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superbum
Mar 23, 2003, 2:27 PM
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I recently became aware of a knot called the "alpine butterfly." To me it looks like it was sent directly from heaven. You can check it out here: http://www.chockstone.org/TechTips/Butterfly.htm Now it is principally used to tie-in to the middle of a rope for glaicer travel. I am curious if it can or should be used when rigging and equalizing anchors???
You are rigging the whole shabang with the lead rope and have sunk three bomber pieces in a vertical crack. You, say, tie into the first piece, then connect the other two pieces with clove hitches (this isn't an argument for or against an upward directional so overlook the fact that there isn't one) and get them all taut. Now the question is, what is the best knot for tying into that first piece?
John Long (author of "Climbing Anchors") would probably say the figure eight on a bite. The problem here is this knot, when placed perpendicular to the rope, tends to "squish" and roll towards the tie-in point. To see what I mean, tie a fig. 8 on bite, then pull the two free ends of the rope, hard. Harder.
Some would say the Inline Figure Eight. Here it is: http://www.chockstone.org/TechTips/F8Knots.htm#F8Inline Now maybe the problem is with me, but this knot takes a bit of practice to perfect. Depending on how you form the first loop, you have to tie the fig. 8 part of it in a specific direction...which can get confusing 400 feet of the deck. Also more experiance is required in order to get the knot to "face" in the right direction.
So...is the alpine butterfly the answer to all these [admittidly] problems? Maybe. My question has to do with weighting the knot. If you tie the butterfly, clip it to piece #1, then tie off #2 and #3 with clove hitches...then weight the butterfly...will the load pass the loop entirely, and run straight to the clove on #2? Does the tie-in loop act only as a "keeper" making this knot sutible ONLY for glacier travel? Or, will the tie-in loop and the rope end going to the #2 clove hitch distribute the load equally?
Sorry for the length...thanks for any/all replies....
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alpinerocket
Mar 23, 2003, 2:51 PM
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I would suggest using a cordallette or webalette. These things wiegh very little and are very easy to use. the buterfly is inteneded to be loaded in 2 directions (hence it is a multi-directional knot), that is why it is used in glacier travel with 3 or more on the same rope. Another problem w/ using the rope as an anchor is you will have a harder time leading in blocks. Or, if you are switching leads and the guy leading gets gripped and wants to come down and give you the sharp end. eithir both of you have to untie the ropes from you harneses and switch or you have to re-rig the anchors. dont get me wrong I use the rope as an anchor at times but it is usually on alpine type climbs thet are well w/in the ability of my partener and I. John
Big Gulps, huh? Well, see ya latter.
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mountainmonkey
Mar 24, 2003, 8:59 AM
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superbum, I think you misinterpreted J.Long in the anchor set up. The knot to the top piece should be a figure 8 and the lower pieces should be clove hitches. This will not 'squish' the figure 8 or deform it out of shape because the top piece is only pulled in one direction. The alpine butterfly is a great knot but not in an anchor set up because the figure 8 is stronger.
A very useful knot in an anchor set up is the bowline-on-a-bight (or the dog-eared bowline according to Climbing magazine). By far the most useful anchor knots are the figure-8, the clove hitch and the bowline-on-a-bight.
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superbum
Mar 24, 2003, 1:37 PM
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If you look at a few of J. Long's pictures, he uses a fig. 8 on a bite as the lowest tie-in or a middle tie-in in a vertical crack many times. If you were to load the anchor when the fig. 8 was used on the lowest or middle nuts, the two "free" ends (which aren't really "free" because they are either clove hitched, or tied to the belayer) are pulled away from eachother, and thus perpendicular to the knot. Now, if used in such a manner that both rope ends are pulled in the same direction, or down, then the Fig. 8 on a bite is the one to use. If not, then another knot is needed. A bowline on a bite, an in-line fig. 8, or butterfly.
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mountainmonkey
Mar 24, 2003, 2:12 PM
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I don't have the book nor will I say that I remember it perfectly, but from what I learned from the book is that the best way to rig the rope is with a figure-8 at the top and clove hitches down the line to the belayer. I also remember the pictures you describe. Also remember that in both books the anchor setups that are pictured are not necessarily best or ideal setups possible given the protection possibilities. A figure-8 with the strands being pulled perpendicular is not ideal, but it will work. The in-line figure-8, the butterfly and the clove hitch will be better. I highly prefer the clove hitch because it takes up much less rope and is much easier to equalize with the other pieces.
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fitz
Mar 24, 2003, 2:28 PM
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There is nothing wrong with the Alpine Butterfly, but it is hard to tie one handed, easy to tie incorrectly, and hard to visually inspect. It also is not the strongest of knots, because of the tight circumference of the inside loop.
I think your concern about direction of pull is off base. If a figure 8 is pretensioned, the worst that should happen if strands are side loaded is that it should 'roll' or 'invert'. This actually tightens the knot, though not to the same degree as a simple overhand. If one of the cloved pieces fails, either above or below, then the 8 will be generally loaded in its strongest configuration.
An AB is strongest with the strands pulled perpendicular to the bite. This might be the case when the strands are clove hitched to other pieces, but it would not generally be the case if one of those pieces failed. Still, like side pull on the figure 8, failure of a properly tied AB is the least of your problems. The sudden shock loading of your remaining pieces is a much greater concern.
I'd have to agree with another poster, unless your needs are really specialized, you would do well to look at a cordolette or web-o-lette type setup. Rope tie-in has the benefit of simplicity and speed, but other setups generally do a better job of equalization and minimizing extension. Cordolette type setups also make it easier to not swing leads every pitch and escape the belay if there is an emergency.
-jjf
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billcoe_
Jul 7, 2009, 12:20 PM
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If this thread was started today, we'd see 50 pages of disagreements interspersed with interesting 1 liners accompanied by another Angry/Majid verbal deathmatch.
Moral of the story: the old days were not necessarily better.
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bill413
Jul 7, 2009, 6:02 PM
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billcoe_ wrote: If this thread was started today, we'd see 50 pages of disagreements interspersed with interesting 1 liners accompanied by another Angry/Majid verbal deathmatch. Moral of the story: the old days were not necessarily better.
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theguy
Jul 7, 2009, 6:14 PM
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billcoe_ wrote: the old days were not necessarily better.
Yes they were.
Hey, you asked for it ;)
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gunkiemike
Jul 8, 2009, 5:19 PM
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And when someone re-resurrects it from the dead thread bin another 6 years from now, today will be the good old days.
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gimmeslack
Jul 9, 2009, 5:17 AM
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Why don't you go over to supertaco and ask mr. long?
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