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Construction and pull testing of specific itmes.
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TarheelJD


Jul 21, 2011, 5:59 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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Very nice. Thanks for doing the test. I figured it would break somwhere between the knots or at the knot. Granted in real world applications the bolt spacing would be further apart but this definitely gives an accurate enough picture of what a "quad" failing looks like. I would imagine an 8m cord would have a similar failure mode with just much higher forces involved, like double -- which would exceed the strength of just about everything else in the system.

Thanks again


tugboat


Jul 21, 2011, 10:27 AM
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Re: [TarheelJD] Construction and pull testing of specific itmes. [In reply to]
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Yup....no prob. It was fun.


"Next...."?


mambembe


Jul 22, 2011, 4:28 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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I would like to see the equallete tested. The real equallete, simulating an equalization of 4 pieces whit 4 clove hitches.
I suppose the point of failure will be the hitches and at lower force than the quad.

Sorry for the broken english.


tugboat


Jul 22, 2011, 11:20 PM
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Re: [mambembe] Construction and pull testing of specific itmes. [In reply to]
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I picked up some mammut 7mm cord today. And have more of the 6mm cord.

I found some hardware to simulate a multi point station that is about two feet wide.

I would enjoy carrying out your request.


(This post was edited by tugboat on Jul 23, 2011, 12:12 AM)


ncrockclimber


Jul 24, 2011, 10:49 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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Hey tugboat. Great work! This reminds me of what the lab was like at its best, just with a better personality.

I would like to see you test a double figure 8 / bunny ears knot. Specifically, I would like to see the knot set as you would at a 2 bolt anchor, weight the knot, then cut one of the ears. I have always thought that if one of the strands was cut, the anchor would completely fail. I know that this is not a common occurrence, but I am curious if this is the case.

An example of the knot can be found here:
http://www.chockstone.org/TechTips/BunnyEars.htm


tugboat


Jul 24, 2011, 11:28 AM
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Double eight anchor test. [In reply to]
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Ok....i understand your scenario. Some specifics though; i assume using the 11mm dynamic climbing rope as the anchor. Now how much weight on the anchor? and then nick the one eight or start with a 10% cut or ?.....

If your just going to want body weight then cut....i wouldn't think the anchor will fail. But i think you want 'heavy weight' the anchor then pull to destruction.

I use to use the double eight alot when i climbed.


(This post was edited by tugboat on Jul 24, 2011, 7:43 PM)


tugboat


Jul 24, 2011, 12:04 PM
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Re: [tugboat] Double eight anchor test. [In reply to]
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Can someone send me a pic of the setup "mambembe" would be wanting. There seems to be so many variations on the theme of "true equillete" when i research it. So what would be considered the true equillete as he describes? When i climbed i mostley tied in with the rope.... i wasn't as much into building guide sling stations as i found them time consuming. And my game was light and fast multi pitch. So i am not as well versed as many of you in the varieties of anchor setups. I went to buy JL's anchor book from MEC the other day but they were sold out.


Is the attatched image what he would be considering?[/image]


(This post was edited by tugboat on Jul 24, 2011, 3:49 PM)


acorneau


Jul 24, 2011, 2:28 PM
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Re: [tugboat] Double eight anchor test. [In reply to]
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Yes, that's the original equalette.


tugboat


Jul 24, 2011, 3:51 PM
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Re: [acorneau] Double eight anchor test. [In reply to]
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thanks acorneau. I'll set it up then for his request. I think the static mammut 7mm would be a good size eh?


mambembe


Jul 24, 2011, 4:23 PM
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Re: [tugboat] Double eight anchor test. [In reply to]
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Hey Tugboat,

Thats exactaly what I was looking for. Sorry I didnīt post a picture, I donīt know how.

7mm is a good size.

Thanks


tugboat


Jul 24, 2011, 11:36 PM
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Re: [ncrockclimber] Construction and pull testing of specific itmes. [In reply to]
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Hey ncrockclimber.... I've been thinking/looking over the ' bunny ears' knot and have formed some ideas regarding possible outcomes and issues with making the test worth any real world reflection;

1st off, i believe the most important determining factor of total anchor failure would be where one of the "bunny ears" breaks. In forming the knot, the pass over loop to form the two ears, effectively makes two independent loops that would pass a pull if neither loop was cut. But when you cut one or the other loop near the hanger...the remaning loop effectively becomes a bowline around the original figure eight. The bowline is formed around double strands rather than a single strand of rope, thus increasing bite radius. Now, if the bite is not effected by the double strand radius and the break left enough "tail"...then i believe you would have a fully functioning bowline for an anchor left over. The remaning pull would eventually break at the bowline knot.

This brings us to #2) Is there a scenario (other than a cut in the rope) that would leave us with a break far enough away from the main knot?...so we have enough bowline tail?

then #3) i do believe, that the use of this anchor usaully leaves the belayer tighed in to the rope and off to one side of the belay ....the rope leading to the main knot. And the rest of the rope either is set for the 'jugger' or is belayed for the second. Here....the most likely case i would think would be a failure in the belaying and hence single strand loading of the main knot from below the 'ears'. Thus for a test should we not be pulling a single bottom strand for the rope end anchor?.

In conclusion, i think, the main test should be "what would happen if one of the ears (somehow....and unlikley) broke close to the main knot"?.....say from unequal loading of the loops? Then what could possibly happen, is that the lack of long enough bowline tails, would lead to 'pull through' (undoing) of the knot under load.

Anyone else want to chime in....am i off base on this guess? whacha think?


(This post was edited by tugboat on Jul 25, 2011, 1:15 AM)


tugboat


Jul 25, 2011, 12:33 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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some pics trying to show progression on loop break, to effective bowline, to progressive undoing of bowline:

1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)


(This post was edited by tugboat on Jul 25, 2011, 1:16 AM)


JimTitt


Jul 25, 2011, 1:43 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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One of the ears isnīt going to break since we donīt get high enough loads for that so itīs going to have to be a cut from a rock for example. This is a random effect so worst case is it cuts at the knot leaving no tail and the whole things fails.
Iīd be clove hitching into one anchor, into the other and back to myself to give two easily adjustable independent tie-ins like climbers have for generations.

Jim


ncrockclimber


Jul 25, 2011, 10:02 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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In reply to:
In conclusion, i think, the main test should be "what would happen if one of the ears (somehow....and unlikely) broke close to the main knot"?.....say from unequal loading of the loops? Then what could possibly happen, is that the lack of long enough bowline tails, would lead to 'pull through' (undoing) of the knot under load.

Tugboat, I think that is a spot-on summary of what i wast thinking about. To replicate a real-world scenario, I would first apply a 300 pound load, replicating a climber at a hanging belay and thus tightening the knot. Then I would cut one of the strands. If the know holds, start to apply more weight. I don't know if uneven loading makes any difference or not.

Again, I appreciate your contribution here and look forward to your next post.


Partner cracklover


Jul 25, 2011, 11:07 AM
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Re: [tugboat] Construction and pull testing of specific itmes. [In reply to]
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tugboat wrote:
Yup....no prob. It was fun.


"Next...."?

Hi Tugboat, you still have time to kill?

I have some fixed draws I pulled (and replaced) from a sport climb after discovering how worn they were. I'd love to see just how much they could have held.

GO


tugboat


Jul 25, 2011, 2:41 PM
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Re: [JimTitt] Construction and pull testing of specific itmes. [In reply to]
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JimTitt wrote:
One of the ears isnīt going to break since we donīt get high enough loads for that so itīs going to have to be a cut from a rock for example. This is a random effect so worst case is it cuts at the knot leaving no tail and the whole things fails.
Iīd be clove hitching into one anchor, into the other and back to myself to give two easily adjustable independent tie-ins like climbers have for generations.

Jim

Oh....for sure...i agree Jim. Its just an analysis in refernece to the previous members pulltest request. More of a brain teaser than anything else. I like all the requests regardless of how unlikley they might be in real world scenario.Smile


tugboat


Jul 25, 2011, 2:42 PM
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Re: [cracklover] Construction and pull testing of specific itmes. [In reply to]
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cracklover wrote:
tugboat wrote:
Yup....no prob. It was fun.


"Next...."?

Hi Tugboat, you still have time to kill?

I have some fixed draws I pulled (and replaced) from a sport climb after discovering how worn they were. I'd love to see just how much they could have held.

GO

yup....no prob... i can bust em.

ill msg you my mailing address if you want them checked.


(This post was edited by tugboat on Jul 25, 2011, 10:36 PM)


cellige


Jul 25, 2011, 9:17 PM
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Re: [tugboat] Double eight anchor test. [In reply to]
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Hey tugboat,
Thanks for the free testing and especially for the results here. Its nice to see climbers give back, even if they haven't climbed lately !

I was going to suggest if you end up testing the equalette, I would love to see the "dorkalette" as seen in an adjacent thread in the Lab tested in the same manner. Especially the cases when a point of pro fails.

Also a strength test I would love to see out of pure geekdom would be the final tucked eight tie in knot that is so common today amongst the sport climbers. Does the extra diameter of that tail provide less strain on the first bend of the knot? Lets find out :D

Thanks again and let me know if you need cord or biners etc.


tugboat


Jul 25, 2011, 10:30 PM
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Re: [cellige] Double eight anchor test. [In reply to]
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cellige wrote:
Hey tugboat,
Thanks for the free testing and especially for the results here. Its nice to see climbers give back, even if they haven't climbed lately !

I was going to suggest if you end up testing the equalette, I would love to see the "dorkalette" as seen in an adjacent thread in the Lab tested in the same manner. Especially the cases when a point of pro fails.

Also a strength test I would love to see out of pure geekdom would be the final tucked eight tie in knot that is so common today amongst the sport climbers. Does the extra diameter of that tail provide less strain on the first bend of the knot? Lets find out :D

Thanks again and let me know if you need cord or biners etc.

thanks for the kind comments,...your requests are noted. I'll put them on the listWink


tugboat


Jul 25, 2011, 11:02 PM
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Re: [cellige] Double eight anchor test. [In reply to]
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Just so people looking for testing know... I do have time to spare these days for testing,... however my poor old dog, Tugboat, is living day by day with cancer. Generally, with medication, and lots of treats and love he has mostly good days still. However, as you could appreciate, since he is my only family and best friend, he comes first. Sometimes, out of the blue, i get tied up for a few days, full time, taking care of his needs. So tests might get put on hold all of a sudden for a couple days. Hope you all understand. But, be reassured, all requests will get carried out..... cause when it comes to 'bustin' stuff, i just can't resistWink




Partner cracklover


Jul 26, 2011, 7:43 AM
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Poor Tugboat! Good luck to you both, and of course we'll give you plenty of slack.

Cheers,

GO


ncrockclimber


Jul 26, 2011, 9:34 AM
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Re: [tugboat] Double eight anchor test. [In reply to]
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I think everyone will understand that Tugboat comes first. Best wishes to the both of you!


tugboat


Jul 27, 2011, 10:18 PM
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Re: [cellige] Double eight anchor test. [In reply to]
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Got your pic cellige. Very interesting... never saw that back when i climbed.

I dont see the tuck back doing anything in terms of helping the strength becasue of any radius increase.

My main concern with knot would be; are the people using this leaving enough tail before they tuck back? Otherwise they might be thinking that the loading of the knot will cinch down the short tail to stop 'initial' knot load / tail slide. I personallly wouldn't want to put money on that idea. But thats what some testing would show. maybe check differnet tail tuck back lengths to see if short tail slip is an issue.

But if they are leaving a nice long tail and then tucking back, than i don't see any probs with this knot. They gain the advantage of cleaning up the rope/ knot so they dont have a fisherman's tie-off to get in the way for clipping draws.

Will test it out.




(This post was edited by tugboat on Jul 27, 2011, 10:23 PM)


tugboat


Jul 27, 2011, 10:43 PM
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Re: [tugboat] Double eight anchor test. [In reply to]
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Actually... playing with the knot, i can't imagine people would be leaving little tails to tuck back. It seems intutivley dangerous and not that easy to do. You actually have to work at producing a tiny length to tuck back. Its much easier to tie your knot with at least 4 inches and then tuck it back.....without much work. I hope thats what people are doing.


JimTitt


Jul 28, 2011, 12:23 AM
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Re: [tugboat] Double eight anchor test. [In reply to]
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If you want to horrify yourself tie the ends of two ropes together (like for rapping) and tuck BOTH ends back exactly as in your picture. Then pull the two ropes apart, you donīt need to put this one on the tester!
And yes, it was fatal.

Jim

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