High tenacity Loop Line

Just got a length of the All Gear dyneema 32 strand flat braid hollow loop line. My interest is in making short attachments for certain parts of my ropewalker and frog rig. I'll still use Tenex extensions for my main attachments due to it's shock loading capacity. Does anyone have any reasons not to use this for extensions.

I saw a discussion that spoke of dyneema loops failing at Factor 1 or even Factor 0.5 falls:

http://pcia.us/pro/node/215

I'm getting some to try it out, did you see the splicing vid for it on the allgear site? looks easy and it is supposed to make a neat , super strong finished product.

Cary,
I did see that, about the same effort as tenex to splice. What bothers me is strength in a static situation is more than adequate, but it has no stretch to speak of and fails in a dynamic load situation. I use a Basic by my left knee on an extension from a foot strap and a Pantin on my right foot for ropewalker system. Also a strap to locate the Croll that I run from back of my saddle over shoulder to top hole of Croll for the frog system. Neither holds my life, so i thought I'd try it for those.

i'm thinking it would be up to the task man, I'm going to use if for rigging stuff, so it will be a good test for it

That is what I was thinking TreeD. I use 5-7 mm utility prusik cord for non life support components of my SRT set up. It's super inexpensive and very light. One has a mid-line loop knot tied about 8 inches from the end so I can use use it in multiple setups instead of having two separate lengths. As long as you segregate life support/critical gear from utility I go light and inexpensive where I can skimp.

pigwot said:

...I'll still use Tenex extensions for my main attachments due to it's shock loading capacity. Does anyone have any reasons not to use this for extensions...

Click to expand...

Energy absorbtion in such short lengths (under 3' I presume) will be largely insignificant.

I'll stick to nylon slings after watching this... http://www.dmmclimbing.com/video.asp?id=5

If you are climbing on a steel cable (essentially zero stretch) and using dyneema, it will be very different that if you are climbing on normal rope (some stretch, normal as in not UHMWPE) and using dyneema.

That video is an example of what can happed if you are at a belay anchor where you are not tied in with a rope, have some slack between you and the anchor, and slip off of a belay ledge, shockloading the anchor, akin to being attached to a steel cable.

That's an excellent video, damn good find, but it's not a case for nylon vs. dyneema, it's an illustration of the importance of elasticity to shock loading.

It's pretty well understood that Dyneema doesn't stretch and nylon stretches a lot, polyester (lifelines, tenex, etc.) is somewhere in between. Nylon has problems with UV degradation. Depending on the weave and the loading, nylon doesn't necessarily recover completely after stretching so cycles to failure is more critical. They're just different.

Stick a dynamic rope in the system and all those numbers will change dramatically, the longer the rope in the circuit, the lower the numbers. Without a rope in the system a fall factor of 1 or 2 would do serious damage to your body before the sling broke regardless of material.

I don't use dyneema for handling significant shock loads but it rocks for getting trees off houses and lifting with MA. I do use those skinny runners for light shock loads. I have a little kit with a carabiner and two slings, a 60cm and a 120cm. I can tie off most limbs with it quickly so I don't have to cut and hold small stuff over targets.

Most arb ropes are polyester, not nearly as stretchy as nylon but super durable. Polydyne is a composite double braid with a nylon core and a polyester jacket and it stretches like crazy but it also recovers fast, sucks for lifting but it's sweet for catching chunks.

I made a tether for my CMI Expedition Dual ascender with HTLL, it's nice and clean but I still back it up with 5mm tech cord. Like Carl said, shock absorption on a line that short is pretty insignificant with any of those three fibers.

I also used the HTLL to rig up a really sweet hammock anchor between two trees for a customer. I like it but it's limited and kinda pricey, 16 strand technora is cheaper and does more different stuff.

Great video.
Thanks for posting that.

yeah, but I still think that if there is a chance of some dynamics in my rigging, even with my rigging line being stretchy( the allgear version of polydyne); I like the fact that nylon generates way less kn's of force, which translates into being kinder to the rope and rigging gear.

i do agree Chip that for MA's and static loads, dyneema would be great.

To get back to pat's original question, I don't think you'd ever be harmed by static slings in an SRT setup. Your shock absorption is going to come from the give in your climbing line. I agree with carl on this one. If your leg stirrups (or whatever component) are only 2-5' long, even a nylon sling is only going to stretch an inch while your rope is going to stretch a foot.

I've made some of my rope walker pieces out of zing-it!

love
nick