4

I recently purchased a Petzl ice axe and it came with a leash tired to it using a simple knot that allows the length of the leash to be adjusted.

I am interested in this knot because I had previously made a Purcell Prusik to leash my ice axe to my harness but I could use this knot to make a harness leash that would allow the same amount of adjustability, be more compact and use much less cord. I would like to know if it has a name and if there is a reason to prefer a Purcell Prusik for leasing my axe to my harness.

In particular, I would like to know if it is strong enough to withstand the shock loading that would occur in the case of a fall after sinking the shaft of the axe into the snow. The knot would need to still be reliable even when the cord is icy. If you know of any references that would also be interesting.

Here is the knot and how it is tied. Note that my question is about a harness leash that I would make using some accessory cord. I'm only using the wrist leash to illustrate the knot.

Step 1

Step 2

The finished knot

Improve this question
8
  • Once you release the axe there is nothing to hold it in the snow.
    – paparazzo
    Apr 29, 2017 at 10:07
  • Not an answer, but still: Remove the leash, it does more harm than good - so no knot at all required
    – imsodin
    Apr 29, 2017 at 14:02
  • @imsodin I'm asking about using a harness leash --- not the wrist leash that came with the axe.
    – Qudit
    Apr 29, 2017 at 14:50
  • I didn't realize that and still can't make this out from the text and pics - you might want to add a sentence to the question clarifying this aspect.
    – imsodin
    Apr 29, 2017 at 19:26
  • @imsodin I've edited it so that it is hopefully clearer now.
    – Qudit
    Apr 29, 2017 at 20:35

2 Answers 2

Reset to default
5

I would call it a basic munter hitch.

Take the eye in the end of the cord (through which you are pushing the bight in the first image) and imagine it to be a carabiner. This should make the structure more obvious.

A difference between this and a Purcell Prusik is that the prusik can slip when catching a fall, absorbing some energy that would otherwise be passed along to you.

As to whether it can hold a fall, that would depend on circumstance and the type of cord used. Dyneema cord would obviously fare worse than nylon, but presumably if you're sinking the shaft into the snow you're not on pure vertical terrain and probably also standing below the axe.

The wisdom of leashing or not leashing an axe to one's harness has been debated in many places; you should be aware of the risks of either method.

ref for PP slippage: https://dirtbaglawyer.wordpress.com/2016/01/15/a-case-for-the-purcell-prusik-as-a-personal-anchor-system/

Improve this answer
2
  • If the intent of having a munter on your leash is to reduce fall factor forces, then dyneema will out perform nylon with this set up. Dyneema is more abrasion resistant, stronger, and has less friction, so it'll slip better. Nylon will get wet, stretch, tighten and then freeze that munter to a point where it may as well be a bowline.
    – ShemSeger
    May 3, 2017 at 21:50
  • @requiem. The question What footwear did mountaineerers wear in the 19th century has been re-opened. Some how you have an answer on a closed meta version of the question here would you like to post you answer to the mainspace question?
    – James Jenkins
    Dec 19, 2017 at 14:49
1

Since asking the question, I've done some experimentation and discovered a potentially serious problem with this knot.

When it is tied from cord, the size of the loop around which the munter is tied (thanks to @requiem for pointing out that it is a munter) is critical. If the loop is too large, it can twist into a configuration where the rope can simply slide through the munter. This cannot occur with a carabiner because carabiners are rigid whereas the rope is not.

After tying the munter

After pulling on the rope

This problem can be fixed at least to some extent by using a slip knot for the loop. However, I worry that it might still have problems under the strong and sudden force that would occur during a fall.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.