Author Topic: Best gripping hitch around a tensioned rope  (Read 34603 times)

Dan_Lehman

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Re: Best gripping hitch around a tensioned rope
« Reply #15 on: February 18, 2011, 06:11:22 PM »
First, I have to say that I see no opponent, whatsoever, in the "best hitch around  a tensioned rope" "Knot battle" !  So, the B hitches will win hands down !  :)

An obvious candidate is the ProhGrip / Blake's hitch,
which can be amended per need by increasing the number
of turns, and e.g. having the tail be tucked under three
vs. two, with two or three following beyond these.

--dl*
====

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #16 on: February 18, 2011, 06:21:16 PM »
First, I have to say that I see no opponent, whatsoever, in the "best hitch around  a tensioned rope" "Knot battle" !  So, the ww hitches will win hands down !  :)

An obvious candidate is the ProhGrip / Blake's hitch,... having the tail be tucked under three vs. two, with two or three following beyond these.

  Les go!
  ww hitch vs Blake s hitch !  :)
  (Same number of nipping round turns/coils around the Main line, of course )
  Gentlemen, place your bets !

  
« Last Edit: July 28, 2011, 11:42:30 AM by xarax »
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knot4u

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Re: Best gripping hitch around a tensioned rope
« Reply #17 on: February 18, 2011, 08:40:31 PM »
The Knot Wars for fishing would not be of interest to me if the exact same rules were applied to rope.  I know this Knot Wars commentary in this thread is halfway tongue in cheek.  However, a Knot Wars for rope needs to be approached at a completely different angle then the Knot Wars for fishing.  At least it would have to be different for my interest.

For fishing line, the Knot Wars involves jamming a knot and seeing which knot breaks first.  Those two criteria are definitely important for fishing knots.

For rope, these criteria (jamming and break point) are not at the top of my priority list.  So, if we're going to have a Knot Wars for rope, then I recommend agreeing on a set criteria that is important for a particular challenge.  If break point is the only criteria, then I don't think it would be super difficult to design knots that have a higher break point than a Blake for example.  The competition would end up including only knots that are a complex braid of mild turns.  I don't have any knots in my personal library that are like this for rope, nor do I particular need such knots at the moment.

Here are other criteria that may be more important than strength in rope:

-Ease of adjustment (subjective)
-Ease of tying (subjective)
-Tendency NOT to jam (opposite of what you want for fishing)
-Efficiency (perhaps measured by the amount of rope used)
-Security (as opposed to strength)
« Last Edit: February 18, 2011, 09:08:28 PM by knot4u »

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #18 on: February 18, 2011, 08:49:34 PM »
Thank you Knot4,

If break strength is the only criteria, then I don't think it would be super difficult to design knots that have a higher break strength than a Blake for example.  The competition would end up including only knots that are a complex braid of mild turns.  

  I think we should have some sorting of knots according to their "complexity".We need only practical knots, that is knots that accomplish the task, being as simple as possible. However, I do not think that you can find many "less complex"  knots that : 1. can hold, and, 2: be less "complex" than DL s Blake or my ww hitch. I might well be mistaken here, of course. That is why I have initiated this thread at the first place. We are calling for competitors ! You are invited to choose your favourite.
   As of the other criteria :
  The ease of tying can be less subjective, if we adopt a simple measure. For the hitches around poles or ropes, the number of round turns around the axis. For the bends, the number of turns we have to pass an end through an opening . ( If we just re tuck the end through the same opening, the number would increase for only half a point, as this task is easier)
   The jamming or not is a difficult issue that I do not know much about. I guess we can sort the knots in two rough categories, (easily) jamming. or not (not=less?) jamming.
  The security is sine qua non. Not secure knots would be offered to senior members of the forum to tie their pack of old notebooks with...
« Last Edit: July 28, 2011, 11:41:09 AM by xarax »
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Bob Thrun

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Re: Best gripping hitch around a tensioned rope
« Reply #19 on: February 22, 2011, 05:23:25 AM »

The "B hitch" is what Gary Storrick has called a "hitch series"
--repeated half-hitches/turns of alternating handedness-- ;
Gary is following the usage in my book.  I coined the term Hitch Series to describe what Bill Plummer described without givinf it a name.  Fig. 17 is mine.
These other drawings are tracings from Plummer's article so that they could be reprinted in the book. 
« Last Edit: February 24, 2011, 08:00:58 PM by Bob Thrun »

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #20 on: February 22, 2011, 04:45:55 PM »
   Thank you Bob Thrun.
  
   First, let us not confuse two ENTIRELLY different things : A hitch around a tensioned or not rope, and a hitch around a ( round, solid, slick ) pole.  I am not gong to analyse this any more here, but I feel that I have to repeat it, because people that have not much experience in this tend to confuse them. I suspect that they are fooled by the similar "looks" of the relevant hitches... In this thread, I am speaking ONLY of hitches around tentioned ropes, and with ropes of similar sizes with the "Main line", around which those hitches are tied. For hitches around poles, I have decided that the best hitches are the "normal", many-coils friction hitches, when we do a simple modification : in some way, we have to keep the two ends under tension with another friction mechanism ( I have chosen my modified Gleipnir-like knot for this, see (1).)
   The THIRD hitch is "wrong", I am afraid. It is a part of a Blake s hitch, so it is worse than this well known and proven hitch. No reason to tie this hitch - instead of Blake s hitch - whatsoever. It works as a typical climbing multi-coiled friction hitch, no relation with a ww hitch. I suggest you to remove it from your book.
   The SECOND hitch is a peculiar micture of a ww hitch and a coil hitch. ( It is even described as "tandem Prusiks", in the second picture). I am a purist, I think you have to folow the one route or the other, but this is probably nothing but a personal prejudice. I feel that the round turn between the two successive nipping loops is detrmental for the constricting power of each of them on the "Main line". On the other hand, we have more of a classic climbing friction hitch (Prussik), based upon large contact areas and coils. But those are two different words apart, you have to decide to go with the one or the other, and their micture is probably worst than both of them.
   I would be glad to exchange more with you on this kind of hitches, and learn from your evidently greater knowledge and experience on this matter.

1) http://igkt.net/sm/index.php?topic=2075.msg16893#msg16893


« Last Edit: July 28, 2011, 11:45:51 AM by xarax »
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xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #21 on: February 24, 2011, 06:06:32 AM »
   Some preliminary tests show that the ww hitches hold better than a series of half hitches. Moreover, the ww hitches do not seem to need the pre-stretching that series of half hitches probably need, to "lock" on the Main line. I have tried many different "closings", knots that secure the tail on the lower part of the hitch. The simplest closings ( two variations of which are shown in the attached pictures) are among the stronger and the safer of them all.
   Ashley presents a similar hitch tied around a spar, the ABoK#1755-1756 :
"A cross-lashed strap made fast in the rigging...Shakespeare terms this method of lashing..."cross gartering".'' (1)
   However, he goes on saying : "...straps are easier on spars and rigging than corded rope, besides being less liable to slip. "
   My tests are showing the exact opposite. The "cross-gartering" method is more useful, indeed indispensable, around ropes than around poles - where we can use the better suited many-coils hitches. Is this remark of Ashley a reason why this method is not applied and used in climbing, for example ?
  
1) Shakespeare, Twelfth Night. Also, there :
Malvolio to Olivia :
And tell me, in the modesty of honour,
Why you have given me such clear lights of favour.
Bade me come smiling and cross-gartered to you.
To put on yellow stockings, and to frown...


http://www.folger.edu/imgdtl.cfm?imageid=1437&cid=1829
« Last Edit: July 28, 2011, 11:47:12 AM by xarax »
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xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #22 on: February 24, 2011, 05:25:24 PM »
   The reader who happens to have a yellow Main line, is kindly requested to post a picture of a ww hitch around it.
   It would be a great Fancy knot, Decorative knot , Practical knot, Knot in Literature, ( if there is such a "Knots in literature" forum here... :))
« Last Edit: February 25, 2011, 06:57:07 PM by xarax »
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Bob Thrun

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Re: Best gripping hitch around a tensioned rope
« Reply #23 on: March 01, 2011, 04:29:49 AM »
The ww hitch is similar to ABOK 1755 and several named and unnamed hitches.  They all have the crisscross lashing.  The ww hitch, as shown, is different in two respects.  1) The sling rope is the same size as the main rope.  2) The finishing knot is different.

I am not as good at deciphering knot structure from a photo as some of the others here.  Would you show the sling rope as a loop, without the standing rope.  For instance, some of the other hitches are finished with a bowline.  I do not recognize the knot used to finish the ww hitch.

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #24 on: March 01, 2011, 06:15:14 AM »
The ww hitch is similar to ABOK 1755 and several named and unnamed hitches.  They all have the crisscross lashing.
...let us not confuse two ENTIRELY different things : A hitch around a tensioned or not rope, and a hitch around a ( round, solid, slick ) pole. ... [we must not be]  fooled by the similar "looks" of the relevant hitches... In this thread, I am speaking ONLY of hitches around tensioned ropes, and with ropes of similar sizes with the "Main line", around which those hitches are tied.

"I think that the "classic" hitches are based upon the large areas of contact between the multiple coils and the Main line, or the pole. The hitches I presented in this thread work differently: 1. The ropes strands of the hitch and the Main line cross each other at some points. 2. At a small area around those points, the surfaces of the ropes are deformed. 3.  On the surface of the Main line, these localised deformations, these "dents", act like obstacles that prevent the sliding of the hitch.
   In the ww hitches, we have something like the mechanism that keeps the warps of a fabric in their place, and prevent them from sliding though the wefts. The warps are pushed upon the wefts, and are squeezed in between the other warps. As in the case of the friction mechanism of a fabric, in a ww hitch we do not have the multiple coils and the large areas of contact of a "classic" friction hitch."


  Let me make a brief comment on his. The pole in not deformed locally by the compression or sheer forces that are exerted on it by the rope. So, the ABoK#1755-1756, and several named and unnamed hitches that have criss cross lashing and LOOK the same as ww hitch, work by friction. On the contrary, a ww hitch, or any similar hitch tied around the rope, deform the rope, in two ways.
   First, a ww hitch deforms the cross sections of the Main line, and makes its surface bumpy. On a bumpy surface, the rope strands of the hitch can not move freely, so their motion is blocked. This is not happening in the case of a hitch around a pole.
   Second, a ww hitch changes the geometry of the Main line. It does not remain a straight line any more, but it becomes slightly crooked, its axis changes direction, just fractions of a degree, at each node. This is also not happening in the case of a hitch around a pole.
    Ashley believed that this "cross gartered" pattern would be less slippery around poles, than around ropes, so he does not present any ww hitches : "... are easier on spars and rigging than corded rope, besides being less liable to slip. " ( However, we now see something similar on the lower section of a VT climbing hitch.)
    Now, on the matter of the closing knot. This is of not much importance, really. The only thing we have to achieve is a connection/bend of the two ends, so that that the pulling of the each one of them would be transferred to the other, too. We do not want the one rope to creep on the surface of the Main line more than the other, and the whole hitch to loose its initial symmetry. So, we should preserve a symmetry of loading as much as we can, somehow. The most simple and easy  way is to tie, with each leg/end, an overhand knot around the Main line, and to interlink those two overhand knots in some way. Two interlinked half hitches/nipping loops would also do the job. An other way is to "weave" the legs/ends around the main line and between them at the lower section of the hitch, so they would also be fastened together.
 
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xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #25 on: March 01, 2011, 08:18:26 PM »
   A picture of a ww hitch with another "opening". The higher form of the knot is probably more important than the lower, the "closing" - if we keep in mind the requirement of symmetric loading.
   ( I prefer show to show relatively short hitches, for presentation purposes. Depending upon the loadings and materials, the number of crossings/nodes can vary. A 4+4, or even a 5+5 nodes hitch would be satisfactory enough in most cases, I believe.)
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squarerigger

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Re: Best gripping hitch around a tensioned rope
« Reply #26 on: March 02, 2011, 03:06:58 AM »
Hi Xarax,

I know that you are presenting here a "Why Not" scenario rather than a "How To" scenario.  However, I would ask "Why re-invent the wheel?".  A great solution that I have found for gripping around a tensioned rope or a solid bar (close to the same thing) is the selvagee as noted by Ashley (#3147) made from twine, cord, marline, codline or any other continuous piece that is wrapped into a circle and then either marled over or served over so as to give many years of helpful attachment.  The wrapping around the base cord (rope, tensioned, or bar) is not shown in ABOK at the number above, but there are plenty other descriptions in older texts than ABOK and even a few in ABOK but under other numbers.

However, I do not deny you your search for an improvement, for by searching we may yet find that a better alternative exists.  Have you any practical experience with the aforesaid selvagee?  If not, and here I speak from many years of experience hands-on with said selvagee, "Why Not" give it a try?   :D

SR

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #27 on: March 02, 2011, 05:42:45 PM »
Thank you Squarerigger,

   First, I have to repeat what I have already said in previous posts (1), about the the hitches around ropes or poles being "close to the same thing", as you say : They are, in fact, SO different, in how they work, in the mechanisms they use to do the job, that their superficially similar "looks" should not make them even called by the same name ("hitch").

  I have tried ABoK #3141, as all the hitches around poles or ropes of ABoK. Much, much inferior to a ww hitch, believe me, or do the tests yourself to see it. I am afraid we have not invented the wheel here, not yet. It is the most difficult task we could possibly meet in knotting, and I would love to participate in a "Knot War" with a ww hitch against any other known solutions. ( Of course, with the same  number of coils, because with a X number of coils, if X approaches to infinity, anything works !  :))
   Let me describe a real situation, that happened to me personally some years ago. A beautiful wooden boat was driven ashore by the waves, and it had already reached the sandy beach just in front of my summer house. I hate to see a wooden boat dying, so I run on the beach, tied the boat with the only long enough rope I had and I could find at the moment, tied the other end from my truck on a road before my house, and tried to pull the boat on the beach, so it will not be beaten by the waves any more. Needless to say, the boat was now very heavy with the water that came into it by the overcoming waves, and was almost parallel to the beach, so it was very difficult to accomplish the towing. In the middle of the task, that was difficult, as well as dangerous ( the rope could be broken any time), I heard the noise...The rope was starting to break, strand by strand, at the anchor point on the truck. Tensioned rope, no time, no way of fetching a second rope, if it brakes I would not even have the time or enough rope length to tie it again on the truck, IF I could bring it back from where it would have gone after it would have been launched...
   Well, I had a shorter rope in the truck, but I could do nothing, because I did not know the ww hitch at the time... :) I was saved by a dozen (1) of men that came by, after they heard me shouting for help, grasped the rope from some point with their bare hands, and we, all together, managed to tow the boat high on the beach, away from the breaking waves.
   I still have the rope of this day we saved the beauty. It is in so deformed, thinned, ugly, lamentable, condition nobody would believe what a great heroic task it had accomplished in its life ! Every summer, I see this beautiful boat ( painted deep blue) in front of my eyes, rocking on the turquoise waters, and I say : Well, I have done something in my life..If I knew the ww hitch, I would have done it all by myself.

1) http://igkt.net/sm/index.php?topic=2849.msg17435#msg17435
« Last Edit: March 05, 2011, 10:59:04 PM by xarax »
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xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #28 on: July 28, 2011, 12:14:03 PM »
   I have now tried/tested the ww hitch with the various endings described in (1), but I have seen no significant difference in holding power. If we just make sure that the loading of the two ends ( of the series of crossed nipping loops alongside the main line ) is equalized, by the use of any of those endings, the ww hitch would work fine. The main purpose of those ending interlinked nipping loops at the end/bottom of the ww hitch, is to distribute the loading to both ends of the ww hitch, so, when the hitch is loaded, it is not deformed, and the pairs of the gripping crossed nipping loops are evenly tensioned.  
   I also edited my previous posts, so only the ww hitch is presented in this thread. I hope that the sequence of replies remains comprehensible. The discussion about the series of pairs of hitches, (that I have called "B hitches"), which is mentioned in (2), is left for another thread.

1) http://igkt.net/sm/index.php?topic=2948.0
2) http://storrick.cnc.net/VerticalDevicesPage/Ascender/KnotPages/KnotHitchSeries.html
« Last Edit: July 28, 2011, 12:18:16 PM by xarax »
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xarax

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Rat-Tail stopper
« Reply #29 on: January 13, 2012, 08:47:45 AM »
   I have recently visited, for the first time, the most offen visited knotting web site in the world (according to Google...)  :) No wonder I have met many interesting things there, some very correct and some very wrong - as it happens all the time with such "popular" sites.
   I was really astonished to find that the very idea of the ww hitch is very well known after all, to all but me, obviously ! The mechanism is called Rat-Tail stopper, and is used to secure the mooring lines with a secondary, auxiliary  "cord" ( well, "cord" here means just a much thinner rope, in relation to the very thick mooring lines ). Although I used to be a sailor when I was young(er) , I had never met something like that - or I had, but because I had not paid any attention to it, I do not remember it. With the small sailing boats we used to sail, 60 ft at most, there was no real need for such a rope mechanism. I guess that there are sailors on the big commercial vessels that know this mechanism very well... but they do not participate in this forum   :). As for the the knot tyers, they were, most probably, been deceived by a wrong comment on ABoK.
   What is really surprising is that climbers do not know it...and I am sure they do not even wish to learn about it, test it and accepting it as a most safe friction hitch around tensioned ropes. No wonder, as they do not even know the variations of the fig.8 knot they use all the time ! Same old story : "Professionals" that do not dare to do anything else than just repeat the prior art of their field, without much thought. And they are sooo sure they know better...
   For the use I have proposed it, the particular endings I have proposed are much tighter than the square knot used in the common rat-tail stopper. But that is of secondary only importance. The main thing is the alternative over-under crossings of the two legs of the hitch around the main line, so that we have this effective "cross-gartering", this tight "Malvolio sock". So, the title of this thread stands, as it stood when I first posted it ; The best gripping hitch around a tensioned line.

See Pictures 7-12, at ;
http://www.animatedknots.com/rattailstopper/index.php?Categ=boating&LogoImage=LogoGrog.jpg&Website=www.animatedknots.com
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