Author Topic: What's a good way to tie two ropes in the bight?  (Read 6865 times)

palapiku

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What's a good way to tie two ropes in the bight?
« on: June 14, 2013, 06:52:51 PM »
What's a good way to tie two ropes together, without access to the ends of either rope? Can it be done accurately enough that you are effectively tying a specific point on one rope to a specific point on the other?

I can only think of really ugly ways, e.g. forming a bight with both ropes held together and tying a stopper knot in it.

roo

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Re: What's a good way to tie two ropes in the bight?
« Reply #1 on: June 14, 2013, 06:54:14 PM »
What's a good way to tie two ropes together, without access to the ends of either rope? Can it be done accurately enough that you are effectively tying a specific point on one rope to a specific point on the other?

I can only think of really ugly ways, e.g. forming a bight with both ropes held together and tying a stopper knot in it.
See if this fits your needs:
http://notableknotindex.webs.com/midspan.html
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X1

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Re: What's a good way to tie two ropes in the bight?
« Reply #2 on: June 14, 2013, 07:10:45 PM »
   Read, and have a look at the knots, at :
  http://igkt.net/sm/index.php?topic=3640.0

Dan_Lehman

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Re: What's a good way to tie two ropes in the bight?
« Reply #3 on: June 15, 2013, 03:15:48 AM »
What's a good way to tie two ropes together,
without access to the ends of either rope?

Can you conceive of some situation / application
in which this problem arises?

Which can lead to seeing whether the joined ropes
need to be braced against any sort of loading,
or rather a specific loading of one vs. another end.

--dl*
====

knot4u

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Re: What's a good way to tie two ropes in the bight?
« Reply #4 on: June 15, 2013, 12:49:10 PM »
Here are examples where I have used a midspan bend:

Towing a vehicle...
Tie a sling. Wrap sling around each anchor of each car, so there are 4 strands of rope extending from each vehicle. Connect rope ends with midspan sheet bend.  The overall rope strength just quadrupled or at least it increased a bunch.  You are now a rock star.

Lifting weights...
Similar concept to towing a vehicle, except the advantage here is more surface area on which to pull the rope.  For example, the rope may go around my waist when I do weighted dips/pull-ups.  It's much more comfortable than just one line of rope around my waist.

By the way, the midspan sheet bend has been plenty of security for me in my applications. The security is assured even more if you can take the knot you tied for the sling and use that as a fail-safe stopper in the midspan sheet bend. That is, the small loop formed by the midspan sheet bend has the stopper in the loop.

I'm curious to know when others  have needed more security. I'm not saying you don't need more security. I'm just wondering what has been your experience.
« Last Edit: July 22, 2013, 11:33:17 PM by knot4u »

X1

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Re: What's a good way to tie two ropes in the bight?
« Reply #5 on: June 15, 2013, 04:48:40 PM »
   If I had to point out the less clever ( = most dumb ) knots I know, this so-called "midspan Sheet bend" would probably be the first ! And I am really sad that the knot tying community has been parroting this ugly tangly over and over again, all those years !   We have taken a double line Sheet bend ( you know, the ABoK # 1 ! ) and we are proud that we have managed to reduce just a tiny fraction of the required material? A great achievement, indeed ! Then, we try to conceal the fact that this tangle is working like a proper Sheet bend only in a few of all the possible orientations and loading patters of the two lines. In particular, when the two lines are parallel to each other, and both ends of the one, at least, line are loaded, this ugly tangy reveals its true monstrous face ! However, in the web sites where the beast is presented / advertised as a beauty, one will not see even one picture of a loaded knot : perhaps because it would have been difficult for us, the lesser knot tyers, to follow the segments of the ropes, the owners of the sites are kind enough to present only sketches of "exploded", loose knots... :)   
   As a bight-to-bight bend, the midspan Sheet bend behaves as a proper Sheet bend, indeed - and this is the only case when it deserves this name. In this particular role, and in this role only, it is quite satisfactory, and I believe that a more complex bend, like the ones presented in (1), would seldom be needed and required. 
   However, when each of the two bights is formed on each of two parallel lines, the ex-Sheet bend will hold only if it is lucky enough to squeeze every last tiny fraction of friction generated within its deformed, ugly body. The tensile forces which should help the bights close and embrace each other, work in the exact opposite, destructive way : they tend to open them up, and to tear them apart. Especially the poor bight with the uncrossed legs, is suffering a lot in this spagato it is forced to perform, and only a miraculously balanced distribution of tensile forces would alleviate its pain - but there are no miracles taking place in real life recently, I am afraid. One would expect the utilization of one or more nipping loops, to squeeze a double line going through them, so the loading of the lines would become beneficial, and not catastrophic, for the connection. When one has the Gleipnir, the Bowline, the Sheepshank, the Captain Mullin s knot, all those knots that utilize / take advantage of the loading of the ends, he can not be satisfied with this tangle which suffers from it. 
    The problem is : What can we do ? There are things we simply are not able to do with knots, and we will never be. The variety of possible rope-made mechanisms is condemned to be limited, if the allowed complexity of them is also limited. Will we ever fly using a simple knot ? I doubt it !  :)  Now, should we use an ugly tangly, when we have not anything else ? That is a matter of personal taste. Personally, I will not. I respect knots, and I do not like to see them suffering, trying to do things they simply can not do, given the limits of complexity allowed to them. I would better chose another method, or tie a much more complex knot, but I will not use an ugly tagly that "would simply do the job" - provided the loading will not be heavy, and we will keep our fingers crossed !   
   Simplicity is a great thing, but it should not be used as an excuse, in situations it simply does not apply ! I myself do not know any simple TIB knot that would hold two lines together, independently of the loading pattern of the four limbs. This "midspan Sheet bend" is a decent bight-to-bight bend, and nothing more. Its name is deceiving, and has mislead people to believe that it is the miracoulous simple medicine that cures all diseases? It does not. Instead of trying to figure out the few applications where this knot will work, (simply because any tangle can work, if it is loaded in a particular way and with light enough loads...), I suggest we try to find something better, even if this will require a much more complex knot. Perroting will continue, that is for sure, because it is such a successful strategy of nature. However, imagination and creativity should continue, too. And if it is proved that there is nothing else satisfactory enough, there will be always the option of a line-to-line mechanical fastener !  :)
1. http://igkt.net/sm/index.php?topic=3640.0
 
« Last Edit: June 15, 2013, 04:56:19 PM by X1 »

James Petersen

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Re: What's a good way to tie two ropes in the bight?
« Reply #6 on: July 21, 2013, 04:58:09 PM »
If bulk is not an issue and I had to bend two ropes in the bight, I would probably try the water/tape knot (ABOK #296) first. It would simply be a matter of making an overhand knot in one bight and rethreading the other bight through. I don't know how it would perform under varying conditions, but it's the first thing I would try.

Festy

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Re: What's a good way to tie two ropes in the bight?
« Reply #7 on: July 21, 2013, 05:10:15 PM »
Zepplin Bend surely, with two lovely ears on it, pleasing to look at  :)

Dan_Lehman

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Re: What's a good way to tie two ropes in the bight?
« Reply #8 on: July 22, 2013, 08:07:16 PM »
What's a good way to tie two ropes together, without access to the ends of either rope?

Still waiting to learn of some practical need for such
a joint, and what sort of loading is to be anticipated.


Quote
Can it be done accurately enough that you are effectively
tying a specific point on one rope to a specific point on the other?
:o   This would be seizing !!  Otherwise, I can't imagine
what you mean by "specific point [-2-point]" joining.

 ;)

roo

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Re: What's a good way to tie two ropes in the bight?
« Reply #9 on: July 22, 2013, 08:16:07 PM »
What's a good way to tie two ropes together, without access to the ends of either rope?

Still waiting to learn of some practical need for such
a joint, and what sort of loading is to be anticipated.
I'll add one:
If you have a long rope passing by a large object like a tree, and you want to pinch off a loop around the tree without access to either end of the rope.


Concerning Xarax's/X1's latest stalking-harassment-name-calling-BS, I'll let him argue with himself:

   If I had to point out the less clever ( = most dumb ) knots I know, this so-called "midspan Sheet bend" would probably be the first ! And I am really sad that the knot tying community has been parroting this ugly tangly over and over again, all those years !

versus

  The midspan sheet bend is a fine bend. In fact, I do not know any other simple bend that can do its job.
;D ;D ;D ;D
« Last Edit: August 03, 2013, 06:12:46 PM by roo »
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Dan_Lehman

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Re: What's a good way to tie two ropes in the bight?
« Reply #10 on: July 22, 2013, 08:27:39 PM »
What's a good way to tie two ropes together, without access to the ends of either rope?

Still waiting to learn of some practical need for such
a joint, and what sort of loading is to be anticipated.
I'll add one:
If you have a long rope passing by a large object like a tree,
and you want to pinch off a loop around the tree
without access to either end of the rope.

Huh?  Are you tossing said loop ("eye") over this tree?

The implication I see for your scenario is more of an
eye knot formed in the bight, and the eye used qua
single line to tie to the tree.  Well, that would be if
the tree say lay on the north side of the endless line
running E<->W and you want to preserve that state;
else (and maybe this was your intention) you could
advance the line N-wards, bringing material around
from either side, and tie "two ropes (so to speak)"
together, now with tree S of this new joint.

???

roo

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Re: What's a good way to tie two ropes in the bight?
« Reply #11 on: July 22, 2013, 08:33:01 PM »
Huh?  Are you tossing said loop ("eye") over this tree?

Not at all.

For clarity, see the middle diagram here:
http://notableknotindex.webs.com/midspan.html

Imagine that the black circle is the trunk of the tree, looking down.
« Last Edit: August 05, 2013, 09:59:42 PM by roo »
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knot4u

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Re: What's a good way to tie two ropes in the bight?
« Reply #12 on: July 22, 2013, 11:34:16 PM »
Still waiting to learn of some practical need for such
a joint, and what sort of loading is to be anticipated.

I provided two examples above.  Cheers