By Jesse Davidson
From san diego, ca
Apr 30, 2011
| I'm sorry to bring up the same old topics, but I have been thinking about this lately and searching has not revealed an answer. I like using long (240 cm) dyneema slings as a cordolette. Same way as normal, clip the pieces, pull the slack together, tie a figure-8 to clip in. Is this dangerous? I know that a knot can weaken dyneema a LOT but with this fairly bulky knot, is this effect reduced? I like how clean the system is, and how small it racks. Am I going to die? | 
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By jmeizis
From Colorado Springs, CO
Apr 30, 2011
| Quick answer is no. |
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By Derek W
From Larkspur, CO
Apr 30, 2011
| Biggest downside is the lack of stretch in your dyneema sling. All of the force generated is transferred directly to your placements. This potentially increases their chance of failure. Regarding the knot specifically, I would not be worried as this bulky knot does not put any sharp bends in the material. |
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By MikeS
From Boulder, CO
Apr 30, 2011
| Using static sling doesn't matter as much if you're tied into the anchor with a dynamic rope. Dyneema becomes dangerous when you use it without any dynamic component in the system. |
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By Kyle Stich
From Winchester, TN
Apr 30, 2011
| Tech cord from Bluewater. Super strong, lightweight, thin, takes up minimal space on the harness. You can by 20' lengths at your favorite outdoor store, or by spools on EBAY and cut to your desired length. |
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By apeman e
May 1, 2011
| just use nylon. it's cheaper and safer.
or just use your rope. it's a even cheaper and safer. and lighter. |
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By Jesse Davidson
From san diego, ca
May 1, 2011
| Nardo wrote: www.dmmclimbing.com/news.asp?nid=293&ngroup=1
What I got from the table is that, even with a super tight knot, I can still expect 10kn from each leg. That's plenty strong in my book. And as far as cheaper goes, I already have the slings.
I guess I am ok to keep doing what I am doing. |
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By Jeremy Bauman
From Lakewood, CO
May 1, 2011
| If you are relying on your anchor material to stretch you're doing something wrong. There is nothing wrong with using Dynema as part of your anchor system. If you don't believe me just read Long's Climbing Anchors book. Just be sure to tie in with your rope to the master point and you'll be fine. The 240cm and 180cm length was designed for use in anchors. "and the 180cm length for an ultralight cordelette" (www.backcountry.com/mammut-dyneema-contact-sling-8mm-mam0081>>>. |
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By Rich Farnham
May 1, 2011
| Jesse Davidson wrote: What I got from the table is that, even with a super tight knot, I can still expect 10kn from each leg. That's plenty strong in my book. And as far as cheaper goes, I already have the slings. I guess I am ok to keep doing what I am doing.
In general, I'd agree you're fine to keep doing what you're doing. There is typically plenty of strength in our anchors, and many of the solutions that people argue endlessly about are all adequate in most situations.
One thing I will suggest you consider if you want to use the stiffer material for "cordalette"-style anchors is that it is impossible to achieve perfect equalization among the three legs in any material, and possibly even more difficult with stiff material. It's been a while since I read the paper, but check out Marc Beverly's "Multi-Point Pre-Equalized Anchors" paper here . My recollection is that he found that legs of similar length would stretch enough (with nylon cordelettes) to distribute the load reasonably well. When he had a shorter leg, it ended up carrying a lot of load. Without getting too detailed, using stiffer material will likely be similar to that shorter leg situation. In a typical 3-point anchor, you will probably be mostly on 2 points, and possibly heavily on 1.
So, in almost all situations, the 10 kN per leg is plenty strong. But, as you start to imagine a worst-case scenario in a multi-pitch setting, you could get a high FF fall putting a lot of load on a single piece. The sling can hold it, but can the gear and the rock? Med stoppers could start to have problems, and some rock types might have issues as well. A stretchier anchor material might help distribute the load better. In other words, ultimate strength of the material may not always be the most important factor.
So, you aren't going to die. But I think understanding this limitation of the material can allow you to decide when it is the right time to use it, and when you may want to find a way to incorporate the rope or a nylon sling into your anchor rig.
Hope that helps.
-Rich
PS - regarding the possibility of a larger knot being stronger, I'd say that it's probably true, but the effect is likely to be very small. |
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By Jesse Davidson
From san diego, ca
May 3, 2011
| Thanks for the well thought out answers, guys. MP FTW! |
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By Mike Pharris
From Longmont, CO
May 3, 2011
| apeman e wrote: just use nylon. it's cheaper and safer. or just use your rope. it's a even cheaper and safer. and lighter.
How would you use the rope to connect a 3 piece trad anchor to yourself and then swap the lead on a multipitch climb? Am i mis-interpreting your suggestion? |
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By Rick Blair
From Denver
May 3, 2011
| Mike Pharris wrote: How would you use the rope to connect a 3 piece trad anchor to yourself and then swap the lead on a multipitch climb? Am i mis-interpreting your suggestion?
1. Tie a bight below your anchor rig.
2. Follower clips in to bight, gear gets swapped, new leader takes off.
3. Bight gets untied.
If you are belaying with a plaquette, bight is already there. |
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By Jesse Davidson
From san diego, ca
May 3, 2011
| Rick Blair wrote: 1. Tie a bight below your anchor rig. 2. Follower clips in to bight, gear gets swapped, new leader takes off. 3. Bight gets untied.
I think what Mike Pharris meant to ask, unless I am misreading, is how to NOT swap the lead if using the rope to build the anchor. Sometimes I climb with a less experienced partner, and end up leading every pitch. Using the rope to build the anchor, then, seems unreasonable. |
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By apeman e
May 3, 2011
| Jesse Davidson wrote: I think what Mike Pharris meant to ask, unless I am misreading, is how to NOT swap the lead if using the rope to build the anchor. Sometimes I climb with a less experienced partner, and end up leading every pitch. Using the rope to build the anchor, then, seems unreasonable.
this is true. but in my experience I would still rather use slings, which have many uses, than carry a cordalette dedicated to anchor building. but if you enjoy the cordalette, by all means use one. |
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By Frank K
From Bishop, CA
May 3, 2011
| I bring cordelettes on long or alpine routes for bailing. a 20 foot cord will buy you 2 or 3 bail anchors. |
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