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Shortening slings another way


Original Post
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

Usually slings are shortened by tying an overhand knot and clipping in to the shortened loop but untying the knot is all but impossible if the sling gets loaded.
Here´s another way which is stronger, easy to adjust for length and effortless to untie. I´ve seen it mentioned twice before as used by a mountain rescue team in the UK but there doesn´t seem to be a correct name for it so if anyone actually knows what it´s called it would be nice.

Step 1

Clip in

Then you can slide the knot to adjust the length.

An alternative one-handed way:-

Wrap

Pull through

Clip

Does it slip under load-no.
How strong is it? I tested a couple of used Dyneema slings which I would normally expect to fail around 16kN and saw 13.22 and 13.8kN before the sling cut at the hitch. The remains I then tied as a loop with an overhand and tested the loops. The overhand in furrier of the two slings locked-up and failed at 8.68kN, the better condition sling the overhand rolled continously off the end at 6.7kN.
A 1" tube tape sling made from some 20 year old tape and tied with a water knot failed at the hitch at 12,56kN and the water knot was already failing at this point.
I also tested a sling from some wierd Edelrid material, 14mm wide tube tape which failed at the hitch at 18.66kN.
mark felber · · Wheat Ridge, CO · Joined Jul 2005 · Points: 28

Very nice. I don't like the way overhand knots weaken the sling, fuzz the sling up when I untie them, and are hard to untie after I weight them.

Mountain Mark · · Unknown Hometown · Joined Jul 2013 · Points: 0

Learn something new everyday.

Thanks for sharing

Marty C · · Unknown Hometown · Joined Aug 2008 · Points: 70

I have been using this technique for awhile now; nice to see some real test data on strength.

As to an "official name" - I have seen two reference sources to this or a similar knotting scheme:

Topher Donahue, in his two books, calls it an "adjustable hitch"

Rocorescue has a video showing what they call "webbing shortening technique"
www.rocorescue.com/roco-rescue-blog/tag/techniques/page/2/

Rocorescue shows doing this with a double strand basket hitch, but it can easily be done with just a single strand loop of webbing.

Obviously, this technique can be used to adjust the length of anchor arms at a trad belay or when using very long tied slings when setting up top rope anchors.

drewdogg2112 · · halifax, MA · Joined Aug 2015 · Points: 20

nice. I like this

Lee Durbetaki · · Unknown Hometown · Joined Apr 2016 · Points: 5

I'd be curious to see how it affects peak load on the anchor when tied in nylon.

Derek DeBruin · · Unknown Hometown · Joined Jul 2010 · Points: 585

Correct me if I'm not seeing this correctly, Jim, but I'm pretty sure I've seen/used this one before. Isn't it a standard slip knot with an abnormal loading configuration?

Guideline #1: Don't be a jerk.

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