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I recently was given some old Chouinard hexes my uncle used back in the 70s. They look great, and I see no reason why I can't re-sling them and use them as perfectly safe protection.

I've found some 5mm Dyneema rated for over 5000lbs, but I can't find any as good rope with a sheath.

I know that with Kevlar, this isn't really a problem because its abrasion resistance is so high, but what about Dyneema? Am I mistaken about Kevlar? Can I use this rope without a sheath for building anchors?

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    Are you sure there is no sheet? If yes can you point me to it as I've never seen one yet.
    – imsodin
    Jun 6, 2015 at 18:24
  • @imsodin yep! It's not specifically marketed for climbing, but it's rating is more than enough. Just don't know if not having a sheath would be a problem. I'm looking here
    – user6042
    Jun 6, 2015 at 18:28
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    Could you post a picture? Where did you get it? Dyneema's used a lot in slings for example, which typically don't have a separate core/sheath like ropes do. But I wouldn't trust anything that looks like it used to have a sheath and now doesn't.
    – nhinkle
    Jun 6, 2015 at 18:36
  • "Can I use this rope without a sheath for building anchors?" Is not a question anyone should be asking. Start at the beginning.
    – llama
    Jun 19, 2015 at 16:01

2 Answers 2

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Do not use this cordelette for your protections: Knots will slip so the connection of the cordelette ends to form a ring will fail under load. Only use sewed Dyneema slings.

Still Dyneema cordelettes are often used for climbing as they are much lighter for the same strength than nylon based ones. To know how this is possible despite the problem mentioned we look at the materials used to construct ropes:

Dyneema, a trademark name for high-density polyethylene (PE), Nylon (polyamid PA) and Kevlar (aramid Ar). Dyneema and Kevlar have both about 4 times more strength per diameter than Nylon. Nylon is highly elastic and breaks at ca. 37% elongation, Dyneema and Kevlar are almost static (break at 2-4% elongation). The resistance against abrasion is only given qualitatively in my source: Nylon small, Kevlar medium and Dyneema high. The melting points are 250degC for Nylon, 130degC for Dyneema and 550degC (actually it decomposes) for Kevlar.

From the image provided in your link it really looks like the Dyneema cordelette in question has no sheath. The abrasion is not a problem as it has a very high resistance, but another characteristics is: Dyneema has very low friction on itself. Never ever form a ring of Dyneema webbing or cordelette using a knot, the knot will open under tension. Only sewed Dyneema slings can be used.

For this reason dyneema cordelettes for climbing come with a sheath made from nylon or polyamid. These are perfectly suited for your case but more expensive than plain nylon cordelettes. Dyneema webbing which does not have a sheath is always sold as sewed sling.

My source is the alpine security journal bergundsteigen 3/12 "FAQs-Dyneema". It may be accessible online, but is maybe behind a paywall: http://www.bergundsteigen.at/file.php/archiv/2012/3/62-67%20%28faqs-dyneema%29.pdf

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  • is a triple fisherman's not enough?
    – user6042
    Jun 6, 2015 at 20:41
  • Short: No. Longer: I don't know of any tests and I don;t have a dyneema cordelette to try it out myself but it is absolutely discouraged by all "climbing-authorities" I know. And just holding dyneema it feels very slippery (of course thats not at all objective). Another point is: Nobody sells it while somebody certainly would if it was not deadly.
    – imsodin
    Jun 6, 2015 at 20:46
  • Did some more research, and it looks like the heat generated by the knots tightening is enough to melt it if it's subjected to a shock force, as well. Yep. Sounds like a bad idea.
    – user6042
    Jun 6, 2015 at 22:48
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PPE or ALL climbing gear in general should only be used if there is ZERO question in your mind about the safety of the equipment (ropes, slings, anchors, prussiks, carabiners etc). Your life depends on this stuff. Don't short cut or try to save a few bucks. Do it right or don't do it at all.

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  • well, the funny thing here is that it's not actually to save a few bucks. Because there isn't a sheath, the break strength is waaaay higher than other cord with the same diameter. So, really, it could be safer. (I didn't downvote, btw.)
    – user6042
    Jun 6, 2015 at 20:31
  • My guess would be that whoever down-voted thought I was sounding preachy or like a broken record in regards to the obvious importance of using bomb-proof gear. But ironically (perhaps) had nothing to add to the conversation themselves. All that aside, this question sounded to me like it was posed in an attempt to save a few bucks by re-using ancient gear by trying to kludge it together into a working form. I know that climbers often have little disposable income, so ingenuity is sometimes required, but safety should still be paramount. Perhaps I misread?
    – renesis
    Jun 6, 2015 at 21:07
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    The ancient gear in this case is a set of Chouinard hexes; as long as the slings are replaced, their age isn't really a factor. The issue I see is introducing a product from outside the "climbing realm" when there's already appropriate products to use inside the climbing realm. I didn't cast the downvote, but the "don't use if there's any doubt" trope is a bit too general; you could apply it to almost any question on this topic.
    – requiem
    Jun 6, 2015 at 21:48
  • @requiem: Indeed. I use gear older than that with steel "slings" for 'biner attachment places. On the spring checkout they get checked for rust with all the other gear (We've had aluminum corrosion problems in storage before so ...).
    – Joshua
    Feb 1, 2017 at 19:52

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