Butterfly or Alpine Butterfly?

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Re: Butterfly or Alpine Butterfly?

Postby ek » Jan 23, 2009 1:44 am

Yeah, that'll just face it one way or the other (left or right on the rope).
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Re: Butterfly or Alpine Butterfly?

Postby knudeNoggin » Jan 24, 2009 2:16 pm

Bob Thrun wrote:I regard Wright and Magowan to be the correct definition of Butterfly Knot because they invented the name.

It should be possible to track down where "Alpine" entered the
name space. I used to try to kill it, believing it a gratuitous
addition to the already unique name (subsequent goophs being
so-named don't count to my mind as legitimate contenders);
but, now, seeing more clearly through RetroSpectacles (tm),
I'll get revisionisticly inventive and conclude that "Alpine"
derives from the publication, Alpine Journal (!), and
all is well ! what a deal, eh?!

Alpine Caving Techniques has several slips of terminology due to the translation process. The translator was not an expert on knot names.


Who is? At THIS stage of the game (and noting even Ashley, who
apparently at least made some effort to reflect practice, often has
a set of names per knot, and often a set of knots per name, for
that matter--what's good for the gander is good for the goose),
deciding on what a "correct" name is will entail a deliberation
on naming correctness. (E.g., it might be held w/o doubt that
Ms. M discovered and named some knot "Mmmm", but others
might be aware that that name was already "taken"; or, those
using the knot and giving it currency might have decided on
some other name, which found printer's ink!? What is "right"?)

What ACT calls a False Buterfly is called an Angler's Loop by Ashley, ABOK 1038. The Butterfly Knot is given by Ashley as the Lineman's Loop, ABOK 1053. Ashley credits J. Drew for the name and publication of the Lineman's Loop. Drew had publications in 1912 and 1936, neither of which I have seen, so I cannot tell if he has priority over Wright and Magowan.


Really, the Perfection aka Angler's Loop qua "butterfly"?!
(FYI, this year I did find this knot in some discarded Commercial
Fishing discarded ropes, apparently used qua mid-line eyeknot
--the first I've found it at all, in looking over CFKnotting around
Cape May/WIldwood/Del.Bay haunts.)

It seems that Ashley's given history of the knot at least is good
reason to believe that it arose separately in a couple places
--neither "linemen" nor W&G so likely to have known the others'
doings?! (Well, if anything, I guess I'd more suspect W&M of
knowing about knotting in broader terms; but I take it that
they asserted originating the knot for themselves.)

-----------------

I'm skeptical about the assertions of slippage given to the
one "false Butterfly" formed by casting a HHitch over the
Slip-Knot eye; that seems more stable than is given; and
it seems a half-decent way to effect directional eyeknots
from some common starts (and can be repeated, turning the
HH into a Clove H.).

As for someone's assertion of a "family of Butterfly" knots,
I wonder how many he thought he'd seen? We're talking mostly
of just two, and now Bob reveals an unseemly third (which, btw,
has also be called a "Single Bowline on a Bight").
There are also various DRESSINGS of the Alpine Butterfly; it is
most often most clearly shown with the eye legs abutting rather
than crossing each other; W&M, however, explicitly specified
a particular crossing in the knot body (which orientation I think
will tend to be lost, gradually, upon loading the eye).

There ARE MANY BUTTERFLY-LIKE mid-line eyeknots, though.
Bob holds sketches of these.
Some, I think, hold more promise than the *original*.
E.g., with a half-twist more to one half of the knot, you
form a Fig.8 and so orient the draw of that side's end to
match the other--i.e., both will twist the eye legs one
way (clockwise or ...), which seems beneficial.
Ashley's bend #1408 can produce a Butterfly-like mid-line
eyeknot, which if loaded in one direction is significantly
less prone to jamming than the original. Then there are
many ways to take a slip-knot beginning into workable
directional eyeknots.

Which leads me to ask/survey: in how many applications
is it desired that an eyeknot be able to be LOADED IN EITHER
DIRECTION!? --in contrast to there being only one possible
direction for loading the eye (and for which, thus, any of
the larger set of directional eyeknots will work).

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Re: Butterfly or Alpine Butterfly?

Postby potholer » Jan 24, 2009 7:44 pm

Bob Thrun wrote:Wow! Two quick replies. I regard Wright and Magowan to be the correct definition of Butterfly Knot because they invented the name. Alpine Caving Techniques has several slips of terminology due to the translation process. The translator was not an expert on knot names. Perhaps the French prepended the "Alpine". I do not know.

I don't think there was an English translation of ACT before the 2002 edition, and the double-twist knot was pretty universally called the Alpine Butterfly decades before then, at least by the people I know over here.
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Re: Butterfly or Alpine Butterfly?

Postby knudeNoggin » Jan 24, 2009 11:40 pm

In another forum, one poster wrote:
"I have uploaded a sequential photo set on Flickr.
My username in the "People" search field is ursusgummis.
The set is entitled "A Better Way To Tie The Alpine Butterfly".


Here is a Flickr URLink (which might fail--I've reached it "the ol'-fashioned way")
http://www.flickr.com/photos/28164211@N05
The SlideShow is probably the way to go; otherwise, the strongest thought
you'll have is "(there must be) a better way to organize these photos!",
which are not in step-wise tying order (geesh).

-----------------

The, um, "Twirly-Flop method" (irresistible, once it's called that (probably
will be verboten in SAR, thus :o) ) provides the doorstep to the 8-Oh version:
at the point immediately prior to pulling the eye loop through the center of
the knot, give one side a half-twist extra (only one side can take this--in
the other, you'll be untwisting), and then pull the eye-bight through.
It is less liable to jam if the extra-twist side is the one NOT loaded when
loading the eye (i.e., it will be harder to pull the fig.8-side's collar tight than
the Overhand-side's collar). This version much resembles Ashley's bend #1452
in orientation/working, which is a good thing.

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Re: Butterfly or Alpine Butterfly?

Postby NZcaver » Jan 25, 2009 5:27 am

Bob Thrun wrote:Many refer to a certain mid-rope loop as an "Alpine Butterfly Knot". Others call it a "Butterfly Knot". Is there any difference? The 1928 Wright and Magowan article introduced the name as simply "Butterfly". That article may have been the first publication of the knot too, though with knots it is probable that somebody tied it much earlier. Alan Warild's book, Vertical, has BOTH the Butterfly and Alpine Butterfly! He does not explain the difference. The small drawings in the strength table do have not enough resolution for me do tell the difference.

Interesting question, and some interesting answers. Time for my 2 cents. :grin:

I learned to tie the Butterfly soon after I started caving, and I'm guessing it was first taught to me by my fellow cavers. My first (and only) caving reference back in those days was the new 1988 edition of Warild's book Vertical. I took a look at the electronic copies I have, and I agree it's difficult to determine between the Butterfly and the Alpine Butterfly by the quality of his illustrations. In the 2002 edition it shows both versions under the "non-recommended knots" category (page 39), but in the 2007 edition it shows only the Alpine Butterfly under the heading "other rigging knots" (page 52).

I was initially taught the hand-wrap method for tying the Butterfly. It works great for me, so I never bothered messing with the twirly flop thing. By my hazy recollection, I always thought the Alpine Butterfly was similar to a regular Butterfly but required one extra wrap before poking the bight through. This is totally contradicted by Alpine Caving Techniques and other sources, so I'm probably wrong. However that was always my understanding based on ancient hearsay and indistinct cave drawings (and by that I mean the illustrations in Vertical). :wink:

Rather than trying to work through the complicated verbiage of knot terms with Dan and others, I've taken a few photos instead. For what it's worth, I only use the version I know as a regular Butterfly knot. But if the various authoritative sources are to be believed, this knot IS the Alpine Butterfly.

Image
My Butterfly hand wrap method


Image
An extra wrap makes this some other version of the Butterfly?


Image Image
The Butterfly


Image Image
The mystery version of the Butterfly which I once thought was the Alpine :shrug:
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Re: Butterfly or Alpine Butterfly?

Postby fuzzy-hair-man » Jan 26, 2009 6:57 pm

ek wrote:
fuzzy-hair-man wrote:I found it reassuring that using twirly flops I found it actually harder to tie a false butterfly rather than an Alpine Butterfly the false butterfly tries to fall apart so you actually have to hold it together to tie it, which makes me certain I've tied the right one even before I inspect it.

Is this to say that you managed to tie a false butterfly with the finger poke method?

No I only use the twirly flop method now, it's just that if you are using the twirly flop method to tie a Alpine butterfly the twists which go in the same direction stay in place without much effort, if you are tying a false butterfly you have to put some extra effort in to make sure the twists don't untwist before you tuck the bight up through the middle. Did that explanation make any sense at all? :nuts:

ek wrote:
fuzzy-hair-man wrote:If you wanted a false butterfly you could do the half hitch over the loop of a slip knot suggested earlier in this thread.

If you did that, you would have to pay very close attention to the orientation of...everything, to make sure to get it right. I wouldn't particularly recommend this method for actually tying it.

..... after a couple more looks it does look somewhat more stable if you swap the side (back rather than front) which the half hitch is on... I hadn't noticed this previously :oops: the ukcavers forum mentions the butterfly as a knot suitable for Y hangs but you need to be careful which tail out of the knot is connected to the other anchor (the link before explains it) but the method with tying the overhand allows for easier adjustment of the length of the loop before finishing with the half hitch.

I'd prefer not to use the false butterfly anyway (I'd find the complications with it's use a bit much for the little bit of rigging time it might save) so it's all a bit irrelevant to me anyway. :shrug:
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Re: Butterfly or Alpine Butterfly?

Postby potholer » Jan 26, 2009 7:25 pm

fuzzy-hair-man wrote:No I only use the twirly flop method now, it's just that if you are using the twirly flop method to tie a Alpine butterfly the twists which go in the same direction stay in place without much effort, if you are tying a false butterfly you have to put some extra effort in to make sure the twists don't untwist before you tuck the bight up through the middle.

The way I tie it, building the growing knot up in my left hand, it's no harder to tie a false butterfly than an alpine butterfly, though I never tie false butterflies except when teaching knot tying, to show people what the wrong knot looks like.
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Re: Butterfly or Alpine Butterfly?

Postby fuzzy-hair-man » Jan 26, 2009 11:21 pm

potholer wrote:
fuzzy-hair-man wrote:No I only use the twirly flop method now, it's just that if you are using the twirly flop method to tie a Alpine butterfly the twists which go in the same direction stay in place without much effort, if you are tying a false butterfly you have to put some extra effort in to make sure the twists don't untwist before you tuck the bight up through the middle.

The way I tie it, building the growing knot up in my left hand, it's no harder to tie a false butterfly than an alpine butterfly, though I never tie false butterflies except when teaching knot tying, to show people what the wrong knot looks like.


:doh: I never really want to tie a false butterfly so I haven't spent the time playing with it much (previous to this thread anyway), I was trying to say that using a method similar to my way of tying an Alpine butterfly it was difficult to tie a false butterfly (Alpine butterfly is easier to tie using this method) so I could be sure I'd tied a Alpine Butterfly because (unless by considerable fluke) I wouldn't have done the more difficult holding it together required for the false butterfly. I accept I might be tying a false butterfly in a inefficient / more difficult way, that's OK I don't want to end up with a false butterfly. I don't even tend to use the alpine butterfly much anyway!!! :laughing:
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Re: Butterfly or Alpine Butterfly?

Postby knudeNoggin » Jan 27, 2009 8:42 pm

I don't even tend to use the alpine butterfly much anyway!


In what rigging situations is a multi- (bi-) directional eyeknot needed,
and not merely a (single) "directional" one?

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Re: Butterfly or Alpine Butterfly?

Postby potholer » Jan 28, 2009 5:09 am

knudeNoggin wrote:In what rigging situations is a multi- (bi-) directional eyeknot needed,
and not merely a (single) "directional" one?

Generally, the main place it's 'needed' is for a fraction of Y hangs where it's better than using a double-loop knot.
Personally, I tend to do *most* Y hangs with bowlines-on-the-bight, but there are times when using an Alpine Butterfly works better, such as where the arms of the Y are very long.

Also, for traverse lines, the Alpine Butterfly does seem to be the knot of choice, at least over here. Even though it's possible to use fig-8s, hardly anyone does.
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Re: Butterfly or Alpine Butterfly?

Postby Jeff Bartlett » Jan 28, 2009 5:05 pm

knudeNoggin wrote:In what rigging situations is a multi- (bi-) directional eyeknot needed,
and not merely a (single) "directional" one?


Typical caving uses of an alpine butterfly:


(1) To isolate a section of rope with a damaged sheath - here the value isn't that it can be loaded in multiple directions but, rather, that it can be loaded normally as a mid-line knot. If the rope is still in reasonable condition, the bight also makes for a handy safety loop to clip a cow's tail into when passing the knot.

(2) As the "primary" in a Y-belay where, as potholer suggests, a typical double-loop knot (double figure eight / bunny ear) isn't suitable. Situations include those where the secondary bolt is, like, directly above the primary, or where the secondary bolt is far away for some reason. These are cases where, if the primary bolt fails, the knot needs to be loaded acceptably as the weight transferring to the secondary bolt (whereas a figure eight would be loaded abnormally). Here, the "multi-directional" value of the knot is more prevalent, as without a failure the load is on the bight/eye via the primary bolt.

(3) The "middle" bolts in a bolted traverse. Load is applied first to one leg and the bight, then the other leg and the bight.

(4) Complicated rigging situations where 3 or 4 bolts in close proximity are all to be used; you can put a figure eight on the furthest one from the standing line and put alpine butterflies on the others. I haven't encountered this sort of thing but have seen photos/diagrams in rescue literature to this end.


I'm sure more experienced vertical cavers than I can think of more. I used one last month to pull slack out of the line between two pitch heads rigged with a single rope (essentially a rebelay), as I wasn't particularly comfortable with the bolt at the lower pitch; if it failed, I wanted to make sure there wasn't any unnecessary slack between my falling body and the single remaining bolt above.
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Re: Butterfly or Alpine Butterfly?

Postby ek » Jan 28, 2009 11:11 pm

xcathodex wrote:(1) To isolate a section of rope with a damaged sheath - here the value isn't that it can be loaded in multiple directions but, rather, that it can be loaded normally as a mid-line knot. If the rope is still in reasonable condition, the bight also makes for a handy safety loop to clip a cow's tail into when passing the knot.
(emphasis mine)

I strongly disagree with the idea that it is OK to clip into the loop in this situation, ever. I have never before heard anybody champion this practice, either.

If the rope is sufficiently damaged to warrant tying off the damaged section (and thus complicating progression considerably), it's too damaged to clip into that section. Tie another loop knot next to it and use that one.

xcathodex wrote:I'm sure more experienced vertical cavers than I can think of more. I used one last month to pull slack out of the line between two pitch heads rigged with a single rope (essentially a rebelay), as I wasn't particularly comfortable with the bolt at the lower pitch; if it failed, I wanted to make sure there wasn't any unnecessary slack between my falling body and the single remaining bolt above.

I remember your having told me about this. Thinking about it in the context of this discussion, it occurs to me that this may have been a situation where tying a false butterfly (due to its shock-absorption) would have been even better.

There is another kind of situation where I would use an alpine butterfly instead of a figure-eight--when I want to be able to adjust it easily. It is way easier to adjust an alpine butterfly than a figure-eight. I would never use it as an endline knot though. I've heard that there are alternate dressings for the knot that make this appropriate, but I don't know if that's true and I don't know that it's suitable for life-support rigging when tied that way.
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Re: Butterfly or Alpine Butterfly?

Postby Jeff Bartlett » Jan 28, 2009 11:26 pm

ek wrote:If the rope is sufficiently damaged to warrant tying off the damaged section (and thus complicating progression considerably), it's too damaged to clip into that section. Tie another loop knot next to it and use that one.

Fair enough. In practice, a worn sheath segment is isolated before it's anywhere near this bad; I'd isolate a bad "fuzzy" or partial tear (haven't needed to, yet) and wouldn't think twice about clipping into the loop. Likewise, in practice, if I am ever ascending up after a caver above me has isolated a very badly frayed rope segment, but not left a secondary loop -- a situation where I'd need to pass the butterfly before being able to tie another loop knot below it -- I would probably choose "sketchy bight of frayed horror" over "no secondary point of attachment while I transfer my ascenders past the knot." However, what we do in practice isn't always the best practice, and you are correct that advocating a sloppy practice is an exercise of poor judgment.


xcathodex wrote:I'm sure more experienced vertical cavers than I can think of more. I used one last month to pull slack out of the line between two pitch heads rigged with a single rope (essentially a rebelay), as I wasn't particularly comfortable with the bolt at the lower pitch; if it failed, I wanted to make sure there wasn't any unnecessary slack between my falling body and the single remaining bolt above.
EK wrote:I remember your having told me about this. Thinking about it in the context of this discussion, it occurs to me that this may have been a situation where tying a false butterfly (due to its shock-absorption) would have been even better.

If only I'd known at the time that tying a bogusly messed-up alpine butterfly would be my best bet! I thought the very same thing while hanging at the rental house reading your copy of Alpine Caving Techniques that very night. Now, having read that in the book (and I just received my copy of it today), and having been involved with this message board discussion, I will do exactly that should the need ever arise again. Though, honestly, the best choice that day would have been saying "to hell with this sketchy bolt" and turning around.
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Re: Butterfly or Alpine Butterfly?

Postby knudeNoggin » Jan 29, 2009 12:54 am

It seems that a substantial amount of usage of the Butterfly comes when
the direction of loading is known, and a directional eyeknot could also
server. That's helpful to know.

ek wrote:
xcathodex wrote:(1) To isolate a section of rope with a damaged sheath
... the {eye} also makes for a handy safety loop to clip a cow's tail into when passing the knot.
(emphasis mine)
I strongly disagree with the idea that it is OK to clip into the loop in this situation, ever.
If the rope is sufficiently damaged to warrant tying off the damaged section (and thus
complicating progression considerably), it's too damaged to clip into that section.

I recall someone once remarking about the idea of isolating a damaged part
of rope, remarking that, as most knots are around 60% or so, the rope would
have be badly damaged for tying it off to be stronger.
But here I'll suggest that there is a significant difference between one's
hanging on an eye w/damage and just leaving the part in-line: for
starters, there are two legs to the eye, so the tension is half of the
suspended, static load of one climber; whereas inline its subject to
some greater force of ascending and an accident. Esp. if there is
substantial rope undamaged, you're looking at 1-2+ tons of strength.

I would never use it as an endline knot though.

Although, of course, that's how it's tested, qua eyeknot.
But here you'd have to confront its asymmetry head-on
(or ignore it blindly), and choose which way to form it.

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Re: Butterfly or Alpine Butterfly?

Postby ek » Jan 29, 2009 12:42 pm

xcathodex wrote:Fair enough. In practice, a worn sheath segment is isolated before it's anywhere near this bad; I'd isolate a bad "fuzzy" or partial tear (haven't needed to, yet) and wouldn't think twice about clipping into the loop. Likewise, in practice, if I am ever ascending up after a caver above me has isolated a very badly frayed rope segment, but not left a secondary loop -- a situation where I'd need to pass the butterfly before being able to tie another loop knot below it -- I would probably choose "sketchy bight of frayed horror" over "no secondary point of attachment while I transfer my ascenders past the knot." However, what we do in practice isn't always the best practice, and you are correct that advocating a sloppy practice is an exercise of poor judgment.

I would choose to put on my third point of attachment near the knot (which is a Prusik loop) and clip to that while ascending past the knot, and then to remove it and tie an appropriate loop knot just below or above it (probably another alpine butterfly, readily distinguishable from the first by having a way smaller loop[1]).

If I didn't have my Prusik loop (perhaps I am already using it for ascending, having lost my upper ascender?), I would tie a loop knot--like a figure-eight on a bight--in the rope below me and clip it to my harness maillon with a locking carabiner. I would also clip the possibly-load-bearing knot.

If somehow none of these were options, then yes, I would rather be clipped to the bad loop rather than to nothing at all.

knudeNoggin wrote:I recall someone once remarking about the idea of isolating a damaged part
of rope, remarking that, as most knots are around 60% or so, the rope would
have be badly damaged for tying it off to be stronger.

Well, I'm certainly not saying that.

If the sheath of a piece of rope is damaged, then the rope is subject to rapid additional damage at that location. This is the case whether or not it is weighted. This trumps any considerations of how strong the rope happens to be at any particular point where we already know it is strong enough! If a rope has localized physical damage that reduces the strength just a bit, then still, that it is a part of the rope that is subject to being damaged further. Furthermore and specifically, abrasion of the body of a knot is bad only in the long term--it is not an immediate problem, generally. Abrasion of a standing piece of rope is a serious concern if that piece of rope is damaged, especially if the damage is to the sheath, and most especially if the sheath is actually nonexistent at that location.

If it's become damaged in use, then that means that it will most likely become more damaged at that location by the same mechanism that it was damaged initially. Tying off a damaged section of rope may often be accompanied (as soon as it is possible) with a modification to the rigging. But even if it is not, at least an undamaged section of rope is taking over. The knot loop can be enlarged by successive climbers if necessary to contain additional damaged rope.

Physically damaged rope is actually weak, in the qualitative sense that it is likely to break. If it breaks, it is probably not because it was overloaded while hanging free, but because it was cut against an edge (or perhaps by ascenders biting into the core repeatedly...or less likely, one of them doing so in a second shockload event).

Knots are strong, in the qualitative sense that they are unlikely to break. It is OK to have a knot in a rope, in almost all situations (i.e. in all field situations except a minority of highlines stretched very tight and taking very high loads). The rope likely has a knot in it farther up, that would break at around the same tension as the loop knot used to tie off the damaged section. If the rope runs over any edges, even if padded, it will likely break at the edges instead of the knot. If the rope runs (in single strand) through a carabiner or pulley at a high angle, there is some chance that it will break there instead of at the knot.

If you think about the kind of fall that would be necessary to produce forces high enough to break the rope at the knot (i.e. forces of about 2/3 the strength of the rope, since knots in kernmantle rope tend to weaken rope by 1/3 on average), well, take such a fall on ascenders and the ascenders sever the sheath and pull it down, limiting the loading and preventing knots from breaking. Or the ascenders would simply cut the rope--then the rope would break at the ascender-rope interface, and not at the knot. Now suppose you're descending. Then in a shockload your descender would slip, and hopefully you would be able to maintain control as the speed increases above what you had intended, perhaps while swinging against a wall. Suppose you have an auto-braking descender (or a descender with a braking assist, if that is the politically correct term for it these days..since they do not always break by themselves). Well, that will still slip. They are designed to slip...and it would be hard to design one that didn't slip anyway, even if you tried, because you would either have to have an exceedingly long handle or need to apply a tremendous force to move. Sometimes they do damage rope, though. They could even, like an ascender, cut the sheath and pull it down. While this is unlikely, it is theoretically possible for a descender to sever the rope in this situation. (Please note that, aside from the possibility in a shockload of swinging or falling into walls, or dislodging falling rocks, this is actually a safer situation than a free-fall rappel terminated by a release of the brake handle. In a very fast rappel, the friction surfaces of the auto-braking descender become very hot, so then the descender could potentially cut the sheath and melt the core. That is unlikely here.) Whatever happens, like in the case of ascenders, the force applied is limited to being way below what would break a knot.

So when could a knot actually be broken in a vertical caving situation? Well, it's unlikely, which is perhaps why it has (as far as I know) never happened. It is possible. I think the most likely cause would actually be exposure to the part of the rope with the knot in it to dangerous chemicals, e.g. sulfuric acid. However, if we're talking about a properly functioning rope, then no correct use would result in such a breakage. Incorrect use, i.e. really big shock loads, probably having to be bigger than FF1, could do it. But when ascending or descending normally, as detailed above, this cannot happen. Something else will give or break first. Well, there are two situations where the rope could break at the knot. One is when you are actually tied to the rope--in this post, I have already detailed one situation where I would tie a knot in the rope and clip myself to it. If there were another knot above this, that knot might break if the rope were overloaded. But the knot I'm tied to would be just as likely to break, and in any case the actual difference in the rope's strength would be minuscule.

The other situation, which may be more common, is that the descender is hard-locked off. Well, guess what, this is essentially another knot, and I think that the rope would be much more likely to break as it enters a hard-locked descender (of any type) than at another knot along its length. But it could break at the knot. Again, even if it did, at a very slightly higher load on the rope entering the descender, it would be able to break there. So again, the overall strength is not significantly reduced by the knot being in the rope.

I conclude this argument with a statement that is common sense to many cavers and rope users: Except in highly technical and particular situations (i.e. some highlines), knots in a rope do not actually weaken it significantly in a real world situation.

knudeNoggin wrote:But here I'll suggest that there is a significant difference between one's
hanging on an eye w/damage and just leaving the part in-line: for
starters, there are two legs to the eye, so the tension is half of the
suspended, static load of one climber; whereas inline its subject to
some greater force of ascending and an accident. Esp. if there is
substantial rope undamaged, you're looking at 1-2+ tons of strength.

This is also a good point. If you have to load a damaged part of a rope, best to load it doubled.

ek wrote:I would never use it as an endline knot though.

knudeNoggin wrote:Although, of course, that's how it's tested, qua eyeknot.
But here you'd have to confront its asymmetry head-on
(or ignore it blindly), and choose which way to form it.

That is typically how its loop-loaded strength is tested. My unwillingness to rig with an alpine butterfly as an endline knot is not due to any concern about its strength. It's because the alpine butterfly can easily come loose in that configuration--the rope entering the knot from either side is not held firmly in place, and it would be awkward at best to back up (or, more properly, add a security extension) to an alpine butterfly as one does with the bowline.

[1] When tying off a damaged section of rope, there should be at least four inches of rope in the loop on either side of the damaged area to ensure that the damaged area doesn't come back into the knot. Pretend the rope is simply nonexistent in the damaged area--then the alpine butterfly bend needs to have four inch--or longer--tails.
Eliah Kagan
NSS 57892
Syracuse University Outing Club

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ek
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Name: Eliah Kagan
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