Author Topic: Possible new knot - Buffalo Hitch  (Read 10305 times)

Andre

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Possible new knot - Buffalo Hitch
« on: April 14, 2011, 05:09:47 AM »
Possible new knot - Buffalo Hitch

Dear members of this forum, I'm submitting this hitch for your appreciation/ scrutiny. I do believe it's original but understand it may already have been developed by someone else elsewhere at the same time or before I did. Although, I have done extensive web search for a while and through ABOK, could not find it. I included the words "new knot" at the title of the thread to facilitate future searches, but I'm aware it may not be actually new.

This is a hitch I developed to allow a single line rappel from a rappel ring or other type of anchor, reliable enough to stay put during a rappel descent (minimal slippage expected with alternating loading/unloading of standing part) and loose enough to be undone by just shaking the rope from below, allowing the rope to be retrieved without the use of extra gear.  A single line rappel can be the only alternative for rappelling down a route and methods exist with the use of additional gear, the pull cord technique being the most used by the climbing community, but lives have been claimed by that technique when the stopper knot passed through the ring after being loaded with full body weight during the rappel.

It's the same idea from ABOK#399, which I had a hard time getting undone.

Pictures attached (from scanner, hopefully the quality is good enough). Unloaded knot in the pictures, for clarity.

Directions:

With a climbing rope, start the knot some 3 meters from the end of the rope.

Make a running knot with the running end contiguous to the working end of the rope. The loop formed should be some 30-40 cm long.

Pass the working end through the rappel ring.

Form a coil (which may also be referred to as round turn or turNip as in previous discussions here) at the end of the running knot's loop.

Pass the working end through the coil. The distance between the rappel ring and the coil should be at least double the length of the running knot's loop.

Pass the working end through the rappel ring again.

Pass the working end through the coil again.

Leave the working end approximately the same length as the running knot's loop, and no less than 20 cm.

The direction the two sections of rope go through the coil does not really make significant difference in the final result. But in the way shown in the picture it will dress nicely and be easier to be checked.

Hold the working end when loading the knot by putting your weight on the standing part, to which the rappel device will be attached (and the climber). Observe the coil constricting the two sections of rope within it. It does not matter if the coil stays as a coil or if it slides to the side becoming a twisted loop instead, it will function just as the same. Constriction achieved, the knot is ready to withstand the normal expected stresses inherent to a rappel descent (tugs, lateral oscillations, etc) and there will be minimal slippage with each occasional unloading followed by loading of the standing part, that is compensated by the 20 or so cm left as working end.

It does look scary but it is sound.

I appreciate your feedback.

Thanks.

Andre.

roo

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Re: Possible new knot - Buffalo Hitch
« Reply #1 on: April 14, 2011, 04:33:41 PM »
This is a hitch I developed to allow a single line rappel from a rappel ring or other type of anchor, reliable enough to stay put during a rappel descent (minimal slippage expected with alternating loading/unloading of standing part) and loose enough to be undone by just shaking the rope from below,

If this falls apart from shaking from below, why would it not fall apart from strong wind gusts during a pause in the descent if the line goes temporarily slack?
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knot4u

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Re: Possible new knot - Buffalo Hitch
« Reply #2 on: April 14, 2011, 05:54:22 PM »
You may be the first to post this hitch in a pic here, but it's not new.  I have tied and tested this hitch.  It's a natural variation of a binder that dmacdd presented in another thread.

http://igkt.net/sm/index.php?topic=2981.msg17780#msg17780
"Lehman Trucker Binder"


The Buffalo Hitch in the original post is like a trucker hitch with progressively more friction as the load increases.  It seems like the increase in friction is exponential, rather than just linear.  That's bad in many respects.  However, it could be good for people who don't need maximum tension or who have trouble with the ending of a regular trucker hitch.
« Last Edit: April 14, 2011, 06:41:36 PM by knot4u »

Andre

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Re: Possible new knot - Buffalo Hitch
« Reply #3 on: April 14, 2011, 06:27:27 PM »

If this falls apart from shaking from below, why would it not fall apart from strong wind gusts during a pause in the descent if the line goes temporarily slack?

It can and it will if left unattended long enough under a strong enough wind.

knot4u

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Re: Possible new knot - Buffalo Hitch
« Reply #4 on: April 14, 2011, 07:29:42 PM »
You're presenting this for a rappel descent.  I'm uncomfortable with someone presenting a new knot for rappelling without much of a warning.  Here's a good warning:

WARNING
IF YOU USE THIS KNOT FOR RAPPELLING,YOU MIGHT DIE.
PROCEED AT YOUR OWN RISK.
« Last Edit: April 14, 2011, 10:14:11 PM by knot4u »

Andre

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Re: Possible new knot - Buffalo Hitch
« Reply #5 on: April 14, 2011, 10:22:36 PM »
You're presenting this for a rappel descent.  I'm uncomfortable with someone presenting a new knot for rappelling without much of a warning.  Here's a good warning:

WARNING
IF YOU USE THIS KNOT FOR RAPPELLING,YOU MIGHT DIE.
PROCEED AT YOUR OWN RISK.

This is very true. Rappeling is very dangerous and independently of technique used can cause death, and it does. One analysis mentioned rappel to be responsible for 25% of climbing-related deaths. I suspect it's more. Many climbers have died just because they forgot to tie a stopper knot at the end of the rope when rappelling. So sad.

Dan_Lehman

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Re: Possible new knot - Buffalo Hitch
« Reply #6 on: April 15, 2011, 05:21:33 AM »
The knot looks pretty *new* to me, though it has some now
familiar aspects.  But I'm completely amazed that it should
reliably ever come untied, wind or no wind, shaking or not:
what it going to raise the extended tail back up through the turNip?

I tried this in not quite the target material (rockclimbing rope),
but in something I thought should be a good test, nevertheless:
half-inch-diameter double-braid polyester yachting rope, Sta-Set,
through a slightly thicker-than-usual 'biner.  Admittedly, I did
get the knot to slip a little with much shaking; I deliberately
made the tail relatively short compared with the reach of the
tail from the mid-line eyeknot (just a slip-knot, for me),
as ... :  all that I can infer is that the mass of the initial reach
through the ring must be longer than the extension of the
tail through the turNip --that in order for the loops of tail
to rotate through the turNip & ring there must be an imbalance
of mass for gravity to work with (shaking, in isolation, has no
bias for one direction or the other).

But there is friction at both ends of this cordage ellipse, as well
as some resistance of rope to bend.  Beyond this, while my
hand shook the rope within 2 feet of the lower knot, abseilers
will be making their (increasingly, desperate) frantic shakings
of the rope from some 50m distant, with their immediate
effects buffered/ameliorated by considerable friction against
the rock face, possibly!  AND the 50m of suspended rope
will impart tension yielding mild constriction of the turNip!

So, how is this supposed to work?

--dl*
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alpineer

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Re: Possible new knot - Buffalo Hitch
« Reply #7 on: April 15, 2011, 07:27:34 AM »
WARNING
IF YOU USE THIS KNOT FOR RAPPELLING,YOU MIGHT DIE.
PROCEED AT YOUR OWN RISK.
Now that's a very fine warning indeed, knot4u!

Transmitting enough shake energy to loose the far end of a single climbing rope could be very difficult in many rap scenarios, and as odd that might seem, I suspect that is the problem.

alpineer

Andre

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Re: Possible new knot - Buffalo Hitch
« Reply #8 on: April 15, 2011, 10:21:10 AM »
...
But there is friction at both ends of this cordage ellipse, as well as some resistance of rope to bend.  Beyond this, while my hand shook the rope within 2 feet of the lower knot, abseilers will be making their (increasingly, desperate) frantic shakings of the rope from some 50m distant, with their immediate effects buffered/ameliorated by considerable friction against the rock face, possibly!  AND the 50m of suspended rope will impart tension yielding mild constriction of the turNip!

So, how is this supposed to work?

--dl*
====


Transmitting enough shake energy to loose the far end of a single climbing rope could be very difficult in many rap scenarios, and as odd that might seem, I suspect that is the problem.

alpineer

You are both right.

What pulls the working end out of the coil is the sideways momentum/vector force from the mass of rope between the coil and the rappel ring when oscilated along the perpendicular axis. Rigorous rather then gentle shaking is needed, and this can take longer than desired, but that's the tradeoff from having a more sound configuration to begin with.

Although the knot can be undone from below this won't be achieved in 100% of times. The retrievability of the rope depends on many factors, such as steepness and tortuosity of the path, friction against rock, distance from anchor, etc. It's a call the climber will have to make when deciding for which method to use for the rappel. Also, the higher the [coil-ring distance:working end length] ratio, the better, and anything less than 2:1 (which I consider the inferior limit) will make it really difficult to have the knot undone.

Just a note, single line rappels are not the rule, and the best option is to plan ahead so that one won't need to do it. Climbers who do it routinely will be most likely using the pull cord technique and will carry the extra gear necessary to have the rig set.

Thanks.

knot4u

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Re: Possible new knot - Buffalo Hitch
« Reply #9 on: April 16, 2011, 08:25:49 PM »
I tried a Bellringer plus HH (ABOK #173 upside-down).  This knot is probably LESS secure than the Buffalo Hitch in the original post.  However, I still could NOT get the Bellringer plus HH to come loose by shaking the standing end only.  A Bellringer (ABOK #172 upside-down) could be shaken loose, but now we're talking about barely any security.

The Bellringer has been the ONLY loop in this thread that I have been able to work loose by shaking the standing end only.  The lack of security may be just right for a particular application (e.g., a trucker desiring a quick release in a Trucker Hitch).  However, I highly recommend NOT using a Bellringer for rappelling.

WARNING
IF YOU USE ANY OF THESE KNOTS FOR RAPPELLING,YOU MIGHT DIE.
PROCEED AT YOUR OWN RISK.


« Last Edit: April 16, 2011, 08:50:28 PM by knot4u »

[Inkanyezi] gone

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Re: Possible new knot - Buffalo Hitch
« Reply #10 on: April 18, 2011, 03:36:16 PM »
There is a particular feature with climbing ropes that facilitates shaking a jbit loose, and it is its resistance to very tight curvature. It is somewhat springy, and it does not easily nip or jam, so there might be a better chance to work any knot loose in that kind of rope, kernmantle, than anything used in boating. I have tried to make this knot with different materials, and so far the only one I could work loose was one that is rather springy. However, the length of the tail seems to have some bearing too, as it seems to get undone easier with a short tail. I could not shake it loose when the rope touches something underway, only when it swings freely. Now I don't have any climbing rope at hand presently, but its behavior is similar to the one of that springy double braid that I actually succeeded to work loose by flapping repeatedly from the end, inducing an undulating movement, a standing wave, into the rope.
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Dan_Lehman

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Re: Possible new knot - Buffalo Hitch
« Reply #11 on: April 19, 2011, 07:09:36 AM »
There is a particular feature with climbing ropes that facilitates shaking a jbit loose, and it is its resistance to very tight curvature. It is somewhat springy, and it does not easily nip or jam, so there might be a better chance to work any knot loose in that kind of rope, kernmantle, than anything used in boating.

Right on.
I tried it in some 6mm nylon climbing ("accessory") kernmantle
and it performed better in that --not only the aspect you state,
but also the smoothness of the mantle (vs. laid ropes, e.g.).
And, yes, the longer the tail, the more mass resists being
shaken up through the turNip .

(I think I was wrong to so much try to over-counter-weight the
tail with the length of "*reach*" of the end from the eyeknot,
thinking then that that added span was mass to pull the entire
two loops around with, vs. the tail --no, the tail will have some
impetus to work out just in its short span, I believe, though upon
that there will be the draw of other parts to fully spill it.)

But, a hand moving laterally a little below the structure,
in my (and I suspect others') quick shake-test will achieve
an angle of shaking far greater than is achievable from
shaking 50m below, with the mass of 50m of rope
upon the structure, to boot!  One can try to cast up
a big oscillation, but ... you'll need to have lived a
clean life for that to be blessed with success, methinks!

Andre, it would be foolish to think that you've not given
this some kind of in situ testing : how far, how so
... "  --do tell.  Pure overhang I presume is most favorable
for working, versus any bit of *channel* rapping through
which would slap down any oscillation reaching it.
Or how far UP can one *throw* some kind of *roll*
in climbing rope?


Btw, re-reading, I see that you point to the "coil-to-ring span
over tail(-end) length" ratio; I think that i.p. it might be
much just the absolute distance of "coil" ("turNip") from
the ring --i.e., putting the coil lower so that it gets more
shift in the shaking, irrespective of how much tail must
get shaken out!
I tested with rather SHORT span, so was biased against
the structure working (and the Sta-Set lacked that quality
of springy resistance to bending which Inkanyezi cited).


--dl*
====

Andre

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Re: Possible new knot - Buffalo Hitch
« Reply #12 on: April 20, 2011, 01:43:35 PM »


(I think I was wrong to so much try to over-counter-weight the tail with the length of "*reach*" of the end from the eyeknot, thinking then that that added span was mass to pull the entire two loops around with, vs. the tail --no, the tail will have some impetus to work out just in its short span, I believe, though upon that there will be the draw of other parts to fully spill it.)

But, a hand moving laterally a little below the structure, in my (and I suspect others') quick shake-test will achieve an angle of shaking far greater than is achievable from shaking 50m below, with the mass of 50m of rope upon the structure, to boot!  One can try to cast up a big oscillation, but ... you'll need to have lived a clean life for that to be blessed with success, methinks!

Andre, it would be foolish to think that you've not given this some kind of in situ testing : how far, how so ... "  --do tell.  Pure overhang I presume is most favorable for working, versus any bit of *channel* rapping through which would slap down any oscillation reaching it.
Or how far UP can one *throw* some kind of *roll* in climbing rope?

Btw, re-reading, I see that you point to the "coil-to-ring span over tail(-end) length" ratio; I think that i.p. it might be much just the absolute distance of "coil" ("turNip") from the ring --i.e., putting the coil lower so that it gets more shift in the shaking, irrespective of how much tail must get shaken out!
I tested with rather SHORT span, so was biased against the structure working (and the Sta-Set lacked that quality
of springy resistance to bending which Inkanyezi cited).

--dl*
====



There are a few interesting particularities about this hitch.

The search for such a solution is not new, and it's something mountaineers would love.

By reading the "Mountain Climber" section in the "Occupational knots" chapter from the ABOK, one will notice that Clifford Ashley himself was challenged to come up with a solution to this problem. I quote the second paragraph here:

"I was once asked by an official of a mountain-climbing club to recommend a knot that could be used by a man while climbing alone.This necessitates a knot which can be spilled from below after the climber has lowered himself from a higher level.The following knots resulted."

He then presents a few knots but does not really recommend those. Let's not forget those were times of natural fiber ropes, so safety back then may have another meaning now, with the progression to more slippery materials.

I'm pretty positive this hitch is pretty secure while loaded during a rappel, provided climbing rope is used. Discussion now is and must be focused on retrievability, which will render the hitch useful.

I did carry field tests at the Buffalo Crag in Milton, ON, hence the provisional name of the hitch. Unfortunately, living in South Ontario, the cliffs I have available are somewhat modest in height (max 80 feet) and I'm still looking for a crag or facility high enough to carry out a full length (60 m) test. Will try and do it soon now with the winter gone.

I could retrieve the rope quite easily at the 30 m mark with a 20 cm tail using a 10mm dry-treated dynamic Edelrid rope.

My take on it is that there is a minimum "retrievable" distance to the rig that will render the knot useful. So if we're talking about a 50-meter rope, this can be folded in half for a "standard" rappel. So anything beyond 25 meters would be already useful.

As per the tail, I think 20 cm is a good length, and would be happy to stick to it even with longer distances to the anchor. Oh, yes, the distance to the anchor has a limitation, which is the distance of the safety line (cow tail) the climber will be using to clip himself to the anchor while setting up and loading the Buffalo hitch. One would have to use a modified cow tail so that the carabiner would be at the harness instead of the other end of the cow tail. That would allow the climber to release the cow tail from the anchor when time comes to do so, even if the anchor is out of reach.

The theory behind the shaking part is that what is happening is actually an energy transfer. In theory, provided there is no dampening effect (contact to the rock), the same wave (energy) produced at the lower extremity of the rope should propagate upwards and get there with the same amplitude and frequency. So it has more to do with the amplitude of the wave produced and less with the angle of the triangle formed by the anchor point and the two end points of the shaking at the bottom end of the rope.

And in my mind (I may be wrong) there's even a tsunami effect, i.e., when the energy wave gets to the fixed anchor it gives a good lateral whip at that final stretch of rope from finding a fixed point.

After I finish the tests there will be a description of distance ranges which will be easy/ not easy/ difficult/ really hard to retrieve the rope.

This is all open to discussion...

Will post results here as soon as I have them.

roo

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Re: Possible new knot - Buffalo Hitch
« Reply #13 on: April 20, 2011, 04:25:02 PM »
The search for such a solution is not new, and it's something mountaineers would love.
What exactly are you looking for?  The use of just a single thick rope for descent?

If you anchored with a running loop of your liking, would it be a violation of your preferences to use a separate small cord to unshrink the running loop anchor from the ground until it falls apart?

It wouldn't be as light or as simple as a single rope, but the small cord wouldn't add much weight.
« Last Edit: April 20, 2011, 11:39:54 PM by roo »
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knot4u

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Re: Possible new knot - Buffalo Hitch
« Reply #14 on: April 20, 2011, 06:29:26 PM »
It's off topic, but I was thinking along the same lines as Roo...

I'd feel 1,000 times more comfortable tying a running loop to the anchor and then attaching a small cord (e.g., paracord) to the loop.  I can think of at least two different viable locations for attaching the small cord.  You send the small cord down along with your main line.  After the rappel, you pull the small cord to loosen the running loop.  You open the running loop so big that you can work the standing end of the main line back out of the running loop.  Then, you can pull the main line off the anchor.  This option seems fairly idiot proof.  The weakest link is making sure the running loop doesn't jam on the anchor somehow, but that should be easy.

Instead of tying a running loop to the anchor, you could tie the more obvious option of a Slipped Buntline (or similar) and then tie the small cord to the slip.  However, this latter option would be less secure because the small cord may inadvertently catch on something and open the Buntline.

For the benefit of this security, the weight penalty of the small cord would be relatively not much at all.  The small cord just needs to be strong enough to open the running loop.  Heck, the small cord probably doesn't even have to be as strong as 550 paracord.

I figured the climbing community had already thought of these options.  So, I didn't mention them.
« Last Edit: April 20, 2011, 08:27:12 PM by knot4u »