Y-Hang or a Bowline on a bight?

[ianball11]

I've always used a y-belay from a fig.8 knot as the main belay to hopefully provide a free hang. I've been noticing people using what look like double bowlines, I think they are refered to as a bowline on the bight, although I thought that meant a half completed knot that then you complete around say a natural back up.

From looking at the knots, I think they may use less rope, but only a few inches. Is it just a case of what you were shown first? or am I missing something fundamental?

Ian B.

 

[twllddu]

Really depends on situation but a bowline on the bight is fine for Y-hangs. Must confess I usually use alpine butterflies, both knots were used for rigging in the days of Whernside Manor. You can also use a figure of eight on the bight if you want. I'm sure someone will chip in with a comment with regard to the best to use with thin ropes.

 

[paul]

Really depends on situation but a bowline on the bight is fine for Y-hangs. Must confess I usually use alpine butterflies...

Same here - it's much easier to adjust bowline on the bight and alpine butterfiles.

 

[dunc]

I tend to use bowline on the bight and alpine butterfly...

I've heard a few people say that a bowline on the bight will pull through on itself if an anchor should fail whereas a fig8 won't...

 

[danthecavingman]

A figure eight on a bight (bunny ears) is the strongest knot in these situations so probably the best to use with thin rope. I don't have the figures to hand but some tests were done (I think by the guys at Lyon). They drop tested a load onto a single ear of a bunny knot and it out performed all other knots. I was told this by an experienced IRATA roped access trainer so it is probably true...
The problem with bunny ears is that the knot must be dressed properly or it can slip.

 

[Andy Sparrow]

A figure eight on a bight (bunny ears) is the strongest knot in these situations

I would argue that knot strength is irrelevant in most caving situations. The argument goes like this.... We use static ropes in SRT. Static ropes should withstand a fall factor 1 drop, but the human body will be broken by a shock load of less than half this severity. Safe use of static ropes means never creating situations where breaking loads are possible - therefore relative knot strength is not an issue in selecting knots in most rigging situations.

I would also suggest that the only reason to use a figure 8 on the bight (rabbit knot) is not knowing how to tie a bowline on the bight.

 

[danthecavingman]

:shock:

So what's wrong with a figure eight on a bight?
I suspect personal prefernece of rigging knots is about to come into play rather than suitability of use! I find it easier to use than a bowline on a bight.
I generally use a bowline as my initial tie off to save a maillon. Traverses rigged with Alpine butterflies. Main y-hangs rigged with bunny ears or alpine butterflies. I generally use a figure of eight at a rebelay.
What do other people use?

 

[mudmonkey]

I usually use a single fig-8 and an alpine butterfly or two butterflies at a y-hang, bowline at the rope-end and butterflies on traverses. Rebelays - usually butterflies 'cos they're easy to adjust and to undo, but fig-8's sometimes.

Which sort of y-hang is easier to pass depends on the situation, but almost always using two little knots uses less rope than one huuuuuuge knot - which adds up on a complicated pitch to an increased probability of reaching the floor. A number of rigging "guides" are not generous and I know people who've had to re-rig pitches having taken "enough" rope.....

 

[paul]

A figure eight on a bight (bunny ears) is the strongest knot in these situations

I would argue that knot strength is irrelevant in most caving situations. The argument goes like this.... We use static ropes in SRT. Static ropes should withstand a fall factor 1 drop, but the human body will be broken by a shock load of less than half this severity. Safe use of static ropes means never creating situations where breaking loads are possible - therefore relative knot strength is not an issue in selecting knots in most rigging situations.

I agree with Andy - plus in normal prusiking and abseiling you are nearly always (unless when you are only clipped in with cows-tails at the pitch-head or during the passing of re-belays) attached to the rope by either a descender or a couple of jammers and these will fail in a fall at a force MUCH lower than the rope irrespective of what knot you use.

 

[paul]

:shock: So what's wrong with a figure eight on a bight?

Difficult to adjust compared to Alpine Butterfiles / Bowline on the Bight, uses more rope than most alternatives, not as simple to learn as most alternatives.

I suspect personal prefernece of rigging knots is about to come into play rather than suitability of use! I find it easier to use than a bowline on a bight.
I generally use a bowline as my initial tie off to save a maillon. Traverses rigged with Alpine butterflies. Main y-hangs rigged with bunny ears or alpine butterflies. I generally use a figure of eight at a rebelay.
What do other people use?

Same here but substitute Bowline on the Bight for "bunny ears" on Y-hangs.

I suspect you can easily get involved in "religious wars" over the correct knot(s) to use. I think its best to learn a few knots for different occasions and learn all their advantages/disadvantages.

 

[danthecavingman]

I think its best to learn a few knots for different occasions and learn all their advantages/disadvantages.

Well said sir!

 

[Glenn]

Whilst it depends on the nature of the pitch, I personally don't like any Y hang that has two loops. I much prefer a Y that consists of a single rope going to a knot, and the long loop of the knot (of whatever type) creating the other arm of the Y. This is because you can use the single rope side of the Y to gain extra height to get off the pitch (which is useful if the pitch head is constricted) which you can not do if you have created a Y hang with two loops (bunny ears), the loops just pull through the maillon/anchor.

Cheers,

Glenn (hope that makes sense...)

 

[danthecavingman]

Does make sense and I agree if the pitch head is awkward.

 

[dunc]

Glenn (hope that makes sense...)

Yep it makes sense to me too as it can help in getting off a pitch.. The same method is also useful for large y-hangs where the anchors are far apart, but for anything else then either bowline or fig8 on the bight..

As for other rigging - bowline or fig8 as backup (more so bowline as its quick and easy to tie), alpine flutterby for traverses, rebelays of a single anchor type I go for a fig8..

I suspect you can easily get involved in "religious wars" over the correct knot(s) to use. I think its best to learn a few knots for different occasions and learn all their advantages/disadvantages.

True, but I would probably guess that like most people its five knots in all (fig8/bowline + bights, butterfly) that I use underground for rigging and in one form or another they do the job everytime.. The finer details of pitch rigging are all up to the individual on the day.. I do know a number of knots but most are worthless underground - unless you're sitting around with nothing better to do. :roll:

 

[Mike W]

A useful variant of the bowline (for the start of a traverse) is to pass the short tail through the knot to emerge alongside the traverse line. Quick, neat and uses less rope than finishing with a thumb knot, or two half-hitches.

If you want to start an argument, ask the person next to you how they tie a 'butterfly'. Among cavers, there are generally two variants - but more exist ! For the paranoid amongst us, both are excellent knots. (If I had to cave on one knot, this would be it - although for sensible Y hangs, the bowline on the bight rules !)

 

[Stu]

A useful variant of the bowline (for the start of a traverse) is to pass the short tail through the knot to emerge alongside the traverse line. Quick, neat and uses less rope than finishing with a thumb knot, or two half-hitches.

You're describing a Yosemite Bowline, yes?

 

[dunc]

I would say he is describing the Yosemite bowline... On the subject of bowlines does anyone use the mountaineering (2 turns) bowline??

 

[ianball11]

Hmm interesting stuff, thanks people, I may investigate what's better for constricted pitches as I've always had problems at this area, making it safe and also useable, even more so as the guys I usually cave with are half a foot shorter than me.

Ian B.

 

[Mike W]

I've heard it called a Yosemite Hitch. You can also add two turns ( double or mountaineering bowline ) which is stronger - but I agree with Andy that strength is not the issue. To my mind, ease of tying, ease of adjusting and ease of undoing are more important.

 

[Stu]

I would say he is describing the Yosemite bowline... On the subject of bowlines does anyone use the mountaineering (2 turns) bowline??

Use the mountaineering version for climbing with the extra yosemite bit thrown in. Sits through the harness very neatly and can be loaded as a loop without the risk of it rolling undone.

Whilst in rehab mode learnt a spanish bowline which I've now perfected and it's similar to both fig 8 and bowline bunny ears but without the potential for loops to pull through. Not used in anger yet (obviously). Interested to hear if anyone has used this knot.