Natural anchors

Is it safe to use 2 nuts to make a natural TR anchor?

can it be safe....yes....through the internet...no

seek proper instruction or read a book about anchor building such as john longs

Nuts would make a gear anchor. Trees, boulders, chicken heads, etc are natural anchors.

You generally want 3 pieces for a gear anchor. Some would want more for a tr setup as you aren't next to the anchor to make sure nothing goes wrong.

If it's 2 bomber pieces sure go for it, but I would personally recommend a beefier anchor for a tr situation.

eli poss wrote:Is it safe to use 2 nuts to make a natural TR anchor?

As noted, nuts would be a gear anchor, not a natural anchor.

For a top-rope anchor, which is going to be unattended, I would prefer 3 solid pieces rather than just two. They could be nuts, cams, tri-cams, or whatever other pieces of gear work.

If the two nuts were absolutely completely bomber -- lovely constrictions, or even threads, and I was utterly confident in both of them, then yes, I might go with just two.

The way you asked this question, though, suggests you aren't ready to be making that judgement yet.

Also, as a multi-pitch belay anchor, or as an anchor used to belay from the top, where the belayer can keep an eye on the state of the anchor, two pieces are far more acceptable.

Thanks guys I'm just not going to do anything with this climb since I am clearly out of my league. Just saw a really cool slab either really highball problem or short TR on an abandoned building but not going bother since I can't adequately protect it. The line looked awesome but there isn't much for gear placement aside from the bottom 10 ft.

Bricks are a lot softer than rock. A lot of concrete is too.

Don't rely on passive pro on bricks!!

How about using 50ft of webbing to sling something on the roof?

I trust expansion bolts in concrete with my life just about everyday, but nuts and cams are not designed for concrete. I wouldn't trust anything with my life placed in brick...

In quality rock, Id prefer 3 pieces for a TR but as mentioned above, id have fun if both nuts were as good as they get.

My instructor for my SPI course put this really well.. So imagine that 2 perfectly placed anchor bolts have a collective strength of 50kN (25kN per bolt). For an anchor, wouldn't you want to get as close to 50kN as possible? I'm not saying place 4 12kN pieces but having a rule of "at least 3 pieces" sounds a little funny to me. If you're at a good stance for an anchor, I personally would want as close to that 50kN mark as possible but at the same time keeping your anchor simple. Just my thoughts..

Why 50kN? Why not a more realistic number, no piece of gear on your rack comes anywhere near the strength of a bolt.

I used to use cams for natural anchors. Then I read on some vegan web site that cams are genetically modified.
Now I only use free range stoppers for anchors. You can get them in the climbing section at Trader Joes and Whole foods.

DavisMeschke wrote:My instructor for my SPI course put this really well.. So imagine that 2 perfectly placed anchor bolts have a collective strength of 50kN (25kN per bolt). For an anchor, wouldn't you want to get as close to 50kN as possible? I'm not saying place 4 12kN pieces but having a rule of "at least 3 pieces" sounds a little funny to me. If you're at a good stance for an anchor, I personally would want as close to that 50kN mark as possible but at the same time keeping your anchor simple. Just my thoughts..

You take a lot of 50 kN whippers?

Answer: no because you would be dead.

It important to understand the "why" behind anchor building -- not just blindly follow some random rule. The "why" behind a 3+ piece anchor has nothing to do with attempting to protect against impossible fall forces.

To the OP: If you have to ask on the Internet the answer is no.

No I don't take 50kN whippers. What I'm saying is that you can piece together 12-14kN pieces (the average strength of your cams) to EQUAL 50kN. If you're constructing a toprope anchor, which it sounds like the OP is trying to do, I would want mine as close to that 50kN mark (the strength of 2 25kN bolts)as possible.

I don't think you understand the way trad climbing anchors work very well, or the forces involved.

DavisMeschke wrote:No I don't take 50kN whippers. What I'm saying is that you can piece together 12-14kN pieces (the average strength of your cams) to EQUAL 50kN. If you're constructing a toprope anchor, which it sounds like the OP is trying to do, I would want mine as close to that 50kN mark (the strength of 2 25kN bolts)as possible.

Either:
1. your instructor was clueless
2. you misunderstood your instructor
3. you're trolling

I'm going to assume 2.

When we use a pair of (say 25kN) bolts for an anchor, we're not trying for 50kN, or even to get close. We're trying for redundancy -- to make sure we have that 25kN (which is, still, way more than we need) guaranteed. So, in case one of the bolts was poorly installed (over-tightened, under-tightened, not properly cleaned hole, near a crack or weakness in the rock or whatever), and fails, we are still protected by the other bolt.

When we say that we prefer 3 pieces of gear (at, say 10-12 kN per piece) it is not because we're trying to achieve 50kN or 30kN or something like that. It is because we're trying to make sure we get that 10-12kN for sure. But, because gear is made to be removable, and is inherently used in weaknesses in the rock (that is, it is usually placed in cracks, with edges, etc) the chance that one of those pieces is bad (will not give the 10-12kN we expect) is far higher than with a bolt. It might initially be bad, or due to use (unexpected off-angle pulls or whatever) it may become bad. So, since the gear placements are less certain, to give an appropriate level of confidence that we have at least our minimum (10-12kN) we use three pieces.

In summary, using two bolts, or 3 pieces of gear, isn't to get a higher strength, it is to increase the chance that we get a minimum needed strength.

Sounds like I had a misunderstanding on my part. My bad.

It's no big deal, I am glad he could explain it so clearly. It always warms my heart when Mountain Project works as intended! A beautifully done transfer of important climbing knowledge from one individual to another, over the interwebz!

D.Buffum wrote: This is true, with one exception. Sometimes we use two or more pieces equalized because we believe that those pieces are individually inadequate, but together will be strong enough to hold fall forces. In those cases, of course, we treat those pieces together as one piece for the anchor.

Yes, I did ignore that case.

But, that almost always occurs in the context of multi-pitch trad climbing. And, if that is the only way to set a top-rope anchor for a particular climb, then it is probably not a good idea to TR that climb, especially not for a beginner or near-beginner to do so.

Also, on this topic, there is the question of whether or not equalization can actually be achieved. A bunch of the reports/discussions on this that I've seen in the last few years are suggesting that actually achieving equalization is nearly impossible. (i.e. due to issues of change in direction of pull, different lengths of arms on anchors with stretch causing almost all force to be applied to just one piece at a time, etc)

What I learned from this thread is that I am not top ropeing correctly. What am I doing wrong when I toprope that I don't put 10+ KN stresses on my anchors?

Anyway, I think nicelegs is onto something here...

D.Buffum wrote: I usually only use this to equalize two pieces which are close together, and use a sliding X in a dyneema sling. Shouldn't that be fully equalized for all intents and purposes?

I think the answer to that is, currently, unclear. I have seen discussions of "clutch" effects in sliding-X setups that suggest it may not auto-equalize under stress in the way that is hoped for. I don't know if testing has been done with dyneema as well as nylon -- dyneema is generally more slippery, so there may be less friction effect in the tension point sliding along the slings, so it may do a better job. Whether it is equalized may, actually, greatly depend on the angle of application of load -- do you need the carabiner to slide along the sling or not? If not, you'll get your equalization -- but might have gotten that with a simple over-hand in the sling. If it does need to slide, will it do so quickly enough to distribute the load (equalize) as needed? That, I don't know. But, if it doesn't equalize, and one point fails, you now get extension and shock-loading on the other point, and this may cause it to fail.

Steven James wrote:Anyway, I think nicelegs is onto something here...

But that would be on topic.