Author Topic: Best and quickest hitch for a smooth pole?  (Read 30166 times)

xarax

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Re: Best and quickest hitch for a smooth pole?
« Reply #45 on: February 24, 2012, 04:11:37 PM »
   We have used the Constrictor, the Clove hitch, and a hybrid of those two hitches, in their milti-coiled versions, as tight gripping hitches around slipper poles. We could nt forget the humble Cow hitch, could we ?  :) See the attached pictures for a multi-coil Bull X hitch, used as a gripping hitch able to resist a lengthwise pull. I was really surprised by the magnitude of the tension I was able to enclose inside the coils of this hitch, when I pulled the standing ends perpendicularly to the axis of the pole ( ...using my hand and feet, placed against the pole !  :) ) During/after each pull, it is recommended that one pushes this X "neck" towards the surface of the pole as much as he can, to consume any slag created there.
   I have two more things to mention for this multi-coil Bull X hitch.
1. The long, double "neck" stands in between the standing ends and the surface of the pole, acting as a kind of fulcrum...So, when we pull the standing ends from the one side of the neck, there is a leverage that tends to pull the ends of the coils on the other side more forcefully, while compressing even more the coils onto the surface of the pole at the same time. Those two effects can not but be beneficial to the overall gripping power of this hitch.
2. This "neck", by its mere volume - that can not be compressed -, allows the axis of the standing ends and the axis of the pole, ( which are parallel during a lengthwise pull ), to stay apart at a larger distance. This is good, because if the lengthwise pull is acting from a distance and over this fulcrum, it can not force the coil tube to slip as easily, as if the standing ends were connected directy to the coils themselves.
   I have to repeat that those hitches are not "experimental" at all, they are hitches that are evidently improved versions of other, well-known practical hitches, used from time immemorial. However, I have not tested any of those hitches to the ultimum tensile strength the rope itself can withstand...
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SS369

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Re: Best and quickest hitch for a smooth pole?
« Reply #46 on: February 24, 2012, 05:25:18 PM »
One question that comes to mind here with these is: Which line is to be the SP and deal with that ultimate tensile load? In a sidelong pull I think this is important.

I suspect, conjecture here, that the point of failure will be at the "leveraged" area. The squeezing and strain there is multi-fold.

SS

xarax

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Re: Best and quickest hitch for a smooth pole?
« Reply #47 on: February 24, 2012, 09:40:59 PM »
Which line is to be the SP and deal with that ultimate tensile load? In a sidelong pull ...this is important.

   I have thought of it, but I was not able to answer this question in any convincing way. When we have a lengthwise pull, everything is different between the two free ends. There is the leverage issue, there is the issue of how hard the bulk of the neck would be pressed upon the coils, and there is also the issue of the wide first curves - because we want the hitch to be as strong as possible, even if we do not plan to load it in the rope s limit...Of course, as in the case of the parent Cow hitch, we can always use both lines as standing ends...
« Last Edit: February 24, 2012, 09:45:27 PM by xarax »
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xarax

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multi-coil DL gripping hitch
« Reply #48 on: February 25, 2012, 04:37:28 PM »
   As I am afraid I can not wait Dan Lehman to buy a new pair of glasses, or a new camera ( and a new bicycle, which was proven such a dangerous combination of possessing...), I take the liberty to present by myself the "multi-coil DL gripping hitch", a direct consequence of the DL binder (1). ( I do not include here the clever "twist" of the tails, which  is probably not needed much in this particular application - and might even be detrimental to the pre-tensioning mechanism/procedure ).
   I mention that the mechanical advantage exercised on the two separate coil tubes is 4 :1 (almost, because the friction around the bight lowers it a lot - we do not have pulleys here...), which is very  helpful as regards the tensile force we can transfer into the coils. See also the hitch presented at (2), for another solution of the same problem : Figure out a way we can pull the two ends of a multi-coil "tube", using a mechanical advantage - and have those ends somehow "locked" and secured at their final position, so the tension already accumulated within the coils can not escape, even when there is not ( or there s not yet ) any loading of the standing end(s) of the hitch.

1. http://igkt.net/sm/index.php?topic=1451.0
2. http://igkt.net/sm/index.php?topic=3794.msg22252#msg22252

P.S. A slight different variation of the same hitch, is shown at the next post.
« Last Edit: February 25, 2012, 08:45:08 PM by xarax »
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xarax

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multi-coil DL gripping hitch
« Reply #49 on: February 25, 2012, 09:02:13 PM »
   A slightly different variation of the same hitch shown at the previous post. The end(s) of the two halfs of the coil tube are entering through the central bights by passing "under"- and not "over", as previously.
   I use the opportunity to say that this is a rock-solid hitch - something one would need to strangle more effectively the neck of a hostile alien invader, for example  :). I was forced to use a marlin spike to release and untie it ( at least to release the one/first tail of it ), every time I had tightened it using my hands and feet against the pole... I would say that this is a hitch that is capable - by accumulating strong tensile forces within the coil "tube"-  of forcing even the weak versatackle-like self-locking mechanism of the tail- through-two-interlinked-oposed--bights to "jam"- a very useful thing if we wish a very strong, permanent gripping hitch.
« Last Edit: February 25, 2012, 09:04:47 PM by xarax »
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xarax

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Simple, pre-tensioned gripping hitch using a m.a.
« Reply #50 on: February 26, 2012, 03:06:07 AM »
   Finally, here is the simplest and easiest-to-tie multi-coil gripping hitch, using the mechanical advantage and the self-locking mechanism of the Versatackle knot that I was able to think of. The multi-coil "tube" is continuous here - it is not cut into two halves, like it was in some previously presented, similar hitches - and that may be an advantage, as all the coils are tensioned evenly and at the same time, along the entire length of the tube. The similarity with the continuous coil tube hitch of Reply#26 is obvious - but here we do not have to tie the two overhand knots at the two ends of the coil tube. This enable us to adjust the optimum distance of the two end anchors more easily ( Here, as anchors,  we have two single Versatackle-like opposed bights, instead of two overhand knots we had at the hitch of Reply#26). As we can not possibly know, in advance, how much is this coil tube going to shrink after the pre-tensioning, we have to make a guess at the first time, and then to adjust and re-adjust the end anchors... so they will not touch each other before the end of the pre-tensioning procedure.

P.S. 2012-03-02
I have started a new thread about this hitch, at :
http://igkt.net/sm/index.php?topic=3813.0
« Last Edit: March 02, 2012, 06:13:47 PM by xarax »
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xarax

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Simple, pre-tensioned gripping hitch using a m.a.
« Reply #51 on: February 26, 2012, 04:29:17 PM »
   Some pictures of the same hitch presented previously, this time with the minimum number of coils this hitch can be tied with/on : four.
   I think that, with this small number of coils, it is more effective if tied with/on a nylon-based rope, because nylon can be elognated much more than other materials of similar strength. That is beneficial to the even distribution of tensile (and friction) forces along the entire length of the coiled rope segment.
   
   P.S. I have forgotten to mention that, in sharp contrast with some of the other pre-tensioned hitches presented in this thread, this last but not least one is untied very easily ! We have just to push, rather slightly, the tips of the two opposed bights apart from each other, towards opposite directions, and their grip on the tails that pass through them is suddenly released - and so does the whole knot. This might be considered another great advantage of this gripping hitch in relation to other, similar ones.

P.S.(2). 2012-28-2. I have now read the initial DL post more carefully, and I have seen what I describe at (1). The hitch presented at the post above and shown at the attached pictures can be considered as a "generalized" multi-coil DL gripping hitch, because the possibility of having more than one central wraps, was, in fact, explicitly stated at this post - but I have not paid any attention to it till now...

1) http://igkt.net/sm/index.php?topic=3794.msg22402#msg22402
« Last Edit: February 28, 2012, 12:31:08 AM by xarax »
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Dan_Lehman

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Re: Simple, pre-tensioned gripping hitch using a m.a.
« Reply #52 on: February 27, 2012, 07:21:59 PM »
   Some pictures of the same hitch presented previously, this time with the minimum number of coils this hitch can be tied with/on : four.
Why not three (no completely around, center wrap)?

This structure is more or less what I initially discovered
when seeking some sort of self-tightening/-locking snood
hitch --design goal : attaching snood to thicker, object rope,
both to grip in position AND to stay tightly tied.  (Current,
practical knotting used on lobster long-lines that I've seen
include clove & (sort of) reverse ground-line hitches
with tails reeved through the object-rope lay --simple, effective.
(In my fusion-type : " 'simplEffective' "  ;D  ) )

It was really that way : only after deducing/figuring the hitch
in terms of step-by-step structural desiderata (!), I looked
at the result and only then realized its symmetry (after all,
I was designing for the asymmetric loading of a hitch
--one end loaded, one slack)!  And, so, the notion for a pure
binder was born, and was critiqued/amended to ... :
http://igkt.net/sm/index.php?topic=1451.msg10074#msg10074


Quote
I think that, with this small number of coils, it is more effective if tied with/on a nylon-based rope, because nylon can be elognated much more than other materials of similar strength. That is beneficial to the even distribution of tensile (and friction) forces along the entire length of the coiled rope segment.

Hmmm, I'm not sure : for one might gain, on initial setting,
elasticity of parts near the hauled-on ends, only to
see that tensional imbalance (friction resisting the transfer
of this tension throughout) move towards equilibrium
by a loosening there and more tension elsewhere.
Whereas with more "static" material, the setting tension
would be more forced around ... ?  (But frictional resistance
could mean simply that one got less movement of near
parts, that's all.)  And the elasticity changes where one
will want to position the bights prior to tightening, as the
movement got must be anticipated, lest bights come too
close together or in some other way out of desired position.

"I'm not sure ... ".

But surely smoother/slicker materials --i.e., less friction--
leads to better-set knots; more WYSIWYG (what you see
is what you get).  Ah, yes, I recall working out such "problems"
on smooth hard poles, then finding SUCH differences in the
rope movement (much less flowing & binding-tightening)
when put on the intended real object, some ground-line rope!!
(My fascination began with what has been called "the ossel
hitch"
, a simple ring hitch in which there is a sort
of *opposed-bights* nipping of the SPart, to keep tightened
(more of a U-turn bight opposing an L-turn of the tail).)


--dl*
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xarax

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Re: Simple, pre-tensioned gripping hitch using a m.a.
« Reply #53 on: February 27, 2012, 08:24:59 PM »
   Some pictures of the same hitch presented previously, this time with the minimum number of coils this hitch can be tied with/on : four.
Why not three (no completely around, center wrap)?

 As I have said, when we have less than two wraps per coil segment, the coils can not pre-tensioned enough - because they can not be elongated enough - at least with this rope/pole diameter relation. I have presented the last pictures at Reply#51 with the 4 coils,  just for clarity. In fact, if we use only two "central" coils, we would probably need a pair of double "outer" coils, too - that is, 2+2+2 = 6 coils in total.

This structure is more or less what I initially discovered

   The "DL multi-coil gripping hitch" is exactly what you have discovered. . ( I have "discovered"  the "simple pre-tensioned gripping hitch using a m.a." by replacing the simple overhand-knot-based binder (of Reply#26) with this Versatackle-like binder). I believe that, when we have more coils, all the known binders, the Clove, Constrictor-based, hybrid, DL s, are transformed to something else, because they can now be pre-tensioned, and the outer coils can squeeze the inner coils, so any accumulated tensile forces during pre- or post- tightening are firmly enclosed inside them.

the elasticity changes where one will want to position the bights prior to tightening, as the movement got must be anticipated, lest bights come too close together or in some other way out of desired position.

   True. I have mentioned that effect, and said that we must adjust and re-adjust the position of the opposed nights a number of times. In fact, the required easiness of adjusting the anchor points of the whatever binder we choose to use is what drove me to replace the overhand-knots binder, of reply#26, with the simple Versatackle-like binder of reply#50

But surely smoother/slicker materials --i.e., less friction-- leads to better-set knots; more WYSIWYG (what you see is what you get).

   True, but also the smoother/slicker materials mean, as a consequence, less friction forces between the adjacent coils. And we want this friction, so our coils retain the accumulated tensile forces during the pre-tensioned stage.

"the ossel hitch"[/i], a simple ring hitch in which there is a sort of *opposed-bights* nipping of the SPart, to keep tightened (more of a U-turn bight opposing an L-turn of the tail).)

   Yes, indeed, there are elements of the "ossel hitch" at the hitches I have presented, and vice versa. However, do not forget the many coils, the extended coil tube, the "torsion spring" that transforms everything, in an entirely new way ! 
« Last Edit: February 28, 2012, 12:42:14 AM by xarax »
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xarax

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Re: Best and quickest hitch for a smooth pole?
« Reply #54 on: February 28, 2012, 12:13:57 AM »
   Ooops ! Now I see/read it ! I was wrong, and DL was right...for once !  :) Mea culpa.
   In the first post he presented the "DL binder" (1) - which can easily be transformed into a pre-tensioned gripping ,hitch by just adding more coils, as reported in this thread - he clearly states :
   Tensioning this structure puts more into the centre wrap -- which as you see is loaded from both sides -- than in the outer ones; one way to eliminate this bias (vs. just living with it) is to make a full turn centrally, which takes more material and effort.

   He was wrong about the "more effort"- because, with actually much less effort, this hitch, in its multi-coiled variation, can hold much better than many others which use the same number of wraps - but he saw the crucial point : We can adjust the number of central coils, so that the three segments of the coil tube will be pre-tensioned evenly.  Because, in a "generalized" multi-coil DL gripping hitch, we can have a number of outer coils at the one end, ( the "higher" one, if we have a vertical pole), a number of outer coils at the other end ( the "lower" one ), and a number of central coils, in between the two opposed bights. Adjusting the number of coils in each one of the three segments of the coil tube would require some attention to the particular characteristics of the material of the rope ( it would depend, for example, of how slippery it is, as well as how springy - how much it can be elongated) and the material of the pole. Also, it would depend upon the way the load is applied - i.e. on the one or both the standing ends. However, I think that this possibility - of altering the number of coils in each segment - is a great advantage of this gripping hitch, not a nuisance...
    Hic Rhodus his saltus ! This is a knot Dan Lehman should start testing knots - and I mean, testing them repeatedly, and presenting NUMBERS.  :)

1. http://igkt.net/sm/index.php?topic=1451.0

« Last Edit: February 28, 2012, 12:17:11 AM by xarax »
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Dan_Lehman

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Re: Best and quickest hitch for a smooth pole?
« Reply #55 on: February 29, 2012, 08:41:40 PM »
   Ooops ! Now I see/read it ! I was wrong, and DL was right...

Finally, something we all can agree on.

 ;)

xarax

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Re: Best and quickest hitch for a smooth pole?
« Reply #56 on: February 29, 2012, 10:06:41 PM »
   Ooops ! Now I see/read it ! I was wrong, and DL was right...
Finally, something we all can agree on.
 ;)

  Good try...To cut my sentence in half, where you have had wished it to end... :)
However, I will not let you do it so easily, will I ?  :) My  sentence was ;
   Ooops ! Now I see/read it ! I was wrong, and DL was right...for once !(sic)

   Ooops ! Now I see/read it ! I was wrong, and DL was right...for once !  :)

I know you have some difficulty with numbers...so you prefer to try your hand with words. However, to subtract words, is not only wrong counting, is also wrong wording... :)
(And I wonder if you would ever be capable to say something like this for yourself - at least once...)

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DerekSmith

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Re: Best and quickest hitch for a smooth pole?
« Reply #57 on: March 04, 2012, 05:37:47 PM »
When I was developing the KC hitch, I deliberately used the slickest surfaces I could find to test the functionality of this knot - I used a slick finish braided polyester onto a high gloss chrome tube -



As Dan stated, I tested it to destruction and provided sufficient turns were used to ensure the two anchor turns did not open, then the knot would never slip and always broke at the tieoff point.

To make the knot more practical and much easier to make and use, I mover the principle into the KC Sling hitch



Using a 2ft loop of 3mm polyester braid, hold one end of the loop against the pole, wrap the sling three / four times around the pole (tube), then back over itself three times and pass the remainder of the sling through the starting end of loop.  Close all the wraps up snug and take up the slack.

In working use, I would then Larks foot the sling onto my hauling rope.

Ultra easy to remember, ultra easy to make, and because it hardly qualifies as a knot - it is only wraps afterall, it is ultra easy to 'untie'.

In real world usage of course, the loading force is going to be all over the place, both in terms of magnitude and direction, and may even have to cope with jerking and flogging.  To simulate this, I made the KC Sling hitch onto new 15mm copper tubing using 3mm polyester braid.  The shiny copper tube had a surprisingly high CF, and only the first loop needed to open to create the necessary grip to hold the tube.  I then yanked, flogged/bounced the pipe to see if I could induce it to 'walk' along the pipe.  After about ten minutes of exertion the hitch had remained stubbornly in place.  I think this is because the moment any tension is applied, the first coil opens and creates tension which automatically grips the pipe and so establishes a positive feedback of tension - grip - greater tension - greater grip etc.

When it comes to wet, muddy pipes etc, an interesting phenomenon occurs with the KC Hitch.  Because of its design, no drag force is transferred to the anchor coils of the hitch, but the full tension developed in the cord as the coils are forced open, is expressed through the cord to these anchor coils.  You can feel this by loading the hitch and then seeing how hard the cord has become in the anchor turns.  This 'inwards force' is very effective at squeezing mud / water etc out from between the cord and the pipe and so recovering the CF.

Of course, if the pipes are covered in grease (which is going to lubricate the surface even at the molecular level), then more and more coils are going to slide open in order to develop the necessary gripping force and if the force needed to grip the pipe is excessively high, the cord will snap before it manages to sufficiently amplify the force to grip the pipe (remember, the leverage is almost infinite as a coil starts to open).

As an aside, in the UK tube come in bundles of ten, capped and strapped.  This bundle has lots of high spots and intervening gaps and is a challenge for any gripping hitch.  But the KC Slinghitch grabbed hold and only opened the first coil before it had developed enough frictional grip to hold the weight of the ten 3m lengths of tube.

Derek

xarax

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Re: Best and quickest hitch for a smooth pole?
« Reply #58 on: March 04, 2012, 09:17:25 PM »
I tested it to destruction and provided sufficient turns were used to ensure the two anchor turns did not open then the knot would never slip and always broke at the tie off point.

Do you remember the number of turns ( and the diameters of the rope and the pole ) ?
I believe that, if we would like to compare apples to apples, we should compare friction hitches with the same number of turns - because this is the most characteristic aspect of them. The rest structure is more or less auxiliary, to help those turns be positioned in the more effective way along the pole.

Using a 2ft loop of 3mm polyester braid, hold one end of the loop against the pole, wrap the sling three / four times around the pole (tube), then back over itself three times and pass the remainder of the sling through the starting end of loop.  Close all the wraps up snug and take up the slack.

Was this hitch tight enough to hold fast on a stainless steel pole, until the rope itself broke somewhere ? What was the maximum load it was holding at the moment of rupture ?

it hardly qualifies as a knot - it is only wraps after all.

  So what ? Should a "knot" have something more, than this knot does not have ? It is a knot, made of many of the "knot elements" I call "riding turns" - AND has this "closure" bight that helps the standing end to close the coil "tube" and re-oriented  to a direction parallel to the axis of the pole . ( The rat-tail stopper does have a pair of interlinked nipping loops or a square knot in the place where your knot has this closure bight.)
  I have seen that even a double, crossed coils nipping loop can be considered as an "element of knot", or, indeed, a knot - because it is all a end-of-line loop needs on its standing part to hold the tail, to a surprising effective degree.

remember, the leverage is almost infinite as a coil starts to open.

Nooo !  :) If that was the case, the rope itself would have evaporated long before the leverage reaches "almost infinity" !
« Last Edit: March 04, 2012, 09:18:01 PM by xarax »
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Dan_Lehman

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Re: Best and quickest hitch for a smooth pole?
« Reply #59 on: March 04, 2012, 09:34:43 PM »
When I was developing the KC hitch, I deliberately used the slickest surfaces I could find to test the functionality of this knot - I used a slick finish braided polyester onto a high gloss chrome tube -

As Dan stated, I tested it to destruction and provided sufficient turns were used to ensure the two anchor turns did not open, then the knot would never slip and always broke at the tieoff point.

Whoa, when Xarax demands OPT results, he is NOT looking
for ones that shatter his delusions of grandeur for his own
knotted structures!

Quote from: Xarax
(The hitch presented by Derek Smith is a good hitch when tied around a tensioned line,
but not so effective a hitch when tied around a slippery pole. )

Of course, we have not seen the OP's (or OPT's) test results
that support this claim.  In light of the KC hitch's holding, w/o
slippage, to break, it's hard to conceive of how that is "not so
effective" --and what any more "effective" behavior would be!


--dl*
====