Using Threads as Anchors?

I climbed the First Flatiron in Boulder today and used a few threads as anchors - as a newer trad climber, I wonder if there are guidelines for thread usage?

I know with a tree, for example, they should be well rooted, alive, thick enough, etc. but what about threads?

Obviously the rock has to be solid with no cracks, but how thick should the rock be? Any tips? Attached is a photo of a thread I used. I tried to get the sling on to the thickest part... Thanks.

-David

Back it up with something solid.

That looks bomber. The rock would have to completely blow out for there to be an anchor failure. There is somebody already standing on it, and it looks low angle, so no worries.

People use chicken heads to anchor in Cochise, and they aren't nearly as bomber as that.

I think that evaluating threads is pretty straightforward. You just look to see if there's any possible way your sling could come loose, and gauge the quality of the rock as best you can.

As with cam and nut placements you want a feature that's a crack in the planet, rather than a detached feature when possible. With that said, I have frequently threaded chockstones in constricted cracks/chimneys that were wedged in place like a good nut placement and climbed above them with confidence.

Usually a lot more rock would have to break for a thread to fail than a cam or nut placement. Also your sling distributes force over the rock evenly and doesn't create any stress risers. The counterpoint to this is that you do have to watch out for sharp edges that could cut your sling. Often you won't be able to inspect the entire thread and you simply have to hope that there isn't a nasty crystal in the back.

As always it's best to be skeptical and use multiple points if there's any doubt. I would happily belay off the example in your picture alone, because the rock in the thread is substantial.

Julian H wrote: Yes. Use a girth  hitch. What do you have in the back? a biner connecting the sling?

I did fall on thread once and it broke. Unless,  I’m desperate , I usually skip them 

Looks like he took a quadruple length sling, put one end around and tied it into an overhand. It gives 2 independent strands which can be nice in case there might be a sharp edge somewhere. Agreed on skipping but on the flatirons they can be the best pro around.

Julian H wrote: Yes. Use a girth  hitch. What do you have in the back? a biner connecting the sling?

I did fall on thread once and it broke. Unless,  I’m desperate , I usually skip them 

Girth hitch is one of the weakest knots to use. Don’t girth, it would be better to clip both bights with a single binder than make the sling cut across itself. the rock looks good, has a good amount of rock that looks well attached. The lever arm also looks short, which is good.A top rope fall also isn’t likely to create huge forces. 

Don't girth hitch threads. It will cinch down on the thinnest section of the thread, where it is weakest. A basket hitch is best and the carabiner is the master point. As the carabiner can move relative to the sling, the sling does not move relative to the thread, avoiding chuffing.

As a general rule for sandstone, the thread should be of the thickness of a forearm.

Julian H wrote: Yes. Use a girth  hitch. What do you have in the back? a biner connecting the sling?
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I did fall on thread once and it broke. Unless,  I’m desperate , I usually skip them 

I did fall too this is why i skip them either 

basket the the thread and back it up with another piece or two. but yes its acceptable. 

Julian H wrote: Placing gear that needs to be backed up is a waste of time.

yes, that’s why you should always have only one piece of gear in an anchor. Any sort of back up is a waste of time. 

Julian H wrote:

Technically one piece is not an anchor. At least two pieces is an anchor. 

Anyway it is a waste of time to place gear that will not hold. Anywhere on the climb 

But if you are so sure your gear is going to hold why do you bother with multiple pieces in an anchor? 

And are you saying that his thread would not hold? Because I totally disagree. I think it is totally reasonable assessment to use that thread as an anchor and then as someone mentioned up thread, place a piece as a back up. 

A thread through solid rock is one of the best anchors there is, and with good rock a single thread is fine.  Of course,  one has to judge the strength of the rock, which isn't different from having to judge the strength of cams and nuts, not to mention the strength of trees that might be used as a single anchor point, and one has to judge whether the thread has sharp edges that could cut the sling.  Of course, having a backup buttresses possible mistakes in these judgements, and so is itself a judgement call.  

Edelrid makes 6mm aramid cord slings (single and double length) that appear to be more robust than webbing when it comes to abrasion, and the stiffness of the sling turns threading epics into walks in the park.  As an old-school climber who uses threads whenever possible, I find it very handy to have a single length and double length versions of the Edelrid sling.

Julian H wrote:

Technically one piece is not an anchor. At least two pieces is an anchor. 

You have a lot to learn!

Julian H wrote:

Please teach me. 

well, to start, it's super common to use single piece anchors...so i'm not sure why you said anchors, by definition, need to have more than 1 piece (think large tree, boulder, thread etc.)

Julian H wrote:

Please teach me. 

One tree, one boulder, one firetruck.  Obviously something so overwhelmingly bomber for the intended use doesn't really need a rigging concept that uses multi-point load sharing.

dindolino32 wrote:

Girth hitch is one of the weakest knots to use. Don’t girth, it would be better to clip both bights with a single binder than make the sling cut across itself. the rock looks good, has a good amount of rock that looks well attached. The lever arm also looks short, which is good.A top rope fall also isn’t likely to create huge forces. 

Technically - The Girth Hitch strength is dependent on the radius of the object it wraps around (along with the rigidity of the object itself)  Yes, tight, sling on sling or sling to wire girth hitches are weaker but as you scale up the size of the object and make it rigid, strength increases.  Friction around the wrapped object also plays a role as does the angle of the bend at the "choke" point.  BD has a stat where their Link (PAS)  tether holds 27.5 kN girthed around a 10mm pin which is slightly higher than end to end of 27.1 kN.  Crane Rigging stats also support this in their "choker" configuration.  Any angle over 120deg will result in 100% sling capacity.  So girth hitching a wide enough thread (say the suggest 4in+) should not weaken the sling at all.

Buff Johnson wrote:

One tree, one boulder, one firetruck.  

If you aren't equalizing at least two independent firetrucks, you're an accident waiting to happen

Julian H wrote: Yes. Use a girth  hitch. 

Girth hitch is not a good suggestion. It offers half the slings strength and no redundancy. 

everyone who uses webbing or slings for anchors should know this chart from the CMC rope rescue manual (or at least understand the strengths and weaknesses of common configurations).

https://www.cmcpro.com/one-inch-webbing-anchors-minimum-breaking-strength/

Julian H wrote:

Please teach me. 

One object of sufficient strength is an anchor.

similar info to what curt posted above, in a handy infographic. Note the strength rating here only applies to the sling and not the rock or carabiner. Credit GOAS Italia for this image.