Author Topic: Best gripping hitch around a tensioned rope  (Read 43333 times)

Dan_Lehman

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Re: Rat-Tail stopper
« Reply #30 on: January 20, 2012, 07:35:58 PM »
   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.

What (do you think) was "so very wrong"?
--the site is dynamic, making adjustments with new
information.  It is rather more *attentive* in this regard
than "most" sites, IMO.

Quote
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...

That's quite some reprimand coming from a foundation of one's
own ignorance and "guessing" !!  Let's see, you never knew of
such a structure with your mere 60' BOATS, yet (rock)climbers
are admonished for not knowing, although they don't deal with
boats of any size --and use considerably smaller & different cordage!!

In fact, climbers do know of somewhat similar friction hitching,
the valdotain and its ilk, with various alternating or non-alt.
overwrapping parts.  *Tree*climbers in fact find some favor in
these, which for rockclimbers might be both beyond practical
need, and mostly superseded by mechanical devices ("Jumars").

I tried to find a ULRlink to this sort of "stopper", which I've seen
presented on-line as a product --and one (IIRC) with FOUR tails,
which were to be applied, FYI, sequentially (non-alternating wrapping),
and finished (IIRC) w/clove hitches .  --not sure whether the
product used cord/rope or tape/webbing.  Maybe someone with
better Searching skills can find such a thing.


--dl*
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xarax

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Re: Rat-Tail stopper
« Reply #31 on: January 20, 2012, 08:30:47 PM »
   That's quite some reprimand coming from a foundation of one's own ignorance and "guessing" !!
   Let's see, you never knew of such a structure with your mere 60' BOATS, yet (rock) climbers are admonished for not knowing, although they don't deal with
boats of any size --and use considerably smaller & different cordage!!

   You have not yet understood anything  of this friction hitch, have you ? :) It has NOTHING to do with the size of the cordage, or the size of the load !
   With relatively small sailing boats, we do not have any need to secure the mooring line on board for some time before and while we pass it around the bitts, as it happens with the big commercial ships. On the contrary, climbers should have known this friction hitch, because it works very well even with ropes of the same diameter, and can serve to secure their place along a vertical tensioned line. The ropes used by small boat sailors are not so much larger than the ropes used by climbers as you guess  they are - because, although the loads are indeed often greater on sailing than on climbing, the security margins are not go demanding as it happens in climbing - so the required diameters are not very large. I had rarely used a mooring line much larger than 1/2 inch in my life... The rat-tail stopper is tighter than a series of hitches - which IS known, although it is not used so often. So, such a fine friction hitch around a tensioned rope as the rat-tail stopper should have been also known by climbers... and it should have been also known by knot tyers, too !  :) Instead of complaining about "my" ignorance - and ignoring yours - I suggest to use this opportunity to learn more about this hitch, by tying it and testing with a greater variety of materials than I had.

  P.S. A professional teacher of tree climbing - and tester of tree-climbing knots - I asked, was not aware of this hitch... and I doubt that anybody else in the tree-climbing world do know it. It is not mentioned in Storrick s site - although the "lemon" spong  is... and the rat-tail stopper is no lemon at all ! The valdotain and some other similar friction hitches are based on not-crossed coils around the tensioned line, as all the climbing friction hitces are - and the crossed strands are used to secure a sufficiently long knot, so the not-crossed coils work better. I have not seen any climbing friction hitch without nipping/constricting not-crossed coils, so iI guess there is none !  :)
« Last Edit: January 20, 2012, 09:17:16 PM by xarax »
This is not a knot.

roo

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Re: Rat-Tail stopper
« Reply #32 on: January 20, 2012, 08:48:10 PM »
So, such a fine friction hitch around a tensioned rope as the rat-tail stopper should have been also known by climbers... and it should have been also known by knot tyers, too
You can see this principle on p. 299 of the Ashley Book of Knots.

But some people might have a preference for a more compact hitch and and for a hitch that doesn't require two ends of the rope.
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xarax

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Re: Rat-Tail stopper
« Reply #33 on: January 20, 2012, 09:14:02 PM »
You can see this principle on p. 299 of the Ashley Book of Knots.

   I have mentioned the ABoK#1755 soooo many times, and the difference between this around-a-pole hitch and the rat-tail around-a-tensioned-rope hitch we are talking about here sooo many times in this thread, that I really am not going to repeat anything more about it again, sorry. Unfortunatelly, what is also in the ABoK is a wrong comment on similar hitches used around ropes, which made a generation of knot tyers to believe they should better be used only around poles.("...straps are easier on spars and rigging than corded rope, besides being less liable to slip. ")
   The best hitch around-a-pole, to my view, is presented in (1,2). I have tested it, and found it to be much superior to the ABoK#1755. The interested reader is kindly requested to check my findings with more meterials than the climbing kermantle ropes I have used.

1) http://igkt.net/sm/index.php?topic=2075.msg16893#msg16893
2) http://igkt.net/sm/index.php?topic=1889.msg12943#msg12943
« Last Edit: January 20, 2012, 09:55:04 PM by xarax »
This is not a knot.

roo

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Re: Rat-Tail stopper
« Reply #34 on: January 20, 2012, 09:55:50 PM »
You can see this principle on p. 299 of the Ashley Book of Knots.

   I have mentioned the ABoK#1755 soooo many times, and the difference between this around-a-pole hitch and the rat-tail around-a-tensioned-rope hitch we are talking about here sooo many times in this thread,
I didn't name a specific scenario of spar vs. rope, but the general principle involved.  The principle is not unknown by knot tyers.

If you spent less time scolding knot tyers everywhere while assuming the very worst about them, and more time asking knot tyers why they don't use the structure in question for their application (see my previous post), you might be less outraged.
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xarax

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Re: Rat-Tail stopper
« Reply #35 on: January 20, 2012, 10:34:51 PM »
the general principle involved.  The principle is not unknown by knot tyers.

   Oh, yes, it was, and it is still unknown - as your reply clearly proves - and it will remain unknown, if "knot tyers" do not read what is already written about it...
   Read Reply#25 (1) , and then try again. :)


1)  http://igkt.net/sm/index.php?topic=2849.msg17435#msg17435

If you spent less time scolding knot tyers everywhere while assuming the very worst about them, and more time asking knot tyers why they don't use the structure in question for their application (see my previous post), you might be less outraged.

  "Knot tyers" should be ashamed that they did not know this hitch, and never mentioned it when I first started this thread ! In spend more time thinking about knots, trying to understand knots, than asking "knot tyers" to teach me things that are published in their holy book 60 years ago...and I suggest you do the same ! I am not outraged, I am disappointed by those great "knot tyers" that believe all other people are lesser mortals, and do not know a thing ! I study each and every knot is presented in this forum by anybody, I try to tie all possible variations of those knots, I take pictures of them...and I suggest you do the same ( because, obviously, you do not !)
   "Knot tyers" do not use this knot, simply because they do not know it , and they do not want to accept that they do not know it - and possibly because they do not even want to learn it - as they do not know hundreds of other knots that are published, and they do not want to search for hundreds of other knots that are still unknown...Frankly, I do not see much research taking place in the field of knotting, either by "knot tyers" or by "knot untyers" !  :) I suggest you spend more time reading what I write ( or should I better say : spend some time to read at least one or two things of what I have written...), and less time giving me lectures about good behavior and obedience to the Great "knot tyers" . I have no interest in "knot tyers" whatsoever,  I am interested in KNOTS, I am speaking about knots, I tie knots, I take pictures of knots - and I suggest you do the same !
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xarax

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Re: Rat-Tail stopper
« Reply #36 on: January 20, 2012, 10:58:25 PM »
But some people might have a preference for... a hitch that doesn't require two ends of the rope.

   I have spent a large part of this thread trying to show how the "ww hitch"- as I had named the rat-tail stopper when I was not yet aware of it -  will use only one end of the rope, yet will be able to distribute the tension evenly on both legs that go around the main line, crossing each other. The main point of my modification of the original hitch devised by SS369 was just this : how to make sure the "ending" of the hitch will allow the tension of the (one) standing end to be evenly applied to both crossing paths around and alongside the main line. So, those people that "might have a preference for a hitch that doesn't require two ends of the rope'", might also read what I have already written, tie the knot, test it, and then return with more - but less mistaken - suggestions ! :) 
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roo

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Re: Rat-Tail stopper
« Reply #37 on: January 20, 2012, 11:00:11 PM »
   "Knot tyers" do not use this knot, simply because they do not know it , and they do not want to accept that they do not know it - and possibly because they do not even want to learn it -
Then how do you explain the usage of many various friction hitches, many of which are a good deal more complex than the structure you have in mind?

Shall we start making a list?
Kleimheist
Blake's Hitch
Gripping Sailor's Hitch
Prusik
Bachmann
Tautline
Distel
Schwab
Icicle
Hedden
Knut

...for starters.

http://storrick.cnc.net/VerticalDevicesPage/Ascender/KnotPages/KnotVT.html
« Last Edit: January 21, 2012, 12:01:30 AM by roo »
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xarax

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Re: Rat-Tail stopper
« Reply #38 on: January 20, 2012, 11:20:03 PM »
Then how do you explain the usage of many various friction hitches, many of which are a good deal more complex than the structure you have in mind?

  I happen to know all those hitches, at least as much as you do - and perhaps a little better than you, I would say, if I am allowed to judge from the fact that you do not understand their great difference from the rat-tail stopper. However, you did not know the rat-tail stopper, (did you ?  :)), you still do not accept that you did not know it, and you still do not want to learn it... :) I did not know it either... because I am not such a great "knot tyer"...but I have arrived at it, after I have learned the ingenious SS hitch, and I have explored it - because I am more interested in understanding, than in parroting the "established" knowledge...So, for starters, tie the rat-tail stopper with the endings I have proposed, test it, and tell us about your findings. Then, I will be all ears to listen to your lectures, I promise ! :)
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roo

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Re: Rat-Tail stopper
« Reply #39 on: January 20, 2012, 11:23:06 PM »
You didn't answer the question.


« Last Edit: January 21, 2012, 02:00:47 AM by xarax »
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xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #40 on: January 21, 2012, 02:01:28 AM »
You didn't answer the question.


  Should I ? You cited ten or so known hitches, and you asked me to explain why the knot tyers/climbers do not know another one, the rat-tail stopper, which is not among them...So, when somebody learns something new, he has to explain ( to you...) why this something exists in the first place ... because, according to your "reasoning", something should not exist, if it is not known already... :) I had made a favor to you by not answering that "question", but, evidently, you have not appreciated my generosity !  :)  I wonder how do you manage to discover those "questions" of yours ....
   Have you read the thread ? Have you tied the knot ? Come on, it is not sooo difficult !  :)
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roo

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Re: Best gripping hitch around a tensioned rope
« Reply #41 on: January 21, 2012, 02:21:44 AM »
You didn't answer the question.
  Should I ?
It's evident that you don't understand the question, so I will put it another way:

If knot tyers are so prejudiced against the structure you're discussing, so bigoted and don't want to learn, why aren't they prejudiced against all those other hitches?  Your charges of bigotry are once again proving to be empty noise.

Presenting a hitch while insulting prospective users at the outset is not the best way to win over your audience.

Let's hear why some users didn't like a similar hitch:

Quote
The Valdetain Tress, or VT, is a popular knot among arborists, but I do not think it is a good ascending knot for cavers or climbers. The knot is a cross between the Penberthy-Pierson on top and the French Prusik below. It consists of four coils followed by two crisscrosses at the bottom. The resulting knot has a lot of elongation that leads to considerable lost motion (inefficiency) each time it is loaded. This is not a particular concern of arborists, but when using knots on a long free-hanging pit climb, I prefer a knot with less elongation.
source:
http://storrick.cnc.net/VerticalDevicesPage/Ascender/KnotPages/KnotVT.html


« Last Edit: January 21, 2012, 02:39:24 AM by roo »
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Dan_Lehman

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Re: Rat-Tail stopper
« Reply #42 on: January 21, 2012, 08:11:08 AM »
   You have not yet understood anything  of this friction hitch, have you ? :)
 It has NOTHING to do with the size of the cordage, or the size of the load !

In looking back over this thread,
I'm quite dismayed to see that apparently the OP has
been changed --the presented images, no less, about
which subsequent posts remarked.  This renders reading
comments such as
Quote
Scott says "I just tried this affair out" and that sounds
too singular for the plurality of ideas put forward already!?

In Xarax's bottom-shown structure that comprises a strangle
anchor with then interlocked, opp.-handed half-hitch turns,
and then the seemingly neat "cloverhand" final component,

fruitless --as NOW there is a set of photos of one structure,
not the several about which discussion developed and ideas
flowed.

Which throws would-be commenters some doubt about making
comments, if history is to be revised like this.

 :o   >:(


Now, to the point of my understanding --expanding it--,
I've put to some test nearly equal-sized cordage with some
body weight upon ONE of the versions of the "ww hitch"
shown.  Indeed, I'm seeing some gripping I'd doubted
would obtain, with such cordage sizes (as though that
mattered).  I'm not convinced of the behavior in slicker
ropes yet, but impressed enough to look further.
(beachcombed 5/16" mod-soft-laid polyDAC hitched
around 9mm? marine kermantle (aged-frictive), with
the latter tensioned via pulley & tied off.

An obvious antagonist to a climber is how much *retreat*
--extension of the structure upon loading-- must be given
in order to achieve grip!  As though to give the painful
maxim "For every foot forwards, a half-foot back!"  My
hitch released pretty nicely (gripping w/o jamming),
but there is relatively much extension ("retreat") to
come upon re-loading it.  For some uses, this might
not matter; for getting from below to above as quickly
and easily as feasible, it matters much.


--dl*
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xarax

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Re: Rat-Tail stopper
« Reply #43 on: January 21, 2012, 10:25:45 AM »
   In looking back over this thread, I'm quite dismayed to see that apparently the OP has been changed --the presented images, no less, about which subsequent posts remarked. 
   Which throws would-be commenters some doubt about making comments, if history is to be revised like this.

  You have not looked very carefully, did you ? Because if you had, you would had also read this :

  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.

2) http://storrick.cnc.net/VerticalDevicesPage/Ascender/KnotPages/KnotHitchSeries.html

   So, if you try to save roo s ass, make another complain that would make SOME  sense  :)!
   From my part, I tried to facilitate things for you and the other members of this forum, because I had mixed those two different hitches in the same thread, and we had difficulties understanding who is talking about what. At that time, I though it was more important to leave unaltered the sequence of posts about the "ww hitch "( a variation of a rat-tail stopper ), because I thought it was unknown, in contrast with the " BB hitch ( a series of half hitches), which was not.
   So, I would also have said that the fact that you have not read it, "throws would-be posters some doubt about publishing  posts, if history is to be ignored like this"
   When you feel uneasy about something you did not know or like, or when you want to come to the defense of roo, try to pull out a real rabbit out of your magic sheeve...I think you can do better !
   I will not count here the posts of mine that were left unanswered by you, while I answer each and every post made by anybody...including the malicious ones by roo ! I appreciate the times you have answered, and I respect your silence, too. Do the same with me, if you feel you must be fair, and stop complaining with this bitter unjustified tone, just to put something heavier into roo s thin air side !
« Last Edit: January 21, 2012, 11:04:44 AM by xarax »
This is not a knot.

xarax

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Re: Best gripping hitch around a tensioned rope
« Reply #44 on: January 21, 2012, 10:53:42 AM »
An obvious antagonist to a climber is how much *retreat*--extension of the structure upon loading-- must be given in order to achieve grip!

  As I have already said in the very first post - which I think you HAVE read, but you may have forgotten by now - this hitch was not meant to be a climbing hitch ! I have never used a climbing hitch in my life, and the higher peak I have climbed is the last step of a stair or a ladder !  :) I know next to nothing about climbing hitches, so I can not comment on them as you do. I was searching for what the thread says, namely : the best gripping hitch around a tensioned rope. I say nothing about the requirement of this hitch being very short, or able to be transported alongside the main line as easily as the climbing hitches can ! If you have read the thread indeed, you should have also read that the only time I wrote something about a specific application of such a hitch, on Reply# 28 (1), my description has nothing to do whatever with a climbing application...Having said that, I think that, nevertheless, climbers should have known / should better learn this hitch, because it can obviously be used as a security device, to fix their position on a vertical tensioned line, for example...
   Now, the point about the elongation of the rat-tail hitch required in order to grip effectively, is a complex issue. I have already made a comment on this, at Reply# 6, remember ?  :) (2) Because it is not only the matter of the MAXIMUM length that matters, but mainly the question about the OPTIMUM length the hitch should have, to work more effectively ( that is, the required angle of the crossings of the two legs upon the surface of the main line).

   Varying the inclination of the half-coils relatively to the Main line axis do change the gripping power, that is for sure, because, after some point,it vanishes altogether ! But how much ? And which is the optimum value ? ( I believe there would be one or two optimum values, but this should be a mater of very careful experiments ...)
   
   I would be glad if you could say something about this. In the rat-tail stopper video I saw, the angle is about 45 degrees, but is this the optimum ? And is this angle independent of the material in hand ? I do not know anything about this...
   Of course, the tighter one ties the crossings in the first place, the shorter the final tensioned hitch would be...but this does not mean that, in this length, it will grip the main line as effectively as with some other angle ! A very difficult, unknown subject, we should better explore a little more - instead of shouting to each other, for Knot Land s sake !
   
1) http://igkt.net/sm/index.php?topic=2849.msg17452#msg17452
2) http://igkt.net/sm/index.php?topic=2849.msg17129#msg17129
« Last Edit: January 21, 2012, 10:58:26 AM by xarax »
This is not a knot.