I generally use a Figure of Eight and an Alpine Butterfly for rigging Y-Hangs. However a number of years ago I was caving with a friend who used a different method. Anyway, the other night I was discussing Y-Hangs with a mate and we were trying to figure out how to rig one this alternative way.

Basically a Figure of Eight loop goes in the first bolt then at the point where you want the rope to hang you tie and overhand slip knot. The loop of the slip knot is lengthened until it reaches the second bolt and then a bit of extra slack is added, then that loop was hitched around the main rope (I think) before clipping it back into the second bolt.

I hope people can understand what I mean. I can't find this method refered to anywhere, but I believe my friend was taught it on a cave leader assessment. It was definately a quicker way of rigging a Y-Hang and I'm interested in potentially using it.

Has it got a particular name, and has it got any drawbacks?

Sounds like the ordinary butterfly knot as opposed to the Alpine Butterfly. The two loops that have gone around the anchor loop don't loop through each other whereas they do for the Alpine Butterfly. It means you can offer up the anchor loop and get the adjustment right before putting the second loop over, and then attaching to the anchor.

Maj.

I know this variant as the cavers butterfly, and use it extensively in my rigging. I was taught this method by the late Ralph Johnson, who later went on to become a CIC 

I may have to post a photo of the knot. It doesn't look like a butterfly knot. Perhaps I'm tying it incorrectly.

Second stage of Y-Hang rigging - Figure of Eight on first anchor and overhand slip knot with loop to second anchor.


Completed Y-Hang


Close up of knot. It looks odd. What is it? Is it correct? Is it safe?

Hmm! Yes I had misunderstood the last hitch with the anchor loop.
My unqualified thoughts:-
Looks reasonable.
The down rope is clamped in the knot by both sides of the anchor loop before it goes through a tight bend, and if I recall correctly what I've previously read. During drop testing, the rope usually fails at the first tight bend as the down rope goes through the knot.
It does however look as if it could be a bit fiddly to make further adjustments once tied.

Maj.

It certainly sounds like the 'Caver's Butterfly', otherwise referred to as an incorrectly tied Alpine Butterfly knot. I remember having a long discussion with Ralph about why CIC's taught the knot. At a glance it is difficult to tell them apart.

I was taught the 'Caver's Butterfly' by Rory Gregory when he ran the Whitehall Centre in the mid 80's so it has been on the CIC syllabus for some time.

I don't have the figures for the difference in strengths at hand but the 'Alpine Butterfly' is the strongest and is the only one that is equally as strong in all directions and as such is the only true 'Mid-Rope Knot'. It is known as the 'Queen of Knots' by the International Guild of Knot Tyers (IGKT).

Dave Elliots book shows the 'Cavers Butterfly' but calls it an 'Alpine Butterfly'. There's no wonder there is so much confusion.   

I'm not sure where the 'Caver's Butterfly' came from but a mountaineering friend of mine in the 80's suggested it was a well known alpine method of rigging traverses as it was much easier to tie than an 'Alpine Butterfly' if wearing bulky mittens. He called the 'Butterfly' loop a 'Hero Loop' finished off with a half hitch to secure it.

Looking at the photographs its very difficult to see how you get from 1 to 2 because 2 looks like a variation on the 'Lazy 8' but without any of the benefits. I wouldn't be surprised if whoever taught you got the 'Caver's Butterfly' and the 'Lazy 8' mixed up. The tight hitch around the end going to the Fig 8 will be the very weak link in the configuration and will likely cost <50% of strength loss compared to around 35% for an 'Alpine Butterfly'. 

Are you familiar with the 'Lazy 8'? Its a great alternative to the 'Alpine Butterfly' but you will find some don't like the look of it as it looks like a Fig 8 that's been tied incorrectly. 

Mark

Thanks for the replies.

I'm not 100% sure that I've tied it correctly, it was a long time ago when I was shown it.  Having not done any SRT for a long time I had a bit of a reminder session in Devonshire the other week. I used Figure of Eights and Alpine Butterflies to rig the Y-hang but being out of practice I thought I was a bit slow. I remembered how fast my friend had rigged Oxlow all those years ago so tried to remember his knot.

At the end of the day I'd sooner be slow but safe when rigging, rather than fast and not so safe, especially when I'm trying to get my missus doing SRT.

Mark - I'm not familiar with the Lazy 8 Knot and didn't get anything worthwhile from a Google search.

Would an in-line figure-of-eight be appropriate instead of the butterfly knot?

I've just been looking on Youtube and Andy Sparrow shows rigging a Y-hang using a Butterfly Knot rather than an Alpine Butterfly.
I always thought the Butterfly was a weaker knot.

Andy Sparrow is shown in this clip tying what I think is the Alpine Butterfly BUT the video refers to it as the cavers butterfly https://youtu.be/rzzRg66IKHQ

Cant find a video ATM, but the way I tie the cavers butterfly would be to tie a slipknot as shown in your first pic, with the slippy down the pitch / towards the expected load, rather than back along the traverse (as shown). Once adjusted for length a bight from below the knot is passed over the loop to form a hitch to lock the knot in place. It isnt clear to me if your picture shows this finish?

I think the knot I tied in the photo is wrong ( It was along time ago!)

After rigging a y-hang with a Butterfly knot (not an Alpine Butterfly) and then deconstructing the Butterfly by removing a hitch you are left with the Slip Knot and loop.

I think my friend showed me what you call the Cavers Butterfly all those years ago.

I'm still not convinced that Andy Sparrow is using an Alpine Butterfly in his video, he's tying what I've always thought to be a standard Butterfly Knot. The two loops that he forms are not linked as in an Alpine Butterfly.

Does anyone know if Spanish Bowlines are suitable for Y-hangs? It looks neat and evenly-spread when tied, but apparently it can slip if not tightened up. Tried tying it a few times but it often falls to bits in my hands.

An 'In-Line Fig 8' is another name for a 'Lazy 8'. I'm not familiar with any industrial testing of the knot but I would imagine, from the way the rope sits, it would be about as strong as an 'Alpine Butterfly' and maybe slightly less than a standard 'Fig 8'. They are great for single point re-belays and ensure no abnormal loading of the knot if the re-belay anchor fails.

I've seen some interesting rigging over the years but simple is usually best. 'Double Fig 8 on the Bight' ('Bunny Knot' with the common loop sitting on TOP), when the anchors are close together and a 'Fig 8 on the Bight' or 'Fig 9 on the Bight' and an 'Alpine Butterfly' when the anchors are a bit further apart. I always tie 'Fig 9's' as they are usually easier to untie than 'Fig 8's', unless I'm rethreading a 'Fig 8' around something. 'Fig 9's' are a little bit stronger than 'Fig 8's' though the difference is negligible unless knots are properly dressed and set, which they rarely are.

I know 'Double Bowlines' are regularly used for rigging, particularly in France, but again, unless they are properly dressed and set they immediately deform under load and cannot easily be visually examined. I remember following a team down Nettle Pot in Derbyshire. I arrived at the top of Elizabeth as the last man had just set off down. Looking at the knot, what the knot-tyer probably thought was a 'Double Bowline', I could see it slipping quite a lot whenever the abseiler bounced during his descent. I never did work out how it had been tied, it wasn't in the Ashley Book Of Knots. I re-rigged it with a 'Fig 9' and and 'Alpine'. There was some testing shown on this forum about the potential consequences of clipping a cow's tail into the loops of a 'Double Bowline'. The very fact that it is necessary to tie a 'safety' stopper knot behind the 'Bowline' should suggest the knot is unsuitable in favour of a more suitable knot that is stronger, easier to tie, easy to visually inspect and easy to untie after use, e.g. 'Fig 8 on the Bight' or a 'Fig 9 on the Bight'.     

When it comes to knots, the BMC do a great job of endorsing what in industry would be regarded as bad practice. I work at the Glastonbury Festival every year running the free climbing wall in the Kidz Field. There is a mixture of cavers and climbers on the teams and every year when we have our first safety briefing there is usually another BMC recommendation about how we attach the harness to the rope.

If I were risk assessing the attachment method there would be no question in my choice, a double or triple twisted 'Scaffold Knot' with a triple action connector. This would ensure the carabiner cannot be cross loaded and 5 year olds fingers cannot undo the carabiner accidentally. 

Unfortunately the procedures the company who supply the wall follow say they always follow the recommendations of the BMC so its a screw gate carabiner attached loosely in a 'Fig 8' loop, with a 'Half Double Fisherman' stopper knot. This year the stopper knot was only tied around the tail of the knot (around itself). The year before the stopper knot was tied around both itself and the 'Live' part of the rope.

Apparently the change came about following someone clipping into the gap between the main knot and the stopper knot. I can't remember the detail of what happened next but CIC's on here should know about it.

The issue of a stopper knot in addition to a 'Fig 8' has been discussed at length in industry. The consensus is that there is absolutely no need for it. As far as I am aware there has never been a reported case of a 'Fig 8' unravelling itself under load but there has been at least 1 accident because a stopper knot was used.

I think the BMC advice on joining ropes suggests tying the 2 ends with a simple 'Overhand Knot'. Dynamic rope is generally a lot softer than low stretch rope and so you will probably get away with the knot staying firm if you pull the ends apart but if you did that with anything other than new low stretch rope it is likely the knot would unravel if pulled apart with any significant force. I've witnessed that test, its not a method I would recommend with low stretch rope, particularly if it still feels new.

Mark 

Having looked at the knot in the OP and played with it on a bit of rope at home I would be happy enough to use it if somebody had rigged it. It won't slip. It is not as easy as an alpine butterfly to adjust, but I almost always use the Bunny Ears at Y-hangs and that is worse than either. I use it because I find it easier to judge the loop on a rebelay, and for a Y-hang at the end of a rope traverse there is a rope within easy reach of a caver coming up. I do try to dress it properly, but nobody's perfect and I dare say I don't always get it right.

I suppose nowadays we must all (not just instructors and the like) be prepared to show that we have used the "best" knot.

It's possible that in some situations the best knot is not the strongest.
The energy absorbed by a knot as it tightens is important on short drops on static rope. It reduces the peak load.
I don't know of any sources that give information on the energy absorbed by different knots at various loads, although they may well exist because it would be easy enough to do in a slow static pull.

When I rig on trips with friends I use knots which are considered to be "the best" (allowing for differences of opinion between knowledgeable people), likewise if I am showing people how things are done.

But if I was following somebody who elected to rig entirely with overhand knots in 8mm rope I would follow along nicely without saying anything so long as everything else was standard (no rub points, traverse lines correctly tensioned, rebelay loops about right). It doesn't do to be too much of a knot nazi.

I would expect them to untie the knots after the trip. And if I came to a point where 2 ropes had been tied together with an overhand knot I would make my excuses and leave.

I'm interested to see how it tightens after a bit of bouncing.

Chocolate fireguard said:

I suppose nowadays we must all (not just instructors and the like) be prepared to show that we have used the "best" knot... &  It's possible that in some situations the best knot is not the strongest.

Click to expand...

Just my tuppence worth and not picking on you Chocolate Fireguard but developing/having a thought about what you said and is often overheard, is this...

There isn't really a wrong  or right knot, though there might be occasions when one might trump another(*). We all know that knots reduce the strength of a rope, and in spite of everything that's written down the figures that are claimed in terms of a % of rope strength retained are often misleading. The tests are usually conducted on new rope. Usually dry or consistent in their 'wetness'. They're not usually covered in crap and are often at above cave temperatures. The bottom line is the spread of strength retained across a range of knots varies massively.

What seems to be happening from reading papers on rope access, rope rescue and manufacturer literature is that it's fair to judge every knot as reducing the overall strength of a rope to 50%. It's very blunt but there is certain logic to it. But when all is said and done (not by me but by Pit Schubert at UIAA) ropes don't break... They can fail when cut or abraded or chemically altered, but in normal use, they just don't break. We keep out ropes away from chemicals (generally!) and rig to avoid cuts or abrasion hazards so the choice of knot, for me personally and professionally comes down to two things - form and function.

If I'm leading a group I might use a certain set of knots to perform a function e.g. a two loop knot into which I can rig everything centrally - the function here is convenience.

How does this relate to the OP and drawbacks? Well it probably doesn't matter which knot goes where - there is counter logic to even the most steadfastly adhered to principles (take the Alpine Butterfly on a traverse for example). What it might do is confuse or instil either an inquisitive glance or downright fear in those following! I could also see it being a real sod to undo (its form?) (**)

Worthy of note is what might happen should an anchor point within a Y-hang fail -  how would they change the form of the knot? I've very briefly tested a 'caver's butterfly' - the slip knot with a turn placed around it - and had it slip on a wet rope when simulating one anchor point in a Y-hang failing. By no means is this conclusive but the 'caver's butterfly isn't a knot I use as I'm not sure what superior advantage it serves (quicker to tie? Get better at tying knots  )

(* Ropes categorised as really lightweight ropes 8mm and such need tying according to people like Marbach with figure of nine loops - make your own mind up)

(** Knots that are easy to untie in a given situation make for a compelling argument to be used. If you consider that much of the energy absorbed within a rope system comes about at the knot, then it's my conclusion that if the knot is easy to undo after operation then it's probably got quite a margin of 'shock absorbing' capability in reserve.

For what it's worth, if I'm caving by myself I invariably use fig 8 loops for everything...

I believe that the practice in mountaineering of joining two ropes by an overhand knot is solely for when a double rope needs to be used in an abseil. The overhand knot apparently doesn't tend to snag when the ropes are pulled down.

lots of discussion at http://www.needlesports.com/content/abseil-knots.aspx

al said:

I believe that the practice in mountaineering of joining two ropes by an overhand knot is solely for when a double rope needs to be used in an abseil. The overhand knot apparently doesn't tend to snag when the ropes are pulled down.

lots of discussion at http://www.needlesports.com/content/abseil-knots.aspx

Click to expand...

I use an overhand knot in this situation, with another overhand knot immediately behind it to mitigate against the chance of slippage. Probably OTT but when abseiling past the Castellan Cave on High Tor you don't want to be worrying about knot.

I wouldn't join caving ropes this way though.

I would have assumed that if it was necessary to use two ropes then this would be for a double rope abseil or abseiling on a single rope with the other rope rigged in a pull-through arrangement. In a double rope abseil there will only be half the load on the actual joining knot and in a pull through arrangement there would be no load on the joining knot, it would merely be jamming up against the anchor point.

It seams the main reason for the current choice is its ease of going over edges. If this is the case and ropes are going over an edge then the actual load that will be applied to the knot will likely be very low.

In this situation you would probably apply the greatest force to the knot when you actually pull the double rope down.

Mark