International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: xarax on April 15, 2011, 02:22:03 PM

Title: Midspan bends.
Post by: xarax on April 15, 2011, 02:22:03 PM
   There are six classes of two-line bends: in the case when we have to join two lines, and only the one end of only the one line is accessible, we need a "mid-span" or "mid-line" bend. (The bend should be able to withstand a pull coming out of any end(s) and any direction(s).) A very simple midline bend I can think of is the "midline bowline", shown in the pictures below (in three variations). Of the many alternatives one can think of, which are the most practical ?
Title: Re: Midspan bends.
Post by: roo on April 15, 2011, 04:22:29 PM
Of the many alternatives one can think of, which are the most practical ?
Some that I use often:

http://notableknotindex.webs.com/sailorhitches.html
http://notableknotindex.webs.com/midspan.html

...although the Midspan Sheet Bend can also be made with a minor variation that fits your scenario, such that the U shape is the rope without end-access.  This could be modified to a Double Sheet Bend (http://notableknotindex.webs.com/sheetbend.html) form easily.
Title: Re: Midspan bends.
Post by: xarax on April 15, 2011, 09:50:02 PM
  Thank you roo,
  I dont believe that some friction hitch around a straight rope line, any friction hitch, can serve as a reliable bend...(with the possible exception of the ww hitches). We have to anchor our knot to some curved section of the mainline, be it a loop or else, to achieve a sure footing ( take advantage of the vastly greater friction forces along curved segments ).
  The midspan sheet bend is a fine bend. In fact, I do not know any other simple bend that can do its job. However, it addresses the problem/case where we do not have any accessible rope end - so it is probably not the optimum solution for a "midline bend" in the sense described in this thread. Also, even in the modification you propose, it remains a sheet bend, which is not a very secure type of bend for slippery ropes, I believe.
   
Title: Re: Midspan bends.
Post by: roo on April 15, 2011, 10:18:45 PM
  Thank you roo,
  I dont believe that some friction hitch around a straight rope line, any friction hitch, can serve as a reliable bend...(with the possible exception of the ww hitches). We have to anchor our knot to some curved section of the mainline, be it a loop or else, to achieve a sure footing ( take advantage of the vastly greater friction forces along curved segments ).
  The midspan sheet bend is a fine bend. In fact, I do not know any other simple bend that can do its job. However, it addresses the problem/case where we do not have any accessible rope end - so it is probably not the optimum solution for a "midline bend" in the sense described in this thread. Also, even in the modification you propose, it remains a sheet bend, which is not a very secure type of bend for slippery ropes, I believe.
   


The Sailor's Hitch, when tensioned by the standing part and free end, will often cause the passive rope to contort such that it is no longer straight, depending on size ratios.

If you are looking for a high-security joint in slippery lines, I'd suggest tying a Butterfly Loop first, and then attaching to that loop with a high-security structure, such as the Zeppelin Loop.  A Gnat Hitch (http://notableknotindex.webs.com/gnathitch.html) could also be used.

Title: Re: Midspan bends.
Post by: roo on April 15, 2011, 10:33:13 PM
If you are looking for a high-security joint in slippery lines, I'd suggest tying a Butterfly Loop first, and then attaching to that loop with a high-security structure, such as the Zeppelin Loop.

   We are abandoning the KISS principle in this way, I am afraid...

Not at all.  By using knots you already know and and are peer-reviewed and field-tested, you are embracing simplicity and reliability.
Title: Re: Midspan bends.
Post by: roo on April 15, 2011, 10:45:25 PM
Also, since every loop is, at its core, a three-way connection, you can look for some loop knots that can take ring-loading, and can be tied per your scenario.  A Water Bowline form works.

http://notableknotindex.webs.com/waterbowline.html

Although in your scenario, you have the added concern of possible rope dissimilarity.
Title: Re: Midspan bends.
Post by: xarax on April 15, 2011, 11:03:21 PM
By using knots you already know and and are peer-reviewed and field-tested, you are embracing simplicity and reliability.

  Sure, but that does not mean :
1. That all knots that are worth to be known, are already known.
2. That you know all known knots.
3. That only the known knots, or the knots that you know, that are peer-reviewed and field-tested, are the only knots that can possibly embrace simplicity and reliability.

  I know many knots that you do not, and vice versa. And I believe that there are still some knots waiting to be discovered, just under our noses - as was the Gleipnir, for example. The "new knots" I know are not peer-reviewed and field-tested, possibly just because most people believe that all that could be known, is already known...and not because they are complex and unreliable !
  Leaving this issue aside, I think that the "midline bowline" bend, i.e. the knot nub of a simple "mirror bowline", is a knot simple enough, but not tested in this form. I do not know if it is reliable if any end(s) is/are pulled from any direction(s), as required. The Zeppelin loop tied onto a bight formed by a Butterfly loop, is a reliable solution, of course, but too "complex" and not so clever and economical in material use, as it could be, I think. ( I put the word "complex" between quotation marks, because the simple arrangement, the one after the other, of two simple knots, do not make a complex knot...) I feel that, in this solution, much of the rope material used is redundant, and could be eliminated.
 
 
Title: Re: Midspan bends.
Post by: xarax on April 15, 2011, 11:30:01 PM
every loop is, at its core, a three-way connection

   Yes, but, even if the knot can withstand ring loading, the eye leg of the bight tends to deform the knot s nub if pulled from some opposite direction(s), and it should not be able to do this. I am not sure if this happens with the "mirror bowline" base, or the Water bowline base ( the later being more complex than the former...) So, solutions for end of line loops may not work very well, and solutions that are considered complex and unpractical for end of line loops, might well be acceptable solutions for midspan / midline bends.
   
  A Water Bowline form works....Although in your scenario, you have the added concern of possible rope dissimilarity.

    I think that this is not too much of a concern for the Water bowline....It works well with ropes of great differences in diameter, isnt it that so ?
Title: Re: Midspan bends.
Post by: knot4u on April 15, 2011, 11:31:42 PM
Please describe an application that involves pulling any and/or all ends, in any direction.
Title: Re: Midspan bends.
Post by: xarax on April 15, 2011, 11:51:34 PM
Please describe an application that involves pulling any and/or all ends, in any direction.

  The same old argument... :) I believe that the tools make the applications possible, ( and the instruments/experiments make the theories falsifiable ), and not the opposite !
  When you tie a rope with a bend in the middle of a line, you might not know, in advance, if you are going to pull this rope from a right angle or lengthwise. Even if you knew the precise future direction of the pull, you would prefer a bend that is reliable even if the rope you have tied is pulled from any direction, wouldnt you ?
   Consider the object on ABoK page 213. Would you be able to predict, in advance, how it will move if the conditions will change ?  :)    
Title: Re: Midspan bends.
Post by: knot4u on April 16, 2011, 01:11:10 AM
Not arguing, I'm genuinely interested in an application where any and/or all ends of a bend are pulled.  It might be best not to think about solving this problem by thinking about variations of traditional bends.

If all ends need to be pulled and if I have access to only one end of one rope, I'd might go with interlocking Butterfly loops.  I could pull all ends, and the ropes could be completely different.  That's a boring answer, but it should be a good answer to this general question.

If you have a specific application, then we can critique solutions here.  Otherwise, the general solutions rule.
Title: Re: Midspan bends.
Post by: xarax on April 16, 2011, 01:32:14 AM
   In the "midline bowline", any, or even all, of the ends, except the second collar s tail, can be loaded at once.
   The snoods are attached on the longline by means of such midspan / midline knots. However, many of those knots can be tied only with/on very slippery fishing lines, and most of them are similar to many-coil friction hitches. With ropes, the fishing knots I am aware of are not effective, or are too complex and bulky.
   I believe that there would be many more cases where such a bend would be needed, rather than a midspan sheet bend, for example, where neither of the four ends is accessible.
   The interlocking butterfly loops seems an interesting solution, indeed. Still more complex than the "midline bowline", :). but tedted and reliable.
Title: Re: Midspan bends.
Post by: dfred on April 16, 2011, 01:56:44 AM
Here's a fairly simple midline bend not based on the bowline/sheetbend.   A bit jammy, but definitely simple and has a nice perpendicular lead.  The free end of the pendant line can be loaded as well.  And as roo notes above, a three leg knot like this can make a reasonable loop knot.

Many variations are possible here, including a constrictor instead of a clove hitch.  I didn't identify anything simpler and less bulky than a clove hitch though.  I experimented going either right or left first after the first pass through the loop, but wasn't able to discern much difference, at least when using a clove hitch.

(http://www.dfred.net/misc/igkt/20110415/P1050086.thumb.jpg) (http://www.dfred.net/misc/igkt/20110415/P1050086.small.jpg)  (http://www.dfred.net/misc/igkt/20110415/P1050089-rot.thumb.jpg) (http://www.dfred.net/misc/igkt/20110415/P1050089-rot.small.jpg)

If there's concern the hitch is going to slide on the main rope, one can beef it up like this.  In this case the first turn of the pendant line should go around the folded portion of the main line.

(http://www.dfred.net/misc/igkt/20110415/P1050101.thumb.jpg) (http://www.dfred.net/misc/igkt/20110415/P1050101.small.jpg)  (http://www.dfred.net/misc/igkt/20110415/P1050102.thumb.jpg) (http://www.dfred.net/misc/igkt/20110415/P1050102.small.jpg)


EDIT: added comment about loop form
Title: Re: Midspan bends.
Post by: dfred on April 16, 2011, 05:17:01 AM
This is a good thread.  I've never even seen these knots before.  Are they in ABOK?  If so, can I have numbers for future reference?

I'm not aware of ABOK numbers, at least for xarax's knot in the OP or mine.  Given the vagaries of the ABOK index and how spread-out everything is, it's difficult (at least for me) to claim with 100% certainty something is not in ABOK.  As some wise men once said, it would "be rash to claim they have never been used before."

It's also important to note that the pendant line in these knots is preventing the main line from straightening.  Thus if there is a significant difference in strength of the lines, the pendant may fail within the knot even if no load is placed on it.  This is likely a strength/predictability advantage of roo's suggestion of using a butterfly loop and attaching to that in one of many ways.

The term "simplicity" can be viewed two ways here:  there's the simplicity of the knotted structure itself, and there's the simplicity of understanding the likely behavior of the overall system.  By using well-understood components one can gain some confidence in how the overall structure will perform.
Title: Re: Midspan bends.
Post by: xarax on April 16, 2011, 08:26:17 AM
   Nice knot, dfred, very nice indeed, the first one you have presented. It IS based on the bowline,  :), although in an indirect way, but that is not the issue here. It would be great if you test it and compare it with the "midline bowline".
Title: Re: Midspan bends.
Post by: dfred on April 17, 2011, 08:38:10 PM
   Nice knot, dfred, very nice indeed, the first one you have presented. It IS based on the bowline,  :), although in an indirect way, but that is not the issue here. It would be great if you test it and compare it with the "midline bowline".

Thanks very much.  I was pleased when I came across it.  Given how little there is to it I'd be very surprised if it's not already known.  Seems useful perhaps for the edge of a net-like structure.    The simpler first form seems to be sufficient for just about all the rope I've tried it on, so long as it is drawn-up snug before loading.

As far as the bowline/sheetbend relation...  If one withdraws the final tuck of the simple form, it is really one of the so-called "single" carrick bends (e.g. #1445).   I can't find a B/SB structure in there.  The flow of the line through the loop is always in the same direction, opposite to what one would expect in a B/SB structure.  To use the famous bunny analogy: in the knot I pictured the bunny is coming out of the hole, going around something and coming out of the hole again, rather than going back into the hole at any point...

BTW, I did actually present another knot (http://igkt.net/sm/index.php?topic=938.0), quite a while ago.   
Title: Re: Midspan bends.
Post by: xarax on April 20, 2011, 12:30:31 PM
   
As far as the bowline... relation...I can't find a B... structure in there.

  You can " beef up"  the hitch in many more interesting ways, as you have noticed, so it will not run the danger of sliding on the main line.
  Those turn(s) around the main line, can they be considered as collar-like structures, or not ? If not, I have to agree that there is no bowline structure in there, because I believe that the essential elements of the bowlines are the nipping loop AND the collar.
Title: Re: Midspan bends.
Post by: knot4u on April 20, 2011, 05:44:22 PM
Interlocking Clove Hitches...if the bend doesn't have to be untied

I'm talking about interlocking the double loop of each Clove Hitch through each other, nothing fancy.

Features:
-Need access to only one end
-Can be pulled in any direction with any combination of end(s)
-Secure even even while capsized, as long as it's somewhat tight
-Doesn't seem to have a natural dressing
-Jams (or seems like it will anyway)
-Has worked with some amount of difference in rope
-May work with any amount of difference in rope
Title: Re: Midspan bends.
Post by: knot4u on April 20, 2011, 06:48:55 PM
Simple options that aren't jam-prone...

Sheet Bend, the regular version (NOT the midspan version http://notableknotindex.webs.com/midspan.html)

Sheet Bend, Water Bowline version
Title: Re: Midspan bends.
Post by: Dan_Lehman on April 21, 2011, 06:56:41 AM
  In the "midline bowline", any, or even all, of the ends, except the second collar's tail, can be loaded at once.

This makes no sense, for the 1st-shown & symmetric knot : there is no
distinction between "tails", as such.

Quote
Please describe an application that involves pulling any and/or all ends, in any direction.

The OP's knot was presented in the 1928 Alpine Journal by Wright & Magowan
as a middleman's tie-in knot --possible loading of the attachment against
either or both of the tied-to line's ends.  Another multi-loading application
is netting (which tends to add some constraints), and the common
net-knot has a sheet-bend/... form.

Quote
The snoods are attached on the longline by means of such midspan / midline knots. However, many of those knots can be tied only with/on very slippery fishing lines, and most of them are similar to many-coil friction hitches. With ropes, the fishing knots I am aware of are not effective, or are too complex and bulky.

Lobster-pot snoods are tied on with any of a clove, ground-line, ossel
hitch
(and variations), with the tail tucked through the lay of the
ground-line once or more times.  These knots are pulled up through
the pot-hauler's V-grooved wheel compressing the knots.  (See the
photos in "Knots in the Wild".)

--dl*
====
Title: Re: Midspan bends.
Post by: xarax on May 25, 2011, 05:07:28 PM
   The OP's knot was presented in the 1928 Alpine Journal by Wright & Magowan
as a middleman's tie-in knot --possible loading of the attachment against
either or both of the tied-to line's ends. 

   Thank you, Dan Lehman. I was finally able to get a copy of this article, through a friend of mine, that got it from from a friend of his, that got it from you ! :) Nice find, although of a different knot !  :)
   I see that the "two way hitch" presented there - of which I was not aware of - (see attached picture) is different from all the three variations that I have posted in this thread. There is a simple reason for it, that I will try to explain. I wanted a "mid-line bend" that was able to withstand even a lengthwise pull of the attached line, so I made sure that the free end of this line remain as near the point where the ends of the nipping loop touch each other, and as near the axis of the main line, as possible ( see the pictures of this thread, and espesially the first one, where, due to symmetry, this even happens for both ends ). On the contrary, in the "two way hitch" of Wright and Magowan, the free ends leave the nipping loop as far from this point and the axis of the mainline as possible !  :) I am afraid that, doing this, when we pull the free end(s) from certain directions, we ran the danger to disturb and disfigure the whole knot s nub - with detrimental results in the holding power and the  strength of the bend. See the attached close-up picture:  If it were of the "two-way hitch", the orange free end(s) would have been over the orange diagonal strand that also pass through the nipping loop as well, and not under it, as in the mid-line bowline bend(s).
   This useful property of the "mid-line" bend is also present in the most beautiful mid-line bend by dfred. (1)
   The "two way hitch" of Wright and Magowan is also implemented, in this form,  in their "waist rope hitch" ( see attached picture).

1) http://igkt.net/sm/index.php?topic=3020.msg17965#msg17965
Title: Re: Midspan bends.
Post by: Dan_Lehman on May 26, 2011, 06:25:05 AM
   The OP's knot was presented in the 1928 Alpine Journal by Wright & Magowan
as a middleman's tie-in knot --possible loading of the attachment against
either or both of the tied-to line's ends. 

   Thank you, Dan Lehman. I was finally able to get a copy of this article,
 through a friend of mine,
 [who] got it from from a friend of his,
 [who] got it from you ! :)

Well, well : it IS a small world (of knotters, anyway) !   :D


Quote
Nice find, although of a different knot ! 

Slightly, yes.  And I should've referred more narrowly, to the
OP version "a" --the one symmetric one-- as like W&M's.

W&M's knot has the same orientations as the common knots
sheet bend and bowline when so loaded --i.e.,
of a *same-side* sheet bend (not "left-handed") and common
bowline
(not "cowboy"); yours is the other way 'round,
in addition to the orientation of ends vs connecting part.

To put W&M's with a similarly "away" connecting part is
to get a much less stable knot --it shifts considerably when
loading changes!  (Hmmm, I see now two versions of doing
this --ends exiting between bight legs or not.)

I find the W&M version to work okay, well enough.

--dl*
====
Title: Re: Midspan bends.
Post by: xarax on May 26, 2011, 04:05:36 PM
   If the (orange, attached line s) point of exit is as close as possible to the "kiss" point of the (white, attaching line s) nipping loop, ( as it happens in all 3 variations of the "midline bowline" - but not in the W&M knot ), any detrimental effects of a lengthwise pull ( of the attached line ) upon the nipping loop ( of the attaching line ) are minimized.  Dfred s bend, which is simpler still, also retains this useful quality. Who is going to test those 5, getting-even-more-as-the-time-passes, it seems, bends, I wonder...
Title: Re: Midspan bends.
Post by: xarax on August 26, 2011, 02:45:35 AM
   dfred, can you test those two knots of yours as bases for end-of-line loops, and tell us your findings ?
   The first one would be a bowline-like loop with two Myrtle collars, and the second a crossing knot loop, also with two Myrtle collars.
    I think that  those two loops will be as secure and strong as the common bowline, or the crossing knot loops presented at (1).
    At the bowline thread (2), I came to the conclusion that we can not define and classify the end-of-line loops, if previously we have not done the same with the mid line bends that serve as "bases" of those loops. We should first examine the local properties of the nub, and only afterwards deal with the whole picture, the end-of-line loop. So, the study of your two knots takes a new twist.!

1) http://igkt.net/sm/index.php?topic=3467.0
2) http://igkt.net/sm/index.php?topic=3233.0
Title: Re: Midspan bends.
Post by: xarax on September 13, 2011, 10:44:59 AM
   Replacing the simple nipping loop with a double, crossed-coils one - that was proved to be more stable to axial, lengthwise pull- we have a modification of dfred s midspan bend. ( See the attached pictures.)
Title: Re: Midspan bends.
Post by: xarax on November 09, 2011, 03:21:51 PM
   A mid-line bend based on the Constrictor :  a Strangle knot, itied on the attached line, is interliocked with a Constrictor, tied on the main line. (See the attached picture).
Title: Re: Midspan bends.
Post by: xarax on January 07, 2012, 08:36:30 AM
   I have only recently realized that, if we have a complex enough, effective enough structure on the attached line, we do not need a closed nipping loop on the main line ! I was using a closed nipping structure till now, because I was driven by the similarity of a (TIB) mid line bend with the bowline - where the last  thing we want, is a deformed, opened, helical nipping loop ! 
   However, it turns out that any curve - even not so tight, closed curves as dfred and myself have been used till now - can, in fact, be utilizedo to prevent any slippage of the attached line alongside the main line.
   See the attached picture, where such a wide open, helical curve is able nevertheless to hold firmly in place the more complex, tight nipping structure of the attached line. I am sure we can find even simpler midline bends than the one shown here... and the interested reader is called to try his own hand.
 
  Read a comment on this structure on :
  http://igkt.net/sm/index.php?topic=3233.msg21697#msg21697
Title: Re: Midspan bends.
Post by: TMCD on January 07, 2012, 07:31:45 PM
This is an interesting thread and it highlights just how versatile the Constrictor Knot can be. The Constrictor might just be the best all around  knot we have because it can serve as a bend, a loop, a binder and I even sometimes use it as a beefed up BellRinger's (ConstrictorRinger) for my Trucker's Hitches. The Bag Knot can do all of these things too..the fact they can be tied in the bight is what makes them so versatile.

To your orginal post Xarax, I would have to agree with Knot4U's assertion that tying two butterfly loops together would be the best mode of operation because you want something that can take a pull in any direction. I would assume that this would be the safest method too, interesting thread regardless.
Title: Re: Midspan bends.
Post by: xarax on January 07, 2012, 08:00:21 PM
the fact they can be tied in the bight is what makes [the Constrictor] so versatile.
   Yes, indeed... but I think that its high symmetry  is also a very important factor.
   You forgot to mention that the Constrictor can also serve as a fine noose-hitch, ( See the "Buntline extinguisher", at (1) ), the adjustable bowline-like loop (2), the Constrictot-based simple lock(s) for the bowline (3,4), and the Constrictor bend(s) (5).

1. http://igkt.net/sm/index.php?topic=3133.msg18699#msg18699
2. http://igkt.net/sm/index.php?topic=3233.msg21697#msg21697
3. http://igkt.net/sm/index.php?topic=19.msg20905#msg20905
4. http://igkt.net/sm/index.php?topic=19.msg20922#msg20922
5. http://igkt.net/sm/index.php?topic=938.msg21275#msg21275

Title: Re: Midspan bends.
Post by: xarax on January 10, 2012, 02:24:22 PM
   A possible, probably easy method of tying the Adjustable Constrictor loop.*
   We first make a bowline nipping loop ( do not worry !  :)  It is only temporary, it will disappear in due time, and will be transformed into an open helical coil...), and then we pass the working path in the wrong way ... Then we form a "proper", first bowline collar, we pass through the nipping loop again following the same path, and going over the strand it is already there, we form a second collar (around the eye leg of the standing part), and finally we pass the working end again through the nipping loop, for the last time, going over and crossing in an elbow configuration the strand of its first passage . ( This way, the strand returning from the collar around the eye leg of the standing part, will be put in an elbow, X = crossed embrace with the strand going  to the collar around the standing end) . ( So, each time we move "upwards " or "downwards", we pass the working end through the nipping loop from the same direction it had in its previous passage)( Verbal descriptions are often inadequate, my verbal descriptions are always incomprehensible, so : See the attached picture !   :)).

  * I know a few only things about how knots work, and almost nothing about how minds work, so usually I am very reluctant to make any suggestions of tying methods. People should remember and tie knots according to the specific way their  minds and their knots/materials combination work...I would be glad if somebody would figure out an easier way to tie this knot, that would better fit into his  mind - and possibly into mine s as well !  :)

P.S. If we want to tie the two-coils, or even the three coils version of those loops, we simply have to start from a double or triple nipping loop, and proceed as described above. I do not believe that more than one coils will be ever needed in any application, except perhaps for monofilament fishing lines.
Title: Re: Midspan bends.
Post by: Dan_Lehman on January 10, 2012, 07:26:48 PM
the fact they can be tied in the bight is what makes [the Constrictor] so versatile.

Although one can see this as *seeing* a constrictor where
the nature of that binder is lost.  (The clove hitch also can
lead to a nice, quickly tied (in the bight) eyeknot.)

   You forgot to mention that the Constrictor can also serve as a fine noose-hitch,

One might prefer to use it with the other *end* loaded,
so, making a turn/half-hitch and then finishing away
from the hitched object (turning near, reaching far,
vs. vice versa as you show).  Both look interesting.

--dl*
====
Title: Re: Midspan bends.
Post by: xarax on January 10, 2012, 10:57:31 PM
One might prefer to use it with the other *end* loaded,

   You mean to swap the standing end for the tail and vice versa ? I have considered this "inverted" loop, and I have decided that ; 
1. It is better to have the helical coil - that surrounds the Constrictor and thus multiplies its nipping force - tensioned by the standing end s strong pull, rather than by the eye leg of the bight s weaker one.
2. the way the tail is exiting the nub of the inverted knot is not very satisfactory... because, in this last line of defense against slippage, this last tuck, the tail is not nipped very tightly. ( When a tail is nipped in more than one points into a knot s nub, it is better to arrange things so that it is nipped harder and harder as it proceeds closer and closer to the exit - and not the opposite. That way there would be no slack left alongside the tail s path through the knot, and the knot itself would be forced to take a more compact shape).
Title: Re: Midspan bends.
Post by: knot4u on January 11, 2012, 12:00:29 AM
Here's a boring solution:  Hold the two ropes side-by-side as if the ropes are one.  Tie a Butterfly loop on a bight as if the ropes are one.  Tied correctly, you'll have two loops and four ends.

Advantages:

Disadvantages:
Title: Re: Midspan bends.
Post by: xarax on January 11, 2012, 06:25:33 AM
  • Requires more rope than most other solutions here
  • Not as elegant looking as most other solutions here (depending on your taste)

   An understatement ! :) In the first place, you have tied a different knot, a TIB double loop - or a double line midline double loop. Who ordered that ? Then, economy of material is not a matter of taste, one can measure  it, it is not belonging to the "de gustibus et de coloribus" subjective realm.
   Now, there are dozens of midline, TIB single or double loops known, and I guess that there are dozens that are unknown. I doubt that the Alpine Butterfly would be the most economical, or the less jam-prone.  We should measure the material used by all those knots, and see.
    Due to their high symmetry, many of the TIB single or double loops are very interesting knots, and they can be used as bases for loops and bends, as you have noticed. However, if a knot is already bulky as an end of line loop, the same knot would appear much more bulky in the middle of a tensioned line !  :)
Title: Re: Midspan bends.
Post by: knot4u on January 11, 2012, 06:52:10 AM
  • Requires more rope than most other solutions here
  • Not as elegant looking as most other solutions here (depending on your taste)

   An understatement ! :) In the first place, you have tied a different knot, a TIB double loop - or a double line midline double loop. Who ordered that ? Then, economy of material is not a matter of taste, one can measure  it, it is not belonging to the "de gustibus et de coloribus" subjective realm.
   Now, there are dozens of midline, TIB single or double loops known, and I guess that there are dozens that are unknown. I doubt that the Alpine Butterfly would be the most economical, or the less jam-prone.  We should measure the material used by all those knots, and see.
    Due to their high symmetry, many of the TIB single or double loops are very interesting knots, and they can be used as bases for loops and bends, as you have noticed. However, if a knot is already bulky as an end of line loop, the same knot would appear much more bulky in the middle of a tensioned line !  :)

Yes, indeed...It's quite bulky, but it's still a good default solution if the hard-to-remember preferred knot let's you down.

By the way, if joining 4 ropes (8 ends), the Butterfly solution I described in my last post is relatively elegant.
Title: Re: Midspan bends.
Post by: Dan_Lehman on January 11, 2012, 07:38:24 AM
One might prefer to use it with the other *end* loaded,

   You mean to swap the standing end for the tail and vice versa ?

No, I referred to your aside about the "noose-hitch", not eyeknot.
One connects the SPart's flow into the constrictor to its other end.


--dl*
====
Title: Re: Midspan bends.
Post by: Dan_Lehman on January 11, 2012, 07:59:01 AM
In the first place, you have tied a different knot, a TIB double loop - or a double line midline double loop.
 Who ordered that ?

Just a consequence of the situation (no ends).

Quote
Now, there are dozens of midline, TIB single or double loops known,
and I guess that there are dozens that are unknown. I doubt that the Alpine Butterfly
would be the most economical, or the less jam-prone.

???  How about naming some few others to compare?!

I had my doubts about Knot4U's suggestion working for
the ends on the *same side* being pulled against each
other, but (also on brief checking) they seem to do so
(forming, in a sense, sorts of offset water knots (EDK)
in effect, with added bulk that seems to resist distortion).


--dl*
====
Title: Re: Midspan bends.
Post by: xarax on January 11, 2012, 11:53:22 AM
... is relatively elegant.

   I agree, of course, that even a very  bulky knot, can be very  elegant ! Elegance  has to do with symmetries and the harmonious flow of lines, not with the economy of material. However, I ,personally, would rather choose a thin/slim elegant knot, than a thick/fat elegant one !  :)

[/quote]
In the first place, you have tied a different knot, a TIB double loop - or a double line midline double loop.
 Who ordered that ?
Just a consequence of the situation (no ends).

   I mean, the two additional loops ( slack bights ), hanging from the knot s nub. A utilitarian thing for the wet laundry, perhaps, but that was not the prescription of this thread I am afraid...

???  How about naming some few others to compare?!

  I am not going to repeat here some numbers of the ABoK s relevant long chapter on double loops you know very well ! I have a feeling that there are dozens more TIB double loops possible, because, although we can not use the two ends, we can manipulate the two bights in many ways ( so they get entangled the one to the other, around the two parts of line and possibly through some nipping loops formed  in those parts ).(See one possible TIB double loop midline "base", at the attached picture. The over-under relation of an "eye" s legs can be reversed). I was impressed that the first time I tried my hand on double loops, I met a new one ( Beginner s luck ?  :) (1). It has happened to me to have a glimpse of that seemingly endless landscape that is waiting for us there, but I just do not have the motive to exploit it for the time being - I have other priorities. Anyway, from the practical point of view, a new mid line double loop is not such an urgently needed knot, I guess...
Let us first finish this dirty bowline job !  :)

1. http://igkt.net/sm/index.php?topic=3571.0
Title: Re: Midspan bends.
Post by: xarax on January 11, 2012, 12:58:43 PM
One might prefer to use it with the other *end* loaded, so, making a turn/half-hitch and then finishing away from the hitched object (turning near, reaching far, vs. vice versa as you show).  Both look interesting.

   One might remind DL that there are pictures taken at 1826 and 1838, time flows to one direction (unfortunatelly...), and there is knot eternal life..

   I think that the first Constrictor noose-hitch is more of a noose, and this second one is more of a hitch...
Title: Re: Midspan bends.
Post by: knot4u on January 12, 2012, 07:34:54 AM
Hey, what the heck is the knot in a rope cargo net?

(http://i39.tinypic.com/k2k6iv.jpg)

(http://i42.tinypic.com/2qcedlg.jpg)
Title: Re: Midspan bends.
Post by: Dan_Lehman on January 12, 2012, 08:13:38 PM
Hey, what the heck is the knot in a rope cargo net?

In general --i.e., in netting, in general--, such knots are *mesh knots*
or *net knots*, as a class.  In appearance (from your images), these
look to be *mid-line hitches* --i.p., overhand hitches around the
crossing line.  In actuality, we might find that the apparently hitching
line at one point is reeved through the lay of the crossing line
--which helps to stabilize location of the joint.

--dl*
====
Title: Re: Midspan bends.
Post by: xarax on January 20, 2012, 01:40:36 PM
  I think I saw a pussy cat... ( or a puppy dog  :) ) complaining about the complexity of tying the Adjustable Constrictor loop...so I tried to figure out a simpler knot, based on the same idea. It comes out that if we wish to use a less cnvoluted ( than the Constrictor ) knot on the attached line, we have to use more than one coils on the main line- otherwise our knot will slip alongside the direction of the pull. See the attached pictures for such a simpler loop. Given the simplicity of the knot on the attached line - just two non-entangled bights, each one tied as a collar around each pair of ends - we now need at least two coils to secure the knot - and it might even turn out that we better use three, if we use a very slippery material.   
   Nevertheless, the knot is as simple as it can be, and I have named it so one can not forget how to tie it, even if he does not try to remember it...Form two coils on the standing part, then pass the working end/tail through them, in order to form two collars. To have as secure a loop as possible, and depending upon the material used, you might have to pull the two ends of the collar pair at the end, so the knot on the attached line is shortened, and the coils on the main line approach, even touch each other. The interested reader is called to try this knot with a variety of materials, with two or three coils, and with a more or less shortened knot, and report his findings.

This line of though can be explored even further, I believe, as I have already mentioned at the first post of this series:
" I have only recently realized that, if we have a complex enough, effective enough structure on the attached line, we do not need a closed nipping loop on the main line !
... it turns out that any curve... can, in fact, be utilized to prevent any slippage of the attached line alongside the main line.
... I am sure we can find even simpler midline bends than the one shown here... and the interested reader is called to try his own hand. "

   
   
   
Title: Re: Midspan bends.
Post by: xarax on January 21, 2012, 09:27:41 PM
   One might well ask : why do we need this "2 coils-2 collars" bowline-like loop in the first place, that may be quite simple and easy to tie, but it is more complex and more difficult to tie from the common bowline itself nevertheless - or even more complex and more difficult ti tie from the "Janus" 2- collars versions of the common bowline ? 
   I admit that I have a hope I have not mentioned , because I thought it would have been a little premature... I hope that this loop will be stronger  than the common bowline or the 'Janus" 2-collars versions of it...because of the gentle curve the standing part follows as it enters the knot s nub. This wide helical path, without the self-intersections we have when we use closed nipping loops, might be proved beneficial for the overall strength of the knot. Of course, I keep my fingers crossed on this... and I wait the results of the destructive tests I plan to perform, on the sooo many bends and loops we already have... 
Title: Re: Midspan bends.
Post by: knot4u on February 06, 2012, 06:05:40 AM
Four Corners Knot is one of the most elegant solutions to the OP.
Title: Re: Midspan bends.
Post by: xarax on February 06, 2012, 08:28:44 PM
Four Corners Knot is one of the most elegant solutions to the OP.

I am afraid I do not remember or know this knot...Could you please help me here ?
A diagram, picture or reference would be most welcomed.
Title: Re: Midspan bends.
Post by: knot4u on February 06, 2012, 09:34:24 PM
Four Corners Bend

(http://i1221.photobucket.com/albums/dd468/iq201/Public/Bend-FourCorners.jpg)

I got the idea of the knot from this video:
http://www.youtube.com/watch?v=dhm9UIOvQV0

Here's another reference including pics:
http://www.westernhorseman.com/index.php/articles/web-extras-mainmenu-151/item/84/asInline.html
Title: Re: Midspan bends.
Post by: Sweeney on February 06, 2012, 10:36:51 PM
I've used this on a scarf a few times but never heard of it by that name before, only as a "cross knot". Interesting to use it as a bend, I'd never thought of that.

Barry
Title: Re: Midspan bends.
Post by: xarax on February 06, 2012, 10:49:04 PM
  Thanks. Yes, I know this knot pretty well, under other names...
  My understanding is that it is too simple, and it is rather unstable. ( I have said the same thing for a bowline-like loop based on this knot, by Lee. ) If one of the four limbs is loaded much more than the others, this knot runs the danger to be badly  deformed - and it will not return at its initial, symmetric state afterwards.
   My gut feeling is that this knot needs to be beefed up a little, but I have not tried anything yet.
   
Title: Re: Midspan bends.
Post by: SS369 on February 06, 2012, 10:49:58 PM
It is also known as the start of a four strand crown (square) sennit. One will have to have access to  one end, especially if using two cords middled. This bend will be very subject to distortion if the loads on the four strands is uneven.

SS
Title: Re: Midspan bends.
Post by: knot4u on February 06, 2012, 11:19:33 PM
The Four Corners Bend must be fully tightened before loading. Even then, I was able to get the knot to capsize badly with rude and unpredictable loading combinations. It looks cool though.

For the problem in the OP, I'd probably use the Butterfly I described above, no access to ends needed.
http://igkt.net/sm/index.php?topic=3020.msg21724#msg21724
Title: Re: Midspan bends.
Post by: knot4u on February 07, 2012, 02:40:53 AM
Tie an overhand on a bight in one rope. Retrace overhand with other rope. (It's a water knot kinda.) Three ends will extend from one end, and one end will extend in the direction of the bight. Brief testing, it works but seems jam-prone.

...It's not my favorite solution of this thread.
Title: Re: Midspan bends.
Post by: xarax on February 07, 2012, 03:38:50 AM
Tie an overhand on a bight in one rope. Retrace overhand with other rope.

   I do not like this bight hanging around without any active role in the hitch... :)  The same can be said with solutions based on the midline sheet bend. You consume more rope to make a "base', on the main line, and less rope to anchor the attached line on this "base". I think that we should better do the opposite... I have seen that any curved segment on the main line, ( even an open, helical coil), can serve as a firm "base", and prevent the attached line from slipping alongside the main line - provided that the knot on the attached line is a hitch tight enough - as the constrictor, for example. So, we really do not need all this material and volume of the overhand on a bight, for a firm base...
   Your general idea seems to be this ; You use a tight, convoluted knot on a bight tied on the main line, and you somehow entangle the attached line into the nub of this knot - by retracing the path of the main line, for example. I believe that any  such solution will be less economical, and more bulky, than the other bowline-like solutions presented in this thread.     
Title: Re: Midspan bends.
Post by: knot4u on February 07, 2012, 07:01:23 PM
Tie an overhand on a bight in one rope. Retrace overhand with other rope.

   I do not like this bight hanging around without any active role in the hitch... :)

I don't like it either, but it's better to know a few solutions for this awkward problem. A modest change in material and/or rope sizes can make  certain solutions here less than worthless.
Title: Re: Midspan bends.
Post by: knot4u on February 07, 2012, 07:12:30 PM
Your general idea seems to be this ; You use a tight, convoluted knot on a bight tied on the main line, and you somehow entangle the attached line into the nub of this knot - by retracing the path of the main line, for example. I believe that any  such solution will be less economical, and more bulky, than the other bowline-like solutions presented in this thread.     

Well, that's one general idea, not mine. So, within that general idea, what's the simplest and/or most elegant?
Title: Re: Midspan bends.
Post by: xarax on February 07, 2012, 11:59:53 PM
within that general idea, what's the simplest and/or most elegant?

   I do not know !  :) However, I promise I will try to investigate this line of thought shortly -after I go till the far end of the exact opposite  :). Read the next posts, and, please, tie and try the knots presented there, which are based upon a very simple, helical structure on the main line, and a shape "8" structure on the attached line.
Title: Midspan bends, based upon shape "8" knots tied on the attached line.
Post by: xarax on February 08, 2012, 12:01:16 AM
We have seen that, in order to attach the end of a line ( the "attached" line, or the eye leg of the bight of a loop ) on a certain mid span point of another line ( the "main line", or the eye leg of the standing part of a loop),
1. We do not need to anchor the end of the attached line on a pre-tied overhand knot on the main line. So, we do not need to transform a clever, beautiful, symmetric interlocked-overhand-knots bend ( as the Zeppelin bend, for example ), to a not-so-clever, ugly, asymmetric loop knot ( as the so-called "Zeppelin loop", for example). Bends and end-of-line loops are different animals, they should be kept apart from each other. Otherwise, we end with ugly bulky hybrids, or even monsters, which do not retain any of the economy, symmetric distribution of forces and elegance of their parent bends. The main advantage of the bowline, by which this marvelous knot gained the crown of the "king of knots", is the absent of any overhand knot pre-tied on the main line : a single nipping loop is all that is needed to ensure that the attached line will not slip alongside the main line.
2. We do not even need to anchor the end of the attached line on a complex, closed nipping loop structure, like the many convoluted - but not based on interlocked-overhand-knots - bends.
3. We do not even need to anchor the end of the attached line on a simple, closed nipping loop, like the nipping loop of the common bowline.
4. All that we need, is a curved segment at the main line, that can provide enough friction to block the slippage of an attached line, properly entangled around this segment.
When I realized this fact, it was natural for me to try to balance the missed complexity of the structure on the main line, with an added complexity on the structure of the attached line. So, I tried one of the tightest hitches we know, the constrictor. And it worked fine ! Then, I have started to try even simpler knots, like the 2-collars,2-coils knot. It worked fine as well...Now I go one step further, and replace the Constrictor hitch with a Pretzel or a Strange hitch around the main line - i.e. a less convoluted knot based upon another, simpler shape "8" structure. And I should say that i was amazed by how tight and secure those new knots are - and by the fact that I, for one, have never tied or learned anything like them...
At the following posts, I am going to present some "new" knots based upon a shape "8" knot, tied with/on the attached line, that I think they are even simpler than the ones already known and shown in this thread. I do not know if these knots still deserve to be called mid span "bends", because of the minimum, very simple knot structure of the main line. ( I do not even know if we can call a helical segment of a rope, a physical "knot" ! ? ! ? ! ? .However, this is another section s question... ) They are "stoppers', that is for sure, in the sense that they block the movement /slippage of the attached line alongside the main line quite effectively.
   I  would love if any other member of this forum tie those knots, try them, and report his findings here. I do not have yet neither the expertise, nor the necessary equipments to test knots as I would like to. So I would be glad, and much appreciate, OPT ( Other People s Tests...).
   Last, but not least, I would like to state, and make it perfectly clear, that I am not interested very much in mid-line bends !   What brought me here is the search for new loop knots, and the mid-line bends is but a general scheme, a means to accomplish this much more interesting and useful subject. So, the reader should see all these mid-line bends as knots that can be used at fixed or adjustable loops, even when I do not present them as such.
   (The last point might come also as an answer to another reasonable question by the interested reader : Why one should prefer a mid-line bend, where the knot tied with/on the main line is much simpler than the knot tied with/on the attached line ? The answer is that, in a loop - which is what interest me most -, the main line / standing end is loaded with 100 % of the load, while the attached line / eye leg of the bight, is loaded with 50% of the load. We should try to make the path of the main line / standing part as straight as possible, so the strength of the knot is as less effected as possible - at the points where it is likely to suffer most.)
Title: Pretzel 1 midline bend
Post by: xarax on February 08, 2012, 12:05:52 AM
Pretzel 1 midline bend
Title: Pretzel 2 midline bend
Post by: xarax on February 08, 2012, 12:07:08 AM
Pretzel 2 midline bend
Title: Strangle 1 midline bend
Post by: xarax on February 08, 2012, 12:08:48 AM
Strangle 1 midline bend
Title: Strangle 2 midline bend
Post by: xarax on February 08, 2012, 12:11:06 AM
Strangle 2 midline bend
Title: Two interlinked overhand knots midline bend
Post by: xarax on February 08, 2012, 12:13:01 AM
Two interlinked overhand knots midline bend

There are two variations of this knot, just as in the cases of the Pretzel and the Strangle midline bends. Shown here are the top view of the first, and the bottom view of the second.
Title: A Colombus midline bend...
Post by: xarax on February 08, 2012, 12:14:32 AM
Two overhand knots midline bend
Title: Re: Midspan bends.
Post by: knot4u on February 08, 2012, 01:44:35 AM
OK, but pics may violate rules of original post. It looks like there's access to both ends of orange rope. Your own OP makes those solutions more difficult to tie, and way less memorable. The OP is provided here for preservation before Xarax strikes again to change it:

   There are six classes of two-line bends: in the case when we have to join two lines, and only the one end of only the one line is accessible, we need a "mid-span" or "mid-line" bend. (The bend should be able to withstand a pull coming out of any end(s) and any direction(s).) A very simple midline bend I can think of is the "midline bowline", shown in the pictures below (in three variations). Of the many alternatives one can think of, which are the most practical ?
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 02:13:37 AM
It looks like there's access to both ends of orange rope.
   Oftentimes the attached line is short, and there is access to both ends. However, anything that can be tied when we have access to both ends, can also be tied if we have access to only one, is nt it that so ? ... :) The tying method might become more complex, because we lose the symmetry of the tying operation, but the symmetry of the knot structure remains the same...and the mental picture of it is very easy to memorize.
   As I have said many times, I have seen that one needs to tie a new knot at least a dozen times, in order to get the feeling of it, and start to be confident about his opinion. A knot that looks very difficult at the start, may be proved very easy - and vice versa. I believe that the five knots that I have presented in the previous posts are very easy to remember, but I speak for myself - and different people have different ways to memorize things, especially 3D shapes. The adjustable loop based on the Constrictor was more difficult, so I tried to figure out an additional mnemonic rule that would facilitate its tying ( see Reply#30). I do not believe that something similar is really needed here, because the two steps shown at the pictures do not need any verbal instructions.

   
The OP is provided here for preservation before Xarax strikes again to change it:

I do not reply to such ...
Title: Re: Midspan bends.
Post by: knot4u on February 08, 2012, 02:32:23 AM
It looks like there's access to both ends of orange rope.
   Oftentimes the attached line is short, and there is access to both ends. However, anything that can be tied when we have access to both ends, can also be tied if we have access to only one, is nt it that so ? ... :) The tying method might become more complex, because we lose the symmetry of the tying operation, but the symmetry of the knot structure remains the same...and the mental picture of it is very easy to memorize.

Screw that. I'm not letting you weasel your way out of this one. We have access to one end. That's the rule for this entire thread. If we have access to both ends on one rope, I would have come up with some better solutions.

Given the rules of the OP, the knots in Posts #60-62 are simply not going to be remembered after a few days (or hours) of not tying it. This problem is rare (at least for me). Also, that solution is not the preferred solution. So, I am highly unlikely (i.e., will never) practice it.
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 03:36:38 AM
We have access to one end. That's the rule for this entire thread.

   The solutions at Replies #21, #25, #26, #27, #29, #42, #57-62, as well as  dfred s nice solution, are all symmetric solutions that can be tied either with the one end of the attached line ( or the eye leg of the bight of a loop), or with both ends of the attached line.

This problem is rare

 A general problem should be addressed and, if possible, solved, regardless of the number of times we have met it...because its solution could lead to the solution of other, more special and less "rare" problems. I repeat what i have written at Reply#56.

  I would like to state, and make it perfectly clear, that I am not interested very much in mid-line bends !   What brought me here is the search for new loop knots, and the mid-line bends is but a general scheme, a means to accomplish this much more interesting and useful subject. So, the reader should see all these mid-line bends as knots that can be used at fixed or adjustable loops, even when I do not present them as such.


 P.S   I know that few people tie the knots I present, so it is no wonder than even fewer, if any, read what I write about them !  :) Of course, elegant knots, just like elegant mathematical theorems, do not need writers to defend them, nor readers to read them...They are true, and they exist, independently of the every-day "user".
Title: Re: Midspan bends.
Post by: SS369 on February 08, 2012, 04:44:07 AM
Hi xarax,

some people do tie these offerings and evaluate them.

Another symmetrical offering is the prusik knot. It holds position in either direction very well with just four coils. (Not necessarily in all size ropes though.) Nothing new, but it is along the lines. ;-)

I do wonder what effect tensioning the white "pass through" main line will have on the couple you've just offered (#52-62)?

SS
Title: Re: Midspan bends.
Post by: knot4u on February 08, 2012, 05:58:53 AM
I try many of your knots, Xarax. In fact, I've played around with the knot in the OP a lot. I think that solution is pretty good: simple, memorable because of its similarity to Bowline.  All I need to do is remember the Bowline well, and I can figure it out.

As for the solutions that are not memorable, I suppose they could still be considered "practical", but realistically I'm never going to use them. Every knot I've tied in real life for a real application is from memory. That's just my perspective on it, something to keep in mind.  Others may be different, or they may be exactly like me.  It doesn't really matter.  I'm the one tying my knots.
Title: Re: Midspan bends.
Post by: knot4u on February 08, 2012, 06:06:57 AM
By the way, Xarax, for the Strangle solutions in Replies #60-62, there appears there may be a way to make those knots memorable.  For example, can the orange rope show the Strangle in its normal form, with the white rope passing through in a memorable way?

But then you violate the rules of the original post because you need access to more than one end. (Strangle can't be tied on the bight).  I'm not opposed to changing the rules of the original post, or starting a new thread.
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 11:15:00 AM
Another symmetrical offering is the prusik knot. It holds position in either direction very well with just four coils.

I have not compared those knots with the climbing hitches. As I understand, climbing hitches hold well on a certain point of the main line only when -and because - they are loaded, and they are easily transported upwards or downwards when they are not. The bends/stopper/hitches - whatever we may call them - presented previously in this thread, as well as the last ones, tend to stay in place even after the ends of the attached line are not loaded any more. However, the main difference is elsewhere...The knots presented in this thread do not work on a straight, tensioned line, because they are based upon a more or less curved segment of it, to anchor the attached line. At those last knots, this curvature is imposed by the tightening of the attached line, i.e, we start placing the shape "8" knot of attached line on/around the straight main line, then we pull its two ends, and this operation deforms the main line as much as needed, to multiply the friction forces between the two lines. My purpose was this ; Find a knot tied with/on the attached line, that, when the main line is forced to curve inside it, the curvature is : 1 : Enough to offer the proper anchor so the attached line will not slip, and 2 : The curvature of the main line will not be straightened again, if, after the pull of the two ends of the attached line, the main line is tensioned much more forcefully than the attached line ( at about double the load, as it happens with the standing end of a loop, in comparison with the two legs of the loop).
   I was amazed to see that the knots presented were successful in both of those tasks. I have not compared them in any detailed way, but it is clear that, although we start from about the same shape "8" knot on the attached line, we end with quite different knots, that should differ on their slippage characteristics. Great news !  :) Because we want to chose the best of them, and this difference of the end knot makes this much easier. My problem with knots that are e very similar, is that I can not chose which one is really better - and I am forced to keep all of them in the limited space of my brain... :)
   So, I believe that those knots, based upon a more or less deformed main line, are very different animals than climbing friction hitches. And they have the advantage I have repeated many times, that climbing hitches do not : they can serve as knots for adjustable of fixed loops. I have stated that this iwas my main interest in the first place, to find a better mousetrap, sorry, bowline !  :)

I do wonder what effect tensioning the white "pass through" main line will have on the couple you've just offered (#52-62)?

THAT is the crux of the matter !  :) I have seen that, after the attached line is tensioned and have succeeded to impose a curvature on the main line - be it an open helical segment or two 'bumps', a wave-like shape - those deformations of the main line tend to be permanent and stable. The existence of the attached line, even if it is not loaded, is enough to keep those necessary curves on the main line at their final state after the operation, i.e. that the deformation of the main line is, more or less, irreversible ! I say "more or less', because those knots are different, and in some of them this irreversibility is more assured than in others - and also because some straightening is expected. I have loaded the main line at double the load than at each of the two ends of the attached line, like it happens in a loop, and I have been satisfied with the results.  I would love to perform the same tests with more slippery ropes, like the spectra/Dyneema non-coated ones, and see what happens there. volunteers are always wanted, and much welcomed !  :)
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 12:01:06 PM
Every knot I've tied in real life for a real application is from memory.

Till now, my dear knot4u, till now... :) Wait a few more years, and then you tell it to me again... :)
That is correct, of course. A practical knot that we can not tie from memory, is not a practical knot for us - by definition !
However, you should first tie the knots some times, test them, and if you find them satisfactory, tie them again and again !  :)  Only at the very ,end of this process, you can say that it is difficult for you to memorize a knot, and dismiss it. You have not run the full course of this process yet, have you ?  :)

Can the orange rope show the Strangle in its normal form, with the white rope passing through in a memorable way?

   Of course, all those knots can be shown while they are being tied by a different series of pictures and steps. I have only tried to present them in one post, in a unified way - as it is evident from the first step in all of them. I have started from the different variations of a shape "8" - looking knot, on top of the straight main line. But you can tie the same knots differently - and you can memorize them differently. I find very difficult to predict which is the easier way to memorize a knot-tying sequence, because people differ a lot on that matter...What I have presented, is only the way I use to keep all those different knots in the same place in my brain - so I would be able to address them easily, in the future.
   Please, do not pay any attention to the specific names I have used... Many knot tiers will not recognize a Constrictor or a Strangle knot in those mid line bends, and/or will deny the relation. I use those names because they reveal the sequence of thoughts that drove me at them :  We use the simplest knot on the main line, and we start from the most complex knot on the attached line. Then, we try to use a simpler knot for the attached line, too. So, we go from the Constrictor to the Strangler. It is the logic of the research that is labeled here, more than the actual end product, the specific knot.


 


Title: Re: Midspan bends.
Post by: SS369 on February 08, 2012, 03:58:21 PM
Another symmetrical offering is the prusik knot. It holds position in either direction very well with just four coils.

I have not compared those knots with the climbing hitches. As I understand, climbing hitches hold well on a certain point of the main line only when -and because - they are loaded, and they are easily transported upwards or downwards when they are not. The bends/stopper/hitches - whatever we may call them - presented previously in this thread, as well as the last ones, tend to stay in place even after the ends of the attached line are not loaded any more. However, the main difference is elsewhere...The knots presented in this thread do not work on a straight, tensioned line, because they are based upon a more or less curved segment of it, to anchor the attached line. At those last knots, this curvature is imposed by the tightening of the attached line, i.e, we start placing the shape "8" knot of attached line on/around the straight main line, then we pull its two ends, and this operation deforms the main line as much as needed, to multiply the friction forces between the two lines. My purpose was this ; Find a knot tied with/on the attached line, that, when the main line is forced to curve inside it, the curvature is : 1 : Enough to offer the proper anchor so the attached line will not slip, and 2 : The curvature of the main line will not be straightened again, if, after the pull of the two ends of the attached line, the main line is tensioned much more forcefully than the attached line ( at about double the load, as it happens with the standing end of a loop, in comparison with the two legs of the loop).
   I was amazed to see that the knots presented were successful in both of those tasks. I have not compared them in any detailed way, but it is clear that, although we start from about the same shape "8" knot on the attached line, we end with quite different knots, that should differ on their slippage characteristics. Great news !  :) Because we want to chose the best of them, and this difference of the end knot makes this much easier. My problem with knots that are e very similar, is that I can not chose which one is really better - and I am forced to keep all of them in the limited space of my brain... :)
   So, I believe that those knots, based upon a more or less deformed main line, are very different animals than climbing friction hitches. And they have the advantage I have repeated many times, that climbing hitches do not : they can serve as knots for adjustable of fixed loops. I have stated that this iwas my main interest in the first place, to find a better mousetrap, sorry, bowline !  :)

I do wonder what effect tensioning the white "pass through" main line will have on the couple you've just offered (#52-62)?

THAT is the crux of the matter !  :) I have seen that, after the attached line is tensioned and have succeeded to impose a curvature on the main line - be it an open helical segment or two 'bumps', a wave-like shape - those deformations of the main line tend to be permanent and stable. The existence of the attached line, even if it is not loaded, is enough to keep those necessary curves on the main line at their final state after the operation, i.e. that the deformation of the main line is, more or less, irreversible ! I say "more or less', because those knots are different, and in some of them this irreversibility is more assured than in others - and also because some straightening is expected. I have loaded the main line at double the load than at each of the two ends of the attached line, like it happens in a loop, and I have been satisfied with the results.  I would love to perform the same tests with more slippery ropes, like the spectra/Dyneema non-coated ones, and see what happens there. volunteers are always wanted, and much welcomed !  :)


Hi xarax, I intend to differ here.

Some climbing hitches are problematic in that they are hard to release (after load has been released) and this is what drives climbers (and others) to pursue exploring different methods.
A "standard" prusik stays where put very well because it cinches tight and deforms the rope and generally stays that way till advanced. If that rope - main line is soft then there will be a pronounced "dent" and warpage, if hard then the result will be a deforming (bending) of it at the loaded knot. The caveat of sorts here is that some of these "climbing hitches" don't work well in sizes that match the parent line. Or in , very very large ropes.

Maybe I have a problem with this all because in my mind I have the definition of a bend that says "Bend = joinery using the ends of  the ropes)" To me a mid-span bend, as in the OP, is a hitch on a main line.
Quote
There are six classes of two-line bends: in the case when we have to join two lines, and only the one end of only the one line is accessible, we need a "mid-span" or "mid-line" bend. (The bend should be able to withstand a pull coming out of any end(s) and any direction(s).)

As you know, I do try to tie these tangles with the most difficult ropes I have, including the Titan cord that generally fails most knots because of its properties. I also use static and dynamic ropes of varying "hand" (suppleness or lack of) and diameters. It is with this approach that I see, sometimes, the good and bad and can give voice to drawbacks or praise.

I am certainly not trying to hinder exploration, just sharing what I find.

I suspect that some of the knots will be just too hard to tie if the mail line has tension, such as from tree to tree, and therefore not be able to warp. And so I think that we may be really including hitches as bends here.

If the scenario is that there is no existing tension to counteract during the tying, then the possibilities go up, way up. For example: Make a round turn in the main line, then tie a constrictor (or variation) around the crossing point of the round turn.

SS
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 04:45:45 PM
"in my mind I have the definition of a bend that says "Bend = joinery using the ends of  the ropes)" To me a mid-span bend, as in the OP, is a hitch on a main line. "

   Some of the knots presented in this thread can clearly serve as bends of the main line and the attached line. Some are more like a kind of hitch of the attached line on the main line, and some are something in between !
In my mind, I have the following categories ;
1. Gripping hitch on a tensioned line. ( rat-tail stopper, or series of half hitches)
2. (Climbing) friction hitch on a vertical line, that may or may not be tensioned. The main line remains more or less straight, although it is deformed locally.
3. Adjustable friction hitch, or adjustable noose. The main line is curved by the tensioning of the attached line, and remains curved even when the attached line is not loaded any more. However, the main line does not form a closed nipping loop.
4. Knots of fixed end-of-line loops. They main line is convoluted, it forms one or more closed nipping loops.
5. Symmetric ( and a few only non-symmetric) bends.

I suspect that some of the knots will be just too hard to tie if the mail line has tension

They are not designed to work in this situation...This is a job for the 1. and 2. categories mentioned above. Do not confuse those things...

If the scenario is that there is no existing tension to counteract during the tying, then the possibilities go up, way up. For example: Make a round turn in the main line, then tie a constrictor (or variation) around the crossing point of the round turn.

Yes, this is the scenario, and yes, I have done this !   :) I believe that the knots presented are the more simple, stable and secure of the MANY I have tried...Dfred s knot is also an elegant, simple, fine knot, that had not crossed my mind !
The possibilities go up, but so goes the complexity and the bulkiness of the knots...Try to figure out some other solution that stays withing the limits of a practical knot ( and try to avoid complex solutions, as the safe but bulky solution of knot4u, for example). I do not doubt that you may well figure out something that had escaped my attention. That was the meaning of the thread, and of any thread...To introduce  a problem, and persuade some other members to spend some time with it, and come up with different and possibly better solutions.
Title: Re: Midspan bends.
Post by: xarax on February 08, 2012, 06:42:08 PM
A "standard" prusik stays where put very well because it cinches tight and deforms the rope . If that rope - main line is soft then there will be a pronounced "dent" and warpage, if hard then the result will be a deforming (bending) of it at the loaded knot.

   We should make the distincion between a local deformation, a deformation of the surface of the rope, and a deformation of the geometry / of the path of the rope.
   In the first case, we have those "dents", a wave-like deformation of the surface of the rope, that affects its circular cross section, and in the second we have those helical segments, or those "bumps", a wave-like deformation of the linear extension of the rope, that affects its longitudinal profile.
   In the 1st and 2nd categories of hitches around ropes that I have mentioned above, we have the first case, while at the hitches studied in the 3rd category and in this thread, we have the second case. I do not doubt that there are hitches that lie in between those two cases, as when a climbing hitch is tied tightly around a not-so tensioned main line, or a adjustable loop or noose is tied tightly around a very taut main line...but, grosso modo, I think that we can, and we should, make this distinction .
Title: Re: Midspan bends.
Post by: xarax on February 09, 2012, 07:04:33 PM
you violate the rules of the original post because you need access to more than one end. (Strangle can't be tied on the bight).

  I supposed that was a mistaken remark by knot4u, said under the heat of a debate  :), but, as yet another member made the same mistake, I have to mention what I thought was obvious : at the 6 knots shown at Replies#57- #62 the white line is representing the main line, and the orange/red line the attached line. The problem was/is to connect a second, secondary line on a certain point of a main line. The Constrictor, at the Adjustable Loop of Reply#27 and Reply#30, the shape "8' nipping structure of the 2coils-2collar loop at Reply#42, and the Pretzel, Strangle and two-interlinked-overhand knots  at Replies#57-61, are tied with the attached line ( using one or both ends of it).
Title: Re: Midspan bends.
Post by: knot4u on February 09, 2012, 07:25:33 PM
you violate the rules of the original post because you need access to more than one end. (Strangle can't be tied on the bight).

  I supposed that was a mistaken remark by knot4u, said under the heat of a debate  :), but, as yet another member made the same mistake, I have to mention what I thought was obvious : at the 6 knots shown at Replies#57- #62 the white line is representing the main line, and the orange/red line the attached line. The problem was/is to connect a second, secondary line on a certain point of a main line. The Constrictor, at the Adjustable Loop of Reply#27 and Reply#30, the shape "8' nipping structure of the 2coils-2collar loop at Reply#42, and the Pretzel, Strangle and two-interlinked-overhand knots  at Replies#57-61, are tied with the attached line ( using one or both ends of it).

That's not what I meant. Go back and read my post. I was suggesting presenting pics/diagrams in a way that makes the knot memorable. As the pics are presented now (white rope stationary, orange rope doing all the work), the knots are not memorable. My suggestion was to forget the rule in the original post, show the Strangle Knot in its more recognizable form, and then show the white rope passing through the orange rope in a memorable way.

It may not be possible to show pics that are memorable, but for future reference I don't mind if you free yourself from the rule in the OP.
Title: Re: Midspan bends.
Post by: xarax on February 09, 2012, 07:49:50 PM
That's not what I meant. I was suggesting presenting pics/diagrams in a way that makes the knot memorable. As the pics are presented now (white rope stationary, orange rope doing all the work), the knots are not memorable. My suggestion was to forget the rule in the original post, show the Strangle Knot in its more recognizable form, and then show the white rope passing through the orange rope in a memorable way.

   Ok, sorry, I see what you mean. As I have said, this was only a first presentation, and its purpose was to show the different knots that come out of the same shape "8" nipping structure, following the same steps. The "tails" of this shape "8" base form can be crossed or not, the diagonal that goes from the first bight to the second can be over or under them, and the re-tucking can be made at the near or the far bight - but the general image is the same. However, the final products/knots of this process are quite different, and they are expected to address the problem differently - i.e. more or less successfully. That was the logic of the way those 6 knots were presented. Iff, and I stress this iff, we judge that any of them is really a viable solution, and a more interesting one  than the others, then we can try to present its tying method in a more memorable way.
Title: 2 coils-2 collars midline bends-loops
Post by: xarax on February 10, 2012, 02:51:22 PM
Here, I follow the thread from Reply#42-#43. The knot presented there as a midline bend, can also serve as a adjustable end-of-line loop. The same can be said for two variations of it that are presented here.
   If we want to keep the bights of the collars tightly wrapped around the penetrating ends of the main line, we must somehow entangle the ends of the attached line, at their path through the coil tube. Doing this, the bights are nipping the main line hard, they can not move apart from each other, and the main line s helical structure remains intact, however tensioned it might be.
   Of course, to entangle the ends of the attached line, we have to manipulate them carefully inside the coil tube of the main line, and this makes the tying of the mid line bends, or the loops, that are presented here more "difficult",  than when the ends were just parallel to each other, as they were at Reply#42. However, if, while we are tying those mid line bends or loops, we keep the - most simple - knots tied with the attached line in our memory as simple mental pictures, we will not make any mistake.
   I have to mention one more characteristic of those knots, that might have escaped the attention of the future reader. The helical coils, the coil tube, is winded around a core of three rope diameters, which is good because the core remains stable ( each rope line is adjacent to the other two) and the diameter is sufficiently large. We wish the curves of the main line of the mid line bend ( or the standing part of the loop ) to be as wide as possible, because this line bears the heavier loads, and it is this segment of the knot that should be watched more carefully, if we wish to somehow improve its strength.
   See the attached pictures for two variations of the 2 coils-2 collars midline bend, or end-of-line loop, with a more tightly entangled core. At the first, the helical coil of the main line travels around a fig. 9 stopper knot, and at the second around a double overhand stopper knot. I also post pictures of the internal cores, tied with the attached line,  at the same scale, so the future reader would not need to see through the ropes with his X rays vision... :)
Title: 2 coils-2 collars midline bends-loops
Post by: xarax on February 10, 2012, 03:00:25 PM
   Of course, we can also use other stoppers as cores tied with the attached line, around which we will wind the helical coils of the main line. Here I have presented only two of them, but the principle reamains the same : Tie a knot where the attached line will form two tightly connected bights, and the main line will penetrate those bights, while it is wrapped around the whole knot at the same time, forming a single- or multi- collar helical structure, a coil tube.
Title: Re: Midspan bends.
Post by: Dan_Lehman on February 10, 2012, 08:56:09 PM
To the knots shown in #78, "fig.9 stopper" is a bad name,
with a different structure having claimed it already (that
structure that makes --in the same *direction*-- "one more
(half" turn than a fig.8 ).  (I'm w/o inspiration for
such a name suggestion, at the moment; sorry.)


--dl*
====
Title: Re: Midspan bends.
Post by: xarax on February 10, 2012, 11:02:31 PM
To the knots shown in #78, "fig.9 stopper" is a bad name, with a different structure having claimed it already

Yes, I know...It was just a temporary label, because I, too,  had not any inspiration for a proper name... :). I do not even like the "double overhand knot" name, for a shape "8" like knot...
Title: Re: Midspan bends.
Post by: X1 on July 17, 2012, 08:53:26 PM
   Even a "simple" double collar structure on the working end ("simpler" than the more twisted/convoluted one shown at Reply#27, (1) ) - can be linked within the helical nipping structure on the standing part in a sufficiently secure way. ( See the attached pictures for a most simple helical loop.)
   This indicates two things :
   1. That the nipping loop on the standing part is a very efficient mechanism of gripping the legs of the collar - even if this loop is not a closed ring, but a single open helical coil.
   2. That the double collar on the working end is a very efficient mechaism of distributing the tensile forces on the standing part - even if this double collar is nothing more than a simple "S" form.

1) http://igkt.net/sm/index.php?topic=3020.msg21688#msg21688