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Tubular webbing for purcell-prusik?


Original Post
normajean · · Reading, PA · Joined Jun 2015 · Points: 100

I use purcell-prusik tied from accessory cord as PAS. I understand that there are many other options, but I like that its length is easily adjustable without un-clipping and that it is dynamic if you slip near the anchor. I would prefer that they took less room in my tie in loops and were lighter. Are there reasons why nylon tubular webbing or sewn slings should not be not used to tie one?

CrazyLegs · · Cincinnati, OH · Joined Jun 2014 · Points: 0

While I'm not saying it cannot be done, I see 3 main obstacles to using webbing for your purcell-prusik.

1. The purcell-prusik uses a standard prusik for the friction hitch, which does not typically work well when tried with webbing. You would need to change the hitch to something like a klemheist. I don't think it would be impossible to do, but it would be more complicated and difficult to tie correctly rather than a prusik.

2. Friction hitches topically grip round rope as opposed to flat webbing, and I am not sure how well your hitched would hold. Although it would be an interesting thing to test.

3. Last, with cord the weight bearing structure is not the part of the cord that is providing the friction and slipping if you were to utilize the purcell-prusik's dynamic load reduction properties. I would be a little uneasy about the webbing loosing strength my melting through itself in the event of a fall.

But, it is an interesting thought. I might try and make one myself just to see if I can, and test how webbing holds onto itself.

normajean · · Reading, PA · Joined Jun 2015 · Points: 100

Thanks, CrazyLegs! Your first two points make a lot of sense to me and would obviously be sufficient reasons not to do this. I am not sure the last one does; the fall, if it occurred, would generate at most a very short distance (part of the length of the PAS) travel for the friction hitch. Would such short distance produce anywhere near enough heat to affect the strength of the webbing? I am guessing "no." Let me know what you find if you do the experiment!

CrazyLegs · · Cincinnati, OH · Joined Jun 2014 · Points: 0

Honestly, I don't think it would really grip well enough to generate any substantial heat, and it would just turn into a long sling with lots of twists and turns, and the person at the end would not fair very well at all.

But if it did grip, my guess is that it would most likely hold fine but show enough signs of damage from the heat to cause me not to use it again.

Old lady H · · Boise, Idaho · Joined Aug 2015 · Points: 290

Normajean, just push the bight opposite the foot loops through your tie in points, bottom to top, stuff the Purcell part through that bight and tighten. Clip the foot loops to the chains. You get all the adjustability from the prussik, and not much difficulty getting attached to the tie ins. Puts all the bulky knots away from your harness. Bottom to top let's you see that you got both tie ins, lower one is sometimes hard to see.

I've seen webbing tied as a friction hitch, but only the hitches that use a carabiner, not a prussik. I wasn't paying much attention, but I recall they used at least four wraps, maybe even six, and it was around two fat gym ropes.

normajean · · Reading, PA · Joined Jun 2015 · Points: 100
CrazyLegs wrote:Honestly, I don't think it would really grip well enough
Yeap! That was an easy experiment. It has no hold whatsoever. Just slips. Well, onto the next great idea.
wivanoff · · Northeast, USA · Joined Mar 2012 · Points: 472
Old lady H wrote:I've seen webbing tied as a friction hitch, but only the hitches that use a carabiner, not a prussik. I wasn't paying much attention, but I recall they used at least four wraps, maybe even six, and it was around two fat gym ropes.
Helen, not applicable to a Purcell Prusik but check out the FB-Sling Friction Knot. Less wraps, can probable grip a steel cable.
Guideline #1: Don't be a jerk.

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