Releasable Rigging - does it have a place in caving?
Posted: Mar 15, 2011 5:54 pm
A common practice in canyoneering, especially in class C canyons (moving water) is to rig releasable. Also known as a contingency anchor, releasable rigging allows for the person on rappel to be lowered from above. This is especially helpful in two situations. One is when the drop length is unknown or unseeable from the top. A person can be lowered from above in order to efficiently set the proper rope length. The second situation is when someone is stuck on rope, especially in a waterfall. The stuck rappeller can be easily and quickly lowered to the bottom.
There are many ways to set up releasable rigging. One of the simplest is with a contingency eight block, pictured below:
this photo was shamelessly stolen without permission from canyonquest.com via Google images
The photo shows how it is rigged. In practical use, the eight would be locked off until needed using a bight of rope from the non-rappel end. The rest of the rope below the eight is stored in a rope bag. In the event of a lower, you unlock the eight and begin lowering. The extra rope feeds out of the bag until the patient is on the bottom. This is the fastest way I know of to get someone out of a waterfall and prevents any need for a dangerous pick-off or any additional rigging. What it does require is rope double the length of the drop and some sort of rappel ring to lower through on the anchor. What kind of cave trips carry this kind of equipment? Well, TAG pull-down through trips do for example.
As mentioned, there are other ways to rig releasable including munter hitches on carabiners and many other ways that you are probably thinking of in your head right now. The group I canyon with has adopted the contingency eight for its simplicity and versatility. The main advantage I see with the eight is that the rope can be pulled after the last rappel as is. No re-rigging is necessary for the pull. Everyone rappels single-strand on the opposite side from the block. The last person either throws the rope bag or brings it down with them. The rope is then pulled on the eight/bag side.
My question to the caving community is this: Why do we not use this technique on wet, pull-down trips? Is there any reason not to? Should we adopt this technology for all dangerous waterfall drops?
Recent events have caused me to question the appropriateness of hard-rigging in a waterfall. What are your thoughts?
There are many ways to set up releasable rigging. One of the simplest is with a contingency eight block, pictured below:
this photo was shamelessly stolen without permission from canyonquest.com via Google images
The photo shows how it is rigged. In practical use, the eight would be locked off until needed using a bight of rope from the non-rappel end. The rest of the rope below the eight is stored in a rope bag. In the event of a lower, you unlock the eight and begin lowering. The extra rope feeds out of the bag until the patient is on the bottom. This is the fastest way I know of to get someone out of a waterfall and prevents any need for a dangerous pick-off or any additional rigging. What it does require is rope double the length of the drop and some sort of rappel ring to lower through on the anchor. What kind of cave trips carry this kind of equipment? Well, TAG pull-down through trips do for example.
As mentioned, there are other ways to rig releasable including munter hitches on carabiners and many other ways that you are probably thinking of in your head right now. The group I canyon with has adopted the contingency eight for its simplicity and versatility. The main advantage I see with the eight is that the rope can be pulled after the last rappel as is. No re-rigging is necessary for the pull. Everyone rappels single-strand on the opposite side from the block. The last person either throws the rope bag or brings it down with them. The rope is then pulled on the eight/bag side.
My question to the caving community is this: Why do we not use this technique on wet, pull-down trips? Is there any reason not to? Should we adopt this technology for all dangerous waterfall drops?
Recent events have caused me to question the appropriateness of hard-rigging in a waterfall. What are your thoughts?