Purcell prusik slings as Screamers?

Is it absolutely crazy to use Purcells as slings? They are adjustable, and should provide some shock absorption before the prusik bites itself in half. Do you guys know of any tests?

The walls have never been climbed & are all limestone & dolomite with bad rock, mud, shattered stuff etc deep underground

Shock loading a friction hitch? What could possibly go wrong?

Do not do this. /topic

This is what you want. Kong KISA. Maybe

Yes, ok. But are there any tests on the strength of the purcell loop as an adjustable runner? A normal dyneema runner just breaks since it is completely static. I want to know how weak it is. Does it snap at the friction hitch, or at the single strand, or the knot?

I love the idea with that Kong device, had forgotten about those.

Best demo ever of artificial textile on textile friction

youtube.com/watch?v=9A1hX2T…

SS Minox wrote:Is it absolutely crazy to use Purcells as slings? They are adjustable, and should provide some shock absorption before the prusik bites itself in half. Do you guys know of any tests?

You should ask Eric Moss. I hear he's an expert on these kinds of things.

"Can I do this?"

"Don't do that!"

"Like this?"

"Seriously, don't do that!"

"No, like this."

"Don't do it ... you know what, do whatever you want."

I pull tested a few for SAR applications. They fail at about the breaking strength for a single strand of the cord they're made out of. They clutch (slide under load) about half the time. You'd be better off using a sewn daisy chain. At least, that'll make 20kN. (For the record, it's still a terrible idea.)

Never do this.

personally I would just use a bungee cord.. screamers start getting expensive if you suck as much as I do.

Dynamic rope loops as runners?

SS Minox wrote:Dynamic rope loops as runners?

I found a thread that was putting ~6kn on the top runner, that kind of fall is too close to the 7.5kn the Purcell should hold. The nuts I have are rated at 8.5kn, so that's close, but not good enough.

Just out of curiosity, what is your reason for wanting a screamer over a standard runner? You state concerns about dyneema runners "just breaking". They do break, but at forces exceeding 22kN (well beyond your 8.5kN nut). Your lead rope will provide enough dynamic stretch to essentially render any individual piece negligible in terms of dynamic vs static.

I am not sure I can afford the next piece blowing, I had considered using the Purcell only because I have it available. Never heard any actual numbers on it. I am worried about providing a soft catch so as not to blow a single second piece.
So far, I managed to shear off up to 100lb pieces of the wall with cam placements, etc. If something like that ever shears off attached to me, it's going to be a trip.

SS Minox wrote:So far, I managed to shear off up to 100lb pieces of the wall with cam placements, etc.

If this is a frequent concern, it sounds like your time would be better spent working on your gear placements. The dynamic rope provides plenty of energy absorption for most of the gear on your rack in most situations, which is why nylon or dyneema runners are standard and screamers are a special purpose piece.

The part of the wall failed due to an infilled stress fracture thin layer of crystal? The walls are limestone & I know it was a long shot placement, so I tested it with the aider and it blew. Most of the walls combine free & direct aid.

I am constantly working on my placements