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papounet
Feb 16, 2006, 1:02 PM
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Dear vivalargo,
Did you ever come across Multi Point Force Distribution Anchor (MPFDA) ?
as described in http://www.prolearn.org/stealth/r-mpfda.html and other rigging texts ?
It provides load distribution and decreases impact of protection failure. as the anchor adjusts itself, some energy of the fall is also dissipated.
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tradklime
Feb 16, 2006, 6:51 PM
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In reply to: I'm concerned if their is a shift away from the no extension part of sere"ne" their will be potentially new problems for people who don't understand the new factors involved with a potentially extending systems when they've been operating under the principle of no extention for a long time.
Well all this time apparently most people didn't understand the inherent lack of "equalization" (another principal of serene) with a cordalette and the associated problems.
I guess it's just part of the evolution of knowledge. Thanks to John for providing some hard data to support what an apparent minority has understood for awhile.
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vivalargo
Feb 16, 2006, 9:26 PM
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In reply to: VivaLargo, have you tested the "sliding x" with a three-point setup? We've always used sliding x's, but on occasion when the anchor is three points: Instead of using two separate x's (One for two pieces, then another between that x and the third piece) a sliding x with three pieces was built. Same principle, just a slightly different setup. Curious, as I had not seen that mentioned anywhere in the thread...
I PMed you on this 3 piece sliding X configuration, but I'm sure the climbing community would appreciate knowing how you're rigging this. Our way is to use the two strands (on one side) above the limiter knots at the bottom, attaching each strand indidvidually to two placements via clove hitches.
Incidentally, the "Duo Glide" system (aka, "Equalette") I mentioned simply does away with the "X" and clips off both strands (individually, with lockers) at the bottom of the rig, between the pre-tied limiter knots. The ease and equalization of this set up spanks all others--by far.
Pro guides Tom Cecil and Bob Gaines have been field testing this rig along with us cocking around in the lab, and in a few days we should be ready to bust out something that really and truly works like charm--and believe me, it's been months of work to figure all of this out, a regular love of labor by a stack of really talented folks.
JL
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slcliffdiver
Feb 17, 2006, 1:30 AM
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In reply to: Well all this time apparently most people didn't understand the inherent lack of "equalization" (another principal of serene) with a cordalette and the associated problems. I guess it's just part of the evolution of knowledge. Thanks to John for providing some hard data to support what an apparent minority has understood for awhile.
Agreed, I think it's really good of John to put forth the limitations of equalization with cordelletts and I'm looking forward to the details of the results. I'm guessing I might be modifying what I do to an extent at least in some circumstances maybe a lot.
If the equalette performs as advertised (when my brain clears up enough to set it up from the discription) we may have a lot more to be greatful for for those that worked on it. Fast, versitile, truely equalizing limited extention is the holy grail for anchors. I'm really excited to have a chance to try it out.
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jeremy11
Feb 17, 2006, 2:39 AM
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papounet wrote
In reply to: Did you ever come across Multi Point Force Distribution Anchor (MPFDA) ? as described in http://www.prolearn.org/stealth/r-mpfda.html and other rigging texts ?
really interesting article, thanks for filling us in. looks like the trango alpine equalizer http://trango.com/prod.php?id=19 (or the alpine equalizer looks like the MPFDA) but that is another piece of expensive single purpose gear to lug around...
Any testing on this to see how effective it is in light of the new research?
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vivalargo
Feb 17, 2006, 5:19 PM
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Designers of the Trango Equalizer recognized the basic problem: any rigging system with a fixed, non-sliding master point can never load up in a way that will ever achieve really solid equalization/load distribution. However, the Equalizer is not that versitile since it's basically built for three placements. It also has a small master point, is expensive, has too many widgets, and is a single-use item (meaning you can't use it for other purposes other than as a rigging tool). It also is made out of slinig, and tech cord or 6/7 mm nylon rope is much better when using clove hitches--which are required for tying off when you want a system for which you can tie off 2, 3, or 4 primary placements.
Testing of the "Equalette" (aka, the "Jimbolon," after Jim Ewing of Sterling Ropes) is going on just now, and this system simply uses a 20 or so foot piece of cord and can be used to tie off 2, 3, or 4 placements and achieves solid equalization--or that's the way it's looking so far.
JL
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dominic7
Feb 17, 2006, 7:57 PM
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I'm nervous about a couple of things I do now in top belays. John mentions a few times in this thread the relevance of the belayer in the shock absorbtion equation. If you use a Reverso or Gri-Gri attached to the strong point of the anchor, aren't you removing this? Is it significantly safer to attach the belay device to your harness and redirect through the strong point?
Secondly is the importance of the small rope slippage through the belay device. Do auto-locking devices such as the Gri-Gri and Reverso bind so quickly as to remove this from the equation?
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landgolier
Feb 17, 2006, 9:12 PM
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These teasers about this new rig are killing me, I think I can mostly picture it but it seems to rely on single strands of cordelette-sized material (like 7 mil perlon), which conventional wisdom says is too weak; there have been a couple threads where people wanted to make a rabbit runner out of 7 or 8 mil, and the answer was always "death-o-lette." I think somebody did actually buy the farm on a rig like this once, but I can't remember enough details to dig it up. I guess maybe if the thing actually equalizes it's not so bad, tho, or maybe I just have the wrong idea.
In reply to: I'm nervous about a couple of things I do now in top belays. John mentions a few times in this thread the relevance of the belayer in the shock absorbtion equation. If you use a Reverso or Gri-Gri attached to the strong point of the anchor, aren't you removing this? Is it significantly safer to attach the belay device to your harness and redirect through the strong point? Secondly is the importance of the small rope slippage through the belay device. Do auto-locking devices such as the Gri-Gri and Reverso bind so quickly as to remove this from the equation?
Grigris are one thing since you can belay a lead with them, and even petzl admits they increase force on anchors. I think the concensus is that they are best for sport, or situations where autolocking trumps all other considerations (walls being one), though plenty of people belay 1-3 pitch trad with them and don't die.
However, you bring up top belays pretty specifically. In that situation the fall is generally so short and of such low factor that the forces aren't that big, though shit can always happen. I know my B-52 definitely doesn't let much rope slip in a fall, but I also often don't even know the second has fallen or if I'm just belaying too tight. I'm not sure how much slippage there would be if you dropped 80kg on a 3m factor 1, but I'm also not eager to find out. Also keep in mind that belaying off the harness and redirecting increases the forces on the anchor (theoretically 2x but there is friction and other stuff going on), so doing that may lose you in the straightaways what you gain in the curves, so to speak.
Conventional wisdom is that if you have doubts about the anchor's ability to hold a second's fall, and you can't do better on the anchor (double scary since that means there is no good pro above the current location, and you will presumbably be leading up into that and risking a factor 2 onto your crap anchor), you can belay directly from the harness and try to keep the force off the anchor with your legs, assuming you have a decent stance. I'll defer to the alpine masters and old schoolers who passed the Dartmouth belay test on the subject of stance belays.
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clmbnski
Feb 17, 2006, 9:13 PM
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While I realize there are problems with cordelettes I think they are worth defending.
First of all I dont believe that only one peice in the anchor takes 100% of the load when using a cordelette. I know the longest arm stretches more than the shortest reducing the equalization but there is still some distribution of the load between the other peices. Not perfectly equilized but one may be able do deal with it by trying to get the best peice on the shortest arm and puting a little more tension in the longest arms.
That sounds complicated and given a simple anchor with two bolts, the sliding x is probably the way to go, but I think the cordellet really works well when building tricky multi piece trad anchors while keeping things clean and eliminating clusterf*ck. I regularly climb in an area where the anchors vary from all gear to small trees to big trees to boulders and the cord is more versatile than trying to make slings the right length and equilized. I recently topped out on a climb to find a completely flat rock summit without any trees or cracks for an anchor. But there was a very large boulder on top that I was able to wrap the cord around. Without it I would have had to girth hitch 5 or 6 slings together to get something to work.
So my point is while cordellets have some issues they are still useful and versatile.
Chris
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dominic7
Feb 17, 2006, 11:21 PM
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Very interesting. You need the two biners though - you wouldn't want to clip both of the little bottom loops with one biner, because potentially if both pieces on one side of your picture failed the whole rig could slide right through it. Clip just one loop and you are ok though.
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vivalargo
Feb 17, 2006, 11:49 PM
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Jeeeeeeeez, you guys don't let a man rest. But then I went and opened up my fat trap and now I have to explain myself.
Healyje has the basic idea in that graphic, but please understand that as we speak Jim at Sterling is still doing testing on this (looks sensational so far) and pro guides Tom Cecil and Bob Gaines are field testing this rig (I think the name is probably going to be the Equalette) just now as well.
As Healyje has it set up, the pieces are so spread out I doubt any system could cover it and remain well equalized--here you'd probably want to connect both pairs with a sliding x and then last it off with the equalette. For use with 3 or 4 pieces more closely spaced--especially when they are placed in a vertical crack, or side by side cracks or features, the equalization is so far looking quite even, with some good leeway for changes in the direction of pull.
There's still bugs to be worked out with this system, and I'm sure it will change shape in the next few weeks as others keep fiddling with it. I think Healyje's graphic feaurtes a unit that is needlessly big.
We were originally wondering about redundancy in each strand, but because they are connected (looped), and because there is no real world evidence of a strand of 5mm tech cord or 7 mm perlon (in good shape) in a rigging system acutually breaking (how often does the tech loop on Cams ever bust??), this was dismissed as being a practical worry (it is still a theoretical worry, however).
The bottom line here is that testing (upwards of 200 drop tests so far) has shown that any rigging system featuring a fixed masterpoint will never even remotely equalize three or more pieces, and will only partially equalize 2 pieces when the arms of the rigging system are virtually the same length. So the fixed masterpoint knot is the workaround thus far, and the Equalette is just the first of many potential and promising systems that might deliver on the promise of equalization. In the tests with the equalette connected to two pieces, the equalization was almost 50/50 to each piece--by far the best so far.
But the work goes on . . .
JL
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healyje
Feb 17, 2006, 11:56 PM
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John,
Sorry to jump the gun, was just wanting set the other posted drawings straight. Also, I was in no way intending to show scale or a real world anchor, but rather exaggerated it by spreading it all out to be able to show the basic idea / components and have some room for labelling.
My only comment on it so far is it takes at least a little tuning. Like I just want to get it up and loosely cloved, then clip into it so there is a bit of weight on it, adjust one strand to that length, and then load it a bit more and do up all the remaining cloves so they are all really are snug against a load.
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vivalargo
Feb 18, 2006, 12:08 AM
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Healyje--
You didn't jump the gun--I did.
Anyhow, the trick to rigging this is to first clove off the BOTTOM placements on each arm--then you only have to feather the other two cloves. After going thrugh the process a few times you'll find it's nearly as fast as rigging a cordelette-and quicker to break down since the limiter knots stay in the rig, and the cloves untie faster than overhands and figure 8s.
JL
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patto
Feb 18, 2006, 3:30 AM
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An easy way to solve the equalisation issue is with a dynamic cordellete.
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dwebster
Feb 18, 2006, 5:05 AM
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In reply to: An easy way to solve the equalisation issue is with a dynamic cordellete.
This might seem to be true and in some cases it probably is but certainly not always. For instance: a vertical crack where you have a short leg, a medium leg, and a long leg. Think of the legs as three different length rubber bands made of the same thickness of, well, rubber. Hang all three on a pencil. Now put your finger through all three as well. Now pull your finger and the pencil in opposite directions. You will feel the short one load first and if it's a lot shorter than the second one it could be almost fully extended and taking the full load before the second or third starts to take any. Of course there are an infinite number of variables on the lengths of the rubber bands (legs of a cordelette) but the principle will always be the same. It doesn't matter if the cord is super stretchy or super not stretchy (low modulus or high modulus for you techies). As long as all the legs of the cordelette are of the same material this principle will apply.
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patto
Feb 18, 2006, 7:53 AM
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In reply to: In reply to: An easy way to solve the equalisation issue is with a dynamic cordellete. This might seem to be true and in some cases it probably is but certainly not always. For instance: a vertical crack where you have a short leg, a medium leg, and a long leg. Think of the legs as three different length rubber bands made of the same thickness of, well, rubber. Hang all three on a pencil. Now put your finger through all three as well. Now pull your finger and the pencil in opposite directions. You will feel the short one load first and if it's a lot shorter than the second one it could be almost fully extended and taking the full load before the second or third starts to take any. Of course there are an infinite number of variables on the lengths of the rubber bands (legs of a cordelette) but the principle will always be the same. It doesn't matter if the cord is super stretchy or super not stretchy (low modulus or high modulus for you techies). As long as all the legs of the cordelette are of the same material this principle will apply.
True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used.
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dwebster
Feb 18, 2006, 3:39 PM
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In reply to: True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used.
It will only be better in the sense that there will be some energy absorption. Static cord, dynamic cord, webbing, or even wire cable, the principle still applies because elongation ratios between the legs will remain the same (assuming the exact same setup with each material).
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curt
Feb 18, 2006, 4:07 PM
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In reply to: In reply to: True equalisation wont be perfect in this situation, but it would be far superior to static cord used in the same way. In this situations you would be hard pressed to load more than one strand if static is used. It will only be better in the sense that there will be some energy absorption. Static cord, dynamic cord, webbing, or even wire cable, the principle still applies because elongation ratios between the legs will remain the same (assuming the exact same setup with each material).
Correct. Unless the tension is equal in each leg of the cordalette, you won't have equalization.
Curt
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dwebster
Feb 18, 2006, 4:44 PM
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Right, and as long as you have cordelette legs of different lengths you can never achieve perfect equalization in standard cordelette mode. Unless of course you have load/force measuring devices on each leg and can adjust the direction of pull.
Starting with each leg under equal tension (again with different length legs) you will still get different loads on each leg as the load is increased because the longer legs have more potential elongation. In other words they will have to stretch more than the shorter leg to maintain the same load.
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vivalargo
Feb 18, 2006, 5:46 PM
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Mr. Webster--
You pretty much have the thing reckoned. The business of stretch of unequal arms is also germane to most any rigging system with unequal arms, though we're fiddling with one system we're (so far) calling the "Quad" which seems to pretty much equalize (nearly 50/50 on each placement) two anchor points even with unequal length arms. Once you move into three and four arm configurations you're tying off strands of an arm, and while the arms themselves might remain pretty well equalized, the strands will not load with the same degree of equalization. To expect to get equal loading across three or four placements is to expect too much from any rigging system. The boon of these new rigging systems is that they offer far better equalization between the two arms--but it's all a work in progress.
Again, as a general rule, any system (at least all the ones we've looked at) featuring a fixed powerpoint knot is not going to equalize even the two arms very well, and the individual strands (or plus 2 arms) are going to be weighted at very different ratios.
The true magic bullet is going to be a system (rigged on a standard length of cord sans widgets) where you can clip off the placements with loops (not knots), and which features a sliding powerpoint. Perhaps the two are mutually exclusive, but I bet this can somehow be rigged if enough people start fiddling around with the idea.
JL
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bloodyhands
Feb 18, 2006, 6:59 PM
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In reply to: The true magic bullet is going to be a system (rigged on a standard length of cord sans widgets) where you can clip off the placements with loops (not knots), and which features a sliding powerpoint. Perhaps the two are mutually exclusive, but I bet this can somehow be rigged if enough people start fiddling around with the idea. JL
Like Trango's easy alpine equalizer?
http://www.trango.com/.../alpineequalizer.jpg
In reply to: The original versions were made with 9/16" webbing and rap-rings.
Looks pretty easy to replicate.
Slide two(or more) rap rings onto a piece of webbing. Form a loop (not a bight) containing the rap rings in the line with two side by side out water knots about 5" apart. Take the middle of the loop and tie an over hand knot on the bight containing the two rap rings. Ten tread the two ends of the webbing through the rap rings and tie them together with a double fisherman's knot. Clip the powerpoint between the two water knots.
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jakedatc
Feb 18, 2006, 10:07 PM
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John, can't wait until your new book comes out.
i find it funny that when i did a search for alpine equalizers it came back with an thread that had probly 75% passionately defending their cordalettes. Looks like with a knot in one of the legs or cloves on the pro it should be SERENE with actual NE instead of percieved NE of cordalettes. question i have is 6' or 3' for multipitch trad purposes?
http://www.rockclimbing.com/forums/viewtopic.php?t=49735&postdays=0&postorder=asc&topic_view=&start=0
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