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ctardi
Jun 12, 2006, 11:32 PM
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http://www.weldingwiki.com/images/anchor.jpg
So, let's pretend that both points are bomber. Got a figure eight on one anchor, clove hitch on the other, and a double re traced figure eight for the master point, with two opposite and opposing biners. What do you think of that setup? It is totally redundant, and non extending. Simple, safe. (Done with static rope). I think it's good for extending...
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estwing
Jun 12, 2006, 11:37 PM
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same thing as a cordalette, only more knots, less rope
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ctardi
Jun 12, 2006, 11:41 PM
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Well...I'd do my cordlettes differently. :)
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ctardi
Jun 12, 2006, 11:48 PM
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Strength of my cordletted: 1500kg
Strength of that static rope: 3628kg
I'll take the rope...
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euroford
Jun 12, 2006, 11:53 PM
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i do it like that sometimes, but don't bring along a static rope, use your climbing rope. you can also incorporate a third or more points. every climber should know how to quickly build bomber anchors with the rope.
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ctardi
Jun 13, 2006, 12:03 AM
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Yea, I agree. But i'm still learning(isn't everyone?), which means a lot of toprope setups. I beleive it would be hard to toprope anything tall, while using the rope as an anchor.
This is also good for going over an edge, as static rope tends to saw it's self less. I do keep two peices of tubeular webbing, with the ends open, to put over the rope to pad it.
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billcoe_
Jun 13, 2006, 1:51 AM
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Pound some bolts into the wall. Make it solid. :lol:
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ctardi
Jun 13, 2006, 2:10 AM
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My wall is too exposed to bolt on lead, and there's no trail to the top. ;)
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shorty
Jun 13, 2006, 2:06 PM
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ctardi,
That's a bomber setup -- straight out of AMGA's recommendations for top ropes.
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snothead
Jun 13, 2006, 2:18 PM
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What do people think about the clove hitch not being backed-up? I've heard some say that a clove within a closed loop is fine, but in the end of a piece of rope it should be backed up. What's the consensus? overkill? not necessary? necessary?
Also, your eight on a bight on the right isn't well dressed - and I know i'm being picky but you asked for feedback.
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cracklover
Jun 13, 2006, 2:28 PM
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In reply to: http://www.weldingwiki.com/images/anchor.jpg So, let's pretend that both points are bomber. Got a figure eight on one anchor, clove hitch on the other, and a double re traced figure eight for the master point, with two opposite and opposing biners. What do you think of that setup? It is totally redundant, and non extending. Simple, safe. (Done with static rope). I think it's good for extending...
It's all fine, but what's with the double retraced fig-8? A fig-8 on a bight is the right knot for this application, IMO.
Also, I'd use either three non-lockers or a locker and a non-locker at the power point. You can't monitor it - it's out of sight. So better be safe on that one.
GO
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ctardi
Jun 13, 2006, 2:28 PM
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Thanks Shorty, got it from the ACMG, but I beleive the standards are fairly similar.
Snothead, I didn't dress that knot very well, thanks for pointing that out.
The clove hitch is backed up, by the other anchor point. At least that's how I see it. Can't use a clove hitch for any single life line, but it's great to be able to equalize an anchor with it.
I guess it would be easy enough to back it up, but I don't see it as necisarry.
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microbarn
Jun 13, 2006, 2:32 PM
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why retrace the figure 8? Why not just a figure 8 on a bite?
easier to handle, faster, and less bulk
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ctardi
Jun 13, 2006, 2:33 PM
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Figure eight on a bite leaves me clipped into one strand of rope, retraced it leaves me with two, more redundant.
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microbarn
Jun 13, 2006, 2:36 PM
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with that logic, you should use a retraced figure 8 into each of the pieces then
to each their own I guess
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cracklover
Jun 13, 2006, 2:44 PM
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In reply to: What do people think about the clove hitch not being backed-up? I've heard some say that a clove within a closed loop is fine, but in the end of a piece of rope it should be backed up. What's the consensus? overkill? not necessary? necessary?
Please read this paper if you're interested in knot strengths. In particular, it's the best tests I've seen on clove hitch holding strength.
Here's the short version: In static rope, the clove can slip at forces as low as 4.5 kN, though most of the time it was higher. In dynamic rope, the clove never slipped, and broke at the same force as the overhand knot.
So - Ctardi, you're unlikely to see forces higher than 4.5kN on one strand of a well equalized anchor like the one you've built, but my recommendation would be to back up that clove hitch in the static rope if you have the time. Probably just a simple overhand knot set snug against the clove would be enough to keep it from slipping.
GO
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ctardi
Jun 13, 2006, 2:52 PM
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ctardi
Jun 13, 2006, 3:24 PM
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In reply to: with that logic, you should use a retraced figure 8 into each of the pieces then to each their own I guess
How I see it, the peices are backed up, as there is another peice should one fail. If one strand of the master point fails, it'll be okay. If any one part of this anchor fails, it will be fine. Including the master point.
cracklover - I guess i'll throw in an overhand backup, doens't take any time...
Why not backup the master point? ACMG says to do it that way, it only takes me about 4 more feet of rope, maybe 20 more seconds than tying a regular eight on a bite.
That anchor setup, I think it's good for when the anchors arn't near the edge. That's a 22meter work rope, could probably get 8 meters of extension.
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microbarn
Jun 13, 2006, 3:35 PM
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Right, but we tie in with a single strand figure 8 or bowline. There is no redundancy there, and the tie in gets to be in many more unpredictable situations. The anchor is going to be where the anchor is. IF the anchor is rubbing that bad, you should move it. If it isn't rubbing, then it won't rub in the future, and there is still no reason to make that portion redundant.
It takes 20 seconds more to tie and another 20 to untie. If the lengths are off, it can take longer.
Like I said, to each their own. Your method will give you redundancy, but I am not sure how necessary it is. Hopefully my reasoning is sufficiently explained that you understand it.
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cracklover
Jun 13, 2006, 3:54 PM
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In reply to: In reply to: with that logic, you should use a retraced figure 8 into each of the pieces then to each their own I guess How I see it, the peices are backed up, as there is another peice should one fail. If one strand of the master point fails, it'll be okay. If any one part of this anchor fails, it will be fine. Including the master point.
Right on.
In reply to: Why not backup the master point? ACMG says to do it that way, it only takes me about 4 more feet of rope, maybe 20 more seconds than tying a regular eight on a bite.
... this is okay reasoning, as far as it goes. It just doesn't go very far. As soon as you're in a situation where you have to make choices, you can no longer rely on "ACMG says to do it like this". But from the first paragraph, it does seem like you understand what's going on behind the rules, so I trust you'll mostly make the right choices when you have to improvise.
In reply to: That anchor setup, I think it's good for when the anchors arn't near the edge. That's a 22meter work rope, could probably get 8 meters of extension.
Okay, so what do you use to get over the edge? I mean, if you're using up all this lovely static rope with all these fancy knots, and then extending the whole setup with a single loop of mil spec webbing - well doesn't that seem a little silly to you, if the rope could be capable of running over the edge? Keep in mind that if you've got a second line running from the power-point of this anchor, (a single point) over the lip, to another power point where the rope runs through, you're going to wind up dragging that second line across the lip of the cliff every time the TRer falls, unless he's at a direct plumb-line from the original anchor. This sawing of the second line is not good, and you won't be able to see what's happening above the lip of the cliff at all. And I don't think I'd like the idea of dragging those two non-locking biners around above the cliff where you can't see 'em. Oh, unless the ACMG says it's okay. :P
GO
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ctardi
Jun 13, 2006, 3:56 PM
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Yup, I get what you are saying, but it's like anything else, million ways to do it, do what you are most comfortable with.
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radistrad
Jun 13, 2006, 4:10 PM
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I would skip that clove hitch and replace it with a figure 8 on a bight.
I would also prefer to have 3 pieces of pro if your not clipping into bolts.
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ctardi
Jun 13, 2006, 4:30 PM
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In reply to: In reply to: Yup, I get what you are saying, but it's like anything else, million ways to do it, do what you are most comfortable with. Why did you post this thread? I strongly suspect it was just an exercise in mental masturbation for you. But if you're honestly looking for opinions, here's mine in brief: You're making a concrete foundation that's 10% thicker than it needs to be, and then potentially skimping on the concrete between the bricks you lay on top of the foundation because you don't have enough left. GO
Just interested in the opinions out there, have already made a couple of changes to what I will do. I'm still not seeing any reason not to do the figure eight at the master point that way, unless the extra rope used puts the anchor in a bad spot.
ACMG has good guidelines if I can do something how they suggest, why not do it?
Microbarn - This rope would be going over the edge, as I said earlier, it gets threaded through a peice of webbing. The webbing is not strength, it's protection.
radistrad - I didn't really trust the clove hitch the first few times, but it is much easier to equalize, and with the overhand backup, I don't see it coming undone under normal circumdance.
I'd just use this on either bolts, or bomber trees, or one of each. I'm not quite up to 3 point anchor building, but i'm learning. :)
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