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When would you use an alpine butterfly over a figure of 8 or bowline??
In reply to An Triubhas: I only ever use it for rigging abseils where you're equalising several pieces spread over a large area.
In reply to An Triubhas:
It holds up well under a 3 way load, and is easy to untie after it has been weighted. That makes it quite well for a tie in to the middle of a rope or equalising anchors.
It holds up well under a 3 way load, and is easy to untie after it has been weighted. That makes it quite well for a tie in to the middle of a rope or equalising anchors.
In reply to davidbeynon: that is what I was thinking for the middle of the rope situation. Would a figure of 8 do the same job but would just tighten lots?
How come nobody ties into alpine butterflies say at the indoor wall???
How come nobody ties into alpine butterflies say at the indoor wall???
In reply to An Triubhas:
It just gives you a loop, and is easiest to tie in the middle of a rope so you really need a screwgate to attach with one. If you are on the end of a rope then a figure of 8 or bowline is more convenient and gives no risk of cross loading metalwork.
A rethreaded figure of 8 on a bight will let you tie in to the middle without any extra bits, but uses a hell of a lot of rope.
There was another method I was taught recently on a crevasse rescue course involving overhand knots and a screwgate, which is apparently preferred to the butterfly nowadays. Can do it, but can't tell you what to google for.
It just gives you a loop, and is easiest to tie in the middle of a rope so you really need a screwgate to attach with one. If you are on the end of a rope then a figure of 8 or bowline is more convenient and gives no risk of cross loading metalwork.
A rethreaded figure of 8 on a bight will let you tie in to the middle without any extra bits, but uses a hell of a lot of rope.
There was another method I was taught recently on a crevasse rescue course involving overhand knots and a screwgate, which is apparently preferred to the butterfly nowadays. Can do it, but can't tell you what to google for.
In reply to An Triubhas:
Because it's an overly complicated answer?
> (In reply to davidbeynon) that is what I was thinking for the middle of the rope situation. Would a figure of 8 do the same job but would just tighten lots?
>
> How come nobody ties into alpine butterflies say at the indoor wall???
>
> How come nobody ties into alpine butterflies say at the indoor wall???
Because it's an overly complicated answer?
In reply to timjones: ok, thanks, only wondered!
My thinking was say someone who is going to take a lot of falls say at the wall who is a beginner then the knot would be easier to undo???
My thinking was say someone who is going to take a lot of falls say at the wall who is a beginner then the knot would be easier to undo???
In reply to An Triubhas:
just use a bowline with a stopper. much easier to tie.
> (In reply to timjones) ok, thanks, only wondered!
>
> My thinking was say someone who is going to take a lot of falls say at the wall who is a beginner then the knot would be easier to undo???
>
> My thinking was say someone who is going to take a lot of falls say at the wall who is a beginner then the knot would be easier to undo???
just use a bowline with a stopper. much easier to tie.
In reply to An Triubhas: You're a very curious gentleman, aren't you!
In reply to An Triubhas: Nothing at all, just an observation.
In reply to higherclimbingwales:
Better to make an effort and learn what every knot is good for than just use the figure of 8 for *everything*.
Investing time and effort in ropework is always worthwhile.
Better to make an effort and learn what every knot is good for than just use the figure of 8 for *everything*.
Investing time and effort in ropework is always worthwhile.
In reply to An Triubhas: The ONLY time I've used it was for the middle man on a rope when travelling as a 3 over a glacier.
Al
Al
In reply to An Triubhas: you can use it for a top rope set up as well
In reply to Gaston Rubberpants: but even then it is limited as if you leave the loop too small you don't have enough freedom in the system to move about without being pulled back and forth.
much better to over-hand a large bight and over hand the end of that to form a smaller bight for you to attach yourself to.
much better to over-hand a large bight and over hand the end of that to form a smaller bight for you to attach yourself to.
In reply to jon: I didn't say you couldn't but it's easier and quicker to just do an overhand.
In reply to jon:
Indeed, an AB is fully adjustable...
> (In reply to highclimber)
>
> What makes you think you can't make a big loop with an AB?
>
> What makes you think you can't make a big loop with an AB?
Indeed, an AB is fully adjustable...
In reply to An Triubhas: Cavers tell me they use it a lot. Many mountain rescue teams use it with stretchers due to its ability to take 3 way loading safely.
In reply to ankyo:
this doesn't mean it's any more useful in a climbing capacity than the usual fig 8/overhand/bowline. There are situations where an AB is appropriate like when building a belay where you've got a piece in line with another but I wouldn't use it for tying-in to the middle of the rope over the method I described earlier with over hand knots
> (In reply to An Triubhas) Cavers tell me they use it a lot. Many mountain rescue teams use it with stretchers due to its ability to take 3 way loading safely.
this doesn't mean it's any more useful in a climbing capacity than the usual fig 8/overhand/bowline. There are situations where an AB is appropriate like when building a belay where you've got a piece in line with another but I wouldn't use it for tying-in to the middle of the rope over the method I described earlier with over hand knots
In reply to An Triubhas:
It is ideally suited to situations which involve a multi-directional (3-way) load.
Neither the figure of 8, bowline, or overhand are as good for a multi-directional load.
It is used most often when there are 3 people on a rope.
Cheers
It is ideally suited to situations which involve a multi-directional (3-way) load.
Neither the figure of 8, bowline, or overhand are as good for a multi-directional load.
It is used most often when there are 3 people on a rope.
Cheers
In reply to An Triubhas:
Why would you? It's good for forming loops that will tolerate any combination of strands being loaded but it'd be a rubbish tie-in. I'm struggling to think how you'd form it let alone why.
jk
> How come nobody ties into alpine butterflies say at the indoor wall???
Why would you? It's good for forming loops that will tolerate any combination of strands being loaded but it'd be a rubbish tie-in. I'm struggling to think how you'd form it let alone why.
jk
In reply to An Triubhas:
Also good for:
isolating a damaged section of rope
backing up a shunt when TRSing
As for creating an isolation loop for tying into the middle of the rope if people are happy to ab off an EDK why not use one for this purpose too?
Also good for:
isolating a damaged section of rope
backing up a shunt when TRSing
As for creating an isolation loop for tying into the middle of the rope if people are happy to ab off an EDK why not use one for this purpose too?
In reply to An Triubhas:
When you're in the Alps of course (or any time more than 2 people on 1 rope are crossing a glacier).
When you're in the Alps of course (or any time more than 2 people on 1 rope are crossing a glacier).
In reply to andic:
What is an EDk ? I mean which one of 2 or 3 knots that that term has been used for, not what its short for ?
If you mean a simple overhand knot, yes you can use one instead but the multiway loading is likely to make it a sod to untie.
What is an EDk ? I mean which one of 2 or 3 knots that that term has been used for, not what its short for ?
If you mean a simple overhand knot, yes you can use one instead but the multiway loading is likely to make it a sod to untie.
In reply to An Triubhas: I wouldn't know how to tie an AB around my harness. Rethreading a fig8 or bowline is easy.
If I needed a knot or a loop in the middle of a rope, I'd put an AB because its easiest and fastest.
This could be from the way I've learnt the AB from a book.
From my understanding it's a very stable knot.
If I needed a knot or a loop in the middle of a rope, I'd put an AB because its easiest and fastest.
This could be from the way I've learnt the AB from a book.
From my understanding it's a very stable knot.
In reply to Ross Mathers:
...which it also copes with that just fine.
Double overhands are not so easy to adjust and do get very tight very quickly which are the main reasons you might choose to use an Alpine Butterfly over the 'EDK' in some instances.
jk
> Because the load on a EDK when abbing is bi-directional not multi-directional.
...which it also copes with that just fine.
Double overhands are not so easy to adjust and do get very tight very quickly which are the main reasons you might choose to use an Alpine Butterfly over the 'EDK' in some instances.
jk
In reply to andic:
Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
> (In reply to An Triubhas)
>
> Also good for:
> isolating a damaged section of rope
> backing up a shunt when TRSing
>
> Also good for:
> isolating a damaged section of rope
> backing up a shunt when TRSing
Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
In reply to Wide_Mouth_Frog:
....IMHO
> (In reply to andic)
> [...]
>
> Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
> [...]
>
> Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
....IMHO
In reply to An Triubhas: As davidbeynon rightly stated it can be used to equalise anchors, but is most commonly used for travel on glaciers.
Can't visualise a situation where you would use it on an indoor climbing wall!
Can't visualise a situation where you would use it on an indoor climbing wall!
In reply to jkarran:
1.) The overhand is not recommended as a multi-directional knot.
2.) As you say it would be really difficult to untie if after being heavily loaded.
1.) The overhand is not recommended as a multi-directional knot.
2.) As you say it would be really difficult to untie if after being heavily loaded.
In reply to Wide_Mouth_Frog:
I ddn't say how......
> (In reply to andic)
> [...]
>
> Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
> [...]
>
> Bad idea. If the shunt slips (like they do!) and slams into the knot, it can deform and pop off the rope. You're better off taking the drop and letting the shunt do its thing
I ddn't say how......
In reply to An Triubhas:
The answer to your question is, you should use a AB when you require a loop in the middle of the rope, and a Fig 8 (or bowline) when you require a loop at the end of the rope.
Yours,
Neilnt
> When would you use an alpine butterfly over a figure of 8 or bowline??
The answer to your question is, you should use a AB when you require a loop in the middle of the rope, and a Fig 8 (or bowline) when you require a loop at the end of the rope.
Yours,
Neilnt
In reply to An Triubhas:
You've cause me to go and get a bit of absei tat and practise this knot again. Off to Alps in two weeks and that's the only place I use it, and only when we have a rope of three. So not that often.
You've cause me to go and get a bit of absei tat and practise this knot again. Off to Alps in two weeks and that's the only place I use it, and only when we have a rope of three. So not that often.
In reply to Ross Mathers:
Where, by who? It works just fine although the over tightening issue makes it unattractive for jobs where it'll be heavily or cyclically loaded.
jk
> 1.) The overhand is not recommended as a multi-directional knot.
Where, by who? It works just fine although the over tightening issue makes it unattractive for jobs where it'll be heavily or cyclically loaded.
jk
In reply to andic:
Basically the shunt is designed to slide down the rope when you fall to cushion the fall, if there's a knot there then the shunt COULD still have a lot of energy when it hits the knot and this COULD be enough to damage/warp it enough to pop off the rope. I think, like most things in climbing, AFAIK the risk of this happening is pretty small, but still a risk nonetheless.
Basically the shunt is designed to slide down the rope when you fall to cushion the fall, if there's a knot there then the shunt COULD still have a lot of energy when it hits the knot and this COULD be enough to damage/warp it enough to pop off the rope. I think, like most things in climbing, AFAIK the risk of this happening is pretty small, but still a risk nonetheless.
In reply to jkarran:
My understanding is that the use of a overhand knot in a multi-directional load is undesirable as it reduces the strength of the rope by > 50%.
Every type of knot reduces the strength of a rope by some greater or lesser amount.
A figure-of-nine knot will reduce the strength of the rope to around 80% of its original strength.
An alpine butterfly will reduce the strength of the rope to around 70% of its original strength.
An overhand knot will reduce the strength of the rope to around 60% of its original strength under bi-directional load - but less than 50% under multi-directional load.
8mm rope has a typical shear force of around 15kn's:
An overhand knot used multi-directionaly reduces the strength of the rope to < 7 kn`s.
An abseiler weighing 100kg`s exerts a downward static force of 1kn
So the safety factor is 7:1
Good practice suggests that a safety factor of 10:1 is the minimum safety factor acceptable in life threatening situations.
As you point out - using an overhand under multi-directional load will make it extremly difficult to untie - another reason for not it not being recommended.
My understanding is that the use of a overhand knot in a multi-directional load is undesirable as it reduces the strength of the rope by > 50%.
Every type of knot reduces the strength of a rope by some greater or lesser amount.
A figure-of-nine knot will reduce the strength of the rope to around 80% of its original strength.
An alpine butterfly will reduce the strength of the rope to around 70% of its original strength.
An overhand knot will reduce the strength of the rope to around 60% of its original strength under bi-directional load - but less than 50% under multi-directional load.
8mm rope has a typical shear force of around 15kn's:
An overhand knot used multi-directionaly reduces the strength of the rope to < 7 kn`s.
An abseiler weighing 100kg`s exerts a downward static force of 1kn
So the safety factor is 7:1
Good practice suggests that a safety factor of 10:1 is the minimum safety factor acceptable in life threatening situations.
As you point out - using an overhand under multi-directional load will make it extremly difficult to untie - another reason for not it not being recommended.
In reply to Ross Mathers:
Out of curiosity, where did those numbers come from and in the context of a 3 (or 4way) loading which tension are we referring to when we say the knot reduces the rope strength by 50%, max tension in any strand? Also I don't quite see how the knot can shear the rope.
Anyway, taking those figures at face value I don't see them as particularly troubling, even with your 15kN 8mm (down to ~7kN) that's plenty strong enough for normal careful use. Edges and abrasion and operator error would still be my main concerns.
Anyway, thanks for fleshing out your post.
jk
Out of curiosity, where did those numbers come from and in the context of a 3 (or 4way) loading which tension are we referring to when we say the knot reduces the rope strength by 50%, max tension in any strand? Also I don't quite see how the knot can shear the rope.
Anyway, taking those figures at face value I don't see them as particularly troubling, even with your 15kN 8mm (down to ~7kN) that's plenty strong enough for normal careful use. Edges and abrasion and operator error would still be my main concerns.
Anyway, thanks for fleshing out your post.
jk
In reply to An Triubhas: IIRC as well as being a standard knot in Alpine mountaineering for tying on in the middle of a rope (e.g. when moving as a three/four etc...) its geometry lends its suitability, as already mentioned, in situations where a multi-directional load could be applied, for example when setting up a single rope retrievable abseil. In this situation, whilst an EDK, double-stopper, or fig 8 can be used to join the retrieval cord to the abseil rope, the alpine butterfly is used from the dead rope together with a locking karabiner to krab back onto the abseil rope below the anchor allowing the rope to 'lock' around the anchor.
I'm assuming that when the live rope is loaded the AB would be loaded in two of the three directions in which it can be loaded and that after abbing, when the cord is pulled on and the live rope is (hopefully) free-running through the krab, you are in effect loading the AB in the third direction. Not sure if this would work as well with an EDK or fig 8 due to their geometry and the possibility of the knots being deformed, though I'm sure someone on here might have tested one or both of them in this situation, which I have not. If so I, for one, would be pleased to know their thoughts on having used something other than an AB when setting up a single rope retrievable abseil.
I'm assuming that when the live rope is loaded the AB would be loaded in two of the three directions in which it can be loaded and that after abbing, when the cord is pulled on and the live rope is (hopefully) free-running through the krab, you are in effect loading the AB in the third direction. Not sure if this would work as well with an EDK or fig 8 due to their geometry and the possibility of the knots being deformed, though I'm sure someone on here might have tested one or both of them in this situation, which I have not. If so I, for one, would be pleased to know their thoughts on having used something other than an AB when setting up a single rope retrievable abseil.
In reply to jkarran:
There are a lot of publications available that contain information about knots and knot strength. The figures I used are those which are provided by Sterling Ropes.
Here is a list of some common knots and the remaining rope strength when used Bi-directionally.
NO Knot 100%
Double Fisherman's 65-70%
Bowline 70-75%
Water Knot 60-70%
Figure 8 75-80%
Clove Hitch 60-65%
Fisherman's 60-65%
Overhand 60-65%
All knots reduce the overall strength of a rope. Therefore, whenever possible it's best to use a tensionless knot around a cylindrical object with at least a 4’’ diameter. Four inches is the magic number for maintaining full strength in a rope up to 5/8’’. Any bend tighter than 4’’ reduces the strength of rope because they stress the rope in flexure, the fibers’ weaker direction.
7KN may might not be of concern (personally I think it's pretty low), but we were just talking about what is "recommended" as best practice.
There are a lot of publications available that contain information about knots and knot strength. The figures I used are those which are provided by Sterling Ropes.
Here is a list of some common knots and the remaining rope strength when used Bi-directionally.
NO Knot 100%
Double Fisherman's 65-70%
Bowline 70-75%
Water Knot 60-70%
Figure 8 75-80%
Clove Hitch 60-65%
Fisherman's 60-65%
Overhand 60-65%
All knots reduce the overall strength of a rope. Therefore, whenever possible it's best to use a tensionless knot around a cylindrical object with at least a 4’’ diameter. Four inches is the magic number for maintaining full strength in a rope up to 5/8’’. Any bend tighter than 4’’ reduces the strength of rope because they stress the rope in flexure, the fibers’ weaker direction.
7KN may might not be of concern (personally I think it's pretty low), but we were just talking about what is "recommended" as best practice.
In reply to Wide_Mouth_Frog:
A better way would be to use an AB on a separate strand to give an independant back up
A better way would be to use an AB on a separate strand to give an independant back up
In reply to andic:
Yarp!
> (In reply to Wide_Mouth_Frog)
>
> A better way would be to use an AB on a separate strand to give an independant back up
>
> A better way would be to use an AB on a separate strand to give an independant back up
Yarp!
In reply to Ross Mathers:
I wouldn't worry about that if we are talking dynamic ropes.
Unless you are hauling your car up a climb with you or your partner has taken it a bit too far with the pies the night before, static strength within climbing ropes is irrelevant, and for that reason their static strength is not even tested and disclosed.
That is because all the rope has to be able to do is to reduce the impact force from a fall to something manageable by it, so if a rope can absorb enough energy to produce a maximum impact force of, let's say, 1kn, then the rope would be adequate even if its static strength was as little as 2kn. (Theoretically of course).
I wouldn't worry about that if we are talking dynamic ropes.
Unless you are hauling your car up a climb with you or your partner has taken it a bit too far with the pies the night before, static strength within climbing ropes is irrelevant, and for that reason their static strength is not even tested and disclosed.
That is because all the rope has to be able to do is to reduce the impact force from a fall to something manageable by it, so if a rope can absorb enough energy to produce a maximum impact force of, let's say, 1kn, then the rope would be adequate even if its static strength was as little as 2kn. (Theoretically of course).
In reply to Mr Lopez:
Yep, agreed (theoretically).
Although I'm not sure that I'd feel confident on a 2KN rope dynamic or static!!
Cheers
Yep, agreed (theoretically).
Although I'm not sure that I'd feel confident on a 2KN rope dynamic or static!!
Cheers
This is a very interesting thread.
As stated EN 892 deals with elongation and maximum arrest force during drop testing (12 kN for single ropes) rather than strength.
The UIAA standard for a harness of 12 kN is alligned with this thinking and also historical work conducted by Amphoux and his cohort. They found that 95% of the population of test subjects escaped un-hurt when experiencing an MAF of 12kN after drop testing into a harness. The EN for fall arrest lanyards halved this value (6kN), and the Americans and Canadians adopted 8kN as their standard.
Just be careful in assuming that 7kN is strong enough. I think that this is way too low when you consider the potentially high forces generated on runners, rule of thumb 2 x MAF at a change of direction due to the pulley effect could result in forces in the order of 22kN which explains the high strength requirements of karabiners.
Therefore the static safety factor of 7:1 (7 X 1kN climber body weight) will not accommodate the forces generated in a high fall factor event, especially when multiplied at a change of direction. Actually the dynamic safety factors in these instances are just adequate, (1 point something to 1).
The 10:1 factor mentioned in rescue situations was proposed in BC in the late 80s. Their premise was that a rescue system could experience 15kN when subjected to a worst case event (there are specific circumstances describing this). Consider a rescue sized load to be 2kN (conservative!) then adopting a safety factor of 10:1 means building the system to a 20kN rating, which would withstand the 15kN worst case event should it happen. This pemise does not apply to climbers and mountaineers.
The AB as a mid-point tie in option - absolutely as others have described. Just tie to loop long enough so that you can use it to tie in with (say bowline on the bite with a yosimite finish) so you do not have to clip in with a krab. Clipping with a krab in un-tensioned situations that can experience a sudden loading invite cross-loading of the krab.
As stated EN 892 deals with elongation and maximum arrest force during drop testing (12 kN for single ropes) rather than strength.
The UIAA standard for a harness of 12 kN is alligned with this thinking and also historical work conducted by Amphoux and his cohort. They found that 95% of the population of test subjects escaped un-hurt when experiencing an MAF of 12kN after drop testing into a harness. The EN for fall arrest lanyards halved this value (6kN), and the Americans and Canadians adopted 8kN as their standard.
Just be careful in assuming that 7kN is strong enough. I think that this is way too low when you consider the potentially high forces generated on runners, rule of thumb 2 x MAF at a change of direction due to the pulley effect could result in forces in the order of 22kN which explains the high strength requirements of karabiners.
Therefore the static safety factor of 7:1 (7 X 1kN climber body weight) will not accommodate the forces generated in a high fall factor event, especially when multiplied at a change of direction. Actually the dynamic safety factors in these instances are just adequate, (1 point something to 1).
The 10:1 factor mentioned in rescue situations was proposed in BC in the late 80s. Their premise was that a rescue system could experience 15kN when subjected to a worst case event (there are specific circumstances describing this). Consider a rescue sized load to be 2kN (conservative!) then adopting a safety factor of 10:1 means building the system to a 20kN rating, which would withstand the 15kN worst case event should it happen. This pemise does not apply to climbers and mountaineers.
The AB as a mid-point tie in option - absolutely as others have described. Just tie to loop long enough so that you can use it to tie in with (say bowline on the bite with a yosimite finish) so you do not have to clip in with a krab. Clipping with a krab in un-tensioned situations that can experience a sudden loading invite cross-loading of the krab.
In reply to summitjunkie:
You can also use a clove hitch on the karabiner. Bit quicker to tie and untie.
Yours,
Neilnt
> If so I, for one, would be pleased to know their thoughts on having used something other than an AB when setting up a single rope retrievable abseil.
You can also use a clove hitch on the karabiner. Bit quicker to tie and untie.
Yours,
Neilnt
In reply to neilnt: Now, I discounted using a clove hitch because the bi-directional -vs- tri-directional thing and the fact that you can make the loop in the AB as long as you like which might help in setting up. Will have to give it a try and see if I feel comfy with it.
In reply to An Triubhas: some good demos on you tube showing quick ways of tying the ab knot ..very very easy and quick to tie once you know how.
dont know why but i love tying and learning new knots is this odd ?
dont know why but i love tying and learning new knots is this odd ?
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