Author Topic: Fig.9 stoppers.  (Read 5890 times)

xarax

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Fig.9 stoppers.
« on: January 30, 2014, 10:31:19 PM »
  If a double ( or even a triple ! ! ! ) fisherman s knot can fail to hold a slippery Dyneema line, it is reasonable to search for more complex solutions. Moving one lever up from the single, double, triple etc. overhand knot, we can use a fig.8, fig.9, fig.10, etc. knot. In this thread I show the basic fig.9 stoppers which can be used at the ends of a fisherman s knot-like "interpenetrating Standing parts" bend lines, instead of the overhand-knot-based stoppers.
  We have recently seen that, in a knot tied on Dyneema line, many constricting round turns are not as efficient as few sharp U turns and/or few right angle crossings. We should rather increase friction by increasing the local deformations of the lines at their points of contact, rather than by increasing the forces those lines are squeezed on each other.
  A second issue is the easiness we can tie more complicated than the usual simple knots. If the tying of a complicated knot requires more than two-three tucks, it becomes very difficult to remember how to tie, and very difficult to inspect if it was tied correctly in the first place. Also, the time needed to tie such a knot is considerably longer, and the chances there will be some mistake during the tying procedure are multiplied.
  A third issue is the volume of the knot. In many applications, if we have to use complex knots of some considerable volume, it is better if this volume is distributed along the axis of the knot, in elongated bodies, than along large cross sections, in spherical bodies. A rule of thumb I use is that a sleek knot should present cross sections on planes perpendicular to its axis not much wider than 4 rope diameters.
   All those three things combined led me to examine the chance the Fig. 9 stoppers and their relatives would be more secure, when tied on Dyneema line, than the double overhand knot stoppers ( or even the triple overhand knot stoppers ? ).They require two, only, tucks, and in their 8-shaped form they offer those two clearly formed openings through which on can pass the end of a second line very easily, in one stroke. What might be even more important, is that when the one knot will be squeezed on the other, those stoppers will "fold" and the turns of the lines within their nubs will be forced to become sharper. Good news for the taming of the Dyneema shrew !  :)
   As it should have been expected, the three possible 8-shaped fig.9 stoppers are grouped in two classes. The less symmetric forms, based on the symmetric closed 6_1 and 6_2 knots, fold differently than the symmetric one - based on the asymmetric 6_3. (1).
   
1. http://igkt.net/sm/index.php?topic=4719.0
 
« Last Edit: January 30, 2014, 10:45:05 PM by xarax »
This is not a knot.

xarax

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Re: Fig.9 stoppers.
« Reply #1 on: January 30, 2014, 10:40:19 PM »
  The symmetric Fig.9, 6_3 stopper, folded around another line. A quite different animal !  :)
« Last Edit: January 30, 2014, 10:41:05 PM by xarax »
This is not a knot.

SS369

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Re: Fig.9 stoppers.
« Reply #2 on: January 31, 2014, 12:05:46 AM »
Well, this leads me to wonder, till it can be tested , if a retraced Fig. 9 bend would hold in the slippery Dyneema.
If we are going to include hard to untie (Marlin spike assisted untying allowed) then it opens up the field some.

Till I procure some of the uncoated, slippery line, I'll have to use what I do have.
The retraced Fig. 9 makes a neat, fairly streamlined bend with parallel to the standing parts tails.
Tensioned by truck to stationary anchor, 5mm accessory cord in sling form held and was even untieable by hands, but not very easily.

Or one could fashion it similarly and then run the tails through the central area. Looking at it, one would think there isn't anyway for this to slip.
Remains to be seen....

SS
« Last Edit: January 31, 2014, 12:11:46 AM by SS369 »

xarax

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Re: Fig.9 stoppers.
« Reply #3 on: January 31, 2014, 12:24:21 AM »
The retraced Fig. 9

Which retraced fig.9 ? I mean, when tied in the usual elongated form, there are three fig.9 s, as explained in (1) and shown at the attached picture. I would nt expect great differences, but there should be some.
  As I always prefer the more symmetric forms, I prefer the retraced fig.9 bend based on the symmetric fig.9 / 6_3 stopper. See the picture of it, and tell me if this is what you use.

1.http://igkt.net/sm/index.php?topic=4719.0




This is not a knot.

SS369

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Re: Fig.9 stoppers.
« Reply #4 on: January 31, 2014, 12:39:58 AM »
The white knot as in your picture attached, is the base for what I tied.

I did not leave it in the flat form once the bend was tied. Whether it was the "strong form" I don't recall, but it was strong enough.

Dress it as neat and compact as can.

Or before too tight, re-tuck the tails where the green circle is in the edited picture.

SS

xarax

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Re: Fig.9 stoppers.
« Reply #5 on: January 31, 2014, 01:11:38 AM »
... re-tuck the tails [ through the centre]...

  Would nt it be an overkill, even for the Dyneema shrew ?
This is not a knot.

SS369

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Re: Fig.9 stoppers.
« Reply #6 on: January 31, 2014, 03:24:03 AM »
... re-tuck the tails [ through the centre]...

  Would nt it be an overkill, even for the Dyneema shrew ?

Not necessarily. Let's say it inhibited slippage and actually increased the breaking resistance by adding a little resilience to the core.
I don't know that this is the case with this mysterious material, but it could be.

I do know that it will make it easier to insert a spike to ease untying.

SS