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Chockstone Forum - Gear Lust / Lost & Found

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 Page 1 of 3. Messages 1 to 20 | 21 to 40 | 41 to 44
Author
Self equalising anchor
Chipbutty
26/07/2008
6:37:52 PM
I've just been climbing with a mate and noticed he was using this method, I asked him about it and told him the problems that I saw with it. I personally dont use it. He said it had been shown to him by a very famous climber.

He still likes it and will continue to use it and was not convinced by the problems that I pointed out.

Any thoughts?
Paul
26/07/2008
7:19:36 PM
On 26/07/2008 tobyholyhead wrote:
>I've just been climbing with a mate and noticed he was using this method,
>I asked him about it and told him the problems that I saw with it. I personally
>dont use it. He said it had been shown to him by a very famous climber.
>
>He still likes it and will continue to use it and was not convinced by
>the problems that I pointed out.
>
>Any thoughts?

is there a picutre or diagram to go with your post?

IdratherbeclimbingM9
26/07/2008
8:14:55 PM
I agree with Paul regarding having a picture or description of setup, as there are a few variations on the theme of self equalising anchors, and some versions are better/safer than others.
In general the type that has limited extension if one part of the anchor fails are safer, because they don't shock load the remaining anchor parts as much.

The individual components of any anchor are key to safety integrity. If all aspects are bomber then a partially failed equalised anchor can still be safe enough for most loads and loading directions. If however the anchor is equalised because individual pro pieces are less than ideal or marginal, then excessive loading in an unintended direction, or shock loading through partial failure, could prove catastrophic.

... you probably know all this due to raising your concerns with your climbing partner?

Btw; many famous climbers have died climbing. Being famous does not necessarily mean their advice to others is always 'safe' imo, and the same goes for internet advice!
Chipbutty
27/07/2008
8:28:23 AM
sorry no pics, it's the type where a loop or twist is put in one length/side of the sling, the american death triangle type so if the sling fails or is cut the whole lot unvarels or if one anchor fails the other is shock loaded.

rolsen1
27/07/2008
1:51:55 PM
Been discussed before, worth checking out and trying for yourself.

Could your mate answer your concerns? Did he have any concerns about the way you construct your anchors, do they suffer from the same/similar issues? Have a read of the rc thread (very long) and see if you've changed your mind

http://www.chockstone.org/Forum/Forum.asp?Action=Display&ForumID=6&MessageID=3062&Replies=67

foreverabumbly
27/07/2008
2:06:52 PM
Its called a sliding X. I personally use it but not on its own, and with other pieces to minimise any extension, or when used with double bolts etc. you can put limiter knots in it to stop if unravelling if cut through.

It has been suggested that shock loading is not the evil it is made up to be, while the equalisation properties of other methods like cordelettes arnt as great as people think. In fact, in American is seems that Cordellettes have been seen as unfit entirely yet in Australia it still seems to be the most often used, and the one that is taught in all the national Instructor courses. (I still use it as well)
Sliding X's are not dangerous if used correctly and in the right situation - just like every other anchor setup.

John Long goes through many different and new types of anchors in the new edition of his anchors book which is a very good and insightful book. I recommend everyone read it as it also includes the latest tests done on anchor systems, tests which had some interesting results.

dave h.
27/07/2008
5:43:17 PM
Foreverabumbly - could you give a short summary of the "interesting test results"?

Pat
27/07/2008
6:01:32 PM
I would like to know details of how cordelette equalisation properties are not as good as suggested. I
can't think of any other better quicker way of building an equalised anchor that is as easy. If there is one,
I would like to learn it.
gfdonc
27/07/2008
6:20:10 PM
I don't have the book, but my fundamental understanding it that a cordelette only equalises when it is loaded in exactly the direction you set it up for. Otherwise, the strain is loaded onto the tautest piece. As compared to a sliding X which will shift to ensure the load is properly equalised.

I think another factor is that if the cordelette has arms of unequal length, they stretch differently under load, and again you are loading one piece instead of sharing the load.

Others who have the book can add their 2c worth.
Nevertheless I think cordelettes are good and often carry one on multipitch routes.
rolsen1
27/07/2008
6:52:59 PM
On 27/07/2008 Pat wrote:
>I would like to know details of how cordelette equalisation properties
>are not as good as suggested. I
>can't think of any other better quicker way of building an equalised anchor
>that is as easy. If there is one,
>I would like to learn it.

We are talking about suss anchors where equalisation could be very important. And as gfdonc has stated when the cordelette is loaded they've found only one piece is loaded. Which obviously if the pieces aren't bomber is a problem.

The sliding x with limiting knots however is much more likely to distribute the load across the pieces - which if the belay is dodgy is highly desirable.

I used a sliding x with limiting knots a few times and they are not too bad to setup and would be quite quick with practice but I agree with a bomber belay there probably isn't much point but on the flip side there probably isn't much reason not to use a sliding x with limiting knots.

I think its good to know the limitations of various setups and not just rely on what feels safest or what you're used to.
Chipbutty
27/07/2008
9:14:05 PM
Wow, this could go on forever.... I think there are many other factors to consider in choosing your method, horses for courses. If the second falls it is rarely like a leader fall, more of a slump. how good are the placements? if they are not so good surely you would try and get more than two, as I understand it the amount used in a self equalising anchor. personaly I like to build my anchor, belay directly from it and attach myself so that I have freedom to move without having to move the angle of the anchor, independant. Sorry but I'm rubbish at explaining things. with two bomber placements and no chance of the sling being cut then surely it would be very safe. where as if it were used to top rope with people swinging about on it abraiding it on the rock and out of sight it may not be so ideal.
tris
27/07/2008
9:55:25 PM
You can build a sliding X with more than 2 placements (and have it equalize on all of them). I try to have a minimum of 3 placements for every trad belay.

This is a belay I built on the bard using 3 pieces in a sliding X, there is a limiting knot on the piece I thought most likely to fail. This is not the best example, but the only one I could find in a short time.


In regards to shock loading, you usually don't have to worry about this too much because your system has a massive energy absorber build into it (your rope) which will absorb most of the impact if 1 of your pieces fails. And, as mentioned above, seconder falls are never as strong a force as a lead fall anyway.

Tris

shamus
27/07/2008
10:32:45 PM
Is anyone able to put up a diagram of a self-equalising anchor with 3 or more pieces? I've only ever seen with two, after all this discussion i'd love to know. And given nylons love of cutting itself when sliding / rubbing, would the rubbing together when it self-equalises under load / one piece fails be an issue? (either 2 or more pieces)

Pat
28/07/2008
2:31:40 PM
Thanks for the comments gfdonc. I see your point about loading direction and unequal length of
cordelette arms and stretch. I use a spectra set up so stretch is not so much of a problem. I have
learnt to pay attention to the direction of the downward pull. Traverses have always brought this home
to me. Also I usually lead, so the anchor I set is usually built for the downward pull, but I will need to
reconsider the upward pull for the second at the second and subsequent belay. I now use the cord
because I used to build the belay with my end of the rope using clove hitches, which is quick, but I
have found that the cord is quicker to equalise and the speed is good on a multi pitch.

Good points Rolsen about marginal placements. I guess I have always planned on having good
placements. This probably says as much about the types of climbs I have chosen to do when multi
pitching as anything else. Might need to widen my repertoire of anchors if I am gong to push the boat
out on different types of climbs.

Good photo Tris. Is that the limiting knot on the RHS? There seems to be a knot at the top left anchor
as well. The sling knot perhaps? So if the RHS failed, does the limiting knot allow the X to slide just to
the the knot. If so could the knot be closer to the 'biner in the middle or will that mitigate the effect of
the sliding x too much?

I hadn't heard of using limiting knots in the sliding x. Always something to learn.

IdratherbeclimbingM9
28/07/2008
4:04:01 PM
On 28/07/2008 Pat wrote:
>I use a spectra set up so stretch is not so much of a problem.

... then again that could be a problem in itself from a purely engineering perspective!

I too use a spectra cordelette, and regard much of the discussion about anchors as rather arbitary. The over-riding premise to be met, is that the anchor is up to the intended task, and John Long et al acknowledged that anything beyond that (which can be achieved with due diligence and jiggery pokery), is largely over-engineering.

>Good photo Tris. Is that the limiting knot on the RHS?
Yes.

>There seems to be a knot at the top left anchor as well. >The sling knot perhaps?
Yes.

>So if the RHS failed, does the limiting knot allow the X to slide just to the the knot.
Yes.

>If so could the knot be closer to the 'biner in the middle or will that mitigate the effect of the sliding x too much?
Entirely dependant on the anticipated forces it is likely to encounter. The limiting knot/s can be placed as close to the sliding x as you want, provided you have enough sling material left over to tie the knot/s!

Interesting to see how others set a belay at that ledge on Bard.
I did not bother with the sliding x in that location myself, as I regarded it as a straight-forward type of belay location with good/sound placements. If it is the large ledge I am thinking of, then this belay is a fair way back from the top of the previous pitch. I set several pieces and clove hitched my lead rope to them, equalised for direction of pull (towards where my second would top-out that pitch), then tied an in-line figure-eight nearer to the drop-off to anchor myself to, and sit where I could belay while watching the seconds progress.

Post edit:
Further comment on the picture posted by tris.
The centre piece of pro appears to be on it's own sling connected to the sliding-x of the rope sling? The inverted loop (ie the 'x' part of the sliding x), is not obvious?
These factors tend to cause me to believe that this anchor is yet another variation on the sliding-x theme!

On 27/07/2008 tobyholyhead wrote:
>Wow, this could go on forever....
I reckon you are right.

>I think there are many other factors to consider in choosing your method,(snip)
& right again imo.




Tris
28/07/2008
7:16:05 PM
Well, IdratherbeclimbingM9 answered all the questions correctly, full marks :) .

>>If so could the knot be closer to the 'biner in the middle or will that mitigate the effect of the sliding x too much?
>Entirely dependant on the anticipated forces it is likely to encounter. The limiting knot/s can be placed as close to the sliding x as you want, provided you have enough sling material left over to tie the knot/s!

M9 is right on this, but another thing to consider that, as you said in your initial comment, putting the knot closer to the biner will limit how far the sliding X can slide. This will limit how much it can move around to compensate for a climber moving from left to right a lot.


>Interesting to see how others set a belay at that ledge on Bard.
>I did not bother with the sliding x in that location myself, as I regarded
>it as a straight-forward type of belay location with good/sound placements.
>If it is the large ledge I am thinking of, then this belay is a fair way
>back from the top of the previous pitch

Your right, the anchor is very staight-foward and there was not any overriding reason to use the sliding X. I did so because I have been working with sliding X's for a while to familiarise myself with them and I saw a perfect opportunity to use them here (it did not take longer to set up than a normal anchor).

>Post edit:
>Further comment on the picture posted by tris.
>The centre piece of pro appears to be on it's own sling connected to the
>sliding-x of the rope sling? The inverted loop (ie the 'x' part of the
>sliding x), is not obvious?

All the pieces are joined by 1 cordalette, so they are all the same sling. It's just the crap'ness of the photo that makes it appear that way. If there was another sling involved there I would think that it would make the anchor really hard to equalise.

Tris
Tris
28/07/2008
7:26:50 PM
Here is a closer view of the sliding part, I hope it helps.


skink
28/07/2008
9:12:14 PM
So if the cam blows, you introduce a bunch of slack and your bodyweight falling two feet shock loads the other two pieces. Oh, and you are now off the ledge...

I'd rather be cordoletted or tied in hard to each piece with slings/clove hitched lead rope.

Pat
28/07/2008
9:41:17 PM
I think that's the point of the limiting knot, see further back in the posts. Thanks M9 and Tris.

skink
28/07/2008
9:46:48 PM
On 28/07/2008 Pat wrote:
>I think that's the point of the limiting knot, see further back in the
>posts. Thanks M9 and Tris.

The limiting knot only helps for the top right piece. If the cam blows, you go for a ride.

 Page 1 of 3. Messages 1 to 20 | 21 to 40 | 41 to 44
There are 44 messages in this topic.

 

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