Author Topic: Dressing a figure-eight loop?  (Read 18258 times)

DDK

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Re: Dressing a figure-eight loop?
« Reply #15 on: September 19, 2011, 04:24:06 PM »
Along with our love affair with symmetry, this likely explains the popularity of teaching the "perfect" forms.

  There 17 symmetric figure 8 bends, to my latest counting... :) (1) .I doubt that one can prove, with any simple means, that any one of them is more symmetric from the others. The figure 8 bends presented at (2) are symmetric, too ! All those bends can be tied as easily as any one of them, because they are formed by the same number of tucks..I  am afraid symmetry by itself can not help us decide which are the best forms. We need detailed  tests, that are missing. The popularity of teaching the so-called "perfect" forms can only be explained by ignorance from the part of the teachers - and the well known attitude of all ignorant teachers to hide their ignorance under some rug...Are we also going to pretend that we know, when we simply do not, and keep parroting the same old wrong things ? Knotting is not going to be promoted that way, that is for sure.

1) http://igkt.net/sm/index.php?topic=2198.0
2) http://igkt.net/sm/index.php?topic=3148.0


I disagree with your assessment of the ease of tying and identifying a specific non-"perfect" form of ABOK 1411 (Figure 8 Bend).   It is the additional twists which make them less easy to tie and identify and give them the appearance of being less compact in my opinion.  In the absence of other more compelling factors to differentiate the bends, the properties I mention are more than sufficient for preferring and teaching the "perfect" form.

As far as what teachers teach, it is more-or-less expected that they will teach the "tried and true" (meaning tested and it worked, repeatedly), especially if life or limb is at risk.  There is no other reasonable alternative and has nothing to do with their ignorance or pretending to know everything.  While you see ignorance, I see the current state-of-the-art.

DDK

xarax

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Re: Dressing a figure-eight loop?
« Reply #16 on: September 19, 2011, 04:58:40 PM »
I disagree with your assessment of the ease of tying and identifying a specific non-"perfect" form of ABOK 1411 (Figure 8 Bend).   It is the additional twists which make them less easy to tie and identify...

You disagree, obviously, but you are wrong...As I have said in
http://igkt.net/sm/index.php?topic=3618.msg20727#msg20727

the "other", "not-perfect" forms of the Figure * bends have less twists, not more, and are at least as easily to tie as any of them, because they are tied by the same number of tucks. The so-called "perfect form"should need more objective reasons to justify its name...So, because those properties you claim do not exist, and there is "absence of other more compelling factors to differentiate the bends", the arbitrary use of the name "perfect form" for any single one of those 17 bends, is a misnomer.

As far as what teachers teach, it is more-or-less expected that they will teach the "tried and true" (meaning tested and it worked, repeatedly), especially if life or limb is at risk.  There is no other reasonable alternative and has nothing to do with their ignorance or pretending to know everything.  While you see ignorance, I see the current state-of-the-art.

   Those 17 bends are not tried, so we can not tell if they are truly more safe or not. I know that it is "expected" that the teachers teach only what they know, but they should teach also that this is only what they know, and not the "best" or "perfect, as they always do ! The "alternative"e is to test those bends, and prove which is safer, and how much safer it is. So, teaching only the so-called "best" or perfect" form of the many figure 8 bends, is only a proof of ignorance and pretension of omniscience. While you see current state-of-art (sic), I see only ignorance and easy parroting. Fortunately, progress of materials save the poor pupils of those "teachers", but this has a side effect : Those people continue to walk around telling everybody that, in the field of their "speciality", anything that should and could be known is already known, so further research is useless.  
« Last Edit: September 19, 2011, 06:01:37 PM by xarax »
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DDK

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Re: Dressing a figure-eight loop?
« Reply #17 on: September 19, 2011, 06:33:34 PM »
. . . the "other", "not-perfect" forms of the Figure * bends have less twists, not more, . . .

I disagree and base my observation on the use of a single strap to model the "railroad tracking" rope pair and bend.  This process quickly reveals the additional twists in the non-"perfect" ABOK 1411 bends.  edit: tighten the strap to most easily see the effect of the additional twists
  
Those 17 bends are not tried, so we can not tell if they are truly more safe or not. I know that it is "expected" that the teachers teach only what they know, but they should teach also that this is only what they know, and not the "best" or "perfect, as they always do ! The "alternative"e is to test those bends, and prove which is safer, and how much safer it is. So, teaching only the so-called "best" or perfect" form of the many figure 8 bends, is only a proof of ignorance and pretension of omniscience. While you see current state-of-art (sic), I see only ignorance and easy parroting. Fortunately, progress of materials save the poor pupils of those "teachers", but this has a side effect : Those people continue to walk around telling everybody that, in the field of their "speciality", anything that should and could be known is already known, so further research is useless.  

It would seem somewhat tedious to append "by the way, this is our current state-of-the-art and understanding and there might be other things better, but, because we haven't found them yet, I can't tell you about them" to the end of every statement.  It is my experience that this caveat is implicitly understood in most fields of expertise.

DDK
« Last Edit: September 19, 2011, 06:39:10 PM by DDK »

xarax

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Re: Dressing a figure-eight loop?
« Reply #18 on: September 19, 2011, 06:44:42 PM »
I disagree and base my observation on the use of a single strap to model the "railroad tracking" rope pair and bend.  This process quickly reveals the additional twists in the non-"perfect" ABOK 1411 bends.

a car that runs on the (parallel) tracks of the "common" figure 8 A, d'Artagnan bend (1) makes 2 inversions ( it turns upside down two times), so it looks more like a roller coaster car, while the car that runs on the (also parallel) tracks of the figure 8 B, Athos bend, tilts but does not turns upside down, so it looks more like a railroad car. ( A car on the tracks of the C, Porthos bend, makes 2 inversions -like at A-, while at the tracks of the D, Aramis bend, makes only 1.)


  I would be glad to be able to test the state-of-art roller coasters ! Because I see no state-of-any-art-whatsoever in those 19 century , steam-age railroad wrong assumptions about the figure 8 bend !
« Last Edit: September 19, 2011, 06:45:33 PM by xarax »
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DDK

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Re: Dressing a figure-eight loop?
« Reply #19 on: September 19, 2011, 06:51:31 PM »
I just had a thought which might explain different points of views on the number of twists.  If one were to wrap a strap smoothly around a pole, one might say there are no twists, i.e. "perfect" wrapping and another might say there are the same number of twists as wraps.  I have taken the former view where it appears xarax has taken the latter.  FWIW

DDK

edit #1:  the "perfect" forms of ABOK 1411 are smoothly wrapped while the non-"perfect" bends are not.  edit #2: It occurs to me that the amount of rope-to-rope contact will likely be greater in the "perfect" form of ABOK 1411.
« Last Edit: September 19, 2011, 07:02:35 PM by DDK »

xarax

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Re: Dressing a figure-eight loop?
« Reply #20 on: September 19, 2011, 07:20:27 PM »
the "perfect" forms of ABOK 1411 are smoothly wrapped while the non-"perfect" bends are not.

   Nice try. Close, but no cigar... :) The A bend is similar to the C, in the number of wrapping, be them counted your way or mine...And there are MANY more fig 8 bends to test your theory...
   Please, do not try to find other, secondary things to prove the uniqueness of your Standards...The amount of rope-to-rope contact can be measured very easily, and then we can see if it is greater at some bend than at all the others...I bet the so-called "perfect" form will be left far behind in such a race - but this should not be considered as a proof or as disproof about its safety. There are so many other things that should be taken into account... I think that only detailed laboratory tests will solve our problem here.
« Last Edit: September 19, 2011, 07:21:32 PM by xarax »
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DDK

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Re: Dressing a figure-eight loop?
« Reply #21 on: September 19, 2011, 07:53:56 PM »
the "perfect" forms of ABOK 1411 are smoothly wrapped while the non-"perfect" bends are not.

   Nice try. Close, but no cigar... :) The A bend is similar to the C, in the number of wrapping, be them counted your way or mine...

When tied in a single strap, the C bend shows obvious distortion on tightening and must be constrained from contorting to a more smooth wrapping.  As I mentioned in reply #20, how one numbers the twists will depend on your point of view.  With the example I gave, that is smoothly wrapping a pole with a strap, one could easily put in opposing twists at different points in the wrapping and maintain the same number of twists as the smooth wrapping, but, certainly, it would be much uglier and not as smooth.  This is your C bend.

DDK


xarax

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Re: Dressing a figure-eight loop?
« Reply #22 on: September 19, 2011, 08:25:44 PM »
   When tied in a single strap, the C bend shows obvious distortion on tightening and must be constrained from contorting to a more smooth wrapping. ...how one numbers the twists will depend on your point of view.

  Now you move again to other considerations...First,, there was the "additional twists", that, at the C bend, happened to be as many as the ones at the A bend. Then, there was the "amount of rope-to-rope contact", that turned out to be less in the A bend than in other bends. Now, it is the "distortion that must be constrained"...
  I know you try hard to prove your point, but you keep changing points of view, and this might not be the best strategy ! My gut feeling is that there must be a unique, simple factor that should be able to sufficiently single out A, d Artagnan, from the three musketeers, and possibly from the other bends as well, but we are not going to figure it out by such desperate attempts. Try to think in more abstract terms, may be thinking how the rope that forms each link would "see", "feel", and "understand" the knot, i.e. think in terms of a local, intrinsic, rather than a global, outside view of the tangled configuration.   
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SS369

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Re: Dressing a figure-eight loop?
« Reply #23 on: September 19, 2011, 08:50:48 PM »
May I suggest the use of notated pictures for clarity of statements about the dressing of a figure 8 loop?

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xarax

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Re: Dressing a figure-eight loop?
« Reply #24 on: September 19, 2011, 09:04:31 PM »
   We are talking about different dressings of the ABoK 1411 bend here, and if we can really prove that the A bend is the "perfect" one indeed,  the "Gold Standard". See (1), and pictures attached there, and here. Unforunately, we can attach only 4 pictures in ech post, and the different variations of the fig.8 bend are many more !  :)

1) http://igkt.net/sm/index.php?topic=2198.0
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SS369

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Re: Dressing a figure-eight loop?
« Reply #25 on: September 19, 2011, 09:42:30 PM »
Are we going to assume that what works as the proper dressing in a bend will also be best practice for a loop? Figure 8 for both instances.
The loading is a wee bit different in the two. And different in the loop application as determined by a few factors, e.g., diameter of structure that the loop encompasses, unstable moving load (such as  climber tied in or swing), etc.
So if you had to pick just one proper dressing, of the Figure 8 loop, that would most satisfy all scenarios of usage, which would it be and why?.

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xarax

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Re: Dressing a figure-eight loop?
« Reply #26 on: September 19, 2011, 10:22:29 PM »
Are we going to assume that what works as the proper dressing in a bend will also be best practice for a loop?

   This never happens. When the loadings are different, the knots are different. Having said that, the high symmetry of the fig.8 configuration should allow us examine both of them in parallel, at least partially. The more subtle things you mention, "diameter of structure that the loop encompasses, unstable moving load", are beyond my abilities to examine, I am afraid.
   I would be happy if, at the end of the day, it is proved the best dressing for the bend would be the best dressing for the loop, too - but, of course, I can not be sure about it...It would be nice if we have one mental picture for both knots, would nt it ?
   So, I think we have first to examine the bend, and only afterwards, with all the knoledge we would have aquired during this endeavour, to examine the more special and difficult case, the loop.
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