Alpine Butterfly

[Geoff R]

The simple Alpine Butterfly ??

Alpine Caving Techniques (dont mean to advertise) highlights the way to recognise an Alpine Butterfly and a "false" Alpine Butterfly. Both knots look identical apart from how a rope crosses another. They say the false butterfly should only be used as a shock absorbing knot.

It just happens I've only learnt methods that tie a "true" Alpine Butterfly

But does it really make such difference - any thoughts & comment ??

 

[Cave_Troll]

yes .
the false buterfly can easily come undone.
Thus if you were to try and use it to tie out a rub point the bottom end of the rope could fall off.

 

[biffa]

Try tieing both in a rope. The 'true' alpine butterfly doesn't matter which way it's loaded. T'other one will stretch out a fair way when incorrectly loaded

 

[Rachel]

yes .
the false buterfly can easily come undone.
Thus if you were to try and use it to tie out a rub point the bottom end of the rope could fall off.

That's a bit worrying. Could someone in the know post some pics?

 

[darkplaces]

is this the right one?
http://www.animatedknots.com/fig8loopdouble/

 

[Stu]

is this the right one?
http://www.animatedknots.com/fig8loopdouble/

Yes... well it appears to be, it's quite swift even on the slow setting.

 

[Les W]

http://www.animatedknots.com/fig8loopdouble/

What a really useful website

Most excellent.

 

[AndyF]

..err....so how do you tie the false butterfly .... :?:

 

[Les W]

is this the right one?
http://www.animatedknots.com/fig8loopdouble/

Yes... well it appears to be, it's quite swift even on the slow setting.

I don't think that this is the one. The link is for a double Fig 8 on a bight.

The false Alpine butterfly which Geoff R refers to is generally just called the Butterfly Knot (No "Alpine") in the UK. It has been used by cavers for decades with no problems if used in the correct setting.
It is identical in appearance to the Alpine Butterfly Knot except on the rear of the knot the two parts of the rope are parallel and in the Alpine Butterfly they cross over each other. This crossover makes the knot more secure.
Some people have an issue with the Butterfly Knot because "Experts" say that it can slip or deform, this is true, but when used in the correct way it is not an issue and does not compromise saftey. The Butterfly should be used in the middle of a rope for rigging "Y" hangs or tension traverses. It is simple and easy to tie and very easy to adjust> It is absolutely secure in these situations.
It should NOT be tied in the end of a rope (by end I mean not trapped between two other knots) as it could concievably come undone in some situations.

The Alpine Butterfly is slightly more complex to tie (although not by much) It is also harder to untie when it has been loaded. It is more dificult to adjust due to the crossover, this can be an issue when rigging long "Y" hangs, such as the one in Stream Passage Pot, where it is already difficult enough without having to struggle adjusting the rigging any more than necessary. When used in the same setting as the Butterfly it is no more secure.

Perhaps we should start a debate on the most suitable knots...
...on second thoughts it has probabaly already been done here somewhere

 

[Les W]

..err....so how do you tie the false butterfly .... :?:

For those of you who have had some sort of knot tying training the "False Alpine Butterfly" is the one where you are told to start with "Mickey Mouse Ears"

 

[Stu]

..err....so how do you tie the false butterfly .... :?:

Right... are you paying attention at the back? Good. Then we'll begin.

Take cord and make a loop (as you would when starting to tie a bowline). Pass one of the two strands (it doesn't matter but lets call it strand A) and pass it through the "hole" so you have a slip knot. Take strand B and make a similar "loop" as when you started this whole mess. Strand B must be at the bottom of this new loop. The new loop now goes over the the other loop as if you were crowning it. Set the knot and pull the two strands apart. You have what now looks either like rope noodles or a false butterfly.

 

[Stu]

is this the right one?
http://www.animatedknots.com/fig8loopdouble/

Yes... well it appears to be, it's quite swift even on the slow setting.

I don't think that this is the one. The link is for a double Fig 8 on a bight.

The false Alpine butterfly which Geoff R refers to is generally just called the Butterfly Knot (No "Alpine") in the UK. It has been used by cavers for decades with no problems if used in the correct setting.
It is identical in appearance to the Alpine Butterfly Knot except on the rear of the knot the two parts of the rope are parallel and in the Alpine Butterfly they cross over each other. This crossover makes the knot more secure.
Some people have an issue with the Butterfly Knot because "Experts" say that it can slip or deform, this is true, but when used in the correct way it is not an issue and does not compromise saftey. The Butterfly should be used in the middle of a rope for rigging "Y" hangs or tension traverses. It is simple and easy to tie and very easy to adjust> It is absolutely secure in these situations.
It should NOT be tied in the end of a rope (by end I mean not trapped between two other knots) as it could concievably come undone in some situations.

The Alpine Butterfly is slightly more complex to tie (although not by much) It is also harder to untie when it has been loaded. It is more dificult to adjust due to the crossover, this can be an issue when rigging long "Y" hangs, such as the one in Stream Passage Pot, where it is already difficult enough without having to struggle adjusting the rigging any more than necessary. When used in the same setting as the Butterfly it is no more secure.

Perhaps we should start a debate on the most suitable knots...
...on second thoughts it has probabaly already been done here somewhere

Of course. I just went straight to the menu on the left for the Alpine. The link does indeed go to a fig 8.

 

[Les W]

There has been a bit of a holy war in our club (Wessex) about the best knot to use. I apply the KISS principle with the addition that anything which is easy to untie after it has been loaded is better.

The point I made about adjustment on a dificult pitch head holds true. Anyone who has rigged the big "Y" hang on the second pitch of Stream will know that you don't want to be fiddling with knots whilst hanging from a sloping ledge over a large drop. I always end up bridged over the pitch and always get "Disco leg" whilst trying to set the hang

 

[Geoff R]

Les W and all,

thank you very much for your inputs on this. The problem I was having was that although I have only ever tied Alpine butterfly's, I could not see why the so called "false" method was apparently so unusable, provided you took a little care of the circumstances.

Seems its not such a black and white subject as certain books make out.

However from all the comments, would it be reasonable to say that if in any doubt, always tie a "true" Alpine Butterfly ??

 

[Cave_Troll]

indeed.
most knots that form loops do not actually need the continuity of the loop to maintain the bottom bit of the rope being attached to the top bit.
The exception is the plain butterfly or the "cavers buterfly"
I've always called it the Cavers butterfly when explaining it to rescue types, but have never actually known any cavers that intentionally use it.

 

[MSD]

According to a nice report proced by the Combined Services
http://www.cs-caving-association.com/Reports/Knots%20A5.pdf
the false butterfly has strengths of

transverse 53%
Longitudinal 67%

The CS report doesn't give a strength for the alpine butterly, but Life on a Line quotes 60-70%, without making a clear distinction about transverse
and longitudinal loading. See www.draftlight.net/lifeonaline

Obviously these results are not exactly comparable, but a reasonable conclusion is that the false butterfly is very slighty weaker than the alpine butterfly.

I nearly always use the false butterfly, as opposed to the alpine butterfly. It's easier to tie and adjust and easier to untie afterwards. It is a little more sensitive to being set correctly, but I've never found that to be a problem.

Unless you are caving on really lightweight rope, the loss of strength seems a non-issue.

Mark

 

[Brains]

I habitually use the cavers butterfly rather than the alpine as it is easier to tie, adjust and undo.
My way of tying it? - Tie a slip not in the rope so it will pull undone in the direction of load, then take a bight from this side and pass it back over the slip knot loop to lock it off. Before locking the loop can be easily pulled out to the required length or tension.
I have no worries as to its strength - more than enough.

 

[Les W]

I habitually use the cavers butterfly rather than the alpine as it is easier to tie, adjust and undo.
My way of tying it? - Tie a slip not in the rope so it will pull undone in the direction of load, then take a bight from this side and pass it back over the slip knot loop to lock it off. Before locking the loop can be easily pulled out to the required length or tension.
I have no worries as to its strength - more than enough.

My way of tying it.
Form two loops of opposite hand (Mickey Mouse Ears) put them together and take the lower part of rope (between the loops) and pull it up and through the two loops. Job done, now adjust and set.

I always use the "Cavers Butterfly" for the reasons I gave previously and repeated above by others.
It really is much easier to adjust in tricky situations, it has never failed/slipped when set properly (and even if it did it cannot go anywhere or be any less secure if used properly) and it is easier to untie after it has been loaded. It is quite a versatile knot as well.

 

[Les W]

According to a nice report proced by the Combined Services
http://www.cs-caving-association.com/Reports/Knots%20A5.pdf
the false butterfly has strengths of

transverse 53%
Longitudinal 67%

The CS report doesn't give a strength for the alpine butterly, but Life on a Line quotes 60-70%, without making a clear distinction about transverse
and longitudinal loading. See www.draftlight.net/lifeonaline

Obviously these results are not exactly comparable, but a reasonable conclusion is that the false butterfly is very slighty weaker than the alpine butterfly.

I nearly always use the false butterfly, as opposed to the alpine butterfly. It's easier to tie and adjust and easier to untie afterwards. It is a little more sensitive to being set correctly, but I've never found that to be a problem.

Unless you are caving on really lightweight rope, the loss of strength seems a non-issue.

Mark

I agree, in MOST situations, on MOST ropes, the strength of the knot is a complete red herring. A rope with a breaking strain of around four tonnes when tied with a knot of even 50% strength still has a breaking strength of two tonnes, thats a lot of pies

 

[MSD]

One issue which nobody has mentioned is that when you tie a Y-hang with a false butterfly, there are two ways of tying it. When you put the loops one on top of the other (before poking the middle loop through), you can have the "upstairs" or "downstairs" loop on top.

In my experience, it s best to have the "downstairs" loop underneath (assuming you are poking the middle loop through from above). This means that the "downstairs" loop presses against the "upstairs" loop. This is more secure because the downhill part of the rope necessarily has a larger force on it (the load is shared between the two arms of the Y-hang). The knot tends to self-set better this way.

It was a while before I worked this out. I always wondered why sometimes the knot seemed to set OK, but other times seemed to pull apart into a less than ideal shape.

Mark