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chriisu


Jun 14, 2011, 3:28 AM
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Clove hitch anchor equalization
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Alright, let's try yet another anchor critique thread. Flame on!

Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point? Example of such anchor below. The strands between two clove hitches are unweighted.




Partner devkrev


Jun 14, 2011, 3:43 AM
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chriisu wrote:
Alright, let's try yet another anchor critique thread. Flame on!

Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point? Example of such anchor below. The strands between two clove hitches are unweighted.

[img]http://farm4.static.flickr.com/3660/5831723071_c335dc412b_z.jpg[/img]


Lets do some critical thinking...

What do you think some of the pros and cons of such a set up are?


michael1245


Jun 14, 2011, 5:30 AM
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I would have just tied a cordellette. everything would equalize at the master point at one knot, instead of 4 knots that weaken the system.


blueeyedclimber


Jun 14, 2011, 5:37 AM
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chriisu wrote:
Alright, let's try yet another anchor critique thread. Flame on!

Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point? Example of such anchor below. The strands between two clove hitches are unweighted.

[img]http://farm4.static.flickr.com/3660/5831723071_c335dc412b_z.jpg[/img]

Because you're defeating the purpose of actually using a cordellete/powerpoint system. If you are going to go with clove hitches, then why don't you just use the rope?

Josh


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Jun 14, 2011, 5:38 AM
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michael1245 wrote:
I would have just tied a cordellette. everything would equalize at the master point at one knot, instead of 4 knots that weaken the system.


I might be mistaken, but I don't think knots have a cumulative effect of cordage...So your one knot is just as bad as 4 or 5...I think.

Someone correct me if I'm wrong.


trenchdigger


Jun 14, 2011, 5:54 AM
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As with a normally tied off cordelette, you have a statically equalized system. Everything is fine and dandy until your load shifts 3 degrees to the left.

With any statically equalized system, you run the risk (with relatively high probability) of loading only one or two of the strands. Even in the ideal direction of pull, the loads will be uneven due to stretch, however minimal.

So essentially, as with any statically equalized system, you're relying primarily on redundancy for anchor strength rather than good equalization. In most cases that's fine. What I don't like about this case is that you're essentially using single strands of a spectra sling as each arm of the anchor system. The sling as a loop is about 22kn strong, which means each arm will be ~11kn strong. Add loss to a clove hitch to that, and you're down in the 7-8kn territory.

Now combine that decreased load handling with the poor equalization inherent in a statically equalized system and you've got an anchor that's going to start to fail at relatively small loads.

Is it strong enough? Probably... But why not use a simple, quicker, stronger option like the standard tied off cordelette (for static equalization and great redundancy) or if you insist on using clove hitches, the equalette (for the best possibly equalization with adequate strength and redundancy)? The strength of either of these alternatives should be approximately double your pictured anchor system.


(This post was edited by trenchdigger on Jun 14, 2011, 5:57 AM)


TarHeelEMT


Jun 14, 2011, 5:59 AM
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It's not heinously unsafe or anything, but it doesn't offer any advantages that I can see over a tied off cordalette. Which begs the question... Why do it?


michael1245


Jun 14, 2011, 6:06 AM
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I try to use the least amount of knots.

But it's this set up. There's really no need for all the clove hitches. Cordellette is one and done.


michael1245


Jun 14, 2011, 6:15 AM
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trenchdigger wrote:
As with a normally tied off cordelette, you have a statically equalized system. Everything is fine and dandy until your load shifts 3 degrees to the left.

With any statically equalized system, you run the risk (with relatively high probability) of loading only one or two of the strands. Even in the ideal direction of pull, the loads will be uneven due to stretch, however minimal....

That's always in the back of my mind...that a cordellete is never really 100% equalized.

So I ask an AMGA Guide is it really the best option? What about a sliding-x or an equalette? And they always say cordellete.

And so like you say, whenever I tie a cordellette I rely on the redundancy of the pro. I think there were what, four in this picture? For me, four bomber peices is a solid anchor for a cordellete.


trenchdigger


Jun 14, 2011, 6:24 AM
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There is no single anchor option that is always the best. What do I use? Probably in order of frequency of use: 1. a tied off cordelette 2. the rope (double loop 8 or bowline on a bight) or 3. an equalette.


chriisu


Jun 14, 2011, 6:35 AM
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TarHeelEMT wrote:
It's not heinously unsafe or anything, but it doesn't offer any advantages that I can see over a tied off cordalette. Which begs the question... Why do it?

The main advantage of this setup is that it's possible to do with quite short slings. In my example anchor four pieces were tied off with a 120cm sling. The same setup with cordalette would have required about double length of sling. The tradeoff seems to be the strength of the system as tenchdigger pointed out.


(This post was edited by chriisu on Jun 14, 2011, 6:36 AM)


ddooddodo


Jun 14, 2011, 6:36 AM
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On a slightly different note you can also replace the figure eight with a sliding x. That will equalize much better than a figure eight but will bring about the problem of shock loading.
Pick yur poison


trenchdigger


Jun 14, 2011, 6:46 AM
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chriisu wrote:
The main advantage of this setup is that it's possible to do with quite short slings. In my example anchor four pieces were tied off with a 120cm sling. The same setup with cordalette would have required about double length of sling. The tradeoff seems to be the strength of the system as tenchdigger pointed out.

Which I don't think is worth it. Inadequate safety factor is the reason we don't use 4 or 5mm cord for a cordelette to save weight/bulk/$. Spend $23 and get one of these if you're concerned about weight or bulk. Or be like the rest of us and get 25' of 7 or 8mm cord that's a little bulkier but will last 3x as long for about the same price.


patto


Jun 14, 2011, 6:48 AM
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trenchdigger wrote:
So essentially, as with any statically equalized system, you're relying primarily on redundancy for anchor strength rather than good equalization. In most cases that's fine. What I don't like about this case is that you're essentially using single strands of a spectra sling as each arm of the anchor system. The sling as a loop is about 22kn strong, which means each arm will be ~11kn strong. Add loss to a clove hitch to that, and you're down in the 7-8kn territory.

THIS is a very compelling argument.

You are significantly weakening every single arm of your anchor while gaining nothing over many other systems. Stay away from this over complication.


JimTitt


Jun 14, 2011, 9:29 AM
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Personally Id have opened the windows and tied the rope around the pillar between them but then Im a bit old-school anyway.


Partner devkrev


Jun 14, 2011, 12:02 PM
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trenchdigger wrote:
chriisu wrote:
The main advantage of this setup is that it's possible to do with quite short slings. In my example anchor four pieces were tied off with a 120cm sling. The same setup with cordalette would have required about double length of sling. The tradeoff seems to be the strength of the system as tenchdigger pointed out.

Which I don't think is worth it. Inadequate safety factor is the reason we don't use 4 or 5mm cord for a cordelette to save weight/bulk/$. Spend $23 and get one of these if you're concerned about weight or bulk. Or be like the rest of us and get 25' of 7 or 8mm cord that's a little bulkier but will last 3x as long for about the same price.

Besides cost, something that I feel gets overlooked sometimes...

I like being able to chop my cordelette for rap anchors or prussiks or whatever...good luck cutting spectra with a pocket knife.

Those DMM videos of the slings breaking didn't instill confidence in knotted spectra in me either...


dev


Rudmin


Jun 14, 2011, 1:01 PM
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ddooddodo wrote:
On a slightly different note you can also replace the figure eight with a sliding x. That will equalize much better than a figure eight but will bring about the problem of shock loading.
Pick yur poison

^This is my anchor of choice for equalizing a nest of stuff. Load gets spread out somewhat evenly to all arms. Not much shock loading unless two pieces fail, and it's redundant.


patto


Jun 14, 2011, 1:25 PM
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devkrev wrote:
I like being able to chop my cordelette for rap anchors or prussiks or whatever...good luck cutting spectra with a pocket knife.

I must have exceptional luck or an exceptionally sharp pocket knife. Angelic


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Jun 14, 2011, 2:46 PM
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chriisu wrote:
TarHeelEMT wrote:
It's not heinously unsafe or anything, but it doesn't offer any advantages that I can see over a tied off cordalette. Which begs the question... Why do it?

The main advantage of this setup is that it's possible to do with quite short slings. In my example anchor four pieces were tied off with a 120cm sling. The same setup with cordalette would have required about double length of sling. The tradeoff seems to be the strength of the system as tenchdigger pointed out.

The other advantage is that if the clove hitches slip a tiny bit under heavy load they would equalize better than a standard cordelette.

To me, it seems like it's plenty strong, and being able to link 4 pieces with one sling is nice.

The only major downside I see is that when you weight this at the belay, you've got a lot of stuck knots you have to undo every pitch. That's a fair amount of wasted time.

GO


patto


Jun 14, 2011, 6:44 PM
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cracklover wrote:
The other advantage is that if the clove hitches slip a tiny bit under heavy load they would equalize better than a standard cordelette.

Slipping, heavy load, low melting point.... This is getting better and better.


Partner devkrev


Jun 15, 2011, 6:56 AM
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patto wrote:
devkrev wrote:
I like being able to chop my cordelette for rap anchors or prussiks or whatever...good luck cutting spectra with a pocket knife.

I must have exceptional luck or an exceptionally sharp pocket knife. Angelic


I am also able to cut spectra with my pocket knife.....who knows where I got that assumption from, I guess I was wrong.


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Jun 15, 2011, 9:32 AM
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patto wrote:
cracklover wrote:
The other advantage is that if the clove hitches slip a tiny bit under heavy load they would equalize better than a standard cordelette.

Slipping, heavy load, low melting point.... This is getting better and better.

I have never heard of clove hitches in spectra failing in dynamic loading situations due to melting. Have you?

GO


patto


Jun 15, 2011, 5:24 PM
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cracklover wrote:
I have never heard of clove hitches in spectra failing in dynamic loading situations due to melting. Have you?

No. But I've never heard of such an anchor being used in a high fall factor situation. Have you?

I'm not saying they will melt, in fact I'd say they would likely not melt. But that whole anchor seems unnecessarily compromised. There are other many better ways.


nafod


Jun 15, 2011, 6:29 PM
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chriisu wrote:
Alright, let's try yet another anchor critique thread. Flame on!

Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point? Example of such anchor below. The strands between two clove hitches are unweighted.

So it looks like you're using one long runner? In that case, I'd fiddle with it to remove the slack in the strand between the clove hitches where it is unweighted. After that, you'd have your anchor equalized over four pieces of pro with no chance of shock loading for a single piece failure (and the load as designed for). Still, only two loops of spectra going around the hotpoint biner don't give me a warm and fuzzy. Spectra is strong as all, but far too easy to cut. That's just me.


(This post was edited by nafod on Jun 15, 2011, 6:29 PM)


rescueman


Jul 5, 2011, 11:50 AM
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cracklover wrote:
I have never heard of clove hitches in spectra failing in dynamic loading situations due to melting. Have you?

Spectra has a much lower melting point (<300F) compared to nylon (420-480F), an even lower critical temperature of 150F, and is more likely to fail in a shock-load. It also has high lubrisity or slipperiness, so it doesn't hold a knot (or clove hitch) as well.

I do not use Spectra (or any high-strength cordage) in any application, except as factory slings on protection. High strength-to-weight ratio is useless if it has a higher failure potential when the proverbial crap hits the fan.

Nylon cords and slings are still the most versatile, inexpensive and reliable in all applications and failure modes.

Check out the Tom Moyer/Black Diamond test report presented at the 2000 International Technical Rescue Symposium: http://www.xmission.com/...gh_Strength_Cord.pdf


(This post was edited by rescueman on Jul 5, 2011, 5:04 PM)


mc


Jul 5, 2011, 12:19 PM
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Thinking of Aramid/ Kevlar cord probably. Wont cut without serrated edge

In reply to:
I am also able to cut spectra with my pocket knife.....who knows where I got that assumption from, I guess I was wrong.


(This post was edited by mc on Jul 5, 2011, 12:22 PM)


patto


Jul 5, 2011, 12:41 PM
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rescueman wrote:
Nylon cords and slings are still the most versatile, inexpensive and reliable in all applications and failure modes.

I completely agree.

The numbers simply don't add up when using cord. Once knots and possible shock loading is considered then it makes little sense to choose the high tech cords.


rescueman


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patto wrote:
...it makes little sense to choose the high tech cords.

Except they're often prettier ;-)


JimTitt


Jul 6, 2011, 11:52 AM
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rescueman wrote:
cracklover wrote:
I have never heard of clove hitches in spectra failing in dynamic loading situations due to melting. Have you?

Spectra has a much lower melting point (<300F) compared to nylon (420-480F), an even lower critical temperature of 150F, and is more likely to fail in a shock-load. It also has high lubrisity or slipperiness, so it doesn't hold a knot (or clove hitch) as well.

I do not use Spectra (or any high-strength cordage) in any application, except as factory slings on protection. High strength-to-weight ratio is useless if it has a higher failure potential when the proverbial crap hits the fan.

Nylon cords and slings are still the most versatile, inexpensive and reliable in all applications and failure modes.

Check out the Tom Moyer/Black Diamond test report presented at the 2000 International Technical Rescue Symposium: http://www.xmission.com/...gh_Strength_Cord.pdf

However I doubt you can actually buy pure Spectra/Dyneema tape, all the tape I know of is a hybrid with nylon and both ourselves and others have noted in testing that this has a higher friction than pure nylon tape or
cord, the reason and exact mechanism for this is not known.

As pointed out in the link you gave the Spectra/Nylon hybrid tape was an excellent performer and industry tests show a clove hitch in the material is capable of breaking a karabiner.
(See for example the Trango Alpine Equaliser video).

Jim


rescueman


Jul 6, 2011, 12:26 PM
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JimTitt wrote:
However I doubt you can actually buy pure Spectra/Dyneema tape, all the tape I know of is a hybrid with nylon and both ourselves and others have noted in testing that this has a higher friction than pure nylon tape or cord, the reason and exact mechanism for this is not known.
In the Moyers tests, ultratape (spectra/nylon) exhibited similar friction characteristics as 1" nylon tubular webbing, but only about 20% of the friction of 7mm nylon cord when used as a prusik hitch.

In reply to:
As pointed out in the link you gave the Spectra/Nylon hybrid tape was an excellent performer
Not if you look at the results of the cordellete strength and drop tests. Only the 7mm nylon cord, the 1" tubular nylon webbing and the Maxim Spectra-A (spectra/kevlar with polyester sheath) passed the UIAA test without failure.

I stand by my judgement about the reliability of nylon (and polyester where shock loads are not a problem) over any of the high-tech fibers.


JimTitt


Jul 6, 2011, 2:28 PM
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Friction in a Prusik? We/I am talking about friction over a karabiner in cordalette/equalette setups and as related to clove hitches.

There is no UIAA drop test for slings, tape or accessory cord.


rescueman


Jul 6, 2011, 2:56 PM
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JimTitt wrote:
Friction in a Prusik? We/I am talking about friction over a karabiner in cordalette/equalette setups and as related to clove hitches.
Yes, I understand that, but this test offers some suggestion of the relative friction qualities of the various materials. And the main reason that Spectra is mixed with nylon is because the Spectra alone has almost no friction or knot-holding capacity (plus it's vulnerable to UV and tends to creep).

In reply to:
There is no UIAA drop test for slings, tape or accessory cord.
Perhaps there should be, since it's these anchors that we're falling on.

As Tom Moyers states in his ITRS report on Comparative Testing of High Strength Cord, "Since these are used as anchors, the UIAA spec for maximum dynamic-rope impact force is shown for comparison. This represents a typical worst-case force on the rope. However, if the belay is run through the anchor, force on the anchor is multiplied. A level 170% of the UIAA spec - an assumed maximum - is also shown for comparison. It is apparent from this chart that at least some of these cordelettes would be expected to fail a UIAA drop test."

If that's not a concern for you, it certainly should be.


JimTitt


Jul 6, 2011, 11:38 PM
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rescueman wrote:
JimTitt wrote:
Friction in a Prusik? We/I am talking about friction over a karabiner in cordalette/equalette setups and as related to clove hitches.
Yes, I understand that, but this test offers some suggestion of the relative friction qualities of the various materials. And the main reason that Spectra is mixed with nylon is because the Spectra alone has almost no friction or knot-holding capacity (plus it's vulnerable to UV and tends to creep).

In reply to:
There is no UIAA drop test for slings, tape or accessory cord.
Perhaps there should be, since it's these anchors that we're falling on.

As Tom Moyers states in his ITRS report on Comparative Testing of High Strength Cord, "Since these are used as anchors, the UIAA spec for maximum dynamic-rope impact force is shown for comparison. This represents a typical worst-case force on the rope. However, if the belay is run through the anchor, force on the anchor is multiplied. A level 170% of the UIAA spec - an assumed maximum - is also shown for comparison. It is apparent from this chart that at least some of these cordelettes would be expected to fail a UIAA drop test."

If that's not a concern for you, it certainly should be.

The Prusik test shows the relative effectiveness cord against tape, no matter what the material, tapes always performing badly with the knots tested. The poor performance of nylon tape shows that it is not the material but the the way it is woven. There are more suitable knots for tape which were not tested.

And no, it is of no concern to me, I never use a webolette, cordalette or whatever and have a fundamental dislike of running the lead rope through the belay in a way that can potentially lead to such high impact forces. I also use belay devices which ensure such high impact forces cannot occur and try to climb with people who dont take lead falls directly onto the belay on trad routes.
Since the strength of the single webolette leg was about the same as the maximum rated strength of any of the nuts and cams I would build the belay from it strikes me as an irrelevance anyway.

By the criteria the drop test sets ALL the movable protection available and nearly every karabiner will fail as well which makes his test and the theory behind it somewhat questionable.

The standards for climbing equipment are established using a mixture of theoretical possible loadings and historical occurance, since failures of webolettes and clove-hitched Dyneema slings are unheard of we can better spend our time and energy on people who abseil off the ends, fail to tie-in properly, think they are being lowered when they are not belayed and so on.

Jim


sp115


Jul 7, 2011, 5:01 AM
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JimTitt wrote:
...I never use a webolette, cordalette or whatever and have a fundamental dislike of running the lead rope through the belay in a way that can potentially lead to such high impact forces.Jim

Jim, not to de-rail your discussion, but are you referring to belaying a leader directly off the anchor, or is there some other configuration you had in mind?


Edit to add: No intention to nitpick, I'm just genuinely interested...


(This post was edited by sp115 on Jul 7, 2011, 5:04 AM)


JimTitt


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On trad anchors I belay exclusively with the device on my harness and never use any of the anchors of the belay as a Jesus
nut either. If required an extra piece of gear would be placed. Adding extra complication at the belay and imposing higher than nescessary loads on the gear seems undesirable.

jim


StuMsg


Jul 8, 2011, 2:22 AM
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chriisu wrote:
Alright, let's try yet another anchor critique thread. Flame on!

Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point? Example of such anchor below. The strands between two clove hitches are unweighted.

It wouldn't be my first choice of anchor but if I was ever in a situation where I had one sling and had to choose between 4 placements with 4 x 7 KN strands or 2 placement with 2 x 14 KN (or whatever) strands, I would choose the 4 peices of gear. Hypotheticaly anyway.

Love the tricam placement Smile


rescueman


Jul 8, 2011, 10:34 AM
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I wouldn't use clove hitches, or a high-strength sling. If the hitches are not uniformly set then slippage under load would dis-equalize the anchor, and there will be no sling stretch to self-equalize the forces as there would be with a nylon cord.

P.S. that's an OK tri-cam placement, but not sufficiently angled to get a good bite - one size smaller would have been better.


acorneau


Jul 8, 2011, 11:13 AM
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rescueman wrote:
If the hitches are not uniformly set then slippage under load would dis-equalize the anchor, and there will be no sling stretch to self-equalize the forces as there would be with a nylon cord.

So what you're saying is the micro-equalizing of the system by way of material stretch is good but the micro-equalizing of the system by way of cinching/slipping knots is bad?

Sounds like they accomplish the same thing to me.


qwert


Jul 8, 2011, 11:45 AM
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chriisu wrote:
Is there anything wrong using clove hitches for connecting and equalizing pieces of protection to the master point?

OK, easy part first:

Look out of the window.

Which country are you in?

If the answer is USA, then this anchor is a bad idea, overly complicated and will kill you.
If the answer is europe, or even better - germany, then this anchor is a good idea, as well as the easiest and safest solution for a belay that consists of more than just 2 or 3 bomber points.

Essentially what you have built is the "Kraken" (retarded name by the way) and is one of the "official" ways to built a belay, if you believe in the german alpine club.

See here, p20 of the .pdf.

qwert


(This post was edited by qwert on Jul 8, 2011, 11:45 AM)


qwert


Jul 8, 2011, 11:45 AM
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So, since i feel like replying, here is some of my thoughts on various stuff said so far:

blueeyedclimber wrote:
If you are going to go with clove hitches, then why don't you just use the rope?
While the rope - clove hitch system is a nice way to build a quick and easy anchor, it has a few problems, namely that it becomes slow and complicated for block leading, escaping the belay/ emergency situations or "complicated" anchors (i.e. more than just 2 or three bomber pieces).

trenchdigger wrote:
With any statically equalized system, you run the risk (with relatively high probability) of loading only one or two of the strands. Even in the ideal direction of pull, the loads will be uneven due to stretch, however minimal.
Here the clove hitch solution might be better, since the legs that get pulled on the most might slip a tad more, until the load gets shared on all of the legs?
In reply to:
The sling as a loop is about 22kn strong, which means each arm will be ~11kn strong. Add loss to a clove hitch to that, and you're down in the 7-8kn territory.
I dont know the exact numbers how a clove hitch reduces the force, but if we are going to assume 8kn, we are in the range where the anchor points wont withstandt significantly more force anyways.
If we are talking "bomber bolts" there is no need for this thing anyways, so there you use something else, which holds more.
If we are talking self built trad anchors, there is a good chance that the piece or placement itself wont hold much more anyways, so there is no need for the sling to hold double the amount of the placement.
In reply to:
Now combine that decreased load handling with the poor equalization inherent in a statically equalized system and you've got an anchor that's going to start to fail at relatively small loads.
If you manage to built an anchor that gets into trouble when one leg fails, you got other stuff to worry about, and a 22kn sling wont change much.

TarHeelEMT wrote:
It's not heinously unsafe or anything, but it doesn't offer any advantages that I can see over a tied off cordalette. Which begs the question... Why do it?
For me the advantage would be that it is about 20kg lighter and a whole elephant less bulky than a cordalette.
I tried using a cordalette for a while, but i simply couldnt stand it. If i know that i have to built anchors that consist out of 20 bodywheight placements, then i will dig it out of the closet, but otherwise, it will stay buried there, right next to the figure8.
Might be a cultural difference though

patto wrote:
Stay away from this over complication.
Personally, i think the cordallete is more complicated, and most folks i know would say so too, but then again, i not from the USA

cracklover wrote:
To me, it seems like it's plenty strong, and being able to link 4 pieces with one sling is nice.
Make it a 240cm sling, and you can easily more than double that amount, while still staying much lighter and less bulky than a cordalette.
In reply to:
The only major downside I see is that when you weight this at the belay, you've got a lot of stuck knots you have to undo every pitch. That's a fair amount of wasted time.
The only knot in there is the central point, and assuming you have a specific belay sling, that stays there for the whole climb.
The other stuff are clove hitches, you just slip them over the nose of the carabiner, and youre done. Even easier with keylocks.

qwert


qwert


Jul 8, 2011, 11:45 AM
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Oh, and just to add:

I am not that worried about doubletriplequadruple redundancy, as one has with the cordalette, so i might be overlooking some points with that, for the folks that are concerned about that.

And i wouldnt use spectra/dynema for the anchor/ that anchor. Somehow that DMM video made me rethink those slings for many applications (not that i didnt know that beforehand, but actually seeing that is a whole nother thing). Also i think/believe/hope that the more dynamic properties of polyester slings will help a bit with equalization.

qwert


JimTitt


Jul 8, 2011, 12:24 PM
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But the legs are unequal length so surely a stretchy cord will not equalise in a micro or macro sense anyway?

Jim


Partner cracklover


Jul 8, 2011, 1:30 PM
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qwert wrote:
cracklover wrote:
The only major downside I see is that when you weight this at the belay, you've got a lot of stuck knots you have to undo every pitch. That's a fair amount of wasted time.
The only knot in there is the central point, and assuming you have a specific belay sling, that stays there for the whole climb.
The other stuff are clove hitches, you just slip them over the nose of the carabiner, and youre done. Even easier with keylocks.

qwert

To be technically accurate, I should have said "a lot of stuck hitches", but to me that sounds kinda weird.

Anyway, with keylocks on every piece, absolutely, no big deal. But in my experience, load a clove hitch on a skinny sling and it's going to take a little while to loosen it enough to pop it over the nose of the biner. YMMV. Certainly this is not a show-stopper, I'm just saying that part of the analysis of the merits of any anchoring method should be the time needed to create and break it down, and as such, those hitches might add up.

GO


Partner rgold


Jul 8, 2011, 2:09 PM
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I'm with Jim on all of this.

Using just the rope, previously posted multiple times, so apologies to those viewing this yet another time.




JimTitt


Jul 8, 2011, 10:29 PM
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For that belay Id probably use the rope, a couple of slings made from whatever, three draws, karabiners metal to metal and my Prussik would be in there with some knots tied in it. Just like eveyone does!

Jim


rescueman


Jul 9, 2011, 5:07 PM
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acorneau wrote:
rescueman wrote:
If the hitches are not uniformly set then slippage under load would dis-equalize the anchor, and there will be no sling stretch to self-equalize the forces as there would be with a nylon cord.

So what you're saying is the micro-equalizing of the system by way of material stretch is good but the micro-equalizing of the system by way of cinching/slipping knots is bad?

Sounds like they accomplish the same thing to me.

No, I'm saying that a completely static high-strength sling is not going to offer any equalization from stretch, and unless those clove hitches are all equally tight and equally tight to the master point, it's not a well-equalized anchor.

From the picture, it looks like only the top right clove hitch is tight and that piece may take all the load.


qwert


Jul 10, 2011, 6:32 AM
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JimTitt wrote:
But the legs are unequal length so surely a stretchy cord will not equalise in a micro or macro sense anyway?

Jim
Well, it surely wont equalize as good as a sliding x (though that's equalization properties are also questionable), but from how i look at it, it should offer some equalization.

If we are looking at that pic

the load is completely on the two upper points. I have given the lower points a lot of slack for demonstration purposes (also, ignore the to wide angles).
If we are assuming i put a lot of load on the anchor, most (all) of that load will be seen by the two legs leading to the upper points, So those will get strechted a bit/ the hitches will slip a bit, until the lower point/points see some load too, which will mean that the stretching/slipping of the upper points will get less.
Of course they will still see more load, since those two arms are probably stretched to their limit already and cant give anymore, but still, it should self equalize a bit.

But this is all speculation on my side. Havent tested it.

qwert


(This post was edited by qwert on Jul 10, 2011, 6:32 AM)
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qwert


Jul 10, 2011, 6:32 AM
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rescueman wrote:
acorneau wrote:
rescueman wrote:
If the hitches are not uniformly set then slippage under load would dis-equalize the anchor, and there will be no sling stretch to self-equalize the forces as there would be with a nylon cord.

So what you're saying is the micro-equalizing of the system by way of material stretch is good but the micro-equalizing of the system by way of cinching/slipping knots is bad?

Sounds like they accomplish the same thing to me.

No, I'm saying that a completely static high-strength sling is not going to offer any equalization from stretch, and unless those clove hitches are all equally tight and equally tight to the master point, it's not a well-equalized anchor.

From the picture, it looks like only the top right clove hitch is tight and that piece may take all the load.
Actually that is one of the things this anchor is supposed to do (at least according to the DAV).

You thighten the clove hitches in such a way that you put the load mostly on those points that you think that are best, and have the others as a kind of backup.

I am not really sure how clove hitches exactly behave in such a situation (no matter if dynema or nylon), but the "fact" that they slip a bit might be advantageous.
(see post before)

qwert


JimTitt


Jul 10, 2011, 1:01 PM
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Well I guess if you knew the peak end load you could pre-load (tie a bit shorter) the longer legs so the strain was equalised at that set load. Practically this going to be difficult!

If you started with no slack anywhere and all the pieces equalised then under load the longer legs will take less of the strain and the belay is no longer equalised.

With Dyneema the belay would remain equalised.

Whether you actually want to equalise belays is extremely questionable and is only desirable (or achieves any benefit at all) when each of the weaker pieces has a strength greater than the strength of the strongest piece divided by the total number of pieces. Otherwise you need proportional equalisation based on your guess of the relative strength of each piece, again in practice perhaps difficult.

Bolts are a good answer!

Jim


rescueman


Jul 10, 2011, 5:21 PM
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qwert wrote:
Well, it surely wont equalize as good as a sliding x (though that's equalization properties are also questionable), but from how i look at it, it should offer some equalization.

qwert wrote:
Actually that is one of the things this anchor is supposed to do (at least according to the DAV).

You thighten the clove hitches in such a way that you put the load mostly on those points that you think that are best, and have the others as a kind of backup.

If you understand why even the friction of carabiner on sling in a slidingX slows down equalization at the impulse speed of a high factor fall, then you should realize that clove hitches are going to offer tremendously more friction and virtually no equalization under impact.

To have the weaker pieces as backup makes no sense since a force great enough to blow out the strong pieces isn't going to be kind on the weaker pieces.

The opposite strategy may make more sense: load the weaker pieces first to absorb some of the force and then use the best pieces for backup.

Or, better yet, use a pre-equalized, fixed, focused anchor using a somewhat dynamic nylon cordalette with double strands to each piece and tied into a master point so the load is as distributed as evenly as possible.

Then you don't have to bring your calculator or laptop and spreadsheet to calculate the loading potentials for each anchor.


JimTitt


Jul 10, 2011, 11:15 PM
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rescueman wrote:
If you understand why even the friction of carabiner on sling in a slidingX slows down equalization at the impulse speed of a high factor fall, then you should realize that clove hitches are going to offer tremendously more friction and virtually no equalization under impact.
In reply to:

The friction in a sliding X or any other setup doesnt slow down equalisation, it prevents it ever occuring no matter the speed or impact.
To have the weaker pieces as backup makes no sense since a force great enough to blow out the strong pieces isn't going to be kind on the weaker pieces.

The opposite strategy may make more sense: load the weaker pieces first to absorb some of the force and then use the best pieces for backup.
In reply to:

Surely it is irrelevant in which order the pieces are loaded and fail, the total of the energy absorbed by the work of ripping/breaking them is the same?


qwert


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JimTitt wrote:
rescueman wrote:
If you understand why even the friction of carabiner on sling in a slidingX slows down equalization at the impulse speed of a high factor fall, then you should realize that clove hitches are going to offer tremendously more friction and virtually no equalization under impact.

The friction in a sliding X or any other setup doesnt slow down equalisation, it prevents it ever occuring no matter the speed or impact.

In reply to:
To have the weaker pieces as backup makes no sense since a force great enough to blow out the strong pieces isn't going to be kind on the weaker pieces.

The opposite strategy may make more sense: load the weaker pieces first to absorb some of the force and then use the best pieces for backup.

Surely it is irrelevant in which order the pieces are loaded and fail, the total of the energy absorbed by the work of ripping/breaking them is the same?
Tits, meet cheese,
Cheese, meet tits.

Is it right now?

I am unsure how anchor pieces will behave when they fail, but if we are assuming that they only fail after a high load, they should have absorbed that load, thus leaving less load to be absorbed by the remaining pieces (unless the anchor will extend, and thus create new shockloading).

So it shouldnt really matter which pieces you load first (assuming the weak pieces are sti&#314;l somewhat strong. If they are bodywheight only, you are going to get into trouble).

But then on the other hand you could also construct an anchor that is meant to fail (partly), so that it will absorb force like a screamer. The piece that gets loaded the first, is the weakest, the 2nd is the 2nd weakes and so on.

Of course thats totally impractical, but it would be really interesting to test/calculate all that stuff.

qwert


qwert


Jul 11, 2011, 12:17 AM
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rescueman wrote:
Or, better yet, use a pre-equalized, fixed, focused anchor using a somewhat dynamic nylon cordalette with double strands to each piece and tied into a master point so the load is as distributed as evenly as possible.

Then you don't have to bring your calculator or laptop and spreadsheet to calculate the loading potentials for each anchor.
I might be lacking routine, but i would say the clove hitch anchor is easier to tie in such a way that it is equalized that the cordalette.

Also, do you know what happens in the master point? Though that is also a problem with the clove hitch anchor pictured in the OP, it could be much more "problematic" (as in: How the hell does that giant knot get pulled thight?) with a four leg cordalette where you have a knot made up of 8 strands, all somewhat twisted

qwert


JimTitt


Jul 11, 2011, 12:19 AM
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Good man, its a bit early! And Im somehow not quite recovered from the IG Klettern annual fest.

Jim


rescueman


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qwert wrote:
... i would say the clove hitch anchor is easier to tie in such a way that it is equalized that the cordalette.

How is tying a separate hitch on each biner and a master point knot easier than simply clipping a cordelette into each biner, pulling in the direction of load and tying a master point knot?


JimTitt


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As we have tried to point out earlier (but are unlikely to convince a die-hard stretchy-string man) the only realistic chance of getting anywhere near equalised is to clove hitch a dyneema/Kevlar/Spectra sling in the way the OP shows. Unless you first get all the cordalette legs the same length using draws, chain, steel bars or perhaps even Dyneema the unequal stretch will screw it up.
And as is pointed out, tying that enormous knot screws it all up completely anyway.

Ive tested just about all the configurations and equalised is not the word that springs to mind and that includes after fitting bearings in all the bends, so much so that as a company we have shelved that idea as unworkable and are going to try another tack altogether.

The good news is none of the ideas seem noticeably worse than the other and no worse than loads of random joining together which is why weve all survived so long!

Jim


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JimTitt wrote:
...are unlikely to convince a die-hard stretchy-string man

I would use the term "die-hard" only for those too stubborn to learn new and better techniques and likely to die hard on the old ones, not those who have investigated the "new and improved" models and choose to stick with the "tried and true" because it really does work just fine and has for a long time.

Until relatively recently, Rocky Mountain Rescue, the oldest Mountain Rescue team in the US of A, used 3-strand Goldline rope because they'd been using it for 50 years with zero failure. Are they "die-hards" or just reasonable and smart? No one died on their system.

In reply to:
And as is pointed out, tying that enormous knot screws it all up completely anyway.
If you try to tie a figure-8 in six strands of 7mm, it's an enormous knot, but a simple overhand is quite manageable, strong and neat.

In reply to:
Ive tested just about all the configurations and equalised is not the word that springs to mind
The word I don't trust is "equalizing", since that rarely happens in practice and it can lead to an attitude of complacency when setting up marginal anchors.

I use the term "fixed, focused load-sharing anchor system" to describe a pretensioned and pre-directed multi-point anchor.

As for that stretchy-string comment, I don't have John Long's new anchor book but this was apparently a quote from page 192:

"Considering the cordelette equal riggings, slight differences are noted among the sling materials, though substantively they appear to perform equally well. A different conclusion is reached when examining results from the cordelette unequal configuration. Findings show that nylon or Perlon provide better equalization than Spectra or high-tensile-strength cord, in the case of a cordelette with unequal legs. This suggests that for equalization purposes, nylon is the preferred material to make cordelettes. Though these results are based on limited data, it appears that for a cordelette unequal setup, sling material does matter."


rescueman


Jul 11, 2011, 1:55 PM
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Re: [rescueman] Clove hitch anchor equalization [In reply to]
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And, while we're discussing "new and improved" multi-point anchoring tricks, does anyone have comment on the Alpine Cock Ring?

http://www.paulraphaelson.com/downloads/acr.pdf


JimTitt


Jul 11, 2011, 2:22 PM
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Re: [rescueman] Clove hitch anchor equalization [In reply to]
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But we were talking about equalising, well you were
In reply to:
"Or, better yet, use a pre-equalized, fixed, focused anchor using a somewhat dynamic nylon cordalette with double strands to each piece and tied into a master point so the load is as distributed as evenly as possible."
Since you (wisely) dont trust the word equalised I notice its been dropped and now we are just on a "fixed, focused load-sharing anchor system" which sounds like a bit of jargon to describe loads of gear tied together somehow. But load sharing?

To join a load of bits of gear together I would use anything suitable to hand and normally use the climbing rope and some slings. My way is better because it is focused(on me) pre-tensioned (by me) has inertial damping (from me) and requires no knowledge at all! So that will be a Beer-Gut Inertially Stabilised Age-related Macular Degeneration Slighly Focused Belaying System using my Whatever Ive Got Left Over Belay Kit.

Jim


(This post was edited by JimTitt on Jul 11, 2011, 2:23 PM)


rescueman


Jul 11, 2011, 3:15 PM
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Re: [JimTitt] Clove hitch anchor equalization [In reply to]
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JimTitt wrote:
But we were talking about equalising, well you were
In reply to:
"Or, better yet, use a pre-equalized, fixed, focused anchor using a somewhat dynamic nylon cordalette with double strands to each piece and tied into a master point so the load is as distributed as evenly as possible."
Since you (wisely) dont trust the word equalised...

You misquoted me.
rescueman wrote:
The word I don't trust is "equalizing"

"...so the load is as distributed as evenly as possible." Distributed evenly is not the same as self-equalizing or equalizing by faith or miracle, or...

Anyway, did you all know that God prefers 3-strand rope?

God wrote:
"Though one may be overpowered, two can defend themselves. A cord of three strands is not quickly broken." - Ecclesiastes 4:12


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