Author Topic: Which knots for Y hangs?  (Read 2550 times)

Offline Jon

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Re: Which knots for Y hangs?
« Reply #25 on: February 14, 2019, 09:51:57 pm »
For y-hangs I currently terminate the traverse line at the first y-hang bolt, take a single line down to a fusion knot with one loop kept short as a central belay loop and the long loop connecting to the second y-hang bolt. Hopefully the picture has worked.
It uses less rope than a typical bunny ears knot, still has a central belay loop, won't slip and is easy to adjust.

Can anyone tell me if there's anything wrong with this? I'm coming at it from a best practice \ instructing angle.

Offline christopher

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Re: Which knots for Y hangs?
« Reply #26 on: February 14, 2019, 10:55:10 pm »
Well, I'm not sure those coat hangar hooks are unquestionably reliable  :)
Now be thankful for good things below

Offline JasonC

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Re: Which knots for Y hangs?
« Reply #27 on: February 14, 2019, 11:14:04 pm »
Interesting, Jon, can't see a problem with it.

But it wouldn't work substituting your fusion knot with a bunny-ears: with the latter on both anchors of a Y-hang, the two loops will self-balance, in your set-up, I could see the little belay loop being self-balanced out of existence!

Offline Mark Wright

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Re: Which knots for Y hangs?
« Reply #28 on: February 14, 2019, 11:55:58 pm »
For y-hangs I currently terminate the traverse line at the first y-hang bolt, take a single line down to a fusion knot with one loop kept short as a central belay loop and the long loop connecting to the second y-hang bolt. Hopefully the picture has worked.
It uses less rope than a typical bunny ears knot, still has a central belay loop, won't slip and is easy to adjust.

Can anyone tell me if there's anything wrong with this? I'm coming at it from a best practice \ instructing angle.


Coming at it from a best practice / instructing angle, particularly with novices, the well established, tried and tested Fig. 8, 9, Bunny & Alpine Butterfly would definitely be the best starting point. I would consider a Fusion Knot to be a more 'advanced user' type of knot.

When you get to a pitch head you want to be able to instantly recognise that the knots and rigging are safe. If you asked 100 cavers if they recognised the correct tying of the traditional 4 above I would say at least 80% would recognise them. I bet only 10% would recognise the correct tying of a Fusion Knot.

I like to think I know a bit about knots through tying them as a major part of my job for the past 35 years and being a member of the International Guild of Knot Tyers, but I certainly wouldn't recognise the correct tying of a Fusion Knot.

I've not seen the results of any professional testing to comment on whether there's anything wrong with it in terms of the amount of strength loss, including any variations in its tying or any likely slippage in the small central loop but, in an industrial / professional novice training environment, the very fact that it is not easily recognisable would be sufficient for its use not to be considered as best practice.   

If it's ever proven to be safer and over 80% of cavers can easily tie it and/or recognise it, then, with its extra (insignificant really) saving in rope, best practice could develop and see its more widespread use.

I've seen quite a few fancy cow's tail and rigging knots come and go over the years. I'll wager the Fusion Knot will be another one, with just a handful of cavers keeping them alive.

Mark

Offline ZombieCake

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Re: Which knots for Y hangs?
« Reply #29 on: February 15, 2019, 01:18:12 am »
Doesn't matter about the elegance of the embroidery, or a few newtons here or there. If it fails you're stuffed. Minimizing failure is good, I think.

Offline andrewmc

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Re: Which knots for Y hangs?
« Reply #30 on: February 15, 2019, 07:12:48 am »
I was unconvinced by the Fusion until I was shown how to tie a Bowline on a Bight by first tying an overhand on a bight and then reaching through the loop to grab the two new loop. The fusion is the logical extension of this, but replacing the overhand with a Fig 8.

But I was quite surprised, when messing around with rigging at Whitewalls on shiny 8mm, to see a Fusion slip quite a bit when heavily loaded sideways on the incoming traverse line. Rope was pulled from the unloaded Y-hang loop into the loaded Y-hang loop, potentially messing up your careful balancing for a clean hang. That said, I suspect a BoB/Fig 8 BE would have been worse, and I've not seen on it thicker rope.

In TobyK's example, I don't really like it because I'd not really be sure of the motivations. I wouldn't clip the little loop, even though that might reduce the fall if the right hand bolt failed, because that loop comes out of the top of the knot instead of the bottom. I think it will pull the knot in funny ways of loaded (rolling it apart). I also worry about that little loop being pulled tight (although it can't actually pull through).

Offline Jon

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Re: Which knots for Y hangs?
« Reply #31 on: February 15, 2019, 07:21:33 am »


Minimizing failure is good, I think.

I agree. Are you saying this setup is less safe than others?

Offline Jon

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Re: Which knots for Y hangs?
« Reply #32 on: February 15, 2019, 07:28:24 am »


I was unconvinced by the Fusion until I was shown how to tie a Bowline on a Bight by first tying an overhand on a bight and then reaching through the loop to grab the two new loop. The fusion is the logical extension of this, but replacing the overhand with a Fig 8.

But I was quite surprised, when messing around with rigging at Whitewalls on shiny 8mm, to see a Fusion slip quite a bit when heavily loaded sideways on the incoming traverse line. Rope was pulled from the unloaded Y-hang loop into the loaded Y-hang loop, potentially messing up your careful balancing for a clean hang. That said, I suspect a BoB/Fig 8 BE would have been worse, and I've not seen on it thicker rope.

In TobyK's example, I don't really like it because I'd not really be sure of the motivations. I wouldn't clip the little loop, even though that might reduce the fall if the right hand bolt failed, because that loop comes out of the top of the knot instead of the bottom. I think it will pull the knot in funny ways of loaded (rolling it apart). I also worry about that little loop being pulled tight (although it can't actually pull through).

The little loop hasn't slipped yet when I've used it, which did surprise me at first. The loading of the knot due to where the little loop comes out of the knot is what concerns me but it's not caused any issues so far. The knot does stay remarkably stable in use.

Offline Jon

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Re: Which knots for Y hangs?
« Reply #33 on: February 15, 2019, 07:41:23 am »


For y-hangs I currently terminate the traverse line at the first y-hang bolt, take a single line down to a fusion knot with one loop kept short as a central belay loop and the long loop connecting to the second y-hang bolt. Hopefully the picture has worked.
It uses less rope than a typical bunny ears knot, still has a central belay loop, won't slip and is easy to adjust.

Can anyone tell me if there's anything wrong with this? I'm coming at it from a best practice \ instructing angle.

the very fact that it is not easily recognisable would be sufficient for its use not to be considered as best practice.   


Mark

I'm glad you commented, I value your input. I feel that the "not easy to recognise \ not in common use" arguement does have some merit in personal caving as everyone can probably rig and will be looking at the rigging and making a judgement. Although if we wait for 80% usage surely nothing will ever change?

When taking clients they won't know what they are looking at and rigging with minimal rope and loops and one easy to clip central belay loop has its advantages.

On wide y-hangs the saving in rope length over a traditional 2 loop bunny ears is helpful and it's far easier to clip into than the two loops of a bunny ears of almost any variety which also negates the need for a central "master" krab for clients to clip into.

Offline caving_fox

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Re: Which knots for Y hangs?
« Reply #34 on: February 15, 2019, 09:30:26 am »
For y-hangs I currently terminate the traverse line at the first y-hang bolt, take a single line down to a fusion knot with one loop kept short as a central belay loop and the long loop connecting to the second y-hang bolt. Hopefully the picture has worked.
It uses less rope than a typical bunny ears knot, still has a central belay loop, won't slip and is easy to adjust.

Can anyone tell me if there's anything wrong with this? I'm coming at it from a best practice \ instructing angle.

/Not an instructor.

If I met that at a pitch head I'd be concerned. I don't like the central loop, as it's unfamiliar to me, and looks like the knot hasn't been dressed correctly.  I don't like the butterfly as the 'approach' knot because it's at a strange angle (will very much depend on bolt placement), and could be very awkward to reach the rest of the traverse depending on available footing.

I'd rig it with the 'spare' loop brought up to the middle 'bolt', or if that wasn't available with two single fig8s, or most likely with a double fig8 and terminate the traverse a knot earlier - all very much depending on the actual pitch head.
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Online MarkS

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Re: Which knots for Y hangs?
« Reply #35 on: February 15, 2019, 10:08:08 am »
Can anyone tell me if there's anything wrong with this? I'm coming at it from a best practice \ instructing angle.

I've never used a fusion knot, but at first glance it looks to me like a figure 8 that's being loaded in (almost) opposite directions.

Offline Leclused

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Re: Which knots for Y hangs?
« Reply #36 on: February 15, 2019, 10:40:58 am »
In the latest Spelunca (no 152 - 2018) there is a complete article about "Les noeuds en Y".

https://ffspeleo.fr/spelunca-59-17.html 

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Offline Mike Hopley

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Re: Which knots for Y hangs?
« Reply #37 on: February 15, 2019, 11:09:43 am »
Quote
On wide y-hangs the saving in rope length over a traditional 2 loop bunny ears is helpful and it's far easier to clip into than the two loops of a bunny ears of almost any variety which also negates the need for a central "master" krab for clients to clip into.

I can understand your motivation here, but I don't think it's a good idea. You're loading the knot in a way it's not "designed" to be loaded, and that makes its behaviour unpredictable, especially with a relatively "loose" knot such as the fusion.

The fusion has been tested plenty by the French (I believe), but not in this configuration. It's probably okay, but you'd need a lot of testing to make that "probably" into a "definitely".

If you want to keep the same setup, but without loading the knot dubiously, I'd recommend the "Diju" knot as shown in this EFS paper [PDF, page 15]. This knot is formed from a bunny-ears fig-8, with one of the loops passed underneath all three lower strands, creating a clip-in loop that loads correctly.

The Diju knot is intended for use with direct dyneema attachments, which are sometimes very difficult to clip into (e.g. a single-anchor rebelay). Using it on a Y-hang is not the intended application, but the direction of load should be okay.

Offline Jon

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Re: Which knots for Y hangs?
« Reply #38 on: February 15, 2019, 11:44:11 am »
Thanks Mike, I'll look at that. The "incorrect loading" was also my main concern.

Offline Jon

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Re: Which knots for Y hangs?
« Reply #39 on: February 15, 2019, 11:59:11 am »
In the latest Spelunca (no 152 - 2018) there is a complete article about "Les noeuds en Y".

https://ffspeleo.fr/spelunca-59-17.html 

Dagobert
I've followed your link to the online contents list, I assume that the articles only appear in a printed magazine?

Offline Leclused

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Re: Which knots for Y hangs?
« Reply #40 on: February 15, 2019, 01:12:25 pm »
In the latest Spelunca (no 152 - 2018) there is a complete article about "Les noeuds en Y".

https://ffspeleo.fr/spelunca-59-17.html 

Dagobert
I've followed your link to the online contents list, I assume that the articles only appear in a printed magazine?

Indeed (also see PM)
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Offline Mark Wright

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Re: Which knots for Y hangs?
« Reply #41 on: February 15, 2019, 03:15:28 pm »
Although if we wait for 80% usage surely nothing will ever change?

When taking clients they won't know what they are looking at and rigging with minimal rope and loops and one easy to clip central belay loop has its advantages.

On wide y-hangs the saving in rope length over a traditional 2 loop bunny ears is helpful and it's far easier to clip into than the two loops of a bunny ears of almost any variety which also negates the need for a central "master" krab for clients to clip into.

Things will only change when a new knot or technique is proven beyond doubt to be significantly safer than that currently used. I doubt very much that a Fusion Knot is a game changer. As MarkS points out, it does look as though the knot is being misloaded in the 'Y' hang configuration.

As I said before, any saving in rope will be negligible. You wouldn't be using a Bunny Knot for wide 'Y' hangs anyway as a Fig. 8 or 9 and an Alpine Butterfly would be the most appropriate knots to use in this situation. A Bunny Knot is for use when anchors are relatively close together.

I would have thought if you were taking 'clients' on an SRT course/trip it would be paramount that they have a good understanding of what they are looking at in terms of safe rigging.

Mark

Online maxf

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Re: Which knots for Y hangs?
« Reply #42 on: February 15, 2019, 04:10:47 pm »
What's the advantage of the figure of 9 over the 8 ?

Ease of un-tieng ?

Offline Mark Wright

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Re: Which knots for Y hangs?
« Reply #43 on: February 15, 2019, 04:17:02 pm »
What's the advantage of the figure of 9 over the 8 ?

Ease of un-tieng ?

A Fig. 9 is a little stronger than an 8 though negligible really. The main advantage, as you say, is its ease of untying. Mind you, It'll still be hard to untie if a lot of people have been using it and bouncing on it as they invariably do.

Mark

Offline Mike Hopley

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Re: Which knots for Y hangs?
« Reply #44 on: February 15, 2019, 04:23:21 pm »
Quote
As MarkS points out, it does look as though the knot is being misloaded in the 'Y' hang configuration.

Yeah, this is another less-than-ideal aspect. Jon -- this issue will still be there if you substitute the Diju for the Fusion, although perhaps less worrying due to the Diju being more "solid".


Quote
You wouldn't be using a Bunny Knot for wide 'Y' hangs anyway as a Fig. 8 or 9 and an Alpine Butterfly would be the most appropriate knots to use in this situation.

Well I generally would, because I don't like creating a section of rope that is unsafe to clip into -- especially when it's a wide Y hang, because then it might be hard to reach the next section (the traverse) with a cowstail.

While this can be negotiated safely with a jammer, I rarely see people actually do that. That's not to say the rigging is unsafe in itself, it's just less user-friendly. The amount of rope saved is small, so I'd rather just make the rigging nicer for people. And accurately measuring a wide double-loop knot is easy when you know how, so both methods take about the same amount of time.

Offline Chocolate fireguard

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Re: Which knots for Y hangs?
« Reply #45 on: February 15, 2019, 05:02:00 pm »



Quote
You wouldn't be using a Bunny Knot for wide 'Y' hangs anyway as a Fig. 8 or 9 and an Alpine Butterfly would be the most appropriate knots to use in this situation.

Well I generally would, because I don't like creating a section of rope that is unsafe to clip into -- especially when it's a wide Y hang, because then it might be hard to reach the next section (the traverse) with a cowstail.

While this can be negotiated safely with a jammer, I rarely see people actually do that. That's not to say the rigging is unsafe in itself, it's just less user-friendly. The amount of rope saved is small, so I'd rather just make the rigging nicer for people. And accurately measuring a wide double-loop knot is easy when you know how, so both methods take about the same amount of time.
[/quote]

Yes.

I don't understand why this isn't said more often. When passing a wide Y-hang on the way up, especially when carrying a heavy bag, it's so much easier if it has been rigged with a bunny-ears or similar, when the next rope comes to the bottom of the Y.  It can be passed easily and safely.

And with a free hanging Y-hang re-belay to make it as easy with a Fig. whatever and an alpine butterfly the loop that has to be left is such that no rope will be saved.

Offline Mark Wright

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Re: Which knots for Y hangs?
« Reply #46 on: February 15, 2019, 05:25:24 pm »
Well I generally would, because I don't like creating a section of rope that is unsafe to clip into -- especially when it's a wide Y hang, because then it might be hard to reach the next section (the traverse) with a cowstail.

What section of a Fig. 8/9 and Alpine Butterfly wide 'Y' hang is unsafe to clip that is any different to clipping into a wide 'Y' hang tied with a Bunny Knot? I've certainly used an ascender attached to the single rope part of a 'Y' hang in order to reach a traverse but you obviously wouldn't be able to use an ascender to do that with a Bunny Knot or the rope would simply pull through the anchor point.

I have absolutely no issues at all with using a Bunny Knot for wide 'Y' hangs, it just uses more rope. There aren't many situations I can think of where transferring from the rope to a traverse line is that difficult to achieve. If it is such a big reach why not put some slack in the traverse line so your cow's tail will reach.

Every pitch head has its own peculiarities but can generally always be safely rigged with a combination of the traditional knots as previously mentioned.

Mark

Offline mikem

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Re: Which knots for Y hangs?
« Reply #47 on: February 15, 2019, 08:40:56 pm »
Surely the bottom of the fusion knot should have both strands hanging down in the same way that a figure 8 should, otherwise the bottom of the knot will deform.

Maybe the BFK is what you are looking for, the double loops go to the anchors & the single can be used as clip in (if made smaller than shown)....

« Last Edit: February 15, 2019, 09:11:09 pm by mikem »

Offline Mark Wright

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Re: Which knots for Y hangs?
« Reply #48 on: February 15, 2019, 09:09:21 pm »
The BFK, or Big Fucking Knot to give it it's full name, is another one of those knots that comes and go's.

The main issue with it is that when loaded it seriously deforms and becomes almost impossible to see whether it's tied correctly. There is so much rope in the knot that if you tested it 10 times you would likely get 10 significantly different test results.

Some tried to introduce this into the industrial environment about 20 odd years ago. After considering the points above it was not adopted as a suitable knot for industrial use.

Mark

Offline andrewmc

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Re: Which knots for Y hangs?
« Reply #49 on: February 16, 2019, 07:25:02 am »
What section of a Fig. 8/9 and Alpine Butterfly wide 'Y' hang is unsafe to clip that is any different to clipping into a wide 'Y' hang tied with a Bunny Knot? I've certainly used an ascender attached to the single rope part of a 'Y' hang in order to reach a traverse but you obviously wouldn't be able to use an ascender to do that with a Bunny Knot or the rope would simply pull through the anchor point.

I think you are being slightly disingenuous by saying you don't know which bit it is unsafe to clip (the single strand, obviously) and then saying you have used your ascender on it - which doesn't count as 'clipping' it.

I would argue any traverse line approach you have to put an ascender on is awkward. Ideally traverse line should be fairly tight, which precludes using your descender to approach the pitch head and makes ascending tricky. If the pitch head is that much lower than the traverse bolts, then possibly a short rebelay from the traverse bolt/bolts would be easier anyway, but it is often much easier if the traverse line goes straight to the pitch head.

Leaving the traverse line slack enough so that you can reach means you don't have a tight traverse line and you use extra rope anyway.