There some stuff on the UIAA website if you look hard enough. There's an article that I've referenced a few times that talks about the reasoning behind the strength standards but I don't feel like looking it up again. Something like "How strong does gear need to be?".

Turns out that equalization is more important by orders of magnitude and that extension is not a problem at all if there is a dynamic rope in the system. This has been shown with experiments and anecdotally through a lack of accidents attributable to sliding-xs.

psshhh. Like I read those things.

Actually I might if I bothered to buy one. Everytime I try though, another cam just looks so much better


have there been any other tests done somewhere? A brief check didn't turn up anything in the lab. I figure there must be if it's mentioned in the instructions.

SHOCK LOAD!

(sounds like a Metal band)

OK, let's see.... in well over 1000 hand crafted trad belay anchors I've personally constructed, not ONE PIECE has ever pulled under the strain of a fall. Not one.

In good granite with good gear? I fear the Yeti more than I fear shock loading, sorry.

But I get the impression some folks like questionable anchors contructed using marginal placements, as it gives them a chance to show off their wonderful knotcraft.

Very pretty. But can they climb?

DMT

hafilax--you and I have nothing to argue about. But let me try to clear up the "debate" for Lazlo in short, declarative sentences that he may be able to understand. I'll use simplified grammar as it isn't clear that he is capable of understanding standard English. This will still be kind of long; no way around that.

pfwein say maybe use anchor in a way that make fall shorter if one piece fail.

Dingus say pfwein dumb and longer fall on static material no cause more fall force or any other problems.

pfwein say Dingus you wrong.

Dingus say no pfwein you have no proof so me think you wrong.

pfwein say yes I have proof here published book on climb anchors by engineer--he say longer fall cause more force so maybe you should try to shorten fall.

Dingus say that no good proof.

hafilax say Dingus no mean what Dingus say Dingus mean something else and Dingus right about something else.

pfwein say maybe hafilax right about something else but Dingus still wrong about what Dingus say.

Dingus say pfwein has no proof

pfwein say obvious--at some level--longer fall on static material cause more force and cause other problem cause when fall no can belay or may fall onto ground or something else bad may happen

hafilax say pfwein have no point. hafilax may be right, but pfwein say Dingus still wrong.

pfwein can't "prove" Dingus wrong cuz pfwein no can do empirical tests, and pfwein still think it so obvious that longer fall cause more force and maybe cause other problem no need test.

dingus maybe sets his anchors so that he will be OK with a little longer fall. pfwein does to.

lots of people say mean things about pfwein, some even say pfwein bad man for using "logic." Angry tell pfwein shut up--he on crazy drugs. Angry maybe right.

lazlo say pfwein write too much and lazlo no understand. lazlo not good reader. maybe lazlo need work on read skill

Hope that clears it up for you.

I mostly agree with everything you've written on this thread. My only contention, which is a quibble at this point, is that you think I'm missing something, which you may find hard to reconcile with my agreeing with you.

What you've written is not the same as what Dingus has written. You have chosen to reinterpret what he said in a way that makes sense.

A parting point that is more than quibble: there hasn't been agreement as to how long a sling is OK to use without limiter knots. If you think it's OK to use a double- or triple-shoulder length sling without limiter knots, I question that.

Remember that reducing force is not the only point of limiter knots: it is also to reduce anchor movement when a piece pulls. You noted this advantage previously. It may well be that this is the only real-world point to limiter knots. But it is an important one, for reasons that become obvious as the sling becomes longer.

Stated another way, "no extension" in SRNE is not completely worthless, even if may be regarded as less significant now than it has been at other times (and that's food for thought).

Thanks for making your points in a slightly less insulting manner than some of the posters here. I appreciate it, and content of your posts is clearly much better for it.

(My now infamous edit): I saw JT's comment after I posted mine. I have no doubt JT is right. I don't see it as going to the heart of what Hafilax and I were discussing, and I let Hafilax's point about the lack of real-world failures of sliding-x slide (sorry for the pun). There are of course very few failures of any real-world anchors, so invoking the lack of failures doesn't seem helpful when touting the benefit of any particular configuration.

pfwein:

1) your circular logic speaks for itself. You have admitted you use the very system you are speaking against.

2) I have not "come to dingus' defense." If you have read this site for a while you'd know that on the infrequent times we engage each other, more often than not, we disagree. But we usually don't descend into long diatribes.

3) My opinion is, you talk too much. I am grateful for the forum to express my opinion.

4) I've looked through the thread again, and no one has disputed the physics. What's in dispute is the practical application. Which system is better if (as is most likely) NEITHER piece fails, due to being well-equalized?

There is a reason why lab testing is necessary, rather than just slogging through the physics. I have heard it said that some years ago, aerospace engineers did some calculations, and concluded it is not possible for bumblebees to fly.

If you are as passionate about the subject as your too-long responses would indicate, then MAN UP, buy 50' of webbing, design the experiment and send it to the lab. The proposition of a "bet" solves nothing.

Not really important. Your typical sling even at half strength is still likely to be stronger than your protection. Both of which are likely to be stronger than the fall.

Not relevant. Energy in the fall has been absord already, as already mentioned if there is no weight in the anchor then there is no concern.


You don't need data. Again the physics is really simple. Extension of 1 foot, 2 feet of climbing rope = factor <0.5 fall of belayer. This force can be added to the force on the anchor from the lead fall.

-a sliding X in a 20' sling illustrates the folly of using it (even though nobody would).

Your confidence in your conclusions is unjustified in light of the paucity of the data. Sterling doing 6 drops (or whatever) does not settle the question.

Jay

SHOCK LOAD!

(sounds like a Metal band)

OK, let's see.... in well over 1000 hand crafted trad belay anchors I've personally constructed, not ONE PIECE has ever pulled under the strain of a fall. Not one.

In good granite with good gear? I fear the Yeti more than I fear shock loading, sorry.

But I get the impression some folks like questionable anchors contructed using marginal placements, as it gives them a chance to show off their wonderful knotcraft.

Very pretty. But can they climb?

DMT

DMT

I tried...but INRT.

I really did try. I got bored and annoyed with the bad Engrish.

pfWHINER strikes again.........

Bzzzzzt, wrong, thanks for playing.
Use of a sliding-x in a 20' sling without limiter knots does indeed illustrate the folly of your argument that limiter knots have no benefit.
Knowledgeable climbers regularly use 20' slings in sliding-x configuration, with limiter knots. It's called an equalette. Hafilax correctly noted the limiter knots in an equalette serve several purposes. He loses it, however, when he starts pretending that reducing extension is not one of the purposes. His rationality seems to fade in and out, as it is clear that reducing extension has a huge benefit regardless of impact forces. (See cracklover's post about hazard of shift in belayer's position due to extension). If you actually climb, you know this.

Look up the equalette in John Long's updated climbing anchor book if you want to learn something instead of trying (and failing) to expose any shortcomings in my logic. http://books.google.com/...pCSovNJ5XUlQTpxIzLDg

One reason I've persisted in this thread is that there's more going on than discussion of a minor detail. My initial response on this thread was the poster should consult an acknowledged climbing anchor text to learn about climbing anchors. Dingus and you are in effect saying that's bad advice--you know more than the anchor books. That is a truly startling position and warrants exploration. Hence this thread, where your and Dingus's position has been eviscerated.

The density of this thread is tiresome...

The first bolded section, I KNOW! I was repeating you from earlier in the thread. So, if it's wrong, don't blame me. YOU are the one who used a 20' sliding X as an illustration. It was pointed out that nobody does that. It's a red herring.

-I've read all of Largo's books, including his excellent prose. I don't need links to them, I can get them off my bookshelf.

-The second bolded section is a strawman, with a conflation- I never said consulting a book was a bad idea, but it's easier for you to say I did, than to admit that NO RESEARCH EXISTS supporting your position, and I'll repeat, I'm not speaking for dingus, or anyone else.

If drop testing was done, it is plausible that the additional knot is the weakest link, or that the extra knot decreases equalization a tiny bit, either of which weakens the anchor.

But I don't know, and neither do you, because the research is not there. There is only textbook information, which you'll recognize as the logical fallacy known as appeal to authority.

also, the longer the extension, the farther you fall, more force, the more the rope stretches. Shouldn't this also act as a counterbalance?

I'm in the same boat that limiter knots seem pointless

Factor2, meet fall factor:
R = l/r
where R is the fall factor, l is the length of the fall before the rope begins to stretch, and r is the amount of rope available to absorb the energy of the fall (copied from Wikipedia).
In your example, l increases in the absence of limiter knots and r is constant with or without limiter knots. Hence R increases in the absence of limiter knots.

As Jay notes above, there is complexity here. Lots of it. (I'm not going to touch "shock loading" in the presence of a hanging belayer.) But you are missing a very basic point if you don't see why limiter knots reduce the fall factor if a piece in a sliding-x fails. A reduced fall factor is a good thing.

Your point regarding knots weakening slings is valid, and not a single person on this thread has argued that limiter knots are necessary or desirable in any particular anchor configuration.

Indeed, one way to think of limiter knots is just that they affect the effective length of the sling in the sliding-x. The same result as limiter knots could be used by using a shorter sling in a sliding-x, and extending each of the pieces to the sliding-x with separate slings. No one could logically argue that limiter knots are always necessary, as any system with limiter knots is functionally equivalent (regarding extension) to another system that does not have limiter knots. A key question is: how long of a sling in a sliding-x are you willing to use?

Regarding very using very long slings w/o limiter knots, I believe that should be employed, if at all, by advanced anchor builders who have an excellent grasp of the consequences of sling extension in a specific anchor. Regardless of forces, an extending x on a long sling is going to involve significant anchor movement, which could range from no big deal to a very big deal depending on circumstances.

To those who wonder why I've posted so much on this thread--I am just concerned about safety, and don't mind being mocked if I can increase other's knowledge of safe climbing practices (as well as learn myself--I thank those of you such as Jay and patto who made knowledgeable contributions. Interesting that those tend not be the guys hurling the insults.)