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TR Anchor
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matasw


Mar 26, 2012, 7:25 PM
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TR Anchor
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A little apprehensive about posting this after seeing other dudes get flamed. However i'm a beginner and would like feedback on the system. I noticed the twists on the girth hitch and fixed them before using. The only thing I didn't like is that the anchor point was a bit far from the actual edge of the cliff. Had an old rug there but couldn't get it to stay in place. These were the longest piece of webbing I had at 15ft, guess I need some longer ones to make it over the final edge of the cliff. The trees were evenly spaced over the drop so their was no issue with equalization. I imagine this will be hard to repeat on other cliffs.

https://plus.google.com/.../5724396533958953281


(This post was edited by matasw on Mar 27, 2012, 5:40 AM)


tower_climber


Mar 26, 2012, 9:09 PM
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Re: [matasw] TR Anchor [In reply to]
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https://plus.google.com/.../5724396533958953281

Clicky

Three problems right off the bat:

1) Your anchor carabiners are loaded triaxially (sp?). The two sections of webbing and the climbing rope pull the carabiner in three different directions, which can significantly reduce the strength.

2) Girth hitching the slings to the trees is frowned upon, as it can reduce the strength of the webbing a good deal.

3) Minor: Your carabiners should be oriented with the gates pointed down instead of up.

Solution: Increase your webbing supply or invest in a 100' static rope. Two independent slings should be tied together into one master point to avoid triaxial loading.


bearbreeder


Mar 26, 2012, 9:47 PM
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Re: [tower_climber] TR Anchor [In reply to]
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1. IMO with doubled biners, for a TR setup aint best practice with "triaxial" loading, but i aint freeking out

2. 20 kn webbing reduced to ~12 kn each, and doubled ... more than enough for a TR setup

3. it is best practice to have the threads pointing downwards, however i aint going crazy ... in TRing biners will sometimes flip, which is why you use 2 opposed ...

bottom line ... youll live and id wouldnt go "die die die were all gonna dieeee" if i saw this at the top ... i wouldnt set it up that way personally, but for TRing its not "unsafe"


for best practices take a course, learn from someone who knows what they are doing, or buy a good anchor book ...

Wink


bill413


Mar 27, 2012, 6:05 AM
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Re: [bearbreeder] TR Anchor [In reply to]
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1. I'd climb on it.

You probably had more friction than you would have liked from the rope going over the rocks. Getting the master point out over the edge would have helped that, but you already know that and worked with what you had. OK.

I'm fine with the girth hitch on the trees - quick to set up and dismantle, secure enough. However, you can reduce the effect of the loss of strength by rotating the whole hitch around the tree so that the strands exiting the hitch are less bent back. (E.G. on the left hand tree, rotating the hitch to the right would do this). It's a minor point.

I agree the triaxial loading isn't the best thing for the biner. For TR loads this isn't too bad. To avoid it, you could have tied both slings together in an overhand or figure eight knot and then clipped the combined loop.

I also agree that it would be better to have the biners oriented such that gravity helped keep the screw gates locked, especially on a rig like this where they're going to be bouncing up & down with loading on the rope. That said, many people would forget to do that. Having two biners, opposite & opposed (which it looks like yours are) makes it secure even without the lock.

What I like about this setup is that it is safe, simple, and clean. It could be improved, but it's a solid start.


matasw


Mar 27, 2012, 6:05 AM
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Re: [bearbreeder] TR Anchor [In reply to]
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Thanks guys! I hadn't considered the triaxial loading, although it makes sense and I've heard of it before. In this particular case i'd rather be much closer to the cliff. Would it be ill advised to just use two huge pieces of webbing (30-40ft), make 2 giant slings, then tie them together in a figure 8 so I have a single master point?

I'll flip the carabiners in the future.

I feel like as long as the belayer keeps minimal slack in the line the forces from TR are very very minimal. I know the girth hitch isn't ideal but it let me get most distance on the webbing.


Partner cracklover


Mar 27, 2012, 8:31 AM
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Re: [tower_climber] TR Anchor [In reply to]
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tower_climber wrote:
https://plus.google.com/.../5724396533958953281

Clicky

Three problems right off the bat:

1) Your anchor carabiners are loaded triaxially (sp?). The two sections of webbing and the climbing rope pull the carabiner in three different directions, which can significantly reduce the strength.

Doesn't matter.

In reply to:
2) Girth hitching the slings to the trees is frowned upon, as it can reduce the strength of the webbing a good deal.

Doesn't matter.

In reply to:
3) Minor: Your carabiners should be oriented with the gates pointed down instead of up.

Doesn't matter.

The reason your carpet wouldn't stay put is that it's not there to pad the climbing rope (which moves a lot) - it's there to pad the anchor material, which moves a little. Your anchor really was not good. If the top of the cliff had any sharp edges, it could have damaged your rope.

You just need more webbing. @ 30 cents a foot, 75' of webbing will only cost you $25, and should be sufficient for most TR anchors. This is not uncommon. I bought 90' of webbing when I started TRing outside.

The simplest method is as follows:

1 - Tie enough webbing together (using water knots) to get from one tree to the edge and back to the other tree, with several feet to spare.

2 - Tie a knot in a small bight on one end of the webbing, and use this to girth hitch the first tree.

3 - Run the webbing to the edge and back to the second tree. Tie your knot of choice here, or sling the tree and clip the webbing to the sling.

4 - Tie a fig-8 on a bight at the power-point, clip your biners, and double-check everything.

Pad the edge as needed.



GO


Partner cracklover


Mar 27, 2012, 8:45 AM
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Re: [matasw] TR Anchor [In reply to]
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matasw wrote:
Thanks guys! I hadn't considered the triaxial loading, although it makes sense and I've heard of it before.

It's good to be aware of it, but the triaxial loading in your anchor is not severe, and your two locking biners are perfectly capable of handling those loads with no issues.

In reply to:
In this particular case i'd rather be much closer to the cliff.

Not sure what you mean by that. If you mean your power-point should always be hanging over the lip of the cliff, then yes.

In reply to:
Would it be ill advised to just use two huge pieces of webbing (30-40ft), make 2 giant slings, then tie them together in a figure 8 so I have a single master point?

If you want you can make giant slings, but it's not necessary.

In reply to:
I'll flip the carabiners in the future.

This is completely irrelevant. Your biners are oriented fine. The only two concerns to have about biner orientation are:
1 - is the spine of one biner moving in a way that might unscrew the gate of the opposite biner.
2 - if part of your anchor needs to move freely through the anchor biners, it should go through the wide end of the biners, since there's less friction and less binding.

But again, neither of these are relevant in your anchor.

In reply to:
I feel like as long as the belayer keeps minimal slack in the line the forces from TR are very very minimal.

The forces are plenty high enough to mangle your rope running over the top of the cliff, I assure you. That's the only thing that's seriously wrong with your anchor. But it is serious. All it takes is one really rough spot in the cliff top, and (best case) you're buying a new rope after a single toprope session. Much more expensive proposition than just buying some webbing.

In reply to:
I know the girth hitch isn't ideal but it let me get most distance on the webbing.

Actually, you shorten the distance you can get out of your webbing considerably when you make loops out of it. See my method (above) to get more usable length out of your webbing.

Cheers,

GO


Partner cracklover


Mar 27, 2012, 9:02 AM
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Re: [cracklover] TR Anchor [In reply to]
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I'd like to clarify one point in my post above...

cracklover wrote:
matasw wrote:
Thanks guys! I hadn't considered the triaxial loading, although it makes sense and I've heard of it before.

It's good to be aware of it, but the triaxial loading in your anchor is not severe, and your two locking biners are perfectly capable of handling those loads with no issues.

What I mean when I say your triaxial loading is "not severe" is not that triaxial loading is not a serious issue. Rather it's that the degree of triaxial loading on the carabiners you have is small.



In classic triaxial loading, the blue sling and the red clove hitch hold the biner in place, while the yellow striped cord pulls the nose side of the basket open. The biner will fail at much lower loads from a force on the nose end of the basket.



In your anchor, the webbing is all pulling along the spine side and the middle of the basket. So it would fail at a load reasonably close to its rated load.

Hope that helps.

GO


matasw


Mar 27, 2012, 9:06 AM
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Re: [cracklover] TR Anchor [In reply to]
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Thanks for all the advice! Is it a bad idea to join a bunch of webbing together with water knots or is it perfectly okay to join 2,3,4 pieces of webbing together with water knots to get to the edge?

I don't see where the girth hitch would go on that diagram. Assuming you just had one very long piece of webbing wouldn't you just have one water knot at each tree? I do see how it would use half as much webbing or so compared to the girth hitch.


matasw


Mar 27, 2012, 9:52 AM
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Re: [matasw] TR Anchor [In reply to]
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Nevermind, I understand why the water knot wont work on the 2nd tree without another piece of webbing.

When you put the anchor point past the edge of the cliff aren't you then just having the web rub against the rock? But i guess since its fixed the rug will stay put though.


tower_climber


Mar 27, 2012, 10:05 AM
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Re: [matasw] TR Anchor [In reply to]
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cracklover makes a fair point about the triaxial loading not being severe enough to worry about. I would counter that developing good habits is more important than judging this single situation (especially for a beginner).

I'd climb on that anchor. My points were more geared to building the ideal anchor under the circumstances.


Partner cracklover


Mar 27, 2012, 12:36 PM
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Re: [matasw] TR Anchor [In reply to]
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matasw wrote:
Thanks for all the advice! Is it a bad idea to join a bunch of webbing together with water knots or is it perfectly okay to join 2,3,4 pieces of webbing together with water knots to get to the edge?

I don't see why it would be a problem. Aside from the fact that with all those ends, you could get confused.

In reply to:
I don't see where the girth hitch would go on that diagram. Assuming you just had one very long piece of webbing wouldn't you just have one water knot at each tree? I do see how it would use half as much webbing or so compared to the girth hitch.

Tree 1:



Tree 2:



Hope that helps.

GO


(This post was edited by cracklover on Mar 27, 2012, 1:03 PM)


Partner cracklover


Mar 27, 2012, 12:38 PM
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Re: [matasw] TR Anchor [In reply to]
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matasw wrote:
When you put the anchor point past the edge of the cliff aren't you then just having the web rub against the rock? But i guess since its fixed the rug will stay put though.

Exactly. And webbing is cheap. If it starts to look the worse for wear, you cut off a chunk and throw it away.

GO


Partner cracklover


Mar 27, 2012, 1:00 PM
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Re: [tower_climber] TR Anchor [In reply to]
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tower_climber wrote:
cracklover makes a fair point about the triaxial loading not being severe enough to worry about. I would counter that developing good habits is more important than judging this single situation (especially for a beginner).

I agree that it's worth mentioning tri-axial loading even though it's not a deal-breaker for this anchor. Certainly it's worth mentioning that the setup the OP uses has the potential for severe tri-axial loading, so better setups are worth discussing.

But for the rest I don't agree. I think that the ability to differentiate between a potential issue and an actual deal breaker on the spot in your own anchors is absoltely the most important skill. Far more important than "good habits".

In reply to:
I'd climb on that anchor. My points were more geared to building the ideal anchor under the circumstances.

That's puzzling to me. On the one hand, you say the most important thing is following best practices. But then you go right ahead and say the anchor is good enough, despite the fact that the anchor does not extend over the edge.

Personally, I cannot say if I'd climb on that anchor or not - I would have to look at the top of the cliff to see if it looked like a rope-shredder.

GO


acorneau


Mar 27, 2012, 2:02 PM
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I'm surprised no one has mentioned yet that he could have tied each piece of webbing on/around the tree instead of pre-tying it and then girth hitching them.

That would have added a good 2 feet to the length of each sling and as a side benefit would have doubled the strength of the slings instead reducing it in half.


ablanchard17


Mar 28, 2012, 5:41 PM
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Re: [bill413] TR Anchor [In reply to]
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as others have pointed out. there are a couple "flaws" but in all reality if your just toproping and your doing everything else right you will be fine.

I would TR on that.


curt


Mar 28, 2012, 6:09 PM
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Re: [bill413] TR Anchor [In reply to]
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bill413 wrote:
1. I'd climb on it.

I would too.

Curt


matasw


Apr 11, 2012, 4:41 PM
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On Tree #1 in the diagram above... what is the preferred knot to make the bight. I imagine a figure 8 rethread or overhand since their more easily visually inspected on webbing?

Same question as to... If you were not using a girth hitch on the the tree and just wanted to tie a loop.


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