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majid_sabet
Mar 5, 2008, 9:22 AM
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Ok guys, test part V
you got two anchors, both are constructed from the exact same protections. Two cams on each side with one nut in the center.
#1 anchor has the nut directly attached to a biner where your TR goes. A 7 mm dynamic cord is linking both cams to power point via fig 8.
#2 anchor is just like #1 except the nut has been placed little higher and the same 7mm dynamic cord been used to attached all protection to master point with a fig 8 knot.
Keep in mind that all tensions were perfectly equalized in both #1 and #2 anchors before the fig 8 was placed in power point.
Question;
1-If sh*t his the fan and your partner takes a nice fall, which anchor may have a better chance to survive ( if any) ?
2- explain how you came up with your answer
note; please no need to explain that you normally build your anchor with webbing or this type of cord vs. that model sling blah blah blah. This is all you had to build your anchor and what you see here is what you got.
[URL=http://imageshack.us]
[URL=http://imageshack.us]
(This post was edited by majid_sabet on Mar 5, 2008, 9:25 AM)
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sbaclimber
Mar 5, 2008, 9:50 AM
Post #2 of 15
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As I am not a beginner, I will not ruin it for others, but......
Where are you getting 7mm dynamic cord from? I thought most 7mm and below would be static!?
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dbrayack
Mar 5, 2008, 11:26 AM
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My tent came with some.
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Mike805
Mar 5, 2008, 4:47 PM
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So is this a TR (Top Rope) test or a TR (TRad) test? I don't see why a beginner should have to know how to set up cams and nuts for a top rope but whatever...
Once again the picture is kind of confusing and the question kind of vague but I guess I'll give it a try.
#1 anchor is statically equalized between the cams with a nut attached directly to the power point, as I see it. Once the dynamic rope stretches it's going to put the majority of the load on the piece that isn't connected via the dynamic rope, the nut. This is a very poor anchor in my opinion.
#2 anchor is also statically equalized via a cordelette with a figure eight power point (I think, correct me if I'm wrong). This is a better set up but I still wouldn't run it. The load distribution is entirely dependent on the length of the ears and since the anchor cams and nuts are not on the same plane it means that it will never be optimally equalized. Using an equalette or putting in a sliding x somewhere to make it more dynamically equalized would be the better way to tie off from 3 points.
So to answer your question, between those 2 anchors I would choose #2, although in real life I wouldn't use either.
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majid_sabet
Mar 5, 2008, 6:12 PM
Post #5 of 15
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Mike805 wrote: So is this a TR (Top Rope) test or a TR (TRad) test? I don't see why a beginner should have to know how to set up cams and nuts for a top rope but whatever... Once again the picture is kind of confusing and the question kind of vague but I guess I'll give it a try. #1 anchor is statically equalized between the cams with a nut attached directly to the power point, as I see it. Once the dynamic rope stretches it's going to put the majority of the load on the piece that isn't connected via the dynamic rope, the nut. This is a very poor anchor in my opinion. #2 anchor is also statically equalized via a cordelette with a figure eight power point (I think, correct me if I'm wrong). This is a better set up but I still wouldn't run it. The load distribution is entirely dependent on the length of the ears and since the anchor cams and nuts are not on the same plane it means that it will never be optimally equalized. Using an equalette or putting in a sliding x somewhere to make it more dynamically equalized would be the better way to tie off from 3 points. So to answer your question, between those 2 anchors I would choose #2, although in real life I wouldn't use either.
So you think by using an equalette or putting in a sliding x, the #2 anchor becomes superior to what you see right now ?
Is there anyone else agree or disagree with Mike805 statement ?
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shockabuku
Mar 5, 2008, 6:21 PM
Post #7 of 15
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majid_sabet wrote: ...where your TR goes. 1-If sh*t his the fan and your partner takes a nice fall, which anchor may have a better chance to survive ( if any) ?
WTF is a nice fall on TR?
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majid_sabet
Mar 5, 2008, 8:51 PM
Post #9 of 15
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shockabuku wrote: majid_sabet wrote: ...where your TR goes. 1-If sh*t his the fan and your partner takes a nice fall, which anchor may have a better chance to survive ( if any) ? WTF is a nice fall on TR?
I took a 15 footer once and almost decked cause my belayer was picking up girls in the local crag and did not pay attention in taking slack.
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shockabuku
Mar 5, 2008, 9:00 PM
Post #10 of 15
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That almost sucks (as in almost decked); but the real issue here is: were they hot?
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j_ung
Mar 5, 2008, 9:18 PM
Post #11 of 15
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majid_sabet wrote: shockabuku wrote: majid_sabet wrote: ...where your TR goes. 1-If sh*t his the fan and your partner takes a nice fall, which anchor may have a better chance to survive ( if any) ? WTF is a nice fall on TR? I took a 15 footer once and almost decked cause my belayer was picking up girls in the local crag and did not pay attention in taking slack.
Perhaps you should likewise begin paying attention to girls.
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reno
Mar 5, 2008, 9:32 PM
Post #12 of 15
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j_ung wrote: majid_sabet wrote: shockabuku wrote: majid_sabet wrote: ...where your TR goes. 1-If sh*t his the fan and your partner takes a nice fall, which anchor may have a better chance to survive ( if any) ? WTF is a nice fall on TR? I took a 15 footer once and almost decked cause my belayer was picking up girls in the local crag and did not pay attention in taking slack. Perhaps you should likewise begin paying attention to girls.
Apparently he was, rather than paying attention to his rope system.
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Mike805
Mar 6, 2008, 7:25 AM
Post #13 of 15
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majid_sabet wrote: So you think by using an equalette or putting in a sliding x, the #2 anchor becomes superior to what you see right now ? Is there anyone else agree or disagree with Mike805 statement ?
Do I think it would make this particular system better..?... Yes. Would it make it an atomic bomb proof anchor...? ....no.
Is this a top rope test or a trad test? When do I find out my test score?
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jamincan
Mar 6, 2008, 2:47 PM
Post #14 of 15
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majid_sabet wrote: Mike805 wrote: So is this a TR (Top Rope) test or a TR (TRad) test? I don't see why a beginner should have to know how to set up cams and nuts for a top rope but whatever... Once again the picture is kind of confusing and the question kind of vague but I guess I'll give it a try. #1 anchor is statically equalized between the cams with a nut attached directly to the power point, as I see it. Once the dynamic rope stretches it's going to put the majority of the load on the piece that isn't connected via the dynamic rope, the nut. This is a very poor anchor in my opinion. #2 anchor is also statically equalized via a cordelette with a figure eight power point (I think, correct me if I'm wrong). This is a better set up but I still wouldn't run it. The load distribution is entirely dependent on the length of the ears and since the anchor cams and nuts are not on the same plane it means that it will never be optimally equalized. Using an equalette or putting in a sliding x somewhere to make it more dynamically equalized would be the better way to tie off from 3 points. So to answer your question, between those 2 anchors I would choose #2, although in real life I wouldn't use either. So you think by using an equalette or putting in a sliding x, the #2 anchor becomes superior to what you see right now ? Is there anyone else agree or disagree with Mike805 statement ?
I'm not familiar with the equalette, but the main problem with using a sliding x would be extension if one anchor were to break. Of course, that could easily be limited by adding knots to the sliding x to limit the extension.
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fattsmann
Mar 11, 2008, 3:15 PM
Post #15 of 15
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First post on this forum, so first a big "hello" and thanks to the community for the wealth of information on this forum.
My take on this problem:
First, what are the failure strengths of the objects:
Biners: ~20kN
Dynamic 7mm rope in cordelette formation: ~20kN based on 7mm Sterling Rope in Moyer, et al. 2000 "Comparative Testing of High Strength Cord" with some kind of dynamic stretch... so there is some force dissipation.
Nut: ~10-13kN based on Vogwell, et al. 2006 "The safety of rock climbing protection devices under falling loads"
Cam: ~10-13kN as well.
Top rope max impact force? Say 10kN?
In a 3 point anchoring system, the middle anchor (in these cases, the nut in both examples) feels approximately 50% of the load felt on the system (Beverly, et al. "Multi-point pre-equalized anchoring systems").
So say we have a horrible fall, the top rope will absorb some of the forces and transmit a max impact force of 10 kN x 2 = 20kN to the central biner in the anchoring system. In anchor #1, the middle nut will feel 10kN directly on the protection piece, whereas the cams will feel less due to the placement and dynamic stretching of the 7mm cord. Nut may fail.
In the same situation, anchor#2 should transmit less force to the nut due to the dynamic cord stretch and should survive better than in anchor #1.
So my pick is anchor setup #2, all pieces with dynamic cord.
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