud and ice on a rope can cause the rope to become damaged faster, and will also wear down other equipment much faster. They also make it hard for ascenders to grip the rope. Hot descenders can singe or partially melt through a rope, and ropes may be intentionally wetted to avoid this risk. Ropes could be stressed by having two many cavers connected to the same piece of rope, such that their combined weight is held by the same knot. Ropes could also be stressed by tension, such as with a Tyrolean traverse, or by using knots that dramatically reduce the strength of the rope.
Equipment could be stressed in unexpected ways, such as being bent around a rock, or pulled in an abnormal direction, causing it to deform or break. Handled top jammers are the most common case, bending them around a rub point at a pitch head; yet another reason why rub points are bad, and indestructible rope technique should be avoided. Poorly placed anchors could cause extreme stress by pulling on the screw threads, or can cause a knot to rub against the rock at the anchor. Unlocked carabiners could have their gates pulled onto something, causing them to open. Carabiners and maillons could be accidentally left open, causing them to break or release a rope.
Almost all equipment is designed to cope with 5-10 times as much force as it should ever experience during normal use, with a minimum breaking strength normally 5 times more than the recommended working load limit. The seemingly excessive over-engineering of equipment, and repeated use of redundancy, is what allows issues to happen without serious results. A rope being parially worn through by a rub point, a carabiner being bent sideways over an edge. Some rock fracturing and taking an anchor with it, suddenly shock loading the rope as it now has to catch the rock as well as supporting the cavers who were above and below it. It might not ever happen, but if it does, the equipment can cope with far more than just a normal load.
Somewhat less obvious and thankfully less common, a thief could take the ropes or other rigging equipment, leaving cavers stranded. A vandal could damage the equipment, leaving the rigging in a dangerous state. Thieves are somewhat dissuaded by tying the bottom of a rope to something on a surface shaft, so that they cannot pull the rope up from the top.
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