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I've recently started making my alpine (or "trad") draws by girth hitching one end of a sling to the gear side carabiner and then clipping and passing the rope side through as usual. The girth hitch makes it easy to lengthen the draw one handed as all you need to do is unclip the two loose loops from the gear side carabiner and the sling will lengthen automagically.

Its a technique I learned from a german mountain/climbing guide friend of mine. Personally I think it's a lot easier to lengthen the sling than the standard way of making alpine draws. The knot reduced the runner rating in half, but since there are two strands , its back to the UIAA standard of 22KN, well above any forces seen in lead falls on intermediate pro (not to mention the ratings on the pro itself).

On a recent trip a climbing partner pointed out that the girth hitch can induce horizontal forces on the carabiner, and if the hitch slips "up" the carbiner it can even load the gate and slide off. Which got me to reexamine my alpine draw technique.

Just to demonstrate, (not my image), the way a girth hitch looks on the biner. The two loops have a slight tendency to slide up the two sides of the biner if the knot isn't loaded/tightened (I make sure to give it a yank when placing).

sling girth hitched to carabiner

So is what I'm doing bad or known to be wrong? I trust my guide friend, but maybe I should pass on this particular tip?

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related: outdoors.stackexchange.com/questions/7205/… However, you have a shock-absorbing element in your system (the climbing rope). –  Ben Crowell yesterday

3 Answers 3

By coincendince, I asked the same question to a guide last weekend. His response was this:

  • There is going to be some reduction in the strength of the webbing from the girth hitch. Especially thinner materials like dynemma. Its going to be minor, but still there.
  • Its possible to carry a small number of slings (2 or 3) over your shoulder, with 1 carabiner on them, without them getting in each other's way
  • The only time when you really don't have time to fiddle with extending a draw is when you're working a hard redpoint on gear, and in that case, you can just have the appropriate number of slings over your shoulder before you leave the groud. That's going to be easier than extending a sling, regardless of whether its a girthed-hitched alpine draw or not.
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The knot reduced the runner rating in half, but since there are two strands , its back to the UIAA standard of 22KN ...

The 22kN rating is for the loop strength of the sling, not the single-strand strength. Therefore any reduction in strength caused by a knot puts the strength below the 22kN standard. Stated strength for a girth hitch varies from one report to another and with the specific connection (around a large object, sling on sling, on a carabiner), knot orientation (bend angle), and sling material. I encourage you to research this, or even better if you can have your specific combination pull tested.

Also, I'm not convinced the girth-hitch method is that much more convenient. This seems pretty fast:

http://www.youtube.com/watch?v=AERzcQ7xqog


Incorporating article links from the comments that are relevant:

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While I agree the girth hitch doesn't provide a real advantage in this situation (and that's a reason not to use it), strength reduction in the sling is probably not any reason to avoid it. As Long and Gaines document in Climbing Anchors, 2nd Edition, no piece of climbing protection rated at 10 kN or higher has ever been known to break, even in extremely severe (high-factor) falls. The sling would probably have to be badly frayed in the girth hitch (enough so that the climber would presumably have noticed it on inspection), or chemically damaged, for this to cause failure. –  Eliah Kagan Jun 29 '12 at 15:55
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@Eliah I've read that book too. However under some circumstances the girth hitch may reduce strength by more than half, and slings lose strength with age, sometimes severely. Combined these factors could make this the weakest link the the chain with potentially disastrous results. –  Mr.Wizard Jun 30 '12 at 7:24
    
For anyone interested, the now-broken first link in my comment above was to this article: QC Lab: Connecting Two Slings Together. The second link is still working, but here is another entry point: QC LAB: Slings and Quickdraws –  Mr.Wizard Jan 11 at 16:29

If the top biner gets loaded weirdly against a hanger, a fixed connection to the sling (girth hitch) makes it more likely that the biner will break.

This is why non-alpine draws have the top biner free and the bottom one fixed.

Petzl Manual

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Welcome to the site and thank you for your answer. However can you provide additional support for this statement? I was given a different explanation for why the top carabiner in a quickdraw does/should not have a rubber keeper. –  Mr.Wizard Dec 11 at 19:21
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er, my bad, not loaded against an edge, rather, the top carabiner can hook onto the bolt, or the hanger, or some other weird arrangement and the fixed connection to the sling keeps the sling from sliding down the carabiner, so it has more leverage to snap the biner. Warning from a petzl manual –  hintss Dec 21 at 10:41
    
That is the reason I was given before. Why don't you edit your answer to describe that instead and include a reference to the Petzl manual? –  Mr.Wizard Dec 21 at 20:16
    
done. [stuff to take up more characters] –  hintss 2 days ago

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