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Girth Hitched Carabiner Block

Discussion in 'Tech Tips and Gear' started by Canyonero, Jul 16, 2020.

  1. Canyonero

    Canyonero

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    Let's say, hypothetically, that someone did a biner block and accidentally used a girth hitch instead of a clove hitch using typical ropes and carabiners used in canyoneering. How much weight would it take to fail? Anybody with the ability to test that? I'd love to know how much weight a clove hitch, a triple clove hitch, and a constrictor fails at while we're at it.
  2. ratagonia

    ratagonia

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    Strength is not the issue. Reliability is the issue. Reliability with a variety of ropes and a variety of carabiners. Also known as Security.

    Let me review my argument for using a three-loop clove hitch (aka Triple Clove):

    1. More secure, more reliable than a regular clove hitch. Even if it slides into the end of the carabiner - a place where a regular clove hitch becomes something that can fail.

    2. Inspectable. Most people know what a clove hitch looks like - they can easily grasp what a triple clove looks like and effectively inspect it quickly.

    3. Easy to Learn. Since it is a variation on a knot already in regular use, people can learn it more quickly than a new knot.

    4. Fail Resistant: when tied incorrectly, you are almost certain to have at least a regular clove hitch. --> I have seen in the field at least one "clove hitch", tied by an expert, that was actually a munter hitch, and only did not 'run' because it was pinned against a wall. I know of one other mysterious incident that would be explained by that the 'clove hitch' tied was actually a munter hitch.

    Perspective: but really, this is suggested as a way of guarding against a rare event. The problem is rare. A clove hitch is fine, a triple clove or a constrictor knot is just a little bit better.

    Tom
    Yellow Dart and rick t like this.
  3. Brian in SLC

    Brian in SLC Brian in SLC

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    I'd be more worried about slippage than the load required to break a girth hitch.

    I think when you look at girth hitch testing out there for sling-to-sling connections (a lot of data due to a couple of high profile accidents), you'll see pretty good numbers for the strength of a girth hitch. But, that's for a load applied to a loop of webbing, not a single strand of webbing. Strength reduction in slings at around 70% or so. Not huge.

    Be an interesting configuration to test. Especially cycling loads, which, might cause the girth hitch to slip and/or move especially when paired to a rappel ring or rapide.
  4. Canyonero

    Canyonero

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    Agreed the issue is slippage, not breakage. And also suspect, from informal testing, that the weight required for slippage is more than the amount typically applied while rappelling. Not that I would recommend it.
  5. Canyonero

    Canyonero

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  6. ratagonia

    ratagonia

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  7. Brian in SLC

    Brian in SLC Brian in SLC

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  8. Kuenn

    Kuenn

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    Yes, interesting and impressive strength on the dyneema sling.
    Scary dude though, "it's a perfect state...I don't know how far away from the breaking load we were. I saved because I need it." (LOL)

    Future on-rope conversation:
    Q: Hey Walter, this sling looks kinda stressed.
    W: You're safe, it's been tested for strength. 12kN before I heard the first cracking noise.
    Q: o_O
    W: No worries, Q. It's good and... it was easy to undo from the test carabiner with a hammer.
    Q: :help:

    12 Kilonewtons (kN) 2,697 Pounds force (lb)
    John Diener, nkanarik and ratagonia like this.
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