International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: xarax on February 11, 2011, 02:03:51 PM

Title: Best gripping hitch around a tensioned rope
Post by: xarax on February 11, 2011, 02:03:51 PM
   Best gripping hitch around a tensioned rope. The tensioned rope, the "Main line", is of the same material and same thickness with the one used for the gripping hitch. The loading/direction of the end is close and parallel to the Main line s axis.

   In the attched pictures, I present such a Main line gripping hitch that has recently been devised by SS369, with some minor modifications made by me. In those pictures, I present only a 4+4 nodes/crossing points version. A 3+3 version would also hold, in many circumstances.
   Warning : It is strictly NOT permitted to minors to use this hitch.
   This hitch is NOT proposed as a climbing hitch.
   
   P.S. I have also to make clear that this knot, just like all the knots I have presented in this forum are "Why not" questions, not "How to" answers. For many reasons, we all like to use ready-made things and easy recipes, and we are inclined to do so more often than we should. The knots I have tied and presented in this forum do not address this need. They are more like a play with tangled ropes that may also be exploratory, or not. I try to Live Curious.  :)   

   P.S. ( 2012-1-12 )
  This hitch is well known as the "Rat-Tail stopper" used around tensioned mooring lines. I was not aware of it at the time I first posted it as a friction hitch. I guess that now there is no point for me to try to comment on its effectiveness. 
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on February 13, 2011, 05:57:07 PM
Good day Xarax.

I just tried this affair out and what I am finding is that it is a little troublesome to tie with the 10.7mm BlueWater DYNAPLUS and the 1/2 inch BlueWater SPEC-STATIC ropes. So, yes rope particulars do come into play with knots.

It immediately made me think of tying two Prusic knots in tandem (one following the other) when I looked at your pictures (thank you for them).

What I expected to find and did was that the set of  "cow hitch" type coils closest to the load did most if not all of the gripping and the rest of the knot basically was along for the ride, so to speak.
I then tried clove knot based arrangements and found that they were very lacking in gripping power for this use. Subject to the ropes I used.

My testing facility for this is probably not as sophisticated as yours, but I did bodily load the contraption to gauge the performance and draw My opinionated conclusion. ;-)))

Didn't bother with photographing any of this.

SS
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 13, 2011, 07:42:15 PM
  Thank you SS369,

   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.
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 13, 2011, 10:28:45 PM
What is the point for Best gripping hitch around a tensioned rope. ?

I.e., what sort of circumstances does this envision,
and might it be really about the same rope-problem
as tying to some other rigid object?  --pointing to the
qualifier "tensioned", which I take to deny the object-rope's
ability to bend or "dog-leg" and thereby aid gripping.

Another key factor is relative size & nature of cordage
and hitched object --the KC hitch being one favoring
considerable difference in diameters, cordage being smaller.

Not to expect "scientific testing" or anything, but it would
help to know what sort of testing/stressing has been put
to the knots put out for consideration --seems reasonable
to demand of the OP at least SOME sort of testing to at
least find the structure working in some minimal case.

E.g., I'd be surprised if the OP's knots of criss-crossed,
alternating over/under of strands, hitch gripped at all,
in the materials shown (firm, slick, climbing kernmantle)
--for it is roughly a KC hitch, which needs diameter difference
to gain purchase.  Giving this sort of structure (but I tied off
the ends w/a bolwine, for loading) a quick test in old, fuzzed
dynamic 11mm rope around somewhat thinner and much
slicker PMI <Won't-Bend> caving rope, it seems to grip
but with a pulley for loading, I see slippage begin --and
my object rope wasn't anchored in tension, even, so did
bend in sympathy to the hitch's gripping.

The "B hitch" is what Gary Storrick has called a "hitch series"
--repeated half-hitches/turns of alternating handedness-- ;
he believes that with the addition of further hitches, this
should grip on most anything.  That might depend upon
the non-gripping coming from slipping and not from the
cordage being too stiff to turn around the object and bite
(barring some setting that secures the structure until a tight
bite is achieved).

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,
I'd think that the 2nd component is of no use at gripping,
and the series should be of the cloverhands (my name for
a structure that can appear to be a clove hitch except that
the ends are on opposite side of each other in passing under
the overwrap, and topologically this makes an overhand ).
A risk in the cloverhand is jamming; but it seems a good way
to give more material for a stiff rope to grip, and to gain effect
in that way.

One tactic I've played with for getting more grip of stiff cordage
is lessening the helix angle of turns --not sure though that this
is ultimately (vs "seemingly") successful.  So, where one hitch
might take a single strand and wrap it around an object, the
revision would do this with two strands (though perhaps only
one will bear load, to grip), and thereby opens the helix angle,
and makes resistance to the bending a little less !?

One partial answer to my question of the point of this challenge
is to emply a hitching structure in an adjustable-eye knot, such
as the Midshipman's hitch : there, you see, the structure's S.Part
(I regard the *knot* to be what is hitched to this, and overall
we have a *noose-hitch*) will be loaded into and out from this
knot --out from, as one eye leg--, and so be more tensioned
than in some other cases (but less tensioned than an entirely
separate line such as a shroud, or a mooring line being hauled
tighter by a capstan, looking to be off-loaded onto some
<ack, what's the term here for this structure ? ______?>
other line, maybe to tie the bitter end to bitts, the release
the line onto that anchorage).


--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on February 14, 2011, 12:40:40 AM
Hello Dan and good day to you.

Quote: "What is the point for Best gripping hitch around a tensioned rope. ?"

Whose to know when a scenario might call for a gripping hitch on a vertical or horizontal line?
I can conjure up a possibility, but ultimately the use is not the real question I think. IMHO the question concerns a knot that has the ability to grip a rigid structure that happens to be a rope. And to discuss what makes it happen citing/sharing examples of things tried so they can be examined, discussed and debunked if needed.

Take a Tyrolean crossing. That is a tensioned rope and there is a need for a gripping hitch, albeit a releasable, slide and grip, gripping hitch. Yes, there are knots in use that have proved sufficient, perhaps not as good as something we're to find exploring this avenue of inquiry.

There might be some safety insuring uses as well that might be employed if the OHSA approved mechanisms are off sight for some reason and a need great enough.

Quote: "Scott says "I just tried this affair out" and that sounds
too singular for the plurality of ideas put forward already!?"

My comment was with specificity to one of the knots portrayed in the most recent pictures, the first one (sort of a "familiar"  response), not the whole thread. Yes, I am guilty of the negligence of failing to indicate that. Sorry.

Back on topic now. The KC hitch is good for rigid surfaces and I have tested it unscientifically in my shop on a 1.5 inch diameter by 6 foot long brass dowel. Using inexpensive 3/16 inch braided nylon it stuck like glue once set. The cord was tied to the ceiling joists, the knot en-wrapping the brass bar. I did indeed add some weight to the bar by pulling down. My opinion is that I could have broken the cord before the grip of the knot.
No, "stuck like glue" is not scientific terminology, but it is gets the point across for the average layperson.

I would expect no one to ever take my word for it and do the tests for themselves before employing Any knot in a safety or life endangering situation.

What is the point in having a forum about knots, their tying methods and their possible uses, if we can't pose a question or three to try and further our understanding of this itty bitty eclectic microcosm we find interesting.

This place/site is about sharing within the brotherhood of knot tyers, correct?   

   1. Promote research into all aspects of knotting
   2. Act as a primary source of reference and consultation
   3. Publish a periodical [?] about knot crafts and related subjects
   4. Form and maintain a library of books, papers, films, photographs and other materials associated with knots. [?] with a view to making information available to Members of the Guild and the general public
   5. Form collection of knots and knotting and work related crafts
   6. Promote and encourage knotting as an element in the education of children and young persons, and as a therapy for those who may benefit from such remedial activity
   7. Further promote the interest in knotting and associated activities, through its members, to the general public

Etc., Etc., Etc..................

Looking forward to yours and others input.

SS


Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 14, 2011, 12:49:08 AM
    Thank you dan Lehman,

What is the point for Best gripping hitch around a tensioned rope. ?

  Let us say that we do not know, yet. If there is a successfull rope mechanism, I am sure that we will find an application for it !
  If we bult it, they will come !

pointing to the qualifier "tensioned", which I take to deny the object-rope's ability to bend or "dog-leg" and thereby aid gripping.

   Correct, up to a point. Because some bending, local deformation of the absolutly straight line, would be inevitable.

Not to expect "scientific testing" or anything, but it would help to know what sort of testing/stressing has been put to the knots put out for consideration --seems reasonable to demand of the OP at least SOME sort of testing to at least find the structure working in some minimal case.

   Oh, as I have said already, I prefer OPT (other people s tests !) :)
   I used some 10-11 kernmantle climbing ropes, and hang the weight of two people sitting on two quite heavy wooden chairs, and jump on them ! About the same test performed upon my "Pretzel" bowline, with equally satisfactory results. But a reason that I present those hitches here is to persuade somebody to test them in an "scientific" "experimental" way... And to provoke some "theoretical" examination and discussion, like the one we are doing now...
 
I'd be surprised if the OP's knots of criss-crossed, alternating over/under of strands, hitch gripped at all, in the materials shown (firm, slick, climbinkernmantle)
--for it is roughly a KC hitch, which needs diameter difference to gain purchase.

   I am glad I will surprise you !  :) However, I was surprised, too... The central idea came from SS369, and a climbing mechanism he showed to me. It is essentially the same mechanism that keeps the warps into the fabric, making them go over/under the wefts, and squeezed between other warps . See my attempt for an explanation at (1). As I have said there, D.Smith, or Ashley with the 1755, could have well discovered this hitch, had he replaced the pole by a rope.
   You should tie this ww hitch as I show it : In my pictures, the planes of the alternative half-coils are inclined to something like 45 degrees. It is interesting to see how the gripping power is decreasing with the less inclination. If the half-coils are not close to each other, the hitch will not hold, that is evident, because the Main line will not be squeezed enough by going over and under and in between the crossing strands.
 
.
The "B hitch" is what Gary Storrick has called a "hitch series"
--repeated half-hitches/turns of alternating handedness-- ;

   Thank you for this information. I am not aware of thiis work, I have to find the source and read about.

  One tactic I've played with for getting more grip of stiff cordage is lessening the helix angle of turns --not sure though that this is ultimately (vs "seemingly") successful.

  
   Congratulations ! You spotted this most interesting future of this hitch ! Varyng 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 ...)

though perhaps only one will bear load, to grip

 That is a most important point . No ! Both legs of the hitch should grip the same, and this symmetric position and loading of them would be much beneficial for its gripping power . How do  know it ? I do not !  :)I "feel" it, and I wait somebody to look at this matter.
We had a lengthy discussion wit SS369 on this , but we have not reached any conclusions. I insist that the legs should be loaded evenly, so the one in not more straight / aligned, and the other more helical. SS369 is not sure about it. I also want to have the two legs of the hitch braided in a symmetric patten, so that the legs get in touch with the man line alternately, the one after the other, to prevent the one of them have a continous helical contact with the Main line,while the other get around them.
   When the one leg have a large, lengthy helical contact with the Main line, when the hitch is loaded, the contact with the man line can drag the hitch unevenly- and deform it. It's very interesting to explore the differences f the various weaving pattens to the gripping power ! My conjecture is that the symmetric alternative pattern would be the better. But who is going to prove or disprove this experimentally ?

1) http://igkt.net/sm/index.php?topic=2191.msg16938#msg16938
    http://igkt.net/sm/index.php?topic=2191.msg16992#msg16992
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 14, 2011, 04:06:51 AM
Quote: "What is the point for Best gripping hitch around a tensioned rope. ?"

...
 IMHO the question concerns a knot that has the ability to grip a rigid structure that happens to be a rope.

Well, that begs the question, or should move to merge
with the more general topic of hitching to a rigid object,
rope or otherwise.

Quote
Take a Tyrolean crossing. That is a tensioned rope and there is a need for a gripping hitch,
 albeit a releasable, slide and grip, gripping hitch.

Okay, not so familiar with this, but if one needs to haul tighter
a taut line with the hitching line, to then tie off the hitched line,
that fits the bill (as I had mused re the mooring line & capstan's
tightening (and it is "stopper" that is used for the hitching lines)).

Quote
Quote: "Scott says "I just tried this affair out" and that sounds
too singular for the plurality of ideas put forward already!?"

My comment was with specificity to one of the knots portrayed in the most recent pictures,
the first one (sort of a "familiar"  response), not the whole thread.

So, the alternately wrapped KC structure.  --and in ropes similar to
those pictured, both in nature and relative diameters.  Alright, then
there are three of us in the same ballpark on that.
(I'm not going to bother trying to use either the new-seeming
--though chronologically, but not usage-wise, plenty old-- PMI
*Won't-Bend* (my rejoinder to "EZ-Bend", its flexible kin), or
aged & used & "cable-like" Bluewater ropes, in which 3-diameter
bending meets resistance!!

Quote
The KC hitch is good for rigid surfaces and ...

Got anything tapered for it to try?
(A long marlinespike might be the best test.)

Quote
What is the point in having a forum about knots, their tying methods and their possible uses,
if we can't pose a question or three to try and further our understanding of this itty bitty
eclectic microcosm we find interesting.

But itty bitty is also the resource base to be chasing these questions,
or else what's the point?  And if itty bitty is even an amount beyond
visible benefit, that's a point to note in regard to expending efforts.

--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 14, 2011, 04:15:52 AM

though perhaps only one will bear load, to grip

 That is a most important point . No ! Both legs of the hitch should grip the same, ...

I think you missed my point : for a structure of a coil with
twin parts, have only one of them be load-bearing, the other
serves qua spacer to reduce the helix angle (think of the
Klemheist  somehow loading only one of its twins, or of
the ProhGrip having a twin inserted).  --so, I wasn't remarking
about the above knots.'

It is (or was) an opinion of Franz Bachmann (has some kind of
engineering background) given to me that he expected twin-loaded
coils to be less gripping than single ones.

But we must keep clear how dependent knots can be upon materials,
and to try to not think in the common terms of "this *knot* is ..."
but "this **material so-knotted** is ..." .

--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 14, 2011, 05:35:58 AM
   I think you missed my point : for a structure of a coil with twin parts, have only one of them be load-bearing, the other serves qua spacer to reduce the helix angle
   It is (or was) an opinion of Franz Bachmann (has some kind of engineering background) given to me that he expected twin-loaded coils to be less gripping
than single ones.

   But in a double line coil, the angle/inclination is in fact increased, not reduced, since a point in one line, after a 360 degrees turn, is two diameters, at least, apart from where it had started, not one. Am I missing it again ?
   However, I think you got mine. The two interlinked, crossed coils, should bear the same loading, if we do not want to end up with a deformed plait.Their
angle/inclination should be the same, I think, but SS369 is not concerned about that. I have a soft point in symmetry, so I would prefer a plait that is symmetric initially, and retains this symmetry even after its loading, as the ww hitches shown in the pictures. 
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 14, 2011, 09:59:02 PM
   I think you missed my point : for a structure of a coil with twin parts, have only one of them be load-bearing,
the other serves qua spacer to reduce=>widen the helix angle

   But in a double line coil, the angle/inclination is in fact increased, not reduced, ...

No, my mistaken wording.  Yes, the nearly complete circle is spaced
farther apart, with the twin cord between the cord whose helix we're minding.

--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: knot4u on February 14, 2011, 11:17:38 PM
I tested the knot in the original post.  I differ somewhat with what Xarax said.  I don't think the hitch is that simple.  I don't think it's that simple to tie, and I don't think it's simple in its operation.

This hitch is not directly comparable to just about any hitch I know.  It does not behave like a combination of Half Hitches, Overhands or Round Turns.  It's kind of a new category with the way it behaves.  I haven't quite put my finger on it precisely.  I did talk about the related KC Hitch here:
http://igkt.net/sm/index.php?topic=542.msg17072#msg17072

I have to be honest and say this knot is not of great interest to me.  That's not a slight against the knot.  That's just more of a comment about me.  When I see a hitch, I imagine at least one application where I can use it.  Currently, I can't imagine any application where I would prefer this hitch over some other hitches I know.  Again, that's not to say the hitch is impractical because it may prove to be useful to me for an application in the near future.  Who knows?
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 14, 2011, 11:40:59 PM
   Thank you, Knot4u,

  I don't think the hitch is that simple.  I don't think it's that simple to tie, and I don't think it's simple in its operation.
   This hitch is not directly comparable to just about any hitch I know.  It does not behave like a combination of Half Hitches, Overhands or Round Turns.  It's kind of a new category with the way it behaves.  

  I agree 100% with all of these !  :) However, conceptually, when we see this hitch as nothing more than a 3 string braid/plait, where the central string remains straight, it starts to look simpler. And the way we weave those two strings around the central one is following an easy pattern. If we use both hands, moving them in a somewhat mirror symmetric way around the Main line, after some time we can learn to tie it very quickly.
  
   No other friction hitch, climbing hitch, whatever, comes even close with the anti-slippage power of this hitch ! If I want to be 100% sure that my hitch will not slip, I will use a 4+4, or even a 5+5 nodes ww hitch, and then I will sleep like a baby.
 
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on February 15, 2011, 03:38:11 AM
Back to you Dan.

Quote:
The KC hitch is good for rigid surfaces and ...

Got anything tapered for it to try?
(A long marlinespike might be the best test.)"

I will try this suggestion if I find a suitable taper or make one.

But that's for the thread on the KC hitch.

 

"Quote From SS
What is the point in having a forum about knots, their tying methods and their possible uses,
if we can't pose a question or three to try and further our understanding of this itty bitty
eclectic microcosm we find interesting.

Answer by DL

But itty bitty is also the resource base to be chasing these questions,
or else what's the point?  And if itty bitty is even an amount beyond
visible benefit, that's a point to note in regard to expending efforts."

And so we of Itty Bitty Land are the resource base? We are expending energy and efforts are being made, at least by a few members, but we wax intellectually, eventually to wane.

I think the point is being sailed around and around. The IGKT purports to be an authoritative body of all things knotty and so I ask, "Where are the results?" "Where's the data?" "Where are the graphics showing the knots of the world?"

Just because we talk loudly, does not mean anyone is going to listen.

Who has some Real data out there?

SS
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on February 18, 2011, 02:52:28 PM
Good day Xarax,

This B hitch has some good qualities, but I personally am finding drawbacks to choosing this over another.
In my own opinion, if a knot is too fiddly to tie or will exhibit an inherent insecurity, then it only gets cursory use and in most likely will be just a exploratory spring board.

I find this series of hitches and bends subject to instability in that if you don't set it just right Or the load is cyclical, then they slip.

For the bend to work much better it needs to have a significant ratio of rope to rope diameters and the smaller one be the B.
Using my anaconda-like, new Bluewater ropes, I have challenges like those indicated above. So those eliminate the use of this structure with these ropes. Rope qualities are a big consideration that can influence the choosing or devising of a knot.

I may be wrong and not having a accepted test facility to scientifically confirm this, I find there may be an optimal limit of nipping loops that will actually do the "work". The rest may supply support in keeping the orientation(s), otherwise just along for the ride.

>>>I think this needs to be tested more and on an actual already tensioned rope as the thread begs.<<<

There is a big difference between a hitch being applied to a tensioned rope and one that the hitch will be applying the tensional load to the main rope after setting.

So a test for this could be horizontal or vertical. The rope as tight as one can safely get it. Tie the hitch of choice and test its effectiveness.

I personally would opt for a vertical set up and then tie a foot loop in one end of the rope to be used for the hitch, then tie the hitch and use my body weight to load the hitch (slow loading and bouncing too). The hitch's SP (the load) should be swung through a series of angles away from the Main rope, IMHO.

If it passes this lightweight test it can go to the next round of the Knot War.  ;-)

SS
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 18, 2011, 04:40:57 PM
   Thank you SS36,
 
   First, I have to say that I see no opponent, whatsoever, in the "best hitch around  a tensioned rope" "Knot battle" !  So, the ww hitch will win hands down !  :)

  For the bend to work much better it needs to have a significant ratio of rope to rope diameters and the smaller one be the B.Using my anaconda-like, new Bluewater ropes, I have challenges like those indicated above. So those eliminate the use of this structure with these ropes. Rope qualities are a big consideration that can influence the choosing or devising of a knot.

  Of course ! If a rope can not be bent around one rope diameter, you just forget those hitches ! Perhaps to be able deal with such anaconda-type ropes, we have to feed up the loop opening itself, to pass the tails through the nipping loops, as Dan Lehman suggested, but I have not tried those variations. (1)

There is a big difference between a hitch being applied to a tensioned rope and one that the hitch will be applying the tensional load to the main rope after setting.

   Yes, indeed. I am more interested in the "difficult" case, that of a tensioned Main line. A solution to this problem would have many applications , that anybody can think of. But I see no enemy approaching, so I feel confident about the outcome !  :)

I personally would opt for a vertical set up...

   Yes, that is what I have done, also because I can not do otherwise, even if I should to, with my high teck two-chairs-hang-from-the-ceiling-of-the-kitchen laboratory ! :) Perhaps the next level would be more telling, but I find very difficult, technically AND conceptually, to reach it...I mean, persuade the housewife to sit with me and my son on those chairs... :)
  
1) I do not know if the real anacondas can bend their body around a one anaconda body section diameter, or not...Can they, for example, constrict effectively a female anaconda that way ?
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman 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*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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 !

  
Title: Re: Best gripping hitch around a tensioned rope
Post by: knot4u 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)
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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...
Title: Re: Best gripping hitch around a tensioned rope
Post by: Bob Thrun 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. 
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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


Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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... :))
Title: Re: Best gripping hitch around a tensioned rope
Post by: Bob Thrun 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.
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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.
 
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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.)
Title: Re: Best gripping hitch around a tensioned rope
Post by: squarerigger 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
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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
Title: Rat-Tail stopper
Post by: xarax 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
Title: Re: Rat-Tail stopper
Post by: Dan_Lehman 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*
====
Title: Re: Rat-Tail stopper
Post by: xarax 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 !  :)
Title: Re: Rat-Tail stopper
Post by: roo 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.
Title: Re: Rat-Tail stopper
Post by: xarax 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
Title: Re: Rat-Tail stopper
Post by: roo 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.
Title: Re: Rat-Tail stopper
Post by: xarax 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 !
Title: Re: Rat-Tail stopper
Post by: xarax 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 ! :) 
Title: Re: Rat-Tail stopper
Post by: roo 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
Title: Re: Rat-Tail stopper
Post by: xarax 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 ! :)
Title: Re: Rat-Tail stopper
Post by: roo on January 20, 2012, 11:23:06 PM
You didn't answer the question.


Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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 !  :)
Title: Re: Best gripping hitch around a tensioned rope
Post by: roo 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


Title: Re: Rat-Tail stopper
Post by: Dan_Lehman 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*
====
Title: Re: Rat-Tail stopper
Post by: xarax 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 !
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax 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
Title: Re: Rat-Tail stopper
Post by: xarax on January 21, 2012, 11:32:21 AM
   I've put to some test... upon ONE of the versions of the "ww hitch"
shown.

   If you wish to comtinue your tests - for which I am greatfull ! - you can try the other 7 (seven) variations of it, posted back at (1) ! It shows two interlinked half hitches, but the situation is similar with the two free ends of the rat-tail stopper, of which we want to pull only the one. We have four ends in total. We have  two ends going "up", towards the rat-tail stopper s main body - going around helical paths, while, at the same time, they cross each other - and we have two other ends, of which we want to use only the one as a standing end, and leave the other as a tail. So we have two lines coming into / and going out of the end point, in all the possible endings/variations of the rat-tail stopper.  The task is to figure out which ending secures that the two limbs would nip the main line at this end point hard enough - so we will not need many crossed coils and much elognation of the whole hitch, and manage to keep it as short as possible - AND which ending ensures that the two limbs would be adequatelly entangled, so they will work as one, and distribute the tension evenly on the main line. At (1) I have tied all the possible simple variations I could think of, but I may have missed something...Try them, and report your findings here, please.

1) http://igkt.net/sm/index.php?topic=2948.msg17512#msg17512
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on January 21, 2012, 08:53:02 PM
That explains why my posts above are a little off.  I'll delete those posts now.  It's too bad.  This thread had potential.  Now, it's a tangled mess.

Xarax got me again.  I keep falling for it.  LOL

 On the contrary, to separate the "ww hitch"/ rat-tail stopper from the "BB hitch" / series of half hitches, was absolutely the right thing for me to do. I did not do it for me, because I know those knots very well, but for the benefit of the other members, to help them not be confused. I have seen that there were some misunderstandings, because it was not clear about which of the two quite different hitches one was talking about each time. Of course, I have posted the reasons of this re-arrangement immediately, but it seems that some members read only a very small fraction of what I write, and missed the relevant post ( posted at ; Reply #28 on: 2011-07-28, 12:14:03 . i.e. before 6 (six)  months !  :))
  This thread s potential, any thread s potential, is not depending on mine s or your posts, my dear knot4u ! It is depending upon the CONTENT, i.e. the knot presented ! We can easily delete any post we wish, but we can not delete the knot, can we ?  :) The rat-tail stopper is here to stay, and it really does not matter if we like it or not... And the same happens with all the (hundreds) other knots that have been presented in this forum. It should be better perhaps for me to present only their pictures - but I have thought that a little honest discussion will make no harm. I might have been mistaken on this... but not on the usefulness or beauty of the knots themselves I have met and presented here !  :)
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on January 25, 2012, 05:06:29 AM
[NB:  This post is *reconstituted* from memory --it was largely
quoting of fixed sources-- after the system glitch that resulted
in an editing session erasing the text on Xarax's reply (which he
promptly posted an alert about --#50, below--, so we redress it).]

... 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...

I'm abashed to have forgotten that this general structure
earlier surfaced to my awareness --viz., in Dave Merchant's
e-book (2nd edition), Life on a Line , as his #18 "Dog & Tails".
This book is aimed at cavers, but with general application also
especially to SAR, and to other users of similar kermantle ropes.

He confirms Xarax's surmise, saying :
Quote
The Dog & Tails is an anchor system specifically designed for securing a line
to a fixed belay point ... .  The knot does not usually cause damage to the
main line if shock-loaded[,] as the gripping action is distributed along the rope ...
//
The center of a long length (2m+) of cord or webbing is fixed to the anchor point
with a Fig.9 [eyeknot], then a series of alternating under- and over-crosses are [sic]
taken around the main line, ending in a slipped Reef knot ... or something similarly easy
to release.  ...  For 9mm accessory cord and 11mm kernmantel [sic] rope, 10 to 12 crosses
are sufficient.
Under load, the crosses kink and grip the main line, with the friction concentrated
in the centre third of the chain of crosses.  [my underscoring]
//
The Dog & Tails tied in 8mm accessory cord on 11mm rope and using 10 crosses
has been tested and shown to reliably arrest a 200kg FF-0.33 fall event {sounds seasonal  ;D  }
with 50 cm, although the rope and cord will both be damaged by friction.

He adds that the D&T works well also on hoses & electrical cord,
but not on solid objects such as steel cable or pipe,
because they cannot be impressed by the wraps.
(One should remark at this contradicting Derek's finding with a
like structure, though he had relatively small hitching line to
the large, hard, smooth object.)


--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on January 25, 2012, 06:05:49 PM
   Thank you, dan Lehman.

  I must also admit, that from the time I saw this rat-tail stopper published, I keep asking all my friends sailors/fishermen if they knew it...What can I say ? They look at me with a sad face, tap-tap me at my back, and tell me that EVERYBODY knows this stopper, ( except me !), and I should better find another field to try to discover anything, than the field of marine knots... :'( Total humiliation !
   Here in my country-  that has a really big commercial ships fleet- not knowing this knot is a joke...that almost proves you are a shepherd !  :) I feel ashamed I have not met this knot before in my  life... or that I have never paid any attention on it ( because it is only the last 3 years that I have a certain interest in knotting, although I sail the last half century or so...)

   As I have mentioned somewhere, my preliminary tests with 1/2 nylon kernmantle climbing ropes gave me some evidence that 4, ot at most 5 pairs of crossings would be enough ( 8 or 10 crossing points). And that this configuration is safer than a similar-number series of half hitches ( "BB" hitches, as I used to call them)- which IS known by climbers.
   However, I understand the slightly greater number reported in your reference, because the endings I use are much more effective, as nipping structures, than the reef knots used in the common rat-tail stopper. I have already provided enough information about them, and you can try them to see my point : If you use two interlinked half hitches instead of a reef knot, you probably need at least one crossed pair less than the common rat-tail stopper - so your knot iwill be at least 20 -25 % shorter, for the same gripping power.
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on January 27, 2012, 05:01:39 AM
Another link to peruse dealing with a hitch (of sorts) around a tensioned rope.

http://books.google.com/books?id=cO8fAQAAMAAJ&pg=PA484&lpg=PA484&dq=%22four+tailed+stopper%22&source=bl&ots=r7g4O3X-TY&sig=EqFwkPcQT1b7jLqmorTGK5Fr_IQ&hl=en&sa=X&ei=pR0iT6a_GNTMtgeGr4CiCw&ved=0CCAQ6AEwAA#v=onepage&q=%22four%20tailed%20stopper%22&f=false (http://books.google.com/books?id=cO8fAQAAMAAJ&pg=PA484&lpg=PA484&dq=%22four+tailed+stopper%22&source=bl&ots=r7g4O3X-TY&sig=EqFwkPcQT1b7jLqmorTGK5Fr_IQ&hl=en&sa=X&ei=pR0iT6a_GNTMtgeGr4CiCw&ved=0CCAQ6AEwAA#v=onepage&q=%22four%20tailed%20stopper%22&f=false)

And for Dan > http://www.yalecordage.com/oceanographics/grips/yalegrip.html (http://www.yalecordage.com/oceanographics/grips/yalegrip.html)

SS
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on January 30, 2012, 06:04:48 PM
Note that the first-given URLink'd resource in SS369's post
has a structure much like the Dog & Tails but the ends are
seized as well as 2-3 points along the wrapping structure.

With the YaleGrip(s), each *arm* is put on completely and
separately from the others --i.e., there is no alternating
over/under relationship : successive arms are entirely over
the preceding ones.  Surprisingly and sadly, that information
page doesn't clearly show how each arm is tied off.  I recommend
the reverse groundline hitch --a half-hitch which aims
the tail back towards the wrapping and a 2nd h-h which
then reverses that direction and locks the structure.

(I'm about to employ similar working in repairing a breaking
plastic 4gal. pail handle --it's cracked about 3/4 the width of
the flat handle at one point.  I'll employ (planning to...) some
cable-hauling polyester tape by seizing that to the handle
near the sides, and somewhere along the handle, AND THEN
wrap over that in this D&G manner (probably alternating
over/under) with the flat, stiff BAILING TAPE frequently used
on e.g. bundles of newspapers, boxes of copier paper, and so on.
This wrapping should keep the polyester tape in place, and add
security & strength to that.  --not sure how I'll tension & tie-off.)


--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on January 31, 2012, 02:03:50 AM
   I have not found many pictures of the rat-tail stopper in the internet, but perhaps I have not searched long enough...See the attached pictures.

I would like to repeat a few points here :

1. I think that it is of paramount importance to load the two lines ( that go around the main line in those helical, crossed over/under paths), in as a symmetric way as possible.
2. A proper interlinked-half-hitches ending can help to shorten the overall length of the knot, because it replaces at least one node, and connects the two lines firmly together - so the pull from the one is transferred to both, and the symmetric loading is retained intact.
3. We do not know yet what is the optimum angle for the crossings.
4. Around poles, the multi-coil hitch based upon the "simple hitch a la Gleipnir" is superior.
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 02, 2012, 07:59:49 PM
   I am afraid I have to return to the subject, because something I keep saying for a looong time now is not heard, evidently.
  The rat-tail stopper ( and the "ww hitch", as I have named this knot, -with a minor addition/modification by me - when I was not aware of its existence), is symmetric in relation to the two segments/legs of the rope that are encircling the main line, while crossing each other at the same time ( at 8 or 10 points) .That means, that each segment /leg goes over and then goes under the other, in succession, so the distribution of loads is as even as possible. First the one coil presses the other and force it to "bite" the main line, then the order is reversed, and so on. We had an argument about this with SS369, and we have not reached any conclusion, but we have pinpointed the difference clearly ( and I have reported this argument in this thread).
   The "Dog and Tail" hitch presented in Dave Merchant s ( wonderful ! ) book "Life on a line " , is not like this. The one segment/leg of the hitch tied by the attached line around the main line, is always over the other - so , at the crossing points, there is always one and the same leg that does the job of pressing the other, and always one and the same leg that bites hard into the main line s body.This is just as in the original SS hitch, which made me think about the "ww hitch" at the first place.
   Is it of such importance I think it is ? I can not be sure, but my understanding of the "ww mechanism", and my preliminary tests persuaded me that it is, indeed. The main line remains more aligned with the axis of the hitch, if each leg plays both roles, the one after the other. And this axial, even distribution of forces is very important to the total gripping power of the hitch.
   The second - obvious - thing about the D&T hitch is that it is reversed, in relation to the rat-tail stopper ( and the ww hitch ). I am not sure that this is irelevant or rrelevant to the final result - but, not having the possibility of an additional nipping ending/closure, the D&T hitch is condemned to be longer, for the same overall gripping power, than a rat-tail stopper, that is for sure.
   See the attached picture of the D & T hitch, as presented in the Dave Merchant's e-book (2nd edition), "Life on a Line" .
 
   P.S. Does those differences prove that the mechanism of the rat-tail stopper was not known to the climbers ? Nooo... :) On the contrary, they prove that the climbers knew about the essence of the mechanism, but they have not explored it much, because they have all those climbing friction hitches at their quivers. The sailors knew better,  perhaps because the had fewer possibilities, or they do not know so much as the climbers do ... :) ( exactly as it had happened with me. )
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: SS369 on February 02, 2012, 08:18:30 PM
I have a suspicion that the main line material and/or construction method will have influence on which orientation that will be most effective in keeping slippage the least.
Also the line size being used for the stopper is a consideration as well, imho.

As I have seen, the rat tail stopper on laid lines, the first "leg" goes parallel, in the lay of the rope. The following "leg" goes over, crossing the first to press it in place. (Sometimes the loose ends twisted by hand and held, since it is very temporary till the hawser is wrapped around the bollards/bitts.)

With braided rope, if it is of hard density, then there will be little bite as the stopper cord can not penetrate and it is my opinion that there be more crossings and the first leg be wound first (as in the picture xarax just posted). Soft rope -  I would think the opposite would be better. Just an opinion formed by my few unscientific backyard tests using static and dynamic climbing ropes.

SS
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 02, 2012, 08:53:25 PM
With braided rope, if it is of hard density, then there will be little bite as the stopper cord can not penetrate

   I do not agree on this. I have used hard, kernmantle ropes, and I have seen this "bite" there, too - so it must be even more pronounced in the case of braided ropes.
   Let me try to describe the situation, the great difference between the friction hitches based on parallel coils ( like the climbing hitches ), and the rat-tail stopper. In the former case, at the helical lines of contact between the main line and the legs of the attached lines, the compression forces are gradually increasing or decreasing. In the later case, alongside those lines, the compression forces are varying in an alternating way . If you were the main line, you would feel been pressed much harder at the points the coils are crossing each other,  rather than squeezed alongside the whole helical path that nips your neck ! Irrespectively of the degree that the surface of the main line retreat under the compression forces, the generated friction forces are more localized, with many minima and maxima, in the case of the rat-tail stopper than in the case of the climbing hitches.
 
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 05, 2012, 03:52:51 AM
The "Dog and Tail" hitch presented in Dave Merchant s ( wonderful ! ) book "Life on a line " , is not like this.
The one segment/leg of the hitch tied by the attached line around the main line, is always over the other -
I suggest that you get the proper document to cite
--you've apparently copied from the first edition; the
2nd edition shows the structure with the two tails
alternating respective over/under crossings.  Frankly,
I don't think that this will matter much, but I've not
tested it.  (The pinching of the object line comes at
points between the hitching line's crossings.)

--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 05, 2012, 11:52:19 AM
The "Dog and Tail" hitch presented in Dave Merchant s ( wonderful ! ) book "Life on a line " , is not like this.
The one segment/leg of the hitch tied by the attached line around the main line, is always over the other -
I suggest that you get the proper document to cite--you've apparently copied from the first edition; the2nd edition shows the structure with the two tails
alternating respective over/under crossings.

I have copied and posted the free electronic version - the 2nd edition is not for free, and, even if I had bought it, I do not know if I could legally copy and post an image of it here...
The interested reader should visit the relevant site :
http://www.lifeonaline.com/
I am happy that the author has understood the difference and corrected the mistake.

The pinching of the object line comes at points between the hitching line's crossings.)

Nooope. The "pinching" of the main line comes mainly underneath the crossing points. It is there that the "UNDER" leg - that is on contact with the main line at that point- is more forcefully pressed upon the main line - and "bites" it harder -by the "OVER" leg. Of course, both legs are squeezing the main line at their almost uninterrupted helical contact lines, but this squeeze is not uniform, has minima and maxima, as I have tried to explain. And the maxima are preciselly underneath the crossing points. At a climbing friction hitch, the situation is totally different ! there are no minima and maxima, the coils are nipping the main line with a uniform force alonside their contact line . We can not even talk about "pinching" in this case, I believe.
   I understand that people mis-tie the rat-tail stopper, by first wrapping a helical path with the one leg around the main line, and then wrapping again both, the main line and this first helical wrapped leg, with a second leg.  ( GREAT mistake ! Or, A DIFFERENT hitch, different from the one I am talking about all this time, and more like the original SS hitch. ) That is probably the easiest thing one can do - otherwise he has to use both hands at the same time, so he can pull both legs evenly as he crosses them and put the one over and the other under, alternatively, at each crossing. If one is tying the wrong hitch, with the wrong way, it is expected that he will not load the two legs of the hitch evenly at the first place, and also that the hitch as a knot will not be self loaded evenly afterwards - with detrimental effects in its overall gripping power. 
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 06, 2012, 01:27:45 AM
we've seen a quartet of somewhat similar gripping hitches :
  • YaleGrips-like "stoppers" that alternate direction of complete wraps (4 strands);

  • D&T that has just alternating-over/-under wrapping (2 strands);

  • D&T with a leading *guard* nipping/gripping structure (which you've shown);

  • D&T with a trailing gripping structure (valdotain).

   The rat-tail stopper, with a square knot (as the mooring line stopper described more often ) or a two-interlinked-half-hitches ( as the "ww hitch" described in this thread ) closure/ending at its lower end, should better be called a "Tail & Dog" rather than a "Dog & Tail" hitch...  :)
    See the hitch at Reply#25 (1)(and attached picture) , for a "Dog & Tail & Dog" hitch. There I have tried to add some nipping "opening" at the other, upper end of a ww hitch, but that complicated the knot without any niticeable benefit. I remember that it was not clear to me, at any given instance, which one of the three different segments of the hitch was gripping harder, and was doing the main part of the job - so I decided to abandon that line of exploration. ( I have not thought of a "Dog & Tail"- like hitch, because this type of "reversed", upside-down ww hitch needs a carabiner at its lower end  - and I was not searching for a climbing hitch.)

1   http://igkt.net/sm/index.php?topic=2849.msg17439#msg17439
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 06, 2012, 06:54:09 AM
I am happy that the author has
 understood the difference
   and
 corrected the mistake.

Rather, you're presumptive in believing either
--that images are necessarily chosen & understood
by authors (!),
and that this one in particular regards either form
as a mistake to be corrected.
(But I'd bet on your side of this assertion, if forced;
though it might be *stability* more than anything
that appeals of the alternating over/under.)

Quote
The pinching of the object line comes at points between the hitching line's crossings.)

Nooope. The "pinching" of the main line comes mainly underneath the crossing points. It is there that the "UNDER" leg - that is on contact with the main line at that point- is more forcefully pressed upon the main line - and "bites" it harder -by the "OVER" leg.

This seems like nonsense, in that there is no opposition to the
supposed more forceful pressing, so no "bite" can be effected,
as a bite needs teeth on opposite sides (the difference between
a pinch & a poke (which we'd certainly expect esp. European
men to know!  ;D )).  But a quick examination of fat 1/4" laid
CoEx PP/PE rope D&T'd around 11mm dynamic kernmantle
suggests it might be so --i.e., that there might be more
*deflection* of the object line at the doubled points than
there seems to be compression between those points.
.:. We might say that this dog's poke is worse than its bite?!
(I tried once with the as-shown-by-Grog start, and once
with pure wrapping; the former saw a big bite & pinch with
the initial joining of hitch to line.)


--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on February 06, 2012, 11:25:32 AM
it might be *stability* more than anything that appeals of the alternating over/under.)

I have tried to explain that it is "security" which is mostly enhanced by the alternating over/under paths -due to the even distribution of  forces alongside both legs, if the hitch is tied "correctly". However, you are right that "stability" is also an important factor. With the one leg moving around a helical path, in continuous contact with the main line, and the other going over it, I have seen that the position of the crossing points were not stable, i.e. the "over" line was able to slide on top of the "under line", and reposition itself when it was loaded - because, as it was not been kept at its place by the "under" line at any crossing point, it was able to form its own, independent helical path, and the two helices were crossing each other wherever they wished, at unevenly placed crossing points. When we tie the hitch "correctly", by an alternating over/under position of the two legs of the attached line, the crossing points are distributed evenly on the surface of the main line at the first place - and they remain evenly distributed, even when the hitch is loaded afterwards, because both legs hold each other at every second point, and their elongation is even alongside the main line. It is like a normally weaved braid : The threads remain in stable positions, because tensile and compression forces are evenly distributed inside the braid s body.

as a bite needs teeth on opposite sides

  I did not meant this... At each and every crossing point, the "bite" of the upper jaw, the 'over" line, by means of the teeth, the "under' line, was onto the lower lips, the main line.
Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on February 17, 2012, 12:02:55 AM
It should be remarked that there is conflict between two
of the referenced works of this thread:
Dave Merchant says that the D&T cannot be used for
controlled lowering, as once slippage begins, it will (likely)
run out of control;
but the reference cited by SS369 (the electrical journal,
via Googlebooks), gives instructions for just such controlled
slippage --though, given that they specify using at least TWO
such D&T structures, it's not clear how they are to be
each handled for this (might it be that only one is released
from full grip?); they also specify three points of seizing.


--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: estar on April 23, 2014, 05:10:24 PM
BTW, I was just doing some gripper testing. 

I choose to test perhaps the most challenging situation - a loaded dyneema main line, being held by a dyneema gripper line.

An icicle will hold about 1500lbs in this test.

However, the rail tail will only hold about 150lbs, before it slips (you can see the mark move in the two pics below).

Title: Re: Best gripping hitch around a tensioned rope
Post by: Dan_Lehman on April 23, 2014, 05:32:42 PM
BTW, I was just doing some gripper testing. 

I choose to test perhaps the most challenging situation
--a loaded dyneema main line, being held by a dyneema gripper line.

An icicle will hold about 1500lbs in this test.

However, the rail tail will only hold about 150lbs, before it slips (you can see the mark move in the two pics below).

Hi, EStar!  If the middle photo shows the state of
things prior to loading (mark being at right end
of the structure), then you have way too much
slack in the rat tail : by the time it achieves the
sort of open helical angles you show, it should've
been heavily loaded (and thus making severe
compression to have such open angles) --and at
this much openness, there is not much further
tightening/gripping that it could do, but just
deliver force to the endmost securing knot.

Also, I've read one instruction (for the application
of a pre-made, 4-leg helical gripper) that specifies
that each leg ("arm"?) is to be put on entirely,
after/before others --so, over all that precede,
under all that follow (no alternating over/under);
I see that you do this BUT for one crossing,
near the right (pulling) side.  --for what it's worth.

But you have chosen difficult materials!
(What are their respective diameters?)

Thanks,
--dl*
====
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on April 23, 2014, 07:33:18 PM
BTW, I was just doing some gripper testing.

   Fine - but, please, do them PROPERLY !

  You had not said how much loaded is the main line itself ! AND, In the picture with the icile hitch, we clearly see that, contrary to what is happening in the picture with the rat-tail-stopper, the man line is bent  - so it presents a HUGE obstacle to ANY hitch that tries to slide along it...
  If one can force such a pronounced deflexion in the main line, he can use MANY other, less gripping hitches... And, if he can make a whole turn on this main line, he can tie a bowline instead !  :)
   Have you ever seen a mooring or anchor line of a boat stopped by this stopper ? There are only a few pictures in the web, but, even in those, you can see that the main line is supposed to remain STRAIGHT ! ( Trying to achieve this, I had used the MA of a Trucker s hitch - and there I had (re-) discovered the locking of the tail between opposed bights...(1))
   In short, the cross-gartered segments of the rat-tail-stopper tied on his stockings, are meant to encircle Malvolio s STRAIGHT leg   :).
   On the plus side, it is good that you test gripping hitches with the same number of wraps / turns. We should compare apples to apples - with a sufficiently large number of wraps / turns, ANY hitch will grip around ANY main line...

1. http://igkt.net/sm/index.php?topic=1870.msg17364#msg17364

P.S.
 On the very first post of this thread, I had said that :

The tensioned rope, the "Main line", is of the same material and same thickness with the one used for the gripping hitch. The loading/direction of the end is close and parallel to the Main line s axis.

  All my tests were done with same-size ropes. However, it would be interesting, indeed, if you differentiate the sizes, as you have already done, but in a more systematic way. So, you should better first keep a standard-size main line, and then vary the size of the hitching knot in equal increments of the area of the cross section, in order to see if/how those variations alter the results one takes when he tests the hitch with same-size ropes.
   AND, do not forget, the main line is meant to be much-much more loaded than the hitching line, so it would remain STRAIGHT, more or less - I should had included this "Straight", explicitly, in the title of the thread...
   
   
Title: Re: Best gripping hitch around a tensioned rope
Post by: TheTreeSpyder on April 24, 2014, 12:07:43 AM
i'd always and all ways favour Icicle / or variant.

Friction hitches not designed to lower thru; especially higher loads.

Mixed materials best, generally hitchcord would be ~2mm smaller than host line for better grip, maintain more strength % around tight line of host line etc..
Also, by design it would be best; if line below hitch is not loaded, so is 'fatter' than loaded/ gripped line; offering shelf mechanic to hitch.

Would try flat Tenex for hitch cord for greater grip area. 
Would try 3strand as cord too.
Such rough friction duty demands quality materials; maintained w/o glazing from friction slides etc.

Some of this comes down to style of setting and usage, so mileage can vary per user!!!
Some choices offered surpass others in the way they can more easily be pushed up the line, then reloaded.

A 2:1(1 line) climbing system is a different animal than single line drop.
Title: Re: Best gripping hitch around a tensioned rope
Post by: xarax on April 24, 2014, 01:16:02 AM
by design it would be best if the line below hitch is not loaded

   That is for sure - and THEN, only then, it might be the case that the Icicle hitch might be better than the rat-tai-stopper, indeed !  :)
   However, this subject, the "Best gripping hitch around a not-loaded / not-tensioned rope", belongs to another thread...
   I now know ( because it was revealed and proved by the posts in this thread ) that most knot tyers do not (yet) know the rat-tail-stopper, and they do not understand clearly how it works, so they do not believe it works better than all the other gripping hitches around tensioned ropes ! It is not the first time , of course, that arm-chair knot tyers do not know or understand an already known, by the practitioners of another occupation, knot - however, I must say that I was embarrassed by the way commercial boat sailors looked at me, when I showed them this knot they knew it existed from the time of their grand-parents... which, by the way, I have since learned that is used every day for securing the mooring or anchor line of big boats. I had never met this knot in small, recreational sailing boats, or, even if I did, it seems that I had not noticed it, and so I had not appreciated it, or tried to understand its working.
   
   I have a theory, that most knot tyers were misled by the classification and the drawings of similar hitches by Ashley, only as hitches around poles ! They had never considered those hitches as hitches around ropes, where they always had preferred the climbing gripping hitches. And they had never really understood and explained the difference between such a cross-gartered hitch tied around a "compressible" material, a rope, where the knobs of the crossing points can "bite" the surface, and so become able to be attached on it easier, and a solid material, a pole, where they can not. So, they had not tried to maximize the effect of the particular property that makes those hitches very efficient : the even distribution of the crossing points on the surface of the main line, where , at each crossing point, the one leg, as a riding turn, pushes the other to "bite" into the flesh of the material.
   Now, regarding tight hitches around poles, I had also tied or learned some "new" ones. FAR better than the Icicle hitch - as the Locked Cow hitch or the recent Alaskian hitch and Bull Clove hitch, for example  - but this is also the subject of another thread !  :)