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fxgranite
Jun 22, 2009, 5:30 PM
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dingus wrote: pfwein wrote: Limiter knots are not "pointless" although I agree they may be unnecessary in some situations (and I frequently don't use them). The thing is, it's hard to know how unnecessary they are in advance of one piece popping, and then it may be too late. There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all. [snip] I challenge any one of you to PROVE limiter knots actually provide a real benefit and aren't just waste of time. DMT
I have no way of proving any of this but strictly on a theoretical level wouldn't additional extension inherently generate more force in the event of a piece blowing? (greater speed leading to a higher deceleration and all that jazz)
This additional force may be negligible though, thus making you correct. I'm just curious as I generally avoid limiter knots due to laziness.
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no_email_entered
Jun 22, 2009, 5:31 PM
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spikeddem wrote: Lazlo wrote: pfwein wrote: Lazlo wrote: [image]http://www.spadout.com/wiki/images/Sliding_x.jpg[/image] This is called the "sliding x" and is a safe alternative to your setup. Would be better if tied knots in each "arm" to limit extension if a piece pulls. This is very basic stuff (although not always intuitive--the problems with the ADK don't exactly leap out to most people at first glance) and best learned from a good text and/or competent instruction rather than ad hoc questions on this site. Good luck and climb safe--you're not off to a great start I hate to say but that's OK, you can improve. If I'm only using two peices, then both are beyond bomber...and I'm not worried about extension. Limiter knots in a sliding x are pointless. Unless your cat/dog/mom/gerbil/self peed on it. Or you set it next to/on/in your vat of battery acid. Then you'd be wishing you had some knots in it so it was a bit more redundant. 
i think the op needs to worry more about---
---moth balls
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shimanilami
Jun 22, 2009, 5:34 PM
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taydude wrote: Who's more of a dumbass? The bad troll or the people that believe such a weak troll?
Lighten up, 'dude. The believers multiply the impact of the troll. Tree falling in the forest type of thing, follow?
It's just the type of humor I need on a Monday morning.
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moose_droppings
Jun 22, 2009, 5:39 PM
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Totally acceptable anchor,
back in 1965.
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MapleSyrup
Jun 22, 2009, 5:43 PM
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I've been reading both Luebben and Long's books, and somewhere along the line got the idea that the death triangle's problem was just the wide angle.
I got the idea for the 'death triangle' while playing with the equalette, where at the bottom there are two strands each clipped to a different carabiner.
Isn't it proper etiquette around here for noob posts to have a trolling component  ?
btw those coat hooks are rated at 25 kN
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donald949
Jun 22, 2009, 6:18 PM
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MapleSyrup wrote: I've been reading both Luebben and Long's books, and somewhere along the line got the idea that the death triangle's problem was just the wide angle. I got the idea for the 'death triangle' while playing with the equalette, where at the bottom there are two strands each clipped to a different carabiner. Isn't it proper etiquette around here for noob posts to have a trolling component ? btw those coat hooks are rated at 25 kN
To answer the question about forces. With the webbing loaded, all pices are in tension. Therefore in your picture, each bolt has twice the load on it if it was loaded per the sliding x picture provided by Lazlo. One force down from the webbing tension, one across.
But if the angle was wide, the loads would be even higher.
Here's my favorite online achor information:
http://chauvinguides.com/Anchoring.PDF
ONLY a breif starter.
Climb Safe, Don
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MapleSyrup
Jun 22, 2009, 6:33 PM
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donald949 wrote: MapleSyrup wrote: I've been reading both Luebben and Long's books, and somewhere along the line got the idea that the death triangle's problem was just the wide angle. I got the idea for the 'death triangle' while playing with the equalette, where at the bottom there are two strands each clipped to a different carabiner. Isn't it proper etiquette around here for noob posts to have a trolling component ? btw those coat hooks are rated at 25 kN To answer the question about forces. With the webbing loaded, all pices are in tension. Therefore in your picture, each bolt has twice the load on it if it was loaded per the sliding x picture provided by Lazlo. One force down from the webbing tension, one across. But if the angle was wide, the loads would be even higher. Here's my favorite online achor information: http://chauvinguides.com/Anchoring.PDF ONLY a breif starter. Climb Safe, Don
hey thanks for that. I'm taking a day long course in anchor building next week, I'm just cooped up in the house and impatient.
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dingus
Jun 22, 2009, 6:40 PM
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fxgranite wrote: dingus wrote: pfwein wrote: Limiter knots are not "pointless" although I agree they may be unnecessary in some situations (and I frequently don't use them). The thing is, it's hard to know how unnecessary they are in advance of one piece popping, and then it may be too late. There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all. [snip] I challenge any one of you to PROVE limiter knots actually provide a real benefit and aren't just waste of time. DMT I have no way of proving any of this but strictly on a theoretical level wouldn't additional extension inherently generate more force in the event of a piece blowing? (greater speed leading to a higher deceleration and all that jazz) This additional force may be negligible though, thus making you correct. I'm just curious as I generally avoid limiter knots due to laziness.
I don't know if I'm correct or not.
But then again, neither do the limiter knot folks.
DMT
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pfwein
Jun 22, 2009, 7:49 PM
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dingus wrote: fxgranite wrote: dingus wrote: pfwein wrote: Limiter knots are not "pointless" although I agree they may be unnecessary in some situations (and I frequently don't use them). The thing is, it's hard to know how unnecessary they are in advance of one piece popping, and then it may be too late. There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all. [snip] I challenge any one of you to PROVE limiter knots actually provide a real benefit and aren't just waste of time. DMT I have no way of proving any of this but strictly on a theoretical level wouldn't additional extension inherently generate more force in the event of a piece blowing? (greater speed leading to a higher deceleration and all that jazz) This additional force may be negligible though, thus making you correct. I'm just curious as I generally avoid limiter knots due to laziness. I don't know if I'm correct or not. But then again, neither do the limiter knot folks. DMT
Just what do you think is happening as a mass accelerates during the interval between when one piece in a sliding-x pops, the x elongates, and the mass is then held when the sling becomes tight on the second piece?
Here is a simple way to look at it, as a thought experiment. If the sliding-x was a sling, say, 20' long, would your answer be the same?
It is common when setting up top ropes in some places to use very long slings to use trees, etc. as anchors. Would you use one of those very long slings configured in a sliding x confifuation, with no limiter knots?
Since from reading his posts I know Dingus is at the end of the day a rational person and an experienced climber, I'm confident that he would not use a sliding- x on slings of more than a certain length, although I don't what that length is. Whether he admits that on this thread or merely changes the subject (or ignores this post), I don't know.
Another way to look at this is that Dingus's intuition is that with sufficiently short slings, limiter knots are unnecessary. He may well be right, but denying that limiter knots will reduce forces if a piece pops is really getting silly.
If Dingus demands "proof" such as drop tower tests, I'm the wrong guy for that, but I'd be happy to put some money on it and hire Aric (if he's interested) to design and conduct some tests if Dingus wants to put money where his mouth is.
I'm serious on this--subject to us mutually agreeing on a test--loser will pay Aric (or other qualified, interested empirical tester).
Edit: just for the hell of it, I'll note that I did use sliding-x to set up some anchors just yesterday--I confess I didn't use limiter knots (I was using standard should length slings), so I want it to be clear that I'm not Mr. Limiter-Knot.
But if anyone wants to call me out on some very simple points and make it sound like *I'm* the ignoramus here, let's see where that goes. Maybe you'll be right, but I haven't seen any evidence of that so far.
Edit edit: I'm reading a fascinating book called Fooled by Randomness by Nassim Taleb (mostly but not exclusively about financial markets).
The author was called upon by some critics to justify his points with empirical evidence. He replied that "logic does not require empirical verification . . . It is a mistake to use . . . statistics without logic, but the reverse does not hold: It is not a mistake to use logic without statistics."
So you all can chew on that if you fault my lack of "proof" that limiter knots are not "pointless."
(This post was edited by pfwein on Jun 22, 2009, 8:01 PM)
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dingus
Jun 22, 2009, 8:04 PM
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pfwein wrote: Another way to look at this is that Dingus's intuition is that with sufficiently short slings, limiter knots are unnecessary. He may well be right, but denying that limiter knots will reduce forces if a piece pops is really getting silly.
Allow me to requote myself:
In reply to: There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all.
In reply to: Dingus wants to put money where his mouth is.
You sure get worked up My money WHERE MY MOUTH IS? Take a look in the mirror pal, and PAY YOUR OWN PROOFS. I'm not the one asserting the magical properties of limiter knots. I only asked a loaded question.
In reply to: I'm serious on this--subject to us mutually agreeing on a test--loser will pay Aric
I don't use limiter knots so I'm not really that intereeted. I simply asked to see some proof.
Now this question and the subsequent search for proof that doesn't exist may have something to say about conventional wisdom and climbing, as well as the tendency of internet climbing forums to spout theory as if it were fact.
Call someone else out next time.
DMT
(This post was edited by dingus on Jun 22, 2009, 8:04 PM)
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pfwein
Jun 22, 2009, 8:15 PM
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dingus wrote: pfwein wrote: Another way to look at this is that Dingus's intuition is that with sufficiently short slings, limiter knots are unnecessary. He may well be right, but denying that limiter knots will reduce forces if a piece pops is really getting silly. Allow me to requote myself: In reply to: There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all. In reply to: Dingus wants to put money where his mouth is. You sure get worked up My money WHERE MY MOUTH IS? Take a look in the mirror pal, and PAY YOUR OWN PROOFS. I'm not the one asserting the magical properties of limiter knots. I only asked a loaded question. In reply to: I'm serious on this--subject to us mutually agreeing on a test--loser will pay Aric I don't use limiter knots so I'm not really that intereeted. I simply asked to see some proof. Now this question and the subsequent search for proof that doesn't exist may have something to say about conventional wisdom and climbing, as well as the tendency of internet climbing forums to spout theory as if it were fact. Call someone else out next time. DMT
You want to explain why you wouldn't use a sliding-x on a "long" sling without limiter knots?
(I'll let you tell me what "long" means here.)
I don't mean to put a nasty tone on these posts and am happy to take it off.
But you are the one who wrote "I challenge any one of you to PROVE limiter knots actually provide a real benefit and aren't just waste of time."
I accepted your challenge with an offer to put some money on it--now I'm the guy who sure gets worked up?
I'll accept your offer to take a look in the mirror (and upon doing, I may have adopted a slightly different tone in my previous post).
You want to take your own advice about that mirror?
Edit: by the way, your point (if I understand it) regarding the lack of "evidence" regarding limiter knots almost has me wondering if we're talking about the same thing here.
What do think is going to happen to Force as a Mass Accelerates (which, upon a piece pulling, will happen to some extent with limiter knots and to a greater extent without the knots)? Has somebody hacked into Dingus' account here and is just posting nonsense?
(This post was edited by pfwein on Jun 22, 2009, 8:19 PM)
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hafilax
Jun 22, 2009, 8:18 PM
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I think what Dingus is trying to question is whether or not limiter knots add any kind of margin of safety to an anchor?
There is evidence that shock loading isn't an issue as long as there is a length of dynamic rope in the system.
To me the issue with added extension is if it will cause somebody to hit something or get pulled into a compromised position. I'm not all that worried about the added force to the gear.
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pfwein
Jun 22, 2009, 8:27 PM
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hafilax wrote: I think what Dingus is trying to question is whether or not limiter knots add any kind of margin of safety to an anchor? There is evidence that shock loading isn't an issue as long as there is a length of dynamic rope in the system. To me the issue with added extension is if it will cause somebody to hit something or get pulled into a compromised position. I'm not all that worried about the added force to the gear.
I know Dingus knows that--I don't know why he seems so reluctant to acknowledge it.
I speculate that it is because he knows that limiter knots will reduce the force felt on an anchor connected in a sliding-x when one piece pops, and he's become emotionally invested in denying that, or acting like it's an open question.
Here's a link to Rock Climbing Anchors by Craig Luebben regarding use limiter knots with sliding-x. Go argue with him. I guess he's also convinced of the sliding-x's "magical powers".
http://books.google.com/...s_SoiMC4XgygSWuIWWBQ
(This post was edited by pfwein on Jun 22, 2009, 8:39 PM)
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shoo
Jun 22, 2009, 8:38 PM
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They do add some safety against the possibility of anchor material cutting or breaking. Granted, this is extremely unlikely. Assuming your gear is in good condition, the only reasonably scenario for it breaking is if it were cut on the rock somehow, and if you're constructing anchors in which there is any real chance of that, you're doing something wrong.
Given that there are few if any negatives to adding limiter knots, I think I'll stick with using them.
For the record, I'm also a cord anchor kind of guy. Superman has kryptonite, the Wicked Witch of the West has water, and Dingus has equalettes.
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billcoe_
Jun 22, 2009, 8:44 PM
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Nothing as long as you don't fall on it. Ya have 2 slings doubled it appears, why not clip each one to each hook?
Did you bag the FA of the closet? What did ya name it?
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pfwein
Jun 22, 2009, 8:44 PM
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shoo wrote: For the record, I'm also a cord anchor kind of guy. Superman has kryptonite, the Wicked Witch of the West has water, and Dingus has equalettes.
Funny that I started out posting on this thread mainly to say someone should read a standard anchor book if they have general anchor questions, then got called out by Dingus for the specific point I made regarding limiter knots, then finally had to cite to a standard anchor book to show that Dingus is full of it on his attempted calling out.
(This post was edited by pfwein on Jun 22, 2009, 8:47 PM)
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hafilax
Jun 22, 2009, 8:50 PM
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Again, the question is whether or not the force on the anchor will be significantly greater? As in, will it make a difference between the anchor holding or failing?
Even with long slings I don't think limiter knots will make a lick of difference as long as there is a reasonable amount of dynamic rope in the system especially given how much friction there is in a sliding-x when it has to rapidly change position.
The problem with limiter knots is that they detract from efficiency and adaptability. They are either a PITA to tie and untie or they end up on a dedicated single purpose sling. YMMV but really it's not worth arguing about.
BTW pfwein, what percentage of your posts have you edited? In this thread you're batting 80%.
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shoo
Jun 22, 2009, 8:55 PM
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pfwein wrote: shoo wrote: For the record, I'm also a cord anchor kind of guy. Superman has kryptonite, the Wicked Witch of the West has water, and Dingus has equalettes. Funny that I started out posting on this thread mainly to say someone should read a standard anchor book if they have general anchor questions, then got called out by Dingus for the specific point I made regarding limiter knots, then finally had to cite to a standard anchor book to show that Dingus is full of it on his attempted calling out.
Actually, Dingus is probably one of the most respectable climbers who wanders these parts of the internets. His climbing philosophy and style has been honed over many more years than you or I, and you would do well to respect that. He has an opinion, and has made no attempt to state it as anything more than an opinion.
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pfwein
Jun 22, 2009, 9:07 PM
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hafilax wrote: Again, the question is whether or not the force on the anchor will be significantly greater? As in, will it make a difference between the anchor holding or failing? Even with long slings I don't think limiter knots will make a lick of difference as long as there is a reasonable amount of dynamic rope in the system especially given how much friction there is in a sliding-x when it has to rapidly change position. The problem with limiter knots is that they detract from efficiency and adaptability. They are either a PITA to tie and untie or they end up on a dedicated single purpose sling. YMMV but really it's not worth arguing about. BTW pfwein, what percentage of your posts have you edited? In this thread you're batting 80%.
By the way, I agree with the point made above that an advantage of limiter knots is that it will reduce the change in the position of the anchor if a piece pulls, and that may be more of a concern that the change in overall force felt on the anchor when a piece pops. For example, if you're doing what is common which is standing near the edge of a ledge at a belay and think it's just fine to drop down a foot or whatever when a piece pops, feel free to think that and maybe you're right. I find it to be at least a somewhat troubling event--but hay, whatever floats your boat.
On your point that "Even with long slings I don't think limiter knots will make a lick of difference as long as there is a reasonable amount of dynamic rope in the system especially given how much friction there is in a sliding-x when it has to rapidly change position": I'm interested in what you thing a "reasonable amount of dynamic rope is. The foot or two that connects the belayer to the anchor (in, let's say, a hanging belay scenario)? When that foot or two is already being stretched by holding the weight of the belayer? If the sling is a double or triple length"?
I've edited the posts mostly to correct some typos (I know some remain) and also to avoid bumping the thread when I just have another point to make. My goal is to improve the quality of the reading experience and not to continually bump the thread, especially if no one else has posted.
Why do you ask, is this a problem?
Edit--see halifax--here's an example. I saw shoo's post made above, and I don't see a need to make a new post, rather than just edit this one. Shoo--I don't know how "respected" Dingus is a climber, just like neither of us knows anything about each other. Being an rc posting legend is nice, but sorry, that don't mean jack to me when discussing anchors. I just know what he posted on this thread, and that's all I'm responding to.
Finally I got sick of this nonsense and just posted to Luebben's anchor book to settle this once and for all, which has now been done. (And I'm not saying you should always or even usually (or even ever, if you're using relatively short slings) tie limiter knots, which adds to the level or ridiculousness here.)
(This post was edited by pfwein on Jun 22, 2009, 9:18 PM)
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dingus
Jun 22, 2009, 9:20 PM
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shoo wrote: Given that there are few if any negatives to adding limiter knots, I think I'll stick with using them.
Time.
DMT
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hafilax
Jun 22, 2009, 9:27 PM
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Ropes are designed, in part, to be force limiting in that they should impart at most 12kN on an anchor in the most extreme of situations. Most ropes are more in the 9kN range. Add to that knot cinching and other dissipation mechanisms and I think that the meter or so of rope used to tie in to an anchor would be sufficient.
Dingus really has your panties in a bunch. I don't see why your so upset over this.
Excessive editing is poor etiquette and makes you look like a flake. Oh, and putting a line break between paragraphs improves readability.
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pfwein
Jun 22, 2009, 9:59 PM
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Dingus did manage to get my goat by taking an extreme and absurd position, by calling me out and then accusing me of calling him out, etc. What set me off is when he condescendingly referred to limiter knots as "magic" as if the mechanism as to why they will reduce force and reduce change in anchor position when a piece pulls isn't incredibly obvious (much more obvious, at least to me, than the the problem with the American triangle).
I'm over it.
Thanks for the constructive criticism regarding editing posts.
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hafilax
Jun 22, 2009, 10:07 PM
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It's not an absurd position. There is no empirical evidence that limiter knots improve the security of an anchor. Sliding-Xs have not been implicated in any anchor failures or even climbing accidents AFAIK.
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donald949
Jun 22, 2009, 10:19 PM
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billcoe_ wrote: Nothing as long as you don't fall on it. Ya have 2 slings doubled it appears, why not clip each one to each hook? Did you bag the FA of the closet? What did ya name it?
Dang, there you go. Bill cuts through it all and gives a good quick solution.
Why didn't I think of that. D
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pfwein
Jun 22, 2009, 10:25 PM
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hafilax, I thought we were getting somewhere, but now I'm concerned about a relapse.
Dingus wrote the following: "There is virtually no proof whatsoever that limiter knots provide any sort of benefit at all."
Putting aside anchor forces, I believe you noted earlier in this thread the advantage of reducing the change in anchor position. Do you now deny that that is proof, whatsover, of "any sort of benefit at all"?
Dingus's absurdity on this thread is not that he doesn't use limiter knots; it is the failure to acknowledge that they have obvious benefits in some cases. If the benefits don't exceed the costs for him and he avoids the cases where knots are really necessary (long slings), I have no problem with that.
It's also telling that neither you nor Dingus want to have anything to do with the discussion of whether you would use a sliding-x on a long sling (let's say a 20' sling) without limiter knots to, say, set up a top rope. Looking at arguments made in the extreme is a valid way to test the quality of the argument in other circumstances (and use of a long sling to set up a TR is really not so extreme--in fact, it happens hundreds of time across the country every weekend). I respectfully submit that the 20' sling does in fact prove that Dingus's potion in this thread has been absurd, and that's what "got my panties."
If for some crazy reason you still want to debate this, I will extend the invitation I made to Dingus to try to develop a test to submit to Aric or another qualified tester, with a little money riding on the result. For some reason Dingus seems to have been grossly offended by that even though he earlier in this thread issued a challenge. I think it may be interesting. If I "lost," that's great, I wouldn't have to waste time with limiter knots (except for the problem of anchor translation, which may in fact be the more serious issue).
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