Do most people rig Y hangs with two loops

[Stu]

I moved away from rigging a Y using a BotB as my standard as I have never felt comfortable with this knot if only loaded from one of its loops by a cowtail.  Also did not choose the Fig 8 version due to the lay of the traverse rope into the knot when rigging tight.   

Purely out of interest and in no way starting a bun fight: would you explain the last sentence, the rationale behind it, cheers?

 

[Stu]

Makes sense to me; it uses less rope than the BotB as well and so arguably is more efficient in that regard.

Surprisingly it doesn't! I thought this for ages then went out with a marked rope and rigged different lay outs of bolts (sad I know).

With Glenn's rig, what I would call sport rigging, you have two knots (off one anchor and one at the "Y"). Also the rope travels slightly further in the sport rig set up (traverse line to bolt then down to the "Y"), whereas in the double loop variation the rope travels straight to the knot at the "Y".

Granted there are going to be exceptions and a million subtle ways of tying the knots in different places along the rope, but on the whole it rubbished my perception (and my belief of the statement too) of the mantra it used less rope. It's marginal at best I would conclude.

 

[Penguin]

Makes sense to me; it uses less rope than the BotB as well and so arguably is more efficient in that regard.

Surprisingly it doesn't! I thought this for ages then went out with a marked rope and rigged different lay outs of bolts (sad I know).

With Glenn's rig, what I would call sport rigging, you have two knots (off one anchor and one at the "Y"). Also the rope travels slightly further in the sport rig set up (traverse line to bolt then down to the "Y"), whereas in the double loop variation the rope travels straight to the knot at the "Y".

Granted there are going to be exceptions and a million subtle ways of tying the knots in different places along the rope, but on the whole it rubbished my perception (and my belief of the statement too) of the mantra it used less rope. It's marginal at best I would conclude.

I suspect there's a cut of point where it uses more rope than a bunny ears - i would have thought that on a wide Y-hang it becomes more efficient as one of the loops is reduced to a single strand. 

Personally i never liked the bowline on bight, and usually rig a bunny ears (figure eight on bight), or figure eight + alpine butterfly.  Choosen according to the configuration of the pitchhead.  Yes the bunny ears uses a bit more rope than a bowline on bight, but you should have brought enough rope..  However it is no harder to adjust, or untie, and is arguably harder to tie wrongly. 

 

[Stu]

Thing is Penguin even with a wide hang it was similar length.  Mulling it over, but being no mathematician, I'd guess it has something to do with triangles and hypotenuse. Certainly there may be a cut off point, but from then on I've relatively discarded it as a worry.

Equally it could be tester error!  ;-)

 

[NOZ]

Penguin - it is very easy to tie a bunny ears incorrectly. The part of the knot that is common to both loops must sit correctly in the knot. Otherwise the knot will self adjust.

Stu - with 90deg between the arms of the Y-hang, fig8 plus alpine becomes more "efficient" than bunny ears at anchor separations >~2ft. This separation will be greater when comparing with BotB but <4ft I would hazard.

Stu - I think what GeoffR is getting at is; bunny ears knot is best dressed if loops have separation <60deg and tails enter knot vertically from below, not possible if traverse line is tight.

 

[ianball11]

Thanks Glenn, I do the same as you, sporty rigging.

I like sporty rigging as the traverse line is out of the way to one side, and not down the centre of the passage, I feel it's neater, so less confusing when people arrive at the top possible knackered.

 

[Stu]

Stu - with 90deg between the arms of the Y-hang, fig8 plus alpine becomes more "efficient" than bunny ears at anchor separations >~2ft. This separation will be greater when comparing with BotB but <4ft I would hazard.

Have you used some formula for that? I've forgotten everything about maths though agree that measured from bolt to bolt BotB would use more but then I'd say you should include rope from the penultimate bolt (traverse line in?). I tested this out (and I loosely and guardedly use the word test) whilst rigging Jingling Pot from the tree via the internal/cleft route. Over the course of two drops (low sample I guess), there was no difference.

There's no major conclusion really, and I bet there are a mass of flaws to shoot me down; but in practice it made no difference. 

Quick self edit: I suppose why I got got hold of this stick is it's one of those statements that's easily said (I hear debate about which knot is quicker to tie all the time at the wall and the crag --- wtf!) but in reality it isn't worth losing any sleep over; as I'm sure neither of us are! 

Stu - I think what GeoffR is getting at is; bunny ears knot is best dressed if loops have separation <60deg and tails enter knot vertically from below, not possible if traverse line is tight.

Ok. Interested to hear why is all. I have my thoughts on it.

Cheers.

 

[Alex]

Hmm I think that is where I have been getting confused on earlier posts what you are calling bunny ears knot I may be incorrectly calling fig 8 on the bite. Is bunny ears is tie a double fig 8, pull the middle of the bite through and loop the end of the bite over the top yes?

 

[Stu]

Hmm I think that is where I have been getting confused on earlier posts what you are calling bunny ears knot I may be incorrectly calling fig 8 on the bite. Is bunny ears is tie a double fig 8, pull the middle of the bite through and loop the end of the bite over the top yes?

Yes.

Pretty sure in Ashley there is no knot named Fig 8 on the bight (sp?). This is a F8 loop:

What most call bunny ears.

Nomenclature is a bit of a bug bear of mine.

 

[NOZ]

Fig8. is sometimes tied in end of rope as stopper.
Fig8 on bight (fig8 loop) is tied in start of rope to attach first anchor.
Double Fig8 on bight(bunny ears). for Y-hang.
Double Fig8. method of tying two ropes together.

 

[Speleokitty]

It really depends on the situation. If the anchors are close together I will use a double figure 8 loop. If they are further apart I will probably use a figure 8 loop to one anchor and then tie an alpine buterfly below to link into the second anchor.

 

[cap n chris]

Makes sense to me; it uses less rope than the BotB as well and so arguably is more efficient in that regard.

Surprisingly it doesn't! I thought this for ages then went out with a marked rope and rigged different lay outs of bolts (sad I know).

It's not sad - it's very useful to do these exercises!

And talking of which,... it's made me pop out "just to check" whether my recollection about efficiency is erroneous but after a few minutes playing I find that with a 1m traverse to a 75cm wide y-hang (horizontal separation) the rope saving/efficiency of AB v BotB actually is in the region of 20%.

 

[Geoff R]

I moved away from rigging a Y using a BotB as my standard as I have never felt comfortable with this knot if only loaded from one of its loops by a cowtail.  Also did not choose the Fig 8 version due to the lay of the traverse rope into the knot when rigging tight.   

Purely out of interest and in no way starting a bun fight: would you explain the last sentence, the rationale behind it, cheers?

NOZ  is quite right.  I rig tight so all my traverse line is loaded when descending/ascending, so I need an Alpine Butterfly (or cavers butterfly if you must) to fix the traverse line at P's  AND also as the first knot of the Y hang, as the rope leads into this type of knot from the side, and out from the side. I do not want a knot where the in and out rope both comes via the bottom of the knot.  Using the same reasoning of how the ropes enter and leave the knot, my second knot which makes the Y is of course also an Alpine Butterfly. 

At a rebelay, I always use a Fig8 knot as this knots in and out rope naturally hangs downwards, as this is what I need in this >rebelay< situation as the loop comes up to the P hanger.  If the rebelay is to be rigged as a Y hang, then immediately after this Fig8 knot and as close as possible to it, I then tie an Alpine Butterfly.

Hope this clarifies 

I find that with just a little practice there is no problem making and adjusting an Alpine Butterfly to position Y's correctly and to any length,  so this knot is usually my first choice   

BTW,  rather than using a Alpine Butterfly as the second knot to make a Y hang described above, I also like the look of a >directional Fig8< knot but rarely use it. 

 

[Stu]

I get it Geoff, your description was clear.

You're using the Alpine Butterfly because of it's ability to pull in different directions and at a guess you dislike the Bunny Ears because of it might roll (or perceived potential to roll)?

Alpine Techniques cites the Bunny Ears as a suitable knot for Y hangs by the way (in fact most of the text and diagrams the single Fo8 Loop is the standard knot everywhere!). There is method behind the madness, and some madness behind the other methods. Lyons HSE knot strength figures make interesting reading especially when looking at how a lot of cavers actually use the rope in transit.

I also rig tight for redundancies sake.

 

[Stu]

BTW,  rather than using a Alpine Butterfly as the second knot to make a Y hang described above, I also like the look of a >directional Fig8< knot but rarely use it.

Possibly best you don't use it. Alpine Caving doesn't recommend it...

 

[Geoff R]

BTW,  rather than using a Alpine Butterfly as the second knot to make a Y hang described above, I also like the look of a >directional Fig8< knot but rarely use it.

Possibly best you don't use it. Alpine Caving doesn't recommend it...

why 

 

[graham]

Possibly best you don't use it. Alpine Caving doesn't recommend it...

Which is, of course, not the same as recommending that you don't use it.

 

[Stu]

At a guess it can roll itself over easier than a F8 loop if loaded abnormally i.e. its anchor failed. Not tried it.

 

[Cave Mapper]

I've always used an Alpine Butterfly for the Y hang. I like it because it's simple, easy to adjust and relatively fool-proof.

Having read all the stuff on the other two current threads about the various double loop knots, and supposed 'best-practice', I spent some time today experimenting, trying to work out what advantages these knots might have. Maybe I've missed something, but they don't seem to offer any worthwhile benefit and all three alternatives (Bowline-on-the-bight, Fusion Knot, Bunny Ears) have the same major drawback, which is that with an asymmetric hang they can easily slip sideways and leave your main hang with a rub-point.

This is not a theoretical problem, I've seen it happen, as I think have many others. In the instance I witnessed, the rigger was a light youth and the second man down, who was of stouter build, had a very alarming moment when he put his weight on the rope and saw the knot slip six inches. Now this was a sideways slip (not the French death slide), so he wasn't actually in any danger, but it left the hang off-centre and potentially rubbing. I think I was third man down so I had to reset it to make it safe. Maybe this wouldn't have happened with a 'properly dressed' knot, but I think it's best to avoid any knot that can create a potentially fatal situation by simply not being correctly tightened. The Alpine Butterfly doesn't seem to suffer this problem, so I'm going to stick with it.

 

[Cave Mapper]

To illustrate:

Here's a typical Y-Hang using Alpine Butterfly knots (it's deliberately off-centre to avoid a hypothetical rub-point)

and here's how you might do it if your Y-hang is up in the roof and you want to keep the traverse line low

and here's how you can spread the load across three anchors (a 'Triple Y-Hang') - very useful if your main hang is off rusty spits that you don't trust

... and for all these, you just need to know one simple knot and all the adjustments are quick and easy.

I've had no formal SRT training, I'm pretty much self-taught, so if I'm overlooking anything here and this isn't best practice, then I'm keen to be enlightened.