mid rope Y hang - prefered knot ?

[Fulk]

Many years ago I was introduced to a knot that gave two 'bunny's ear'-type loops, plus a smaller loop underneath which, it was claimed, could be used for clipping into (or for hauling, you could use a pulley there). The person who showed me this knot couldn't remember its 'proper' name and referred to it as a BFK, or 'big fat knot'.

Anyway, I was wondering if anybody recognizes / has used this; I took some snaps of it and loaded them onto Flick'r, intending to post them here, but couldn't find the tags that you are supposed to use to copy and embed photos. Can anybody help?

 

[JoshW]

Many years ago I was introduced to a knot that gave two 'bunny's ear'-type loops, plus a smaller loop underneath which, it was claimed, could be used for clipping into (or for hauling, you could use a pulley there). The person who showed me this knot couldn't remember its 'proper' name and referred to it as a BFK, or 'big fat knot'.

Anyway, I was wondering if anybody recognizes / has used this; I took some snaps of it and loaded them onto Flick'r, intending to post them here, but couldn't find the tags that you are supposed to use to copy and embed photos. Can anybody help?

Badger may be able to advise. We were shown by James C down at the Wessex a couple of months back a knot similar to what you describe. seemed a right faff to tie, but sturdy. probably easier to take the route of a BotB with an alpine butterfly below, quicker anyhow.

 

[todcaver]

I can't comment on the BFK knot but I have often rigged an extra loop of rope  for ease of departure but only on certain pitch heads (awkward)
I have seen it used or be useful a few times .

 

[ianball11]

Is the advice for Eurospeleo rigging to use rethreaded knots as often as possible?

 

[Fulk]

OK, I'll try this (bet it won't work, though):

26441531265_c9ab75dae0_z

 

[andrewmcleod]

Presumably the only downside I can think of for an AB hang is if the loop bolt fails then there could be a substantial drop for someone clipped into it - if there is say a 1m long loop then you could take a 1m (+ swing) fall if you are clipped into only the loop (as your cowstail slides along it). An knot in the loop near the Y-hang would stop this. I would also not be at all surprised if a snapgate managed to unclip itself from the loop in such a fall.

Wouldn't you be attached at another point? Either 2nd cowstail or ascender/descender.

Mike

x = bolts, B = butterfly


            (1) (2)
  x    x    x  x
  B----B----B  //
              \//
              B
              |
              |

Not necessarily. If you have a traverse line going straight into a bolt on the other side of the pitch, so tie a small AB on the last traverse bolt (labelled 1) and a large AB to the opposite bolt (labelled 2) to form the Y-hang, then you only have one long loop to clip into (off the 'opposite' bolt, bolt 2). You could clip into the last of the traverse bolts (bolt 1), but you might not be able to reach it.

You may not yet have clipped on a descender, so considering going down you may have the following sequence:
1) clipped onto the 'traverse' line (actually one side of the Y-hang) with one cows tail; the other is removed for the next step.
2) clipped onto the 'traverse' line and into the loop.
3) unclipping from the 'traverse' line; one cowstail still in the loop.
4) clipped into the loop by both cowstails.
similar process for ascending.

If the AB/loop bolt fails (bolt 2), then potentially the knot, loop and bolt/carabiner could all pass through any cowstail clipped onto the 'traverse' line. If you haven't clipped in the loop yet, you might die. It is probably a bad idea to clip _onto_ any traverse line that doesn't have two bolts up and downstream of it? (I don't know if this is a 'rule' or not)
If you are clipped into the loop with one or both cowstails, then if the loop fails you fall until you either hit the bottom of the loop or any isolation knot you have introduced.

I also have twistlocks on my cowstails, so am happy hanging off a single cowstail if it is clipped to something sensible.

 

[andrewmcleod]

Many years ago I was introduced to a knot that gave two 'bunny's ear'-type loops, plus a smaller loop underneath which, it was claimed, could be used for clipping into (or for hauling, you could use a pulley there). The person who showed me this knot couldn't remember its 'proper' name and referred to it as a BFK, or 'big fat knot'.

Anyway, I was wondering if anybody recognizes / has used this; I took some snaps of it and loaded them onto Flick'r, intending to post them here, but couldn't find the tags that you are supposed to use to copy and embed photos. Can anybody help?

...let's go with 'fat' for the F in BFK

It is a standard knot for SPA-type climbing rigging (e.g. setting up a top-rope/abseil), although really it is more of a family of knots. Basically you tie a load of bights together with an overhand - job done. It is 'good' for equalizing lots of individual bits of gear. If you had a rope that went up, through a karabiner, and back down through 3 pieces of gear, then you end up with a 6-stranded (I think?) overhand and a pair of loops sticking out the bottom (as well as the two ends of the rope). Two bolts gives you just the one loop. Easiest knot to fall back on when you are getting stressed on an SPA assessment and struggling to tie knots in fat rope!

It absolutely eats rope though, and any stray loops need to be long enough to not pull through, so probably not really so great for caving unless you have too much rope...
Also (given it is just an overhand, although you can also tie it with a Fig 8/9) not always the easiest thing to untie.

Basically:
http://imgur.com/a/7gORp

except don't clip the tail in the last picture, and use the two top loops separately. That photo is for people with an unnecessary paranoia about redundancy, hence the two crabs...

 

[David Rose]

Just to introduce a rogue element here, is there any reason not to use clove hitches rather than alpine butterfiles on traverse lines? I mean, they are very strong, and use very little rope, and are very easy to tie.

 

[Fulk]

Hi Dave, I asked that question some time go; the reply seemed to be that they're safe enough, but can be a bugger to undo.

 

[dudley bug]

Many years ago I was introduced to a knot that gave two 'bunny's ear'-type loops, plus a smaller loop underneath which, it was claimed, could be used for clipping into (or for hauling, you could use a pulley there). The person who showed me this knot couldn't remember its 'proper' name and referred to it as a BFK, or 'big fat knot'.

Anyway, I was wondering if anybody recognizes / has used this; I took some snaps of it and loaded them onto Flick'r, intending to post them here, but couldn't find the tags that you are supposed to use to copy and embed photos. Can anybody help?

I guess these are the images .....

 

[topcat]

Hi Dave, I asked that question some time go; the reply seemed to be that they're safe enough, but can be a bugger to undo.

eh?  Surely clove hitches are the easiest of all 'knots' to undo?  I sometimes use them when rigging with soft 9mm eg Geostatic but they don't work too well with fatter or stiffer rope.

 

[David Rose]

Come to that, is there any reason not to use clove hitches for main belays? Climbers use them all the time.

 

[andrewmcleod]

Come to that, is there any reason not to use clove hitches for main belays? Climbers use them all the time.

Allegedly (i.e. according to Lyon in research paper thing from the early 2000s?) they can slip in static rope at varying forces, but as you say climbers use them all the time including on static rope for belays.

The only arguments I believe against them (on a traverse line) are:
a) they don't give you a loop to clip into
b) while they are easy to adjust, you don't have a loop so don't have a reservoir of rope to add/take away rope from
c) the rigging has to exactly follow the line of bolts, even if it zig-zags around/runs along the ceiling etc.

Probably only c) makes them inappropriate in _some_ cases. Not sure why you would use them on a Y-hang except maybe on one leg?

 

[Fulk]

dudley bug: Thank you very much; how the hell did you do that?

 

[Mark Wright]

eh?  Surely clove hitches are the easiest of all 'knots' to undo?  I sometimes use them when rigging with soft 9mm eg Geostatic but they don't work too well with fatter or stiffer rope.

The problem with Clove Hitches (when being discussed on a Knot thread) is they are hitches and not knots.

They are brilliant for tying round reasonably sizeable things like, e.g. trees, but unless the rope is new and soft they don't usually stay neat and tidy round a carabiner.

The problem with a BFK (happy to go with Fat for the F) is that they are not likely to be tied as neatly as the photograph shows. Again you might be able to achieve that with a new soft rope but not with a stiff rope in a cave environment. Because of this it would be almost impossible to get a consistent test result so you can never be sure how good they are.

As for the strength of knots, how strong do you want them? Most knots will reduce the strength of the rope by around 30% - 35% with a Bowline reducing the strength by almost 50%. Any type A rope will have a MBL of at least 22kN (usually at least 27kN for 10mm - 10.5mm and 30kN for 11mm) and these days most type B ropes will be at least 22kN, so, even if we tie knots very badly, i.e. not dressed and set, the ropes are still plenty strong enough and not something to be unduly worried about.   

As I pointed out on the Fusion Knot thread and someone has again mentioned here, it would be best if whatever knot you used was easy to examine, at a glance. As soon as you start introducing complex knots, that may actually be really good, it makes it very difficult for even the very experienced caver to examine close up, never mind at a glance.

Mark

 

[badger]

Many years ago I was introduced to a knot that gave two 'bunny's ear'-type loops, plus a smaller loop underneath which, it was claimed, could be used for clipping into (or for hauling, you could use a pulley there). The person who showed me this knot couldn't remember its 'proper' name and referred to it as a BFK, or 'big fat knot'.

Anyway, I was wondering if anybody recognizes / has used this; I took some snaps of it and loaded them onto Flick'r, intending to post them here, but couldn't find the tags that you are supposed to use to copy and embed photos. Can anybody help?

Badger may be able to advise. We were shown by James C down at the Wessex a couple of months back a knot similar to what you describe. seemed a right faff to tie, but sturdy. probably easier to take the route of a BotB with an alpine butterfly below, quicker anyhow.

I think what is being talked about is this https://www.facebook.com/escuelavertical/videos/vb.497630596980434/919130574830432/?type=2&theater
hopefully that works

what Josh was shown is a double bowline (not a bowline on a bight) with a Yosemite backup, because it was made using a doubled over rope when the back up was pushed back through the knot it created an extra loop.

 

[todcaver]

On my first IRATA course I asked why not use a clove  hitch , climbers do ? , I was told because it's a hitch and could slip " if you were hanging from the top of big ben swinging round jet washing the clock,  would you rather be on a bomber knot or a hitch which could slip ?"