Self-equalizing vs. static anchor
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So I am weighing the pros and cons of a self equalizing anchor system (like the sliding X or ACR) vs. a static anchor (Coordilett equalized, then tied off.) |
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anchors 101: SRENE |
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I'm curious why you say a 'static' system can't be equalized? |
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My opinion is as follows: like everything else in trad climbing, the answer is "it depends". Both are advantageous in certain scenarios so learn them both and figure out when you like using them. If you have two straight up and down pitches, tying off the anchor so it's equalized in one direction is fine, can be easier to deal with, and won't move if one piece fails. If the next pitch wanders, or heads off in a different direction than the last one finished in, a sliding x is probably your bet. If you are worried about "shocking" the anchor in case a piece fails, tie extension-limiting knots. What I mean is, if you have a 3 point anchor and one or all of the pieces is far away from the master point, then tie an overhand in the loop of rope that leads to those pieces. That way, if said piece blows, you only introduce a fraction of the slack into the anchor. of note in this situation is that you can only "slide" as far as your knots will allow, but take that into account when you're building the anchor and deciding where to tie the knots, and it will rarely be an issue. As long as you understand the limitations of both and how to apply them safely, then it really becomes a personal preference issue in many cases. |
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I couldn't have said it better than Dave. Including the book recommendation! I would only use a sliding X if the pitch wandered back and forth a lot. Otherwise, equalize and tie a knot. |
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The solid rock & solid pro using good angles are the critical parts. |
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You need to really chose based on what gear you have and what the circumstances are. Obviously you want the best gear possible. If all the pieces in your anchor are bomber and the direction of loading can be reasonably anticipated, I feel a cordolette is a good choice. If the loading may wander significantly, then something with some self equalizing properties can be handy. I haven't used the ACR, but it looks quick to setup as you don't have to try and get that main knot tied just right. |
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With correctly tied limiter knots, extension is not much of a problem. To obtain a full 360 degree circle of use from two points, limiter knots should not be any further apart than the distance between the two points of protection, any extra serves no purpose. They should also be centred about the midpoint between the two points. With this method, the maximum extension you can ever get is the distance between the two points of protection (for a sideways pull), and the more probable extension is half that distance (for a downwards or upwards pull). So for a typical bolted anchor which might be two bolts spaced 2 feet apart. You shouldn't ever be looking at more than 1 ft of possible extension. |
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jmac wrote:So I am weighing the pros and cons of a self equalizing anchor system (like the sliding X or ACR) vs. a static anchor (Coordilett equalized, then tied off.) The self equalizing self equalizes but if one pice blows it will shock load the others. In the static system if one piece blows it does not shockload the others but the equalization is far from perfect. Thoughts?Thoughts? Here's mine... This subject has been hashed, rehashed, sussed, tied and put out to pasture on every climbing website on the interwebz. Not to mention the myriad collection of books available that answers this question directly. Searching MP alone will give you so many results you'll need an assistant to sort through them all. If that doesn't satisfy your lust for anchor info then I might suggest finding a mentor who can teach you hands on. Based on the terminology you use it would appear that you need to go back to the basics and try to forget some things that you have "learned". I agree with Mark Nelson. Good pro in good rock with good angles. That's all you need to know. Shock loading is a myth that doesn't make sense once you actually do the research and look at the forces involved. Big bomber gear in good rock isn't gonna fail no matter how you lash them together. Placing three pieces and cloving them all together nice and tight is perfectly acceptable as long as they are solid placements in solid rock. Attempts to equalize are good but in the end, six shitty placements all perfectly equalized and set for direction of pull are not as good as clove hitching your rope to a couple of big stoppers in bomber constrictions. Dicking around with complex anchor matrix's for hours on end at the belay is a great way to make it difficult to find a belayer as well. Not to say that the information you've been given and the graphs aren't loaded with good data (because they are and I appreciate them being posted) but it's all a bunch of theoretical number crunching that means nothing if you've got good pro in good rock with good angles. If you don't know what this means then you should borrow/buy John Longs "Climbing Anchors" and read it 3 or 4 times. All will be clear. And just use the rope unless you're leading every pitch. As somebody else on MP stated a while ago "It's the strongest, most abrasion resistant and dynamic piece of gear you have with you. Why wouldn't you use it?" |
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equalette rather than cordolette. The testing results near the end of Long's book shows significant advantages. The equalette also provides more lattitude in terms of equalizing falls where the load isn't perfectly aligned with the expected direction of fall (when setting the anchor). |
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I second what Yarp said, except buy Luebben's book and read it 3 or 4 times. |
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Pesterfield's book was pretty good too. Many, many others out there. Reading them all would be the best advice if you don't have anyone to help you out as you learn.
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Buy both the Gaines/Long 2nd ed Anchors AND Leubben's Anchors books. |
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SRENE is an oxymoron. |
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Moof wrote: Rope cloved in: Can be statically equalizied (i.e. 0-100% load on each piece depending on millimeters of error on the knot locations). Zero redundancy for cut rope (we accept this at all times when climbing with single ropes), but as much redundancy as you have extra pieces in. Works well with vertical cracks, poorly for horizontal (greatly effects extension and equalization).For this I would add the equalizing figure 8 with the rope. For the equalette, the master point direction can be changed by adjusting the cloves. |
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Also the clove hitch master point is a good one. Clove yourself to a piece, clove the rope to another piece, clove your master point in between the two pieces. You can slide the knots around to whatever length you need, but it is still redundant. You can add more cloves, but you can only equalize two of them unless you make things more complicated. |
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I don't know how true this is, but i have heard the the sliding x does not equalize well if it is already weighted (e.g. a leader falls, loads, then pulls a piece on the fall, so the direction changes).any thoughts on this? I personally use webbing with full strength lops on either end. It is easy to equalize, static and I am more comfortable building my anchors with webbing then rope. ( mtntools.com/cat/mt/webolet… kinda gimmicky but so easy...) |
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Evan Deis wrote:Larry your Finite Element Analysis is garbage. A cordolete cannot support a moment as your model can. This doesn't even make for a moderately good approximation.That's a really helpful comment Evan. @Larry: However, you should consider some elasticity in your rigging. If you use the traditional 7mm perlon cord which has significant elasticity, the load will be much more distributed. |
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wlashgraham wrote:I don't know how true this is, but i have heard the the sliding x does not equalize well if it is already weighted (e.g. a leader falls, loads, then pulls a piece on the fall, so the direction changes).any thoughts on this? I personally use webbing with full strength lops on either end. It is easy to equalize, static and I am more comfortable building my anchors with webbing then rope. ( mtntools.com/cat/mt/webolet… kinda gimmicky but so easy...)I actually read the same thing about the sliding X but cant remember where. However, about the webolette, I see one minor difference between webollet and cordalette : slings are (mostly) not elastic while a cordalette made of nylon cord is pretty elastic which can distribute the load over several protection. |
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wlashgraham wrote:I don't know how true this is, but i have heard the the sliding x does not equalize well if it is already weighted (e.g. a leader falls, loads, then pulls a piece on the fall, so the direction changes).any thoughts on this? I personally use webbing with full strength lops on either end. It is easy to equalize, static and I am more comfortable building my anchors with webbing then rope. ( mtntools.com/cat/mt/webolet… kinda gimmicky but so easy...)Which is why you should tie one strand a bit shorter than the other. Anyways, the worse a system equalizes, the better it resists unexpected extensions. Think of it like the differential on a car. You can have a regular differential which distributes half of the power (load) to each wheel all the time, but if one wheel slips (protection fails) so that it can't apply that power, then you get a spin out where neither wheel is applying power, or in the climbing analogy, a free fall where both pieces become unweighted until you hit the full extension of the system. By contrast, a limited slip differential would be like a load sharing system that binds up and if one piece fails, then the other pieces don't immediately lose all of their load. Also, a regular cordalette would be the equivalent of no differential, just driving both wheels at the same speed off of one axle. This means that the wheels can't spin out, but you might put all of the load on one side |
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Has anyone here ever blown a piece from their anchor or had any problems with either anchor scenario failing in any way that wasn't due to their own mistake? |