Redundancy in rappel systems
What is the simplest setup for rappelling that is fully redundant?
The most common system seems to be rappelling off of both strands of a rope passing through two rappel rings on separate anchors. While providing the option to recover the rope by pulling on one end, that setup still leaves the rope as a single point of failure.
Assuming the highest degree of redundancy is required, would it not be more safe to tie two figure-eight knots on two bights, connecting each to a separate anchor, and then rappelling off of those two strands? Thus if one of the anchors fail, or even if one part of the rope fails, the other strand is still fully intact.
Any specific reason this setup is not more common?
This post was sourced from https://outdoors.stackexchange.com/q/22554. It is licensed under CC BY-SA 4.0.
1 answer
Strictly speaking, the system you propose (fix each strand of the rope to one anchor, rappel with the same device) is not fully redundant as you still have the device, carabiner and your harness as single points of failure.
If you disregard that point and simply want redundancy against rope failure, then, yes, fixing the strands to their own anchors is more redundant than the standard way.
The reason that this setup is not more common is really simple: In most cases, the goal of rappelling (at least in sports and alpine climbing) is to arrive at the bottom of the rock/pitch and retrieving the rope. Either to climb another route, or to continue the descent. However, you can't retrieve the rope if it is fixed to the anchor with one or two knots! Also, rope failure during rappels is really rare as the load is much smaller than e.g. during lead climbing falls.
This post was sourced from https://outdoors.stackexchange.com/a/22555. It is licensed under CC BY-SA 4.0.
0 comment threads
0 comment threads