Monthly Archives: April 2013

Hot Spectra-on-Spectra Action!

Spectra girth hitched to Spectra

Hot Spectra-on-Spectra Action

I see soft goods girth hitched to other soft goods in anchors all the time. In this case a spectra/dyneema sling is girth hitched to a spectra/nylon mix runner on a hex.

Location: Smith Rock State Park, Oregon

Spectra-on-Spectra Close Up

Spectra-on-Spectra Close Up

I’ve posted more than one “soft goods girth hitched to soft goods” anchor (see Girth Hitch Death Wish), so let’s discuss this knots issue. Any knot in cordage or webbing decreases its strength. These girth hitches reduce the strength of the slings to only 60 – 65% of their original strength. Had a carabiner been placed between the slings, there would be no knots, and the slings would still be full strength.

And how about the webbing material? HMPE (High Modulus Polyethelyne) fiber, sold under the brand names Spectra and Dyneema, is stronger than steel, light weight, and offers minimal elongation (i.e., it doesn’t stretch far before breaking). It also has a relatively low melting point: 147°C. That’s not a lot hotter than the temperature of boiling water. Friction, at enough pressure and speed, can generate enough heat to melt this fiber. An example of this pressure and speed would be if, for example, you girth hitched a Spectra runner to another Spectra runner and then had a climber fall on it. Those girth hitches would immediately tighten very tight, a great pressure and speed, and…well you get the idea. This isn’t just ‘theory’. There are examples from the field of Spectra slings melting and failing at knot points in this way, so it’s just not a good practice to tie Spectra webbing together like this.

If you care to geek out, here’s some testing from Black Diamond and the folks at Caves.org, and here’s a recent article on the pros and cons of Spectra v. Nylon from Rock and Ice. Finally, Here’s an interesting video testing knotted Dyneema from DMM. They don’t test slings girth hitched together, but the basic idea from the results are instructive just the same.

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Update: Todd Eddie offers the following link to tests from Black Diamond testing just what we’re addressing: webbing girth hitched to webbing.

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American Death Triangle!

Ultra-Jive-Ass American Death Triangle

Ultra-Jive-Ass American Death Triangle

Whoa! This is so, so awesome! One rarely sees American Death Triangles anymore. This submission is from Ray Belt, who ran across this anchor at Joshua Tree. Given how Ultra-Jive-Ass it is, he naturally had to snap a photo. He won’t reveal who built this monstrosity  because, well, it’s just the right thing to do. We don’t want to embarrass people here. We just want to learn! Here is Ray’s description:

“It’s hard to tell but we actually have four pieces in this mess… the two hexes are set up “opposite and opposed” but clipped to the same biner that attaches to the bottom of the red “american triangle” webbing… all in all, this anchor would have done a fair job at it’s primary purpose (first piece to prevent a zipper) but wow! Not gonna tell you who put this one together… (!)”

Location: Joshua Tree National Park, California

Jive-ass Sliding ‘X’

Sliding x with jive-ass extension limit.

Sliding x with jive-ass extension limit.

Here’s another item from a recent trip to the Ouray Ice Park. The green webbing is configured into a large ‘sliding x’ anchor, but with no limiter knots to limit extension or offer redundancy. There is, however, a second loop of webbing added (the purple bit), perhaps to provide the sliding x’s missing redundancy, or perhaps to limit potential extension.  It’s not necessarily dangerous, I suppose. It’s just a little ‘busy’ and, well, kind of jive-ass.

In case you questioned the anchor builder’s status as Jedi master of busy anchors, notice the overhand back up knots on the water knot. Nice attention to unnecessary detail.

Location: Ouray Ice Park, Ouray, Colorado

Is it Redundant?

Redundant?

Redundant?

The single loop of one inch webbing is backed up with a carabiner clipped to the chain. Does that make this anchor redundant? I suppose if the steel chain or the forged aluminum carabiner failed, then that back up ‘biner would secure that ‘ultra bomber’ bit of nylon, right?

Discuss amongst yourselves…

Location: Ouray Ice Park, Ouray, Colorado

Girth Hitch Death Wish

Girth hitched soft goods

Girth hitch nightmare

Non-redundant anchor consisting of soft goods (webbing) girth hitched to soft goods. Is it an “EARNEST” anchor? Yeah, right. Maybe “_ _ _ _ _ ST” For a more detalied analysis of girth hitching soft goods to soft goods, see Hot Spectra-on-Spectra Action!).

Location: Ouray Ice Park, Ouray, Colorado

Close up of soft goods girth hitched

Close Up