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7mm Static Cord for Anchor
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rnevius


Jul 7, 2011, 2:29 PM
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Re: [tequilaboom] 7mm Static Cord for Anchor [In reply to]
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Not that my opinion matters much, but I think you're doing the best you can for the moment. Practice on the ground, anticipate everything you can, and always consider the possibilities of what situations you may have to get yourself out of. Before stepping off the ground, make sure you have enough gear, know how to use it, and have a plan for getting down. Walk through the climb in your head step by step (e.g. I'll need x draws, build an anchor, clip in, belay the second, yada yada yadda).


trenchdigger


Jul 7, 2011, 2:41 PM
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Re: [tequilaboom] 7mm Static Cord for Anchor [In reply to]
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tequilaboom wrote:
The fact is, you're all pretty much right - I am inexperienced, but am taking things as slowly as possible. I ask as many people for their opinions as I can and read as much as I can.

I know that when people on this forum criticize me, it's because they see that I am inexperienced and don't want myself or anyone else get hurt, and I truly appreciate that.

This is exactly why I come to these forums and read and ask questions. I count on people being polite, not sarcastic and to the point.

I really do appreciate the help people!

The intent was not to criticize... we were all there at one point and most of us made it through Wink

Anchor building is really one of the most important things you can learn with respect to rock climbing. Your posts give the impression that your anchor building knowledge is minimal and that's what frightens me the most. If you can, get some first hand anchor building instruction rather than just gleening bits and pieces from the John Long book. It's a great resource, but a few hours of instruction will serve you much better than just reading through the book. With a solid foundation in anchor building, you can build safe toprope anchors, set up mock-leads, build an anchor to top-belay, etc. Withuot that, you're just an overzealous n00b who is a hazard to yourself and others at the crag.

Climb safe, my friend, and go get some hands-on anchor building instruction.


squierbypetzl
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Jul 7, 2011, 4:04 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
7 mil is fine. Just tie it in a loop with a flat overhand and if equalized between several pieces it's plenty strong.

The way you phrased this is misleading. Use a double or triple fishermans knot to tie your cordllette into a loop. You can easily equalize an anchor by clipping your cordlette into 2 or 3 pieces of pro, and tying an overhand knot in the middle, creating a second smaller loop to attach biners and the rope. Do not use a simple overhand knot to tie your cordelette into a loop, and do not create an american death triangle.


jmeizis


Jul 7, 2011, 5:11 PM
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Re: [squierbypetzl] 7mm Static Cord for Anchor [In reply to]
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Yeah, it could be misinterpreted, good reason to not learn stuff over the internet. But I did mean to tie the cordelette together with a retraced overhand, aka, a flat overhand, aka, a euro death knot. Just make sure you pull your strands tight and leave plenty of tail (6 in. at a minimum.


Rudmin


Jul 7, 2011, 5:18 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
Yeah, it could be misinterpreted, good reason to not learn stuff over the internet. But I did mean to tie the cordelette together with a retraced overhand, aka, a flat overhand, aka, a euro death knot. Just make sure you pull your strands tight and leave plenty of tail (6 in. at a minimum.

This is a terrible idea. You might as well dip your cordelette in battery acid.


squierbypetzl
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Jul 7, 2011, 5:49 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
Yeah, it could be misinterpreted, good reason to not learn stuff over the internet. But I did mean to tie the cordelette together with a retraced overhand, aka, a flat overhand, aka, a euro death knot. Just make sure you pull your strands tight and leave plenty of tail (6 in. at a minimum.

Yeah, IŽm not sure why youŽd want to do that. Single overhand knots can "walk", and the 6 in. you leave for the tail are enough to accommodate a double fishermans knot. Doesn't make sense to me.


Rudmin


Jul 7, 2011, 6:35 PM
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Re: [Rudmin] 7mm Static Cord for Anchor [In reply to]
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Rudmin wrote:
jmeizis wrote:
Yeah, it could be misinterpreted, good reason to not learn stuff over the internet. But I did mean to tie the cordelette together with a retraced overhand, aka, a flat overhand, aka, a euro death knot. Just make sure you pull your strands tight and leave plenty of tail (6 in. at a minimum.

This is a terrible idea. You might as well dip your cordelette in battery acid.

Dunno why this got downgraded. I figure there is some knot terminology mistakes going on. I can't believe that anybody would seriously want to tie their cordelette together with an EDK:




tequilaboom


Jul 7, 2011, 6:54 PM
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Re: [Rudmin] 7mm Static Cord for Anchor [In reply to]
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yeah I normally tie webbing using a water knot, and cords/ropes with fisherman's knots...


JAB


Jul 8, 2011, 12:29 AM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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This thread is so full of bad advice that the OP probably would have been better off by just trying out this stuff for himself.


Guran


Jul 8, 2011, 5:06 AM
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Re: [tequilaboom] 7mm Static Cord for Anchor [In reply to]
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tequilaboom wrote:
yeah I normally tie webbing using a water knot, and cords/ropes with fisherman's knots...

Keep doing just that.

An EDK is fine when joining two ropes for a long rapell (considered safe enough and less prone to get stuck when you pull the rope) but for a cordelette or prussic out of cord there is no need to use anything but a fishermans.

Building safe trad anchors are mostly a question of common sense actually. Consider varying directions of pull, avoid sharp edges and single points of failure and you'll be fine as long as you dont get sloppy or over confident.


jmeizis


Jul 8, 2011, 8:42 AM
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Re: [Guran] 7mm Static Cord for Anchor [In reply to]
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Now that we're off the original subject please someone come up with actual evidence that using the knot pictured by Rudmin, when tied properly, would not work.

Tied in cord I can tell you from personal experience that it will not "walk". Not sure if you mean the knot will roll down the rope like a figure eight or the tail will creep like a water knot with cyclical loading. I've experienced neither but I still inspect my equipment when I use it. It's easier to untie if you need it for something else, faster to tie or untie, and it's plenty strong (hence the reason you all are willing to use it to join your ropes for rappel.) If it really makes you nervous you can always tie another on top of it.

Now for that actual evidence?


Rudmin


Jul 8, 2011, 9:12 AM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
Now that we're off the original subject please someone come up with actual evidence that using the knot pictured by Rudmin, when tied properly, would not work.

Tied in cord I can tell you from personal experience that it will not "walk". Not sure if you mean the knot will roll down the rope like a figure eight or the tail will creep like a water knot with cyclical loading. I've experienced neither but I still inspect my equipment when I use it. It's easier to untie if you need it for something else, faster to tie or untie, and it's plenty strong (hence the reason you all are willing to use it to join your ropes for rappel.) If it really makes you nervous you can always tie another on top of it.

Now for that actual evidence?

http://www.bwrs.org.au/...1%20main%20paper.pdf
http://www.xmission.com/...yer/testing/EDK.html

Shows strength reductions in the range of 50 to 60 percent (more than any of the other bends tested) and the knot needs huge tails to prevent it from rolling off before that happens.


(This post was edited by Rudmin on Jul 8, 2011, 9:13 AM)


jmeizis


Jul 8, 2011, 10:39 AM
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Re: [Rudmin] 7mm Static Cord for Anchor [In reply to]
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I can't find in those papers where it refers specifically to 7 mil cord.

The xmission one is hard to tell which strengths he's attributing to which cord and it still isn't testing for 7 mil and only one test for 8 mil.

Damn, you're gonna make me do physics aren't you?

So a belay anchor has to handle a factor two fall. Even if you go with the high of 60% and some standard cord (from Sterling's website) it's 7.43kn for that one strand. You shouldn't be slinging your anchors together with one strand anyways but lets say for worst case scenario you have only two anchor points and each leg, perfectly equalizes to have 7.43 kn on each strand for a total of 14.86 at the masterpoint. Who the hell is taking 14.86 kn falls? Even factor 2 falling on the anchor won't get me there (using Jay's Impact Force Calculator).

In a real world event I find it highly unlikely that the cause of anchor failure will be the knot someone tied their cordelette together with given that they have at least two good pieces in their anchor, there rigging is redundant, and they tie their knot correctly. There's too much stretch, sliding, and tightening for that to be the case. I'm bad at math though so I'm probably wrong.


Speed4TheNeed


Jul 8, 2011, 2:48 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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Just to make your head spin even more: try calculating with ropes/rigging that aren't in brand new condition and therefore have less breaking strength than rated. Good luck Wink


redlude97


Jul 8, 2011, 3:02 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
I can't find in those papers where it refers specifically to 7 mil cord.

The xmission one is hard to tell which strengths he's attributing to which cord and it still isn't testing for 7 mil and only one test for 8 mil.

Damn, you're gonna make me do physics aren't you?

So a belay anchor has to handle a factor two fall. Even if you go with the high of 60% and some standard cord (from Sterling's website) it's 7.43kn for that one strand. You shouldn't be slinging your anchors together with one strand anyways but lets say for worst case scenario you have only two anchor points and each leg, perfectly equalizes to have 7.43 kn on each strand for a total of 14.86 at the masterpoint. Who the hell is taking 14.86 kn falls? Even factor 2 falling on the anchor won't get me there (using Jay's Impact Force Calculator).

In a real world event I find it highly unlikely that the cause of anchor failure will be the knot someone tied their cordelette together with given that they have at least two good pieces in their anchor, there rigging is redundant, and they tie their knot correctly. There's too much stretch, sliding, and tightening for that to be the case. I'm bad at math though so I'm probably wrong.
Yep, totally wrong. Sterling 7mm cord has a strength rating of ~12.4kn per strand, 2=24.8kn. 60% reduction in strength = 24.8-14.9=10kn. Not exactly confidence inspiring


majid_sabet


Jul 8, 2011, 3:35 PM
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Re: [JAB] 7mm Static Cord for Anchor [In reply to]
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JAB wrote:
This thread is so full of bad advice that the OP probably would have been better off by just trying out this stuff for himself.

bunch of n00bs are either educating each other or given advice to another poor n00b. in either way, this is a recipe for future anchor disaster


rescueman


Jul 8, 2011, 3:47 PM
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Re: [jmeizis] 7mm Static Cord for Anchor [In reply to]
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jmeizis wrote:
[the flat overhand] is easier to untie if you need it for something else, faster to tie or untie, and it's plenty strong (hence the reason you all are willing to use it to join your ropes for rappel.) If it really makes you nervous you can always tie another on top of it.

Now for that actual evidence?

I've never needed my cordalettes for anything that required untying. I use 7mm nylon cord and tie the ends with a triple overhand bend (triple fisherman's), which is compact, strong, secure and stable.

To tie a much weaker and far less stable knot and then back it up with something secure makes no sense in any way.

And I never have and never would use a flat overhand to join rappel ropes. A double overhand bend is all I've ever used and I've only once got it stuck in a crack when I wasn't being careful.

You're, of course, perfectly free to use whatever makes you happy, but to recommend such a controversial knot - which has resulted in fatalities - to a rank beginner is the height of irresponsibility.


rescueman


Jul 8, 2011, 4:00 PM
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Re: [tequilaboom] 7mm Static Cord for Anchor [In reply to]
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tequilaboom wrote:
This is why I want to use the 7mm equalette to tie in to those bolts.

P.S. I have used the climbing rope itself to tie in, in the past, and that has worked well too.

If you've got reliable bolts at the belay stations, then continue as you've done - use the rope to tie in. Nothing can be more secure than that and it requires nothing more than a couple of 'biners.

Practice tying a two-loop figure-8 (forms two adjustable loops), which is great for equalizing to two bolt anchors. You reach your wrist through the terminal bight, grab the doubled bight, flip the terminal bight over the entire knot to form a girth hitch, and pull out the doubled bight to form two terminal eyes.




rescueman


Jul 8, 2011, 4:13 PM
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Re: [shoo] 7mm Static Cord for Anchor [In reply to]
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shoo wrote:
7mm static???

I don't think so. Last time I checked, the recommendation was 7mm nylon specifically because it ISN'T static. Some stretch is good.

The Cordage Institute sets the rope manufacturing standards for the US. All nylon rope will stretch under load, some more than others.

By Institute standards:

static: <6% stretch @10% of breaking strength
low-stretch: 6-10% stretch @10% of breaking strength
dynamic: >10% stretch @10% of breaking strength

A climbing rope can stretch 25% to 30% under dynamic loads.

7mm accessory cord has a tensile strength of about 2800 lbs and is considered low-stretch.

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