Vertical caving terminology and methods > Ladders, climbs and older techniques
Various methods to use a lifeline without needing a belayer. Typically, this might mean setting up the lifeline so that it is connected above a ladder or climb, and then connecting to it with an ascender. This may be done while solo caving, but even when caving as part of a team, it might occasionally be done with a rope climb, where the handline can also be used as a lifeline while climbing.
For solo caving, it is important to consider whether it would be possible to reach the ladder or rock face after a fall has been caught, since a fall could result in hanging from the lifeline without being able to reach anything in order to get back off the lifeline. Without SRT gear, this could result in the need for rescue, and waiting for the rescue while hanging from the lifeline would probably result in suspension syncope.
Toothed cam ascenders can damage the rope when catching a fall, so lever cam ascenders are preferred, even though many climbers use toothed cam ascenders for this purpose (many claim that since they have never had an issue, it must be safe, but trustworthy testing has shown that issues can and do happen). Progress capture pulleys are sometimes used by climbers, but these are almost never suitable for this purpose, as they typically rely on toothed cams, with even more risk of damage to a rope than toothed cam ascenders. The most common progress capture pulleys used for this, the Petzl Traxion series, are specifically not rated for this purpose by the manufacturer, even though many climbers try to claim otherwise (they are actually rated as an ascender). Because so many climbers make this mistake, Petzl published an article stating that climbers should not rely on a Traxion device, since it is not designed or intended for that purpose, and they need to have another device that can provide proper protection as well. Unfortunately, many climbers misunderstand that article, and assume that Petzl have said that it is good for this purpose as long as it is combined with another inappropriate device, but that is not the case. Petzl have never rated the Traxion devices for catching falls, and have never stated that any of them are suitable for the purpose, no matter how many other devices are used. Because many climbers continue to publish dangerous advice telling each other to copy them, many other manufacturers explicitly state that their progress capture pulleys are not designed to be used for this purpose, sometimes even producing their own videos to show how dangerous the advice is. This dangerous advice is frequently spread by climbers on YouTube, but no matter how knowledgeable they may seem, it is bad advice, even if they have published books about the subject. If a climber ever suggests using a progress capture pulley that is not specifically rated for catching falls by the manufacturer, all of their advice regarding the subject should be treated as dangerous.
It is unusual for cavers to do the kind of solo caving that needs self belaying, but self belaying on a rope climb is more common. In cases where it is used, cavers are also likely to use a toothed cam ascender simply because that is what they already have on their SRT gear. However, it is worth noting that while it normally copes with a bit more, even at surprisingly low fall factors such as 0.06 (2 kN with an 80 kg load) on a static rope, a toothed cam ascender can completely sever the rope's sheath, leaving just the cores. That could be just a 30 cm fall on a 5 metre rope. This rises dramatically with increasing load, and by fall factor 0.3 on a static rope, severing the sheath is extremely likely no matter what weight the climber is. This can happen much more easily on ropes with a thinner sheath, so it happens far more easily on a thinner rope. By fall factor 1, it is almost guaranteed, even on a dynamic rope. The risk is exponentially higher as the top of the rope is reached, as the fall factor is exponentially higher for even a short fall. Toothed cam devices are not meant to be used for self belaying, they are designed for static loads.
The most common lever cam device for self belaying is a shunt, even though the official Petzl Shunt is not classified as PPE. It is important to note that due to the way a fall can pull the Shunt in an unexpected manner, it can end up oriented in a way that causes the lever cam not to engage at all, or to release the rope completely, so that it will not succeed in catching the fall. Shunts should not be used for self belaying. Various Gibbs ascenders can serve the same purpose, as they can take nearly twice the shock load of a toothed cam device before they damage a rope, but the manufacturer recommends against it anyway. The Petzl Rescucender is an ascender which is almost identical to a Gibbs in the way that it works, but is much easier to open, and gives very similar results in testing, so it is a very useful alternative. However, it does not work very well when descending, because it has a spring forcing it to grip the rope, so it does not move downwards reliably, unless it is pushed downwards. It is also not officially rated for catching falls.
Dedicated fall arresters are made for rope access, and although most of these are designed to be used with the thicker ropes used for rope access backup lines, there are some that can be used with the thinner ropes normally used for caving. These devices are designed to minimise the damage to the rope when catching falls, and are specifically made for this purpose, so they are the right type of device to use.
Some cavers, and far too many climbers, may choose to use a dedicated auto-locking belay device, which may seem like the correct thing to use, but auto-locking belay devices are supposed to assist a belayer, not replace them completely, and it is quite possible for an auto-locking belay device to fail to catch a fall if there is no hand to hold the down rope. Many will also fail to catch the fall if something presses on parts of the device during the fall, which is easily possible. Using an auto-locking belay device means having to randomly stop to pull the rope through the device, as it will not normally feed through automatically. Until it has been pulled through, a fall will result in a much longer drop before it can catch the fall. It is also worth noting that the most common dedicated auto-locking belay devices will start slipping down the rope and fail to function at a lower force than where a Gibbs device or Petzl Rescucender would damage the rope.
Climbers typically recommend having at least two self belaying devices in use at the same time, in case one of them gets caught at an odd angle during a fall, and fails to grab the rope. Ideally, they should be two totally different designs, so that whatever caused the first one to fail is unlikely to affect the second one in the same way. In addition, they should each have their own rope, so that if one rope gets damaged by a failure in one of the devices, the other device still has a functional rope to use. These should be configured so that one of the devices normally does not engage unless the other device fails (such as by having it on a much longer tether), since if both catch at the same time, the shock load experienced by the user is doubled (because twice the thickness of rope is performing the catch). However, dedicated rope access fall arresters often expect to be the only device used to catch a fall, and they are tested and certified to ensure that they are trustworthy enough for that.
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