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karlbaba


Apr 12, 2008, 11:26 AM
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ja1484 wrote:
karlbaba wrote:
It's my opinion that there will be shock-loading in any system that has some "extension" in it, if one of the pieces fails. Perfect equalization usually means allowing some extension.

If an anchor piece fails, the anchor is going to be shock-loaded

peace

Karl

Per the research at Sterling ropes, best evidence available suggests that's just not the case so long as the dynamic rope is the attachment to the system. The numbers suggest no shockloading and, at times, lower forces than the initial impact.

Until someone can point me to *other* available evidence suggesting otherwise, I'm sticking with the best evidence we have at this time.

I'd love to see the Sterling link. I could buy that as long as no piece falis, but if a piece fails, it's obvious that the system will extent and it's self evident that sudden extension equals shock-loading. What am I missing here?

Peace

karl


ja1484


Apr 12, 2008, 11:30 AM
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karlbaba wrote:
ja1484 wrote:
karlbaba wrote:
It's my opinion that there will be shock-loading in any system that has some "extension" in it, if one of the pieces fails. Perfect equalization usually means allowing some extension.

If an anchor piece fails, the anchor is going to be shock-loaded

peace

Karl

Per the research at Sterling ropes, best evidence available suggests that's just not the case so long as the dynamic rope is the attachment to the system. The numbers suggest no shockloading and, at times, lower forces than the initial impact.

Until someone can point me to *other* available evidence suggesting otherwise, I'm sticking with the best evidence we have at this time.

I'd love to see the Sterling link. I could buy that as long as no piece falis, but if a piece fails, it's obvious that the system will extent and it's self evident that sudden extension equals shock-loading. What am I missing here?

Peace

karl


Here's the link to the post right here on rc.com where John Long transcribed Jim Ewing (Sterling Ropes) testing numbers and conclusion:

http://www.rockclimbing.com/...post=1317687#1317687

And this was with piece failure in a lead fall situation.

I'll transcribe it again here for posterity, should the link ever die for some reason. As you can read, the load is passed along to the remainder of the anchor, but it is equivalent. The load is not multiplied by extension.

Bolded emphasis is mine.

In reply to:
I was going to hold off on making a definitive statement on "Shock Loading" till I had time to work up what Jim at Sterling had actually found from his tests. But since it seems some folks simply can't let the thing go (nor should they till the data's in), here's basically what Jim scribbled down after doing some tests to try and create a shock load in a normal set up with a pretty stout dynamic fall (factor 1--80 kilo load dropped on 10.2 nylon rope connected to a two annchor point equalette).

Wrote Jim:

Leg failure test of Equalette.

All the same set up as previous unequal leg tests but with the short leg
connected with a 'fuse'. The 'fuse' is meant to break around 2kN. To save some time I also kept using the same cord and dynamic rope that I had just tested the Equalette unequal_arm with (see results below). Note: Using the same piece of climbing rope increases the chances of a shock load since after repeated drop testing, the rope looses it's stretch and becomes little more than a piece of static line.

The force/time curve is quite jagged at the beginning indicating lots of vibration. I can see on the curve the point at which the 'fuse' fails. Immediately after the 'fuse' blows there is a sharp drop in force followed by a normal looking curve. The peak force varied depending on the tenacity of the 'fuse'. The stronger the 'fuse' the lower the peak force on the remaining leg, the weaker the 'fuse' the higher the peak force on the remaining leg. Predictable but still interesting. No catastrophic shock load occurs a result of the extension.

6mm PC Equalette

short long

3.11 2.99
3.58 3.93
4.38 4.26
4.45 5.21
---------------------

The important thing to see is that the secondary loading is roughly the same as the initial loading--meaning there is no "load multiplication" between the initial leg failure and the mass slamming onto the remaining anchor point. Half the time it's less--the rest it's the same or a little more--at most about .75 kN, or 168 lbs. And that's only on the last drop, when the nylon rope was already stretched like crazy. And that's all on a rig with the limiter knots basically 10 inches apart--pretty far by normal standards.

My impression is that a true shock load can be understood in terms of the kind of shock we see in human beings. Shock usually means the level of stress or injury was greater than the resilience of the person's biology. In climbing systems, all the components have a degree of resilience, and these are by and large only maxed out when a section of unbelayed static line or high tensile strength cord sustains a dynamic load that is transmitted directly to the anchor. Like when a leader clips off to an anchor with a tech cord daisy, climbs up two feet and slips, falling 4 feet directly onto the anchor. You can bust biners this way, because the gear can't handle mass decelerating that quickly. Stretch and give allow the mass to decelerate slower. In a shock load you basically have the equavilant of a head on collision--something that's not going to happen when you're on a dynamic climbing rope that is running through a belay device, and when you're clipped into the anchor with the climbing rope.
Here, extension simply means that the next anchor that holds will be subjected to basically the same load--maybe a bit less--as that which blew out the first leg/piece. In other words, the initial loading is not multiplied through extension, it is simply passed on, sometimes at a lesser weight, depending on the strength of the "fuse" (failed arm).


JL


again, this is only one test, but so far as I'm aware, it's really the *only* testing done on this kind of situation by professionals with the equipment to duplicate a realistic simulation of a real-world scenario. I'm open to additional testing/data if anyone knows of any.


(This post was edited by ja1484 on Apr 12, 2008, 11:35 AM)


adatesman


Apr 22, 2008, 8:00 AM
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trenchdigger


Apr 22, 2008, 9:05 AM
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adatesman wrote:
Sometime soon I'll throw some samples of the all three versions (Equalette, Tripplette, ELET) onto the pull tester and get video of how they behave under load with one or more legs cut, but until then here's some non-ASCII pics.

Rad. I look forward to it. I was going to PM you to request this, but never got around to it. I have a few ways I've tied the triplette. Will try to get some photos for you. Thanks for your work on this.

Adam


acorneau


Apr 23, 2008, 1:01 PM
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adatesman wrote:
First, the power point loop should be stronger since it incorporates 2 strands of cord on one side and 2 strands of runner on the other, where the Tripplette has 2 strands of cord on one and one on the other.

True, but does that really matter? The "top" strand is only loaded if one side of your anchor system fails. If that were to happen I think you'd get off of it quick!


In reply to:
Secondly, it has one fewer knot and...

A Tripplette can be tied with two knots, the ELET (as shown) has three. How is that less?

Not being snarky, just looking for clarification.


adatesman


Apr 23, 2008, 1:31 PM
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asdf


Apr 24, 2008, 8:52 AM
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I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents


the_climber


Apr 24, 2008, 10:15 AM
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asdf wrote:
I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents

The issue you are siting is one which involves the ultra-light/ultra-thin dynema slings. As for Nylon on Nylon (or the wider dynema/dynema blend slings) the jury is still out, and the common consensus is it is still common practice to hitch slings together.


moose_droppings


Apr 24, 2008, 11:30 AM
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Is that really a sheet bend. Guess I don't recognize it doubled up, where are the ends?

Anyway, the tripplette (sp), like you mentioned can be tied with two OH knots, is easily adjusted when tying to whatever size triple center you want, and then left that way to carry with you. With 4" tails seems like its not going anywhere. I can't see it capsizing on itself if its weighted on both sides of the knot.

I'm also a little concerned with hitching spectra to nylon, as is asdf. Maybe its unfounded.

Just my .02 with plenty of room for enlightenment.
Thanx.


ja1484


Apr 24, 2008, 11:57 AM
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My question is what are the tangible advantages?

I don't need stronger - the equallette and cordelette are already beyond good enough.

The modified triplette (essentially Trench's version) I use gives me all the strength of the cordelette, better equalization, and no increase in rigging time after a little practice. That's a tangible benefit.

What is the ELET giving me? Is it faster to rig? Is it a less complex, simpler, easier to inspect anchor?

It does not have less knots than a modified triplette. Observe:

Mod. Triplette:

2x OH knot
2x double OH backup.

ELET:

2x double OH (or 1x2fish, but it's really two knots)
2x sheet bend


I have pre-tied my triplette and leave it tied. There's no real reason to untie it. It still functions like a long cordage runner end-to-end in the event of an emergency where I need to prussik with it or something. Faster-to-tie is immaterial to me, as I'm not tying anchor rigging on the cliff.

I want to know what I *need* that it's going to do for me. I've got enough strength. I don't need more of that.


(This post was edited by ja1484 on Apr 24, 2008, 12:03 PM)


majid_sabet


Apr 24, 2008, 12:13 PM
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asdf wrote:
I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents


I am sorry but,the climbers round here are not looking for your logical $0.02 input. These guys are constantly challenging each other on CF eqalette bullsh*t till someone actually breaks one and dies while setting it up .Till then this myth will continues.


majid_sabet


Apr 24, 2008, 12:16 PM
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adatesman wrote:
knudeNoggin made a posting on Page 4 (Link) about another alternative that sounds interesting (the ELET). He only provided an ASCII art diagram, so I threw one together yesterday and took some pics.

Basically you take your cordalette tied in a loop (I used a DF) and use a pair of sheet bends (or any of a number of other knots) to splice a runner into the middle of it for the powerpoint. Playing around with it I have to say I think there's some significant advantages over the Tripplette. First, the power point loop should be stronger since it incorporates 2 strands of cord on one side and 2 strands of runner on the other, where the Tripplette has 2 strands of cord on one and one on the other. Secondly, it has one fewer knot and is much easier to tie and untie. I found the Tripplette a bit fiddly to tie and set neatly with the strangle knots backed up tight against the overhands. The sheet bends in this version were quite simple to tie and easy to adjust. The runner I used was shorter then he suggested, but seems to work fine. I think I'd actually prefer a longer runner though, as it would give room to put an overhand on each end to provide some redundancy in case one of the strands of the runner was cut (tie the sheet bends through the loop the overhand creates on the end).

Sometime soon I'll throw some samples of the all three versions (Equalette, Tripplette, ELET) onto the pull tester and get video of how they behave under load with one or more legs cut, but until then here's some non-ASCII pics.

[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchor.jpg[/image]
Detail of front:
[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchorfront.jpg[/image]
Detail of back:
[image]http://www.shariconglobal.com/misc/pulltesting/anchors/anchorback.jpg[/image]

This a true class I CF anchor.


adatesman


Apr 24, 2008, 12:28 PM
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moose_droppings


Apr 24, 2008, 12:46 PM
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They aren't tied with a ring bend, they're tied with an overhand. There is a difference.
If you tie an overhand in the middle of a rope and apply force to both ends, it cannot capsize.

edit:

In your what to test thread, I suggested you test a ring bend (water knot) with a piece of 7mm and see what happens and asked if there's tests on this someone please point me to it. The capsizing I think your refering to is associated with an overhand bend.


(This post was edited by moose_droppings on Apr 24, 2008, 12:54 PM)


ja1484


Apr 24, 2008, 1:38 PM
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adatesman wrote:
ja1484 wrote:
My question is what are the tangible advantages?

I suppose the biggest advantage would be that its much easier to untie should you ever need a full length looped cordelette, but if you don't feel that you'd ever need to do that then its pretty much on par with the Triplette. I will say that the biner slid on the loop easier on the ELET, but that's not really anything to call home about.

Just for the record, it isn't my design and I don't have a vested interest in it. I just felt it looks promising and deserves some looking into. As I mentioned earlier, sometime soon I'll put a couple of each on the puller and see what they do under load.

Personally I'm not too thrilled with the 2-knot, 3-strand ring bend version of the Tripplette since ring bends are known to roll when loaded like they would if one side of the anchor failed. Although I suppose worst case would be that it rolls until you're only on 1 strand instead of 2..... The ring bend/strangle backup version looks fine since it would prevent the rolling; I just found it a bit fiddly to get tied neatly. And with the ELET, I have no idea how the sheet bends will behave when ring loaded. Hence wanting to bring it up for discussion and do some testing.

-aric.


Yeah, I'm very interested in the pull test results. If there's a disturbing sign from that (i.e. knot failures at unusually low loads, etc.) that could influence my decision.

As it stands now, I like the Trenchelette/Triplette as it is.

My main curiosity with the ELET is that we know soft on soft is not the best attachment methods for runners and cords strength wise, but will the sheet bend attached runner prove stronger than just a plain ol' limiter knot in the same place.

In any case, I look forward to the results of your pulltesting, and thanks again for doing it for us.


knudenoggin


Apr 24, 2008, 2:03 PM
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majid_sabet wrote:
asdf wrote:
I don't want to rain on anyone's parade but I think to tie a sling into an anchor is a really really bad idea. Slings are known to be cut in two when knotted to another material. People think that this is a "static knot" so friction is not an issue but when you load a few thousand pounds of force on those knots they tighten and heat up and I personally would not trust them. If you all remember back, there was a post about a pair of girth hitched slings in a rap anchor that just about cut through one another.

my 2 cents

I am sorry but,the climbers round here are not looking for your logical $0.02 input. These guys are constantly challenging each other on CF eqalette bullsh*t till someone actually breaks one and dies while setting it up .Till then this myth will continues.

Two quite unhelpful posts.
That "2 cents" is absolutely much more, but negative: there was no such
sling-cutting case demonstrated
; if you had paid attention, you'd have seen
a bunch of people making wild conclusions to support their agenda (dental
floss is bad, bad, bad, esp. when knotted), which was ridiculous on its
face, and subsequently tested and proved so by both Kolin Powick's (BDel)
sling testing and Mammut's investigation of the infamous John Sherman sling.
.:. It was cut by a SHARP object (think: knife), NOT by fibre.

And this false charge against such slings has popped up another time even
after this testing, and was then too rebutted. Will it never die? (Yeah, Major
Sorbet, talk about a myth that continues!)
Crazy

As for you, Majid, to find something so simple as the ELET a "CF", gimme
a break. Heck, it hardly has enough to it to merit your trademark arrows!

As for counting knots between the Triplette / ELET:
the ELET has TWO;
whether you want to tie the cord together or not ("to knot or not")
is a separate question--as one end of the twin strands will likely be tied
to protection 'biner for length adjustment, anyway, and the ends can be
there, post-knot, free.

In another implementation, the knotting would be of one 60cm sling through
another, and then cord will be tied (w/Clove hitches?) to 'biners clipped
into the non-PPoint sling bight ends.

And Why ... ? --because HMPE slings give the least friction for the best
equalization (Craig Connally so attested). And the set-up is easily adjusted,
the knots easier to untie to re-set (for one short, one much longer leg),
and the gear is in your pack already.

*kN*


jt512


Apr 24, 2008, 2:11 PM
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knudenoggin wrote:
there was no such
sling-cutting case demonstrated
; if you had paid attention, you'd have seen
a bunch of people making wild conclusions to support their agenda (dental
floss is bad, bad, bad, esp. when knotted), which was ridiculous on its
face, and subsequently tested and proved so by both Kolin Powick's (BDel)
sling testing and Mammut's investigation of the infamous John Sherman sling.
.:. It was cut by a SHARP object (think: knife), NOT by fibre.

Could you possibly provide a link to those investigations?

Jay


ja1484


Apr 24, 2008, 2:18 PM
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Mammut's investigation:

http://www.mammutusa.com/...%20Sling%20Break.pdf


Two BD investigations of sling-on-sling attachment:

http://www.bdel.com/...p_archive.php#110906
http://www.bdel.com/...p_archive.php#052107


C'mon Jay, you know how to use the internet.

Consensus: Sherman's sling was cut, but not by another sling.

Also, sling-on-sling attachment methods seem to sap between 30 to 60% of the sling's rated breaking strength, depending on the combination of materials and the type of loading.


I had to look all this stuff up a few weeks ago when I mentioned there was some "concern in the community that skinny slings might not be suitable for knotting" and kN came along threating to set me on fire during the night as I slept.


jt512


Apr 24, 2008, 2:23 PM
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ja1484 wrote:

Mammut's investigation:

http://www.mammutusa.com/...%20Sling%20Break.pdf


Two BD investigations of sling-on-sling attachment:

http://www.bdel.com/...p_archive.php#110906
http://www.bdel.com/...p_archive.php#052107


C'mon Jay, you know how to use the internet.

I guess my internet skills are only so-so. My initial search turned up nothing, so I posted the question. After that, I changed the keywords, and found at least the Mammut report. I was just returning to this thread to post the links myself, but you beat me to it.

Jay


(This post was edited by jt512 on Apr 24, 2008, 2:24 PM)


jt512


Apr 24, 2008, 3:28 PM
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ja1484 wrote:
Two BD investigations of sling-on-sling attachment:

http://www.bdel.com/...p_archive.php#110906

A couple of interesting details in there: first, that the strop hitch (which I'd never heard of) is stronger than the true girth hitch. Fooling around with a couple of Spectra slings just now, I suspect that we're usually connecting two slings together with strop hitches, and mistakenly calling them girth hitches. If I understand the strop hitch correctly, I have to try hard "de-symmetrify" it into a girth hitch. The other interesting detail is that pre-tensioning the strop hitch increases its strength against a dynamic load, presumably by decreasing slippage, and hence, heat, during loading.

Jay


palidon11


Apr 24, 2008, 3:29 PM
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i looked into this a while ago after i saw that alot of you guys dont like the equalette and didn't find what i was looking for. what is the problem with the equalette? i use it from time to time as the powerpoint for my toprope anchors.


ja1484


Apr 24, 2008, 4:22 PM
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palidon11 wrote:
i looked into this a while ago after i saw that alot of you guys dont like the equalette and didn't find what i was looking for. what is the problem with the equalette? i use it from time to time as the powerpoint for my toprope anchors.


Nothing. I just prefer the trenchlette for the 3-strand powerpoint.


majid_sabet


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GH knot naturally create a 2:1 mechanical advantages within the jointed area. This means, that every time you GH an sling to another rope (cord, whatever). You build an internal 2:1 MA right where the two materials are attached. Adding 2:1 MA in addition to motion will create great deal of heat which causes the GH to fail.

Why do you want to GH an anchor which may come under a massive force?

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(This post was edited by majid_sabet on Apr 24, 2008, 11:36 PM)


adatesman


Apr 24, 2008, 6:50 PM
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moose_droppings


Apr 24, 2008, 7:42 PM
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A waterknot (aka tape knot, ring bend) is an overhand on one end, then retraced the first overhand with the other end. Notice where the ends exit the knot in different directions.
#14
http://www.layhands.com/Knots/Knots_Bends.htm

An overhand bend (aka euro death knot) you take both ends together and tie an overhand with them. The ends come out of the knot the same direction. My understanding of the testing is if the knot is dressed properly and set well with adequate tails, its not prone to rolling off the ends.
The top pic on this page is a water knot, scroll down to see an overhand bend tied.
http://ozultimate.com/.../one-sided_overhand/

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