One of the more useful knots for climbing is the Purcell prusik (related to but not a regular prussik), which can be used as an adjustable tether or for ascending a rope among other things.

How would one tie it?


1 Answer 1


Note: You want to keep the double fisherman's knot close to the opposite end, but offset slightly, this gives you maximum adjustability while being able to use the far end as a prusik as well if necessary.

There are two ways I have done this,

  1. Tie a normal prusik (described here) around something and then pull the end of the cordelette through. A stick might work, I have always just used my arm and then pull the end through with my hand.

    Tying a Purcell prusik

    The difficulty with this technique comes from getting the prusik over your wrist as it has a tendency to tighten.

  2. The other is to tie a prusik on a bight and then pass the end of the cordelette through.

    enter image description here

    It should then look like this,

    enter image description here

    From there you add at least one extra loop to each side, although I usually do two, and then pass the end through.

    enter image description here

There is also an animated demonstration of this, and a good description of how it is tied and used here. Result

  • If you butt the double fisherman's into the prusic, you get a little more working adjustable length. And if you limit the length to be always within arms reach, you can rig the bight to the harness and the locker on the loop to the anchor, then you get some mechanical advantage for shortening and pulling yourself up, and a panic grab on the prusik won't tend to drop you. I built mine as in bluugnome.com/cyn_how-to/gear/purcell-prusik/…
    – Dave X
    Commented Jun 12, 2019 at 15:09

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