Author Topic: Adjustable Loops  (Read 43844 times)

Mobius

  • Sr. Member
  • *****
  • Posts: 338
Re: Bowline "knot wars"
« Reply #15 on: June 08, 2015, 02:14:13 PM »
Thanks Mark,

There are a lot of good points made and good suggestions.

To start with, I would have to find a different braid to use, my current one is stiff and white. Sewing markers into this 3mm braid would require a lot more than carrots ;) Also, I am actually quite happy with the characteristics of the braid I am using (stiff, smooth, holds it cross-section), I would want to find the same type of braid, except not in white.

The methodology you suggest is possible, though this project suddenly got a lot larger if I go that way. I will consider everything you indicated.

Cheers,

mobius

alpineer

  • Sr. Member
  • *****
  • Posts: 507
Re: Bowline "knot wars"
« Reply #16 on: June 08, 2015, 02:34:40 PM »
Hi mobius, here's one of my knot offerings (photo credits agent_smith)...let's call it Alpineer's Bowline for identification purposes.
     
« Last Edit: June 08, 2015, 02:40:10 PM by alpineer »

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 3946
Re: Bowline "knot wars"
« Reply #17 on: June 08, 2015, 09:07:30 PM »
Sewing markers into this 3mm braid would require a lot more than carrots ;)
Methinks the rumor of difficulty is greatly exaggerated!
One merely needs to get the marker beneath some of
the mantle yarns, perhaps making a 2-3-tuck marking;
this can't be onerous!  --NOT going through the center
and all.  If testing w/equals on each end, like marking
should give information from survivor re loser; otherwise,
photo of in-tension knots will help indicate what's what
in position.

Well, re-reading more closely, "3mm" does present difficulty.
On the white thread, though, it offers an easier method : SHARPIE!
(yeah, there's some aspect of claiming that the marking itself has
effected damage; I think one can avoid such charges by marking
safe areas, and if the rupture comes elsewhere, well then ... !)

(While tapered/conical, carrots will not be adequate qua needles.   ;D )

--dl*
====

SS369

  • Global Moderator
  • Sr. Member
  • *****
  • Posts: 1907
Re: Bowline "knot wars"
« Reply #18 on: June 08, 2015, 11:12:03 PM »

I am of the opinion that 3D will lose the strength competition.
Why?
(Let's have some explained theory out there!)

And I echo Alpineer's alarm at the "SS" setting of the bowline !    ::)

--dl*
====


First: The 3D encirclement I suspect and have seen involves more movement under load. Hence the increase of friction and heat. As the load increases and the tighter parts get they are moving and abrading each other, inside and outer fibers. All that movement has to produce destructive forces. I don't believe that the available surface areas will allow dissipation fast enough, instead act like heat sinks and thus accumulate heat to the point of melting a strand and then another.
This may not be as much with natural fibers.

Second: I don't agree with Alpineers' alarm sounding. I have not advocated some "super snugging" as you have been worried about in the past. I do think a firm snugging of all the parts is important, to limit the nub parts movements under loads. A #1010 bowline with its collar snug is less inclined to capsize, imo. Snugging the collar has never been an undo challenge to untie, even after pulling a wooden bridge or crane lifted bundles with a bowline. Just flex the collar and voila! Easy peasy.

I believe that 3D can improve security with the potential for reduction of overall strength.

SS
« Last Edit: June 09, 2015, 12:00:31 AM by SS369 »

alpineer

  • Sr. Member
  • *****
  • Posts: 507
Re: Bowline "knot wars"
« Reply #19 on: June 08, 2015, 11:29:27 PM »
            http://igkt.net/sm/index.php?topic=4687.0     


I'm cautious about this knot due certain security, jamming or unintended misuse with unintended consequences which I've not yet pondered, though it might make an interesting candidate for trialling. There's at least 4 distinct loading configurations. I'll defer to xarax to recommend one. 
« Last Edit: June 09, 2015, 01:11:26 AM by alpineer »

agent_smith

  • Sr. Member
  • *****
  • Posts: 1204
Re: Bowline "knot wars"
« Reply #20 on: June 09, 2015, 12:34:46 AM »
Hello mobius, I have added more key stroking content to my post at reply #14.

Would be good if you could also consider changing the title of this thread from 'Knot wars' to 'Load testing of various Bowline structures' (or something with a more scientific bent).

Mark G

xarax

  • Sr. Member
  • *****
  • Posts: 2781
Re: Bowline "knot wars"
« Reply #21 on: June 09, 2015, 01:01:39 AM »
   1. security,
   2. jamming,
   3. unintended misuse 

1. You must be joking ! It is more secure than it should  :) ( meaning, this convoluted collar structure is an overkill ).

2. Perhaps. ( Although "jamming" is a very vague concept - I prefer the simple "difficult to untie", which is enough ! We want bowlines easy to untie - otherwise we do not need bowlines at all ! )
    When you see a "closed" knot tied on the Standing Part before, or even after the eye ( for example, an overhand knot, a fig.8 knot, etc - here the knot tied on the returning eyeleg is even worse :) ), you should be cautious... Under really heavy loading, even the returning eye leg will be pulled hard, and the knot tied on its continuation, the "collar structure", may "close" around itself too tightly.
    Now, there is a basic distinction we should make here : This "closed" knot can be tied before or after the tip of the "higher" collar, and this makes a great difference. If it is tied before the tip of this collar, it will absorb the full tension coming from the returning eyeleg ( that is, about 50% of the total load  ), and then it will become difficult to untie, that is for sure. However, if it is tied after the tip of the "higher" collar, as it happens here, the situation may be less dangerous. At the U-turn of the collar, the direct continuation of the returning eyeleg "uploads" a significant portion of the tension which runs through it ( because of the capstan effect - the collar is not a pulley, it can not revolve freely around the Standing End ! ), so the tension which "comes down" is much less that the tension which was "going up". With less tension, there is less danger of a too tight closing of the "collar structure".   
   Alan Lee has tied many bowline-like eyeknots with overhand knots or fig.8 knots tied on the returning eyeleg ( on the Standing Part after the eye ) - but, on most of them, they are tied after the "higher" first collar, so there is less danger of them being "closed" around themselves too tightly. Myself, I prefer to follow the rule of thumb, and avoid ANY such knot - so the eyeknots I now tie are PET-2, and they are less prone to jamming / untying difficulties.

3. I do not understand what you mean by this "unintended misuse"... This eyeknot is meant to be loaded mainly as a bowline ( that is, from the "yellow" end - the nipping loop is the yellow one ). If it will be loaded by the other, "blue" end, its "blue" "nipping structure" will be too complex, and its "yellow" "collar structure" will be too simple !   
   HOWEVER, there IS the issue of unintended dressing:) This eyknot can be dressed in a number of different ways, just as it happens with all the "retraced" knots which have parts traced with double lines - the fig.8 bend and fig.8 loop included. In other words, this knot is not self-dressing in one and the optimum way - and, judging from the fact that generations of climbers had not even suspected how many different dressings the fig.8 loop they use can have  :), I think that we should not expect that the average knot tyer would be able to distinguish, and to care, about the different dressings of this knot either. A badly / not-uniformly dressed knot can not be inspected easily, and can even become less strong than a properly dressed one - I think that the twistings and the other irregularities of the flow of the double line, especially around turns, will become the weak links of the nub.
   Read what, by coincidence, I had written just a few hours ago ;
   the double line is fine when it runs along straight segments, but poses problems when it makes O- and U-turns. Exactly as it happens in all such "retraced" knots ( meaning knots which can be tied in-the-end by retracing the path of the first line with a second line ) - the fig.8 bend and fig.8 loop, for example. In each turn, each of the two lines can follow the inner or the outer track, and so the knot can be dressed in many ways, and the most regular, streamlined dressing of them requires attention from the knot tyer. That is the reason I had abandoned the "shrunk", single-eye version of this loop : too many dressing forms mean that the knot is not self-dressing, and it can settle in a not-optimal form .
   
« Last Edit: June 09, 2015, 01:13:15 AM by xarax »
This is not a knot.

alpineer

  • Sr. Member
  • *****
  • Posts: 507
Re: Bowline "knot wars"
« Reply #22 on: June 09, 2015, 01:06:18 AM »
Second: I don't agree with Alpineers' alarm sounding. I have not advocated some "super snugging" as you have been worried about in the past. I do think a firm snugging of all the parts is important, to limit the nub parts movements under loads. A #1010 bowline with its collar snug is less inclined to capsize, imo. Snugging the collar has never been a undo challenge to untie, even after pulling a wooden bridge or crane lifted bundles with a bowline. Just flex the collar and voila! Easy peasy.
SS
I don't hear any alarm bells. :) But your judgement concerns me. 


Hi Alpineer.

I gave your construct a whirl using some Titan (BlueWater) 5.5mm Dyneema and as well I used 1/4 inch solid braid nylon.

I like the compactness of this bowline and it lives up to your claims, almost.

The knot was dressed as tightly as my hands could do, using all the parts individually till I had the affair as snug as possible.

What I find is that the during the ring loading, the parts migrate to the point of the collar almost being drawn into the the upper nip using hand strength and body weight, so I can only imagine what serious loading (both slow or sudden) would do.

The biggest drawback, to me, is that after loading it to 300 lbs and then bouncing using body weight, I had to use round nose pliers and a spike to untie it.

I believe that the double nipping coils act very much like double overhand or perhaps a constrictor. No doubt very secure!

Based on my quick unscientific tests I would say it would be a satisfactory tie in loop, except for the untie-ability factor. In my opinion.

Thank you for sharing this.

SS

In my "whirlings" I've loaded the Tresse Bowline in a range of cord sizes, in some cases by as much as ~750 lbs. and all were untied using only fingers. Loosen up that collar just a bit and you'll have both security and easy enough untying. As for ease of untying, nothing beats #1010. But it's nature is of the proverbial two-edged sword.

 



SS369

  • Global Moderator
  • Sr. Member
  • *****
  • Posts: 1907
Re: Bowline "knot wars"
« Reply #23 on: June 09, 2015, 02:18:45 AM »
Second: I don't agree with Alpineers' alarm sounding. I have not advocated some "super snugging" as you have been worried about in the past. I do think a firm snugging of all the parts is important, to limit the nub parts movements under loads. A #1010 bowline with its collar snug is less inclined to capsize, imo. Snugging the collar has never been a undo challenge to untie, even after pulling a wooden bridge or crane lifted bundles with a bowline. Just flex the collar and voila! Easy peasy.
SS
I don't hear any alarm bells. :) But your judgement concerns me. 
Dan Lehman's  bells of alarm attributed to you.
Quote
   And I echo Alpineer's alarm at the "SS" setting of the bowline!

I don't see why my judgement is in question. I tie/use my knots my way, you yours.
There have been knots that I test and explore that I have snugged very tightly and some not so tightly. It sometimes depends on the material of what I am tying. That is what I deem necessary to evaluate some constructs. My comment to mobius was to snug his test specimens to a consistent point.

Quote
Hi Alpineer.

I gave your construct a whirl using some Titan (BlueWater) 5.5mm Dyneema and as well I used 1/4 inch solid braid nylon.

I like the compactness of this bowline and it lives up to your claims, almost.

The knot was dressed as tightly as my hands could do, using all the parts individually till I had the affair as snug as possible.

What I find is that the during the ring loading, the parts migrate to the point of the collar almost being drawn into the the upper nip using hand strength and body weight, so I can only imagine what serious loading (both slow or sudden) would do.

The biggest drawback, to me, is that after loading it to 300 lbs and then bouncing using body weight, I had to use round nose pliers and a spike to untie it.

I believe that the double nipping coils act very much like double overhand or perhaps a constrictor. No doubt very secure!

Based on my quick unscientific tests I would say it would be a satisfactory tie in loop, except for the untie-ability factor. In my opinion.

Thank you for sharing this.

SS


In my "whirlings" I've loaded the Tresse Bowline in a range of cord sizes, in some cases by as much as ~750 lbs. and all were untied using only fingers. Loosen up that collar just a bit and you'll have both security and easy enough untying. As for ease of untying, nothing beats #1010. But it's nature is of the proverbial two-edged sword.



As for the above quote: It was an honest appraisal using two different media that I have that show different aspects. The hard Titan cord shows off many knot's lack of security and the nylon shows the level of untie-ability.
A range of cord or rope sizes can influence attributes, but in my opinion, the material and construction design influences knot performance more.

SS
« Last Edit: June 09, 2015, 02:41:03 AM by SS369 »

alpineer

  • Sr. Member
  • *****
  • Posts: 507
Re: Bowline "knot wars"
« Reply #24 on: June 09, 2015, 04:30:42 AM »
As for the above quote: It was an honest appraisal using two different media that I have that show different aspects.

The hard Titan cord shows off many knot's lack of security and the nylon shows the level of untie-ability.
A range of cord or rope sizes can influence attributes, but in my opinion, the material and construction design influences knot performance more.

SS

Your honesty and integrity were never in doubt by me, SS.

Of course, all aspects of material nature - including dimensions - determine a knot's performance. But do they explain per se the use of pliers and spike to untie the knot in your case? 

 
« Last Edit: June 09, 2015, 06:53:56 AM by alpineer »

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 3946
Re: Bowline "knot wars"
« Reply #25 on: June 09, 2015, 05:41:45 AM »
Hi mobius, here's one of my knot offerings (photo credits agent_smith)...let's call it Alpineer's Bowline for identification purposes.
     
!! This looks like an excellent variation :
it has a "proper collar" (per X);
it has an "end-binding" (per DL);
it is TiB (per X);
and it Yosemites the tail out the collar (per A_S!   ::) ).
.:. 3.5 for 3.5 !   ;D


Now, to describe the TIB alternative to the "YoBowl" that
I've mentioned, see the returning tail (into turNip of the right
image (which presents the better face to show!) connecting to the
other side of the collar-bight (which makes it like "right-handed" bwl),
and then coming back out of the nip into the final tuck as shown
--bypassing/leaving-off the "end-binding" loop around the right side,
around the crossing-point of the nipping loop.  One thus has a simple
overhand component formed by the tail instead of the fig.8
done by the YoBowl, and the tail will be in a position to be drawn
upon by the S.Part after tension flows over the tail-side eye leg.
(It is also EEL, qua overhand-based eyeknot pulling this
indicated tail, and still TIB.  Of the easy four such knots (varying
the way the collar is made/turned), I think that this described one is
best --most sure of holding orientation, and giving good curvature.)


--dl*
====

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 3946
Re: Bowline "knot wars"
« Reply #26 on: June 09, 2015, 05:59:21 AM »
First: The 3D encirclement I suspect and have seen involves more movement under load.
Hence the increase of friction and heat.  As the load increases and the tighter parts get
they are moving and abrading each other, inside and outer fibers.
But this concern is more for real loading than for
what will likely generate knot strength --standard
slow-rate loading.  (Dave Merchant opined that such
heat aspects made the strengths of esp. the slow-pull
strong fig.9 not so much stronger than an overhand
eyeknot
when dynamically loaded.)

But I don't think that the difference here is like that.
For the common bowline, the tail can act like a roller
bearing upon the draw of the S.Part --moving by rotation
with the heavily loaded S.Part between that and the other
side of the collar bight (eye leg), and I think that that
might give the knot durability over cyclical loading;
but it wouldn't matter so much in slow, break-teast loading,
IMO.  I would like to see the tail set back away from its usual
spot vis-a-vis this rotation, such that the S.Part's draw would
rotate it to where it normally begins; I think that having the
hard-stressed S.Part bear into a relatively unstressed and
hence more compressible tail might be helpful (vs bearing
against a tensioned eye leg).  And so my urging for that
"other variation of Yosemite finish", though there the tail
part will be more held in that "back away" position, not
moving (but taking the fuller pressure of the S.Part vs.
putting that upon the eye leg).

Also, there has to be enough friction to reduce the force
on the eye leg of the turNip by 50% over the S.Part,
else --as has been seen in Dyneema and a double-turNip(!)--
the eye will collapse by feeding out through this turn
--having say a reduction to only 65% and so opposed on
the other eye leg by 35%.  But a sharper turn gives more
resistance-to-bending (additional to friction) ?!

As for the "SS setting", I recall distinctly the sever bend
you put into the S.Part in one image, and that would put
lots of pressure upon the turNip's crossing point, before
force flows around the loop; that worried me.  (Yes, it would
defeat capsizing!)

As for jamming, that will come with elastic ropes when the
diameter diminished so much and parts close around, and
then on tension release the outside-of-constrictions parts
become swollen large and cannot slip back into the knot!
YMMV.


--dl*
====
« Last Edit: June 09, 2015, 07:23:27 AM by Dan_Lehman »

alpineer

  • Sr. Member
  • *****
  • Posts: 507
Re: Bowline "knot wars"
« Reply #27 on: June 09, 2015, 06:34:09 AM »
There's also an interesting #1010 version of the Alpineer Bowline where the working end crosses over the collar's root before plunging into the turNip, continuing around the turNip's crossing part and plunging back into the turNip in the same direction before exiting through the collar. In this case a Fig. 9 on the working end engages the turNip.

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 3946
Re: Bowline "knot wars"
« Reply #28 on: June 09, 2015, 07:30:47 AM »
First: The 3D encirclement I suspect and have seen involves more movement under load.
Hence the increase of friction and heat.  As the load increases and the tighter parts get
they are moving and abrading each other, inside and outer fibers.
We might also look to other knots, such as the fig.8 eyeknot
in which we don't see 3 diameters and yet have --sometimes,
at least(!)-- great strength, and wonder then at how the 3dia
comes to be so needed!?  (I have some idea that the F8 gets
strength from the turning of eyeleg parts around the S.Part
as it enters the knot, taking away some of the importance
of the ultimate U-turn's sharpness; although, in the push
comes to shove competition the S.Part's 100% nipping
might overwhelm the twinned 50% of those legs!?

One might test some rather comical, 5-6diameter? knot
just to so greatly emphasize that aspect, to see if it makes
a difference.  Then, again, one might consider some of
the test results for the bowline and ask How much more
strength is left to get?!
--some figures e.g. go to 80%.
. . . mysteries . . .  ???


--dl*
====

alanleeknots

  • Sr. Member
  • *****
  • Posts: 544
Re: Bowline "knot wars"
« Reply #29 on: June 09, 2015, 08:29:24 AM »
Hi All,
        Mobuis  You will be a very busy man. Please include this loop here with your "knot wars", will make ss  happy.

        謝謝  alan lee.