Leaving caves rigged has some attractions. It reduces that exhausting work of detackling and it also means that we can get going quicker the following year since we don't have to re-rig from scratch. However there are also some risks:
<ul>
<li> Ropes can get damaged by water
<li> Corrosion of metalwork
<li> Increased number of abseil/prussik cycles before inspection
<li> Ropes can become extremely muddy. That can lead to problems abseiling and prussiking and also make in situ inspection harder
<li> Aging of ropes if left in place for a long time
</ul>
<p>
Although not directly related to the technical side of things, another issue is that it makes it possible to go very deep very quickly at the beginning of an expedition. This raises some further issues:
<ul>
<li> Less experienced cavers may descend beyond their comfort zone without realising the effort required to get out. Leaders/experienced core of cavers need to keep an eye on newcomers. Consider a "warm up" trip to a lesser depth to see how people manage and get them acclimatised.
<li> There may only be relatively few people around at the start of EXPO - it could be easy to create a situation where the numbers on the surface are too small to conduct an effective emergency action to such a depth.
<li> Even experienced cavers could get lost if they descend very deep into a cave they are unfamiliar with. There is a need to make sure documentation (descriptions, surveys, topos etc.) is up to date and laminated copies made ready.
</ul>
<p>
One final issue is that we should not see this idea as an excuse for never doing any derigging ever again! When a project is finished it must surely be derigged properly and old ropes etc. need to be carried down the hill and properly disposed of.
<h2>Tackling the risks - When Rigging</h2>
<ul>
<li> Consider using 10mm diameter rope if you know you are going to leave something rigged a long time. If you decide 9mm rope is needed, make especially sure to use new/newer rope, since this starts with something in the best possible condition.
<li> Make sure new rope is properly washed and dried before use
<li> Rigging skills need to be very good. Take the time needed to do a good job.
<li> Allow a bit of extra rope here and there at the start/end of sections so that minor issues can be dealt with without having to carry in a new rope.
<li> At the end of the expedition ropes will need to be pulled up and stored at pitch heads whenever water could be an issue. Bear in mind that what seems dry today might be wet tomorrow.
<li> Note that any sections where there are rebelays etc. left in place will mean that the rope cannot be easily pulled up and inspected in case of any doubt about its condition on return. In the case of short distances this is not so problematic since a visual inspection will be possible with a bright light.
<li> Think about where rope joins are positioned so that partial derigging is feasible in wet sections whilst leaving dry sections in place (or if the rope is rigged through leave a bit of extra slack to allow a cut to be made if necessary).
<li> The above issues mean that it is preferable to not string huge numbers of belays together with a very long rope. Furthermore derigging a long rope to the pitch head can mean lifting more rope up to a higher position which takes more effort. So we have to be prepared to cut ropes into shorter lengths in some places if we are to maximise efficiency savings.
<li> Use stainless steel hardware where possible and never have direct contact between different types of metal (e.g. aluminium/steel) because of galvanic corrosion. Consider removing aluminium karabiners, e.g. on deviations since aluminium can corrode quite fast in damp conditions - though this has never been observed in our Austrian caves.
<li> If may be necessary to derig certain ropes (e.g. for cleaning). But maybe we can identify places deep in some caves where washing can be done? Can we design a lightweight rig which will facilitate this without having hands in freezing water for ages?
<li> Keep track of the age of ropes used and document this carefully. Ropes can be marked with laminated marker tags with a serial number and zip ties.
<li> Something we need to think about is which knots are strongest over time (not just in once off drop tests).
<li> Another issue is wear of ropes where the rope runs over maillons. This is especially acute at free hanging change-overs where people clip in a cowstail, which leads to the rope being crushed at that point. On occasions I have seen ropes quite badly damaged in this way which requires cutting the rope at that point. The minimum diameter of maillons used is one issue. Training is another issue - it's usually possible to manage the change-over another way.
</ul>
<h2>Tackling the risks - When caving</h2>
<ul>
<li> Extremely important to abseil slowly. Fast abseiling and resultant heat generated is one of the main causes of rope damage.
<li> Perform on-rope inspections with documentation to a given specification. Can we make this streamlined enough? Some sort of waterproof fill-in sheet could be carried by the inspector and status of tackle reported?
<li> ANY problem with the rigging must be rectified as soon as possible. A slight rub isn't a problem on a couple of trips but will develop into a worse problem over time.
</ul>
<h2>Tackling the risks - On the last trip</h2>
<ul>
<li> Read the documentation from previous trips before setting off and make a plan
<li> Strategy which will be employed for each section varies:
<li> Leave everything in place (rope in good condition, low water risk)
<li> Derig up to pitch head, leave all knots in place for future re-rig (rope in good condition, but water could be a risk)
<li> Derig up to pitch-head, undo all knots and prepare for re-rig with rope upside down or otherwise displaced (minor rope damage which can be dealt with by ensuring that repeat wear next year is not in exactly the same place)
<li> Derig and remove rope, but leave metalwork in place (rope in poor condition but return intended)
<li> Perform an on-rope inspection ON THE WAY DOWN to check that planned strategies are realistic.
<li> Last person up needs to derig any sections according to strategies outlined above
</ul>
<h2>Tackling the risks - Returning to a pre-rigged cave</h2>
<ul>
<li> Check the documentation carefully so that you know what is in place and whether you need any additional equipment in case some things were removed.
<li> It could conceivably happen that a cave gets left rigged for a long time. The longer ago it was rigged and last inspected, the more cautious you need to be.
<li> Pack one spare rope which is about 10m longer than the longest drop you will encounter and some extra krabs etc. An empty tackle bag (or at least one with some spare space) could be useful.
<li> Inspect the rigging carefully. Always make a visual inspection before descent. On longer pitches were the rope was left in place always abseil extremely slowly so that you can make a visual check that the rope below is intact.
<li> If the rope was pulled up to the pitch head it may be easier in some circumstances to pack the rope in your spare tackle bag to avoid tangling.
<li> If there is any doubt about the condition of a rope and it cannot be pulled up for inspection, do not trust it. Use the extra rope and rig parallel. On descent you can inspect the original rope. If all is well, the next person down can derig the extra rope.
<li> When you arrive at the bottom the spare rope you brought is hopefully available for pushing! Good luck with your exploration!
