prusiking with dyneema slings

I carry little 7mm prusik slings when I'm on multipitch just in case I need em for something. I use 24" mammut dyneema extendos, and was wondering if anyone has any experience trying to prusik with these things so maybe I can forgo that one extra thing on my harness.

I have heard that they can be used for that, but I tried it once and couldn't get it to work as desired. I can't exactly remember the problem; I think maybe it got stuck and was too hard to release.

I've tried that once also and I put a caribiner into the mix, wrapped the sing around the rope and a caribiner at the same time and it seemed to work all right.

For webbing try using a klemheist knot. It seems to work fine on dyneema slings.

ttp://en.wikipedia.org/wiki/Klemheist_knot

Dyneema/spectra melts at like 290 degrees F, which is a possible temperature to reach if you jug fast and your prussik/klemheist knot is slipping a lot (try it! you can totally melt that stuff). So add a couple extra raps if you're going to use spectra, and inspect the slings regularly.

A few weeks ago I used a 24" dyneema runner as a backup for an ascender. I went about 140 feet. I used a prussik. It held very tight, and easily slid up rope. I actually liked how it performed more than regular cord, however I am not sure how much wear and tear it would get if you had to do a really long ascent with it.

I've done it with a klemheist before. It works but like mentioned above is hard on the sling. Even after jugging only 100' it showed wear that a normal prussik (7mil) cord would not. It also seems to be more time consuming than a prusik cord. So it works in a pinch, but tie back up knots in the rope as you ascend in case you burn through.

thanks guys. I was playing around with a klemheist tied through a carabiner, and also a bachmann, in my living room, and it seemed like it would work pretty well. Guess I'll be testing at the crag this weekend and if all goes well, no more 7mm prusik cords for me. Just a smart ass observation: if I actually melt through the sling, what good are backup knots going to do for me?

Jesse Davidson wrote:Just a smart ass observation: if I actually melt through the sling, what good are backup knots going to do for me?

I'm also with the Kleimheist. Yes, dyneema/spectra melts at a lower temp, but just take it easy while using it. Also to note, aren't the slings covered with a nylon sheath? Which would help prevent a problem with friction.

For repeated use, probably not the best material to slide on the rope, but it will work to get you out of a jam if you need to use your slings.

If you can get a Bachmann to work, more power to ya. I'd stay away from a prusik as a friction hitch in using a sling.

With respect to the "back-up knots", I think the idea is to tie in short -- clip a quick 8 on a bight from your mainline below your hitches into your harness with a locker. That way, if your hitches fail, slings get cut, or your jumars are used incorrectly (similar topic, just a different application), your main fixed-line will catch you.

After a few bad experiences melting the edges of a dyneema sling while using it for an autoblock I stay away from using dyneema in any friction knot. A foot long piece of 5mm perlon works much better and takes up less space and is lighter. I think you will find it lasts a lot longer too.

Having seen the effects of sliding up and, worse, sliding down on these low-melting point slings, I'd make sure I had a good backup. This isn't my first or second or third choice.

What I've found works with about every anchor & self/buddy rescue application is about 13-15' of the newer 5.5mm tech-cord with the nylon sheath -- mainly because the cord is strong, workable, & has a nylon sheath. I also keep about 13' of 5mm perlon as leader rescue cord because the 5.5 always seems to end up as the anchor rigging.

All these cords are light & capable of their intended application, which are utility purposes -- always back-up everyone's life with the mainline/climbing rope.

I like a purpose built or cut length of aramid cord. strong, durable, loads of friction. best of all, virtually un-meltable. I use one from Blue water. the additional benefit of the Blue water Vt, is its ability to be re-purposed from autoblock/emergency ascender duty, as a single line Valdy, for descending a loaded line.

its a little big but its versatility keeps it on my harness.

I've used the bachman for ascending after rapping to get stuck gear that my second couldn't get out. Almost like having ascenders. As far as having to set up a z rig using them I haven't tried.

Bachman

John Wilder wrote: Sterling Rope makes a similar product- pre-sewn,

It works but it can put damaging wear onto dyneema which compromising its strength for regular use. Use dyneema for friction knots only if it is necessary. My $0.02

I've always been puzzled at the persistence of the Kleimheist knot, which fairs poorly in every test I've seen compared to various alternatives. The only possible explanation is the strength of uncritical tradition.

Years ago, it was already known that the Hedden knot (1960, Summit Magazine), which is a Kleimheist tied "upside down" (so: start by winding up rather than down) held better than a Kleimheist. (See, for example, the comments on storrick.cnc.net/VerticalDe…. Since then, various forms of the FB-knot have proved to be even better.

For the FB knot, see gudelius.de/fb1.htm. Here's the picture from that site:

the kelmhiest continues because its fast and basic. I Like it with nylon slings I just add a lot of wraps to increase hold friction. however my aramid VT prussic is badass

Nah, doesn't explain it. The Hedden knot is literally the Kleimheist upside-down; just as fast and just as basic, but holds better. And the FB involves tying a simple overhand knot and then wrapping as in Hedden. Holds better than the Hedden and so better than the Kleimheist and adjusts more easily than either of them.