Additional equipment for vertical caving
From Ukcaving.com wiki
Contents |
Ropes
Dynamic rope
Dynamic rope is generally not used for caving or potholing purposes. Its use is limited to ascents of pitches or shafts from the bottom to the top using similar techniques to rock climbing. It is used where a fall may occur due to its elongation properties (8 - 10%).
Semi static rope
Often called static or rigging rope. This type of rope has very little elongation (3 - 4%) and is the primary rope used in caving. It can come in different diameter thicknesses (8 - 13mm generally) though the most common dia. are in the 9 - 11mm range. Its low stretch properties make it ideal for abseiling or jumarring as there is little or no bounce.
Nearly all modern caving ropes are made of nylon. Care must be taken to store and transport them properly. Note that polyethylene and polypropylene ropes are wholly unsuitable for caving, whether for SRT or for lifelines.
Ladders
Cavers use lightweight "electron" ladders. These are made from thin steel wire using alloy rungs and are easily carried rolled up. A lifeline should always be used when climbing ladders no matter how short the pitch is. Many falls have occured over the years on pitches supposedely too short to merit a line!
Connectors
Can either be non-locking often referred to as snap links/gate or locking - screwgates.
Used for connecting ropes or slings either to the caver or when forming belay anchors.
Screw-gates are prefered for nearly all caving purposes, although some users select snap-gates for cows'-tails (see SRT section)
Made of steel or alloy.
Applied in the same usage as karabiners. Thought to provide a more secure and strong connection. Cheaper but heavier than alloy karabiners. The usual sizes are the long pattern 7mm and the 10mm semi round. The latter is used for connecting the caver's harness, the former used like a karabiner.
Usually made of steel though alloy can be purchased. But be sure that the maillons are strong enough. 7mm Maillons made from "zircal" (an alloy) are available and are very light but are nowhere near the same strength as the steel alternatives.
Ascenders
[1] Most European (including UK) cavers use the sit-stand system (aka frog system). With this, there is one ascender mounted onto the main maillon rapide of the sit harness, and held tight to the body by some kind of chest harness or loop. Another ascender is attatched to footloops and also in turn linked in to the harness for safety by a length of dynamic climbing rope. [note: this should be dynamic rope as it can under some circumstances be subjected to a high fall-factor. The stretchyness of dynamic rope will somewhat reduce the shock-load on the caver and most importantly on the top jammer which could cut the main rope if subjected to too great a force. This safety link must be long enough not to impede moving the jammer up the rope, but not be so long that the ascender can be out of reach leaving the caver completely stuck - also see 'discussion for this Page'. Some cavers, especially in France, use the long cow's tail (see below) to clip in as the safety-link, but most UK cavers tend to keep the two functions seperate. No doubt there are pro's and con's for each. Even with a seperate link there is the option of tieing the safety link to the ascender, so you then can't forget or drop it, or cliping in, so you can remove the top jammer completely if required eg for walking passages] As the name "sit-stand" suggests, the caver ascends by alternatively standing up in the footloops and sitting down in the harness. Most caver tend to use Petzl ascenders of various types, though other makers exist. The so-called chest ascender is usually a Petzl "Croll", and the hand ascender may be of the type with or without a handle according to preference. The efficiency of ascent is crucially dependant on getting the lengths of footloops, harnesses, safety link etc just right.
In addition to the two ascenders described above, the caver will also have an abseil device, and a pair of cows' tails - consisting of length of dynamic climbing rope attatched in the middle via a knot to the harness maillon, and to a caribiner at each end giving a "long" and a "short" cow's tail for clipping in to belays etc.
There is a lot to be said for carrying a spare ascender, especially a mini-ascender such as the Petzl one, or the Wild-country Ropeman.
In the USA especially, a variety of alternative systems known collectively as "ropewalking" are popular. These are claimed to be more efficient on long pitches, but entail more difficulty in crossing knots and re-belays. They are rarely used in Europe / UK and are generally considered impractical for, say, Yorkshire caving due to these difficulties with belay-passing.
Descenders
Descenders are devices used for abseiling which allow descent of a rope by giving a controllable amount of friction to slow the descent to a reasonable rate. Although rock climbers have traditionally used the figure-of-eight device or improvised using belay devices such as Stitch plates neither is really suitable for caving use. Cavers almost all use eith a Petzl "bobbin" (aka "simple") or the "stop", or use a rack. The rack has some advantages on very long pitches, although is far less popular than the Petzl descenders nowdays. The Petzl bobin comes in two flavours: the "stop" which has a handle which must be depressed or it locks onto the rope, or the "simple" which lacks this feature. Whichever device is used, the speed should always be controlled by a hand on the rope, and the handle not be used as a brake.
There is an ongoing controversy over whether the "stop" feature is in fact a hazard in itself, since there have been a number of accidents where people [perhaps inexperienced] are believed to have lost control whilst tightly holding the handle in the "go" position. Thus, the supposed safety feature may have contributed to the accident.
Notwithstanding this, in the UK, the Petzl "stop" is by far the most popular, though it is not as clear cut in France where the "simple" has many advocates. If choosing the "Stop" it is especially important that proper use of the handle is understood if the safety concerns are to be minimised.
The abseil device is attatched to the harness main maillon using a screw-gate caribiner. A maillon should not be substituted for this caribener as there was a potential safety issue due to the geometry of certain sized maillons used with the Petzl descenders. The Petzl devices are usually used with an extra steel snap-gate caribiner to provide extra friction and control.
A spare abseil device is not usually carried. Instead, it is worth learning how to improvise using the "Italian Hitch" or similar.
The climbing-oriented figure-of-eight and similar are not generally used caving, as they have to be detatched from the harness to put on and off the rope, with a risk that they may be dropped leaving the caver stuck on a re-belay half-way down a pitch. There is also a view that stitch-plates and figures-of-eight put a twist into the rope, which is a nuisance for those following down.
Harnesses
For caving a harness specifically designed for SRT should be used. These are different from those used by climbers. SRT harnesses have a lower point of attachement to assist in efficiency in prusiking and also allow the legs to straighten more while suspended. Climbing harnesses also have undesirable features like extra padding and gear-loops which are an encumberance underground.
It is worth learning a bit about Suspension Trauma while we are on the subject of harnesses.
