Knot Tying Animation

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Postby Scott McCrea » Jan 4, 2006 6:10 am

Ok, thanks Robert! Looks like I have been tying my fig 8 on a bight's properly. ::): Thanks for taking the time to explain it. I like the picture of tensionless hitch, really drives home what you are talking about.
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Postby hunter » Jan 4, 2006 10:24 am

RescueMan,
Thanks for the explanation, I like better/worse. The knot being more secure with the tail underneath makes complete sense to me. Also an easy thing to demonstrate to people.

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Postby Cheryl Jones » Jan 4, 2006 2:38 pm

RescueMan wrote:[
Image

It appears to me that the rope does not run parallel to itself in the knot in this photo, but crosses itself just before emerging as the bite. Can you see it?

I believe the knot is more secure when the lines run parallel throughout the knot, as shown in Rescueman's diagrams. This is especially important when tying the knot using webbing.

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Postby NZcaver » Jan 4, 2006 4:40 pm

Cheryl Jones wrote:It appears to me that the rope does not run parallel to itself in the knot in this photo, but crosses itself just before emerging as the bite. Can you see it?

I believe the knot is more secure when the lines run parallel throughout the knot, as shown in Rescueman's diagrams. This is especially important when tying the knot using webbing.


Robert's earlier diagram of a figure 8 on-the-bight shows the knot before being dressed. To dress it, you flip the bight around so the knot is nicely rounded and compact rather than flat (that's what I do, anyway). The knot becomes neatly snugged-up, and is more secure.

Technically the figure 8 shouldn't even need a back-up knot. However, I know many people are taught/trained to do that, probably as insurance against them screwing up when tying the knot itself. By comparison the bowline can loosen very easily, and should always be tied with a back-up knot.

Also - you should probably avoid tying any figure 8's in webbing, and use a water knot (aka tape knot, round knot, or overhand loop) instead. But yes, that knot should be tied and dressed flat.

Robert - thank you for your informative posts about the correct tail orientation for the figure 8. Now I can pretend I knew that all along...:kewl:
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Postby Cheryl Jones » Jan 4, 2006 8:00 pm

NZcaver wrote:Robert's earlier diagram of a figure 8 on-the-bight shows the knot before being dressed. To dress it, you flip the bight around so the knot is nicely rounded and compact rather than flat (that's what I do, anyway). The knot becomes neatly snugged-up, and is more secure.

The knot can (and should) be "dressed" and tightened with the ropes remaining parallel throughout the knot. In fact I'd argue that it is more compact this way, for it eliminates the lump where the ropes cross. This method provides maximum friction within the knot -- and friction is an important element in the security of a knot.

In the photo of the knot being used with the blue 'biner to rig a rope around a tree, it appears that the lines are parallel within the knot. Compare to the photo of the red rope.


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Postby RescueMan » Jan 4, 2006 9:52 pm

Cheryl Jones wrote:The knot can (and should) be "dressed" and tightened with the ropes remaining parallel throughout the knot... This method provides maximum friction within the knot -- and friction is an important element in the security of a knot.l


Cheryl,

You're right. That was the best on-line picture of a fig-8 bight I could locate (it's amazing that most of them are tied wrong). But there is a twist, as you stated, just before the bight emerges from the knot.

Dressing a knot, like the fig-8, correctly is important not just to maximize friction between strands, but to minimize the sudden shifting of the strands under shock loading.

It is just such short-duration shifting of the strands in a knot which causes both strand-to-strand and internal fiber friction which raises the nylon to beyond its glass transition temperature (at which it becomes amorphous) and weakens it. (For similar reasons, a wet rope is weaker because the water acts as a plasticizer and drastically lowers the glass transition temperature of nylon.)

So dressing (neatening) and setting (tightening) a knot prior to use is critical to minimize strength loss.

Also, knots that are NOT going to remain tied in one spot should be untied after use to avoid taking a "set" at that point. On the other hand, a knot that's going to remain tied (in nylon rope) will "relax" and regain its strength, and hence shouldn't be untied and reconfigured unnecessarily.

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Postby NZcaver » Jan 4, 2006 10:43 pm

Cheryl Jones wrote:The knot can (and should) be "dressed" and tightened with the ropes remaining parallel throughout the knot. In fact I'd argue that it is more compact this way, for it eliminates the lump where the ropes cross. This method provides maximum friction within the knot -- and friction is an important element in the security of a knot.


:doh: Cheryl - I owe you an apology, I messed up my description. :oops:

That's what happens when I'm too lazy to pull out a piece of rope and actually try it! What I meant to say is that I tie a figure 8 on-the-bight in parallel fashion (see the first photo), and then flip the last strand before the bight over it's neighbor (see photos 2 and 3 - both sides of the same knot).

Image
Image
Image

Still, I'm not sure that this results in the same outcome that you described. Someone please correct me if I'm wrong, but I believe my second and third shots and Robert's red rope shot all show properly dressed figure 8's. (Robert, you disagree?) Robert's earlier tree photo shows a knot that appears to be both incorrectly tied (tail on the wrong side) AND undressed (the last loop before the bight should be flipped over it's neighbor and snugged tight).

:hairpull:
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Postby knudeNoggin » Mar 4, 2006 8:49 pm

NZcaver wrote:
Cheryl Jones wrote:The knot can (and should) be "dressed" and tightened with the ropes remaining parallel throughout the knot.


Image

Still, I'm not sure that this results in the same outcome that you described. Someone please correct me if I'm wrong, but I believe my second and third shots and Robert's red rope shot all show properly dressed figure 8's. (Robert, you disagree?) Robert's earlier tree photo shows a knot that appears to be both incorrectly tied (tail on the wrong side) AND undressed (the last loop before the bight should be flipped over it's neighbor and snugged tight).

:hairpull:


I think you've got it; Cheryl doesn't (Robert shouldn't have conceded).
Moreover, that pretty untensioned knot in BWII(?) for the Tensionless Hitch
is of the "correct" start but needs to be dressed as you suggest--the loose end's
turn should come down around the parallel one. Though, as it is, I'd rate it as
"a good knot"--performs its function, which is to give an eye for the 'biner, quickly
tied & untied (even were the end to work completely free of its last tuck--which
it won't--, the resulting, er, 3/4 Fig.8 would be fine (such knots have been tested)).

Note that NZCaver's first, starting orientation of the knot is the REVERSE (re which
end is loaded, which is TAIL) from that flat, unrealistic diagram of the Fig.8 loopknot
in Robert's msg. (and one that, sadly, is often parroted). Formed like this, the
draw of the eye bight through it can naturally rub it and bring the right loop (of the
standing part) into proper position for dressing. This supposed easily tied knot
poses much more difficulty when tied the "re-threaded" way, such as to a climbing
harness.

But as for arguments pro/con a given orientation, well, YMMV. It's been asserted
that AMGA testing found "properly tied" Fig.8 loopknots weaker than others;
but "sloppy/mistied" aren't terms denoting exact forms, and there are no doubt
some weaker versions of these.

As for the "right" v. "wrong"/"cowboy" bowline, the supposed vulnerability of the latter
to being jerked into some failure seems mythical to me: in most cases, IMHO, even
WERE the end to snagged so as to capsize the knot, if the end was freed, the
knot should capsize back into form (indeed, it's a way to tie it--"the slip-knot way").
Frankly, I think that this is an invented problem.
In any case, what is more certain is that the cowboy/end-on-outside bowline
resists ring-loading, which can occur if the eye snags on something (or if,
as is given anecdotally, some foolish rescue person tries to hoist you by hooking
the eye); loaded this way, the knot becomes the Lapp Bend. The "proper" bowline
will most likely spill. (A Dbl. Bowline in either orientation will resist spilling.)

Back to the Fig.8, in what NZcaver at least posits as proper. I'd set that form by
tensioning the END vs. eye bight; this will put a nice curve into the standing part,
which when loaded (well more than you're likely to manually set!) will bear into its
parallel twin part, and also curver over paired parts crossing it, and out against
paired parts at the end of the knot--much padding, gentler curves.
Based on some testing that claimed this form to be 8-10%pt.s stronger a sort
of bowline-fig.8 compromise loopknot was designed (no testing on this to report).
Cf. Lehman8 at http://www.iland.net/~jbritton/KnotPhot ... tions.html

Image

On the main set of knots (http://www.iland.net/~jbritton/ ) one can see an asymmetric version
of the Fig.8 loopknot.
And below shows more clearly the symmetric version loaded on the other end.

Image

Knots is a field with surprising little rigorous research, and a LOT of outright,
incredible nonsense. Beware bold pronouncements; and realize that material matters
--what works well in that supple double-braid polyester yacht rope might fare poorly
in stiff kernmantle caving rope (PMI No-Flex, e.g.), or some firm rope w/round
cross section vs. a rope w/readily compressible cross section.

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Postby RescueMan » Mar 5, 2006 12:40 am

NZcaver wrote:I believe my second and third shots and Robert's red rope shot all show properly dressed figure 8's. (Robert, you disagree?) Robert's earlier tree photo shows a knot that appears to be both incorrectly tied (tail on the wrong side) AND undressed (the last loop before the bight should be flipped over it's neighbor and snugged tight).


Cheryl is correct that the red fig-8 loop needs a clockwise half turn of the bight before it emerges to form the eye.

But your images are correctly tied.

The oddity is that, in order to keep the strands parallel in the knot, the bight needs to be turned a half turn before it's final tuck. If you try to tie the knot "flat" and parallel, it will need to be dressed.

The fig-8 loop on the tensionless hitch is dressed correctly, but is tied "backwards". I agree with NudeNoggin that, in this instance, it makes no difference.

But, when I'm loading a fig-8 on a bight, I don't want the tail to "walk". If you routinely tie a back-up double overhand, then the tail isn't going to walk too far (as long as the back-up knot is tight to the host knot).

A primary advantage of the fig-8 on a bight over, say, a bowline is that it's a far more secure knot (won't untie itself when relaxed) unless it's tied in very stiff rope. I don't normally use a back-up with a fig-8 on a bight, so I want my tail to stay put. That means tying it "right".

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Postby NZcaver » Mar 5, 2006 6:37 pm

RescueMan wrote:Cheryl is correct that the red fig-8 loop needs a clockwise half turn of the bight before it emerges to form the eye.


I'm not sure I agree with that. Perhaps I'm misunderstanding something, but the red rope figure 8 still appears to be correctly tied and dressed to me. (OK - so the huge bight is overkill for clipping into, but that's just splitting hairs :wink: )

I just copied the picture, and the bight/loop doesn't seem to require any clockwise half turns. When tensioned it snugs up fine. I noticed something odd about the picture, but didn't put my finger on it until I started copying the knot - it's tied left-handed (or the photo has been reversed). Same knot - same result. I always tie it right-handed, so mine looks like a mirror image.

I don't use a backup knot with a figure 8, but I always do with a bowline. knudeNoggin's "Lehman 8" is an interesting concept, but the high-strength bowline probably achieves the same result with a more gentle learning curve (two turns form the initial loop instead of one).

Just my 2 cents... :grin:
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Postby RescueMan » Mar 5, 2006 7:10 pm

NZcaver wrote:the red rope figure 8 still appears to be correctly tied and dressed to me.


And YOU'RE RIGHT! I was trying to mentally turn the picture of the red fig-8 around in my mind to see the back side when I should have just tied a rope into a knot and checked it out.

I don't use a backup knot with a figure 8, but I always do with a bowline... the high-strength bowline probably achieves the same result with a more gentle learning curve (two turns form the initial loop instead of one).


In supple rope, I often don't bother to back up a bowline (except in rescue scenarios, or if going through use cycles). Once it's loaded, it becomes a secure knot.

And I'm not a fan of ANY of the "extra strength" versions of the bowline - double bowline, French (or Portuguese) bowline, water bowline (with clove hitch). The plain vanilla bowline is as good a knot as there is, and strength reduction is simply not an issue unless I'm climbing on 8mm rope (which I don't) or towing a truck out of a ditch (which I don't do with my climbing/caving/rescue ropes).

I find the bowline to be one of the most versatile of all knots and, like any good tool, treated with respect and used properly, it never fails.

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Postby knudeNoggin » Mar 6, 2006 1:01 am

In supple rope, I often don't bother to back up a bowline (except in rescue scenarios, or if going through use cycles). Once it's loaded, it becomes a secure knot.

And I'm not a fan of ANY of the "extra strength" versions of the bowline - double bowline, French (or Portuguese) bowline, water bowline (with clove hitch). The plain vanilla bowline is as good a knot as there is, and strength reduction is simply not an issue unless I'm climbing on 8mm rope (which I don't) or towing a truck out of a ditch (which I don't do with my climbing/caving/rescue ropes).

Suppleness isn't the whole game: some supple rope is quite springy & slick,
and the bowline won't hold a set in that much.
As for "hi-strength" bowlines, one testing (K.Milne) found no difference between
the single & dbl. bowlines, but YMMV--lots of factors ... .
However, the Dbl. Bowline is more secure, and esp. as I noted resistant to spilling
on ring loading--which is a serious vulnerability of the Bowline.
Similarly, the Water Bowline (whose original purpose seems in doubt), based
on a Clove hitch, is more secure against loosening.

A bowline's significant plus is being able to be tied completely in one fell swoop,
after sizing the eye; at that point, additional securing measures can be taken,
if the situation warrants. (For e.g. the Lehman8, one would have to first tie & position
a fig.8 in the rope, then size the eye, and then tie the end into the knot.)
Knowing when the situation warrants, however, is a judgement call not always
made correctly. UtahClimbing has a report of BlackDiamond Equip.'s Adam Abraham's
tragic bowline failure (no details of actual knot workings, though mention of such
a report), and rumor of at least one other. Yeah, sure, they didn't ... .
But one of the considerations in teaching a knot in some cases is that users might
not ... <whatever>, and so a Fig.8 (that set of various things denoted by the name)
loopknot might be the better knot for many to have (half-) learned.
(I'm rather dismayed that the clear image of the red Fig.8 loopknot has taken now
several responses to figure out that it is "right", in THIS forum--this knot that
is soooo easy to check! (I know some pseudo-/quasi-Fig.8's that I'm sure I could
win bets on the question "Is this right?" with Fig.8 tyers.))

And then there are those for whom knot tying should not be in some "half-"
zone, and there, getting it right is required, and the bowline has a place.

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Postby NZcaver » Mar 6, 2006 1:57 am

RescueMan wrote:And YOU'RE RIGHT! I was trying to mentally turn the picture of the red fig-8 around in my mind to see the back side when I should have just tied a rope into a knot and checked it out.

knudeNoggin wrote:I'm rather dismayed that the clear image of the red Fig.8 loopknot has taken now several responses to figure out that it is "right", in THIS forum--this knot that is soooo easy to check!

*knudeNoggin*

Good point. Nice symmetrical knot, looks good, "on rope!"... :goodjob:

However, when one physically checks that a knot is correctly tied and dressed, they should do just that - PHYSICALLY check. A picture - or even an animation (the original topic of this thread) - can be a reasonable training aid, but there's no substitution for actual experience/practice. (Like many things in life and caving, really.)

My point is that some slack should be given (pardon the pun) to those who occasionally misinterpret pictures (or words) - including me earlier in this thread. This subject is a continual learning process for all who consider themselves serious practitioners. Anyone who thinks they know it all is not someone I want to be around!

Many of the folks posting here I either know personally, or at least by reputation. I'd trust my life on their knots, even if they might occasionally miss something in the photo lineup. :wink:

And P.S. Could someone please tell me what on earth the acronym "YMMV" - Your Mileage May Vary - has to do with knots? :question:
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Postby RescueMan » Mar 6, 2006 11:39 am

NZcaver wrote:And P.S. Could someone please tell me what on earth the acronym "YMMV" - Your Mileage May Vary - has to do with knots? :question:


Also, from the Acronym Attic of obscure meanings:

Yam Mild Mosaic Virus
Yes Mum More Vanilla
Yet More Manipulative Villains

But I think NudeNoggin DOES mean "your mileage may vary".

Which reminds me of this completely off-topic aside: a bunch of high school trouble-makers and gangsters who were asigned to an autoshop program in W. Philly built a soybean biodiesel powered hot rod that goes 0 to 60 in 4 seconds and gets 50 mph (YMMV).

http://www.cbsnews.com/stories/2006/02/17/eveningnews/main1329941.shtml
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Postby knudeNoggin » Mar 6, 2006 5:58 pm

NZcaver wrote:And P.S. Could someone please tell me what on earth the acronym "YMMV" - Your Mileage May Vary - has to do with knots? :question:

Much more than most people suppose!
In short, the statement "The Zednought Knot is ..." generally should be replaced
with "The Zednaught Knot in this particular or range of cordage is ...".
"YMMV" points to the varying of behaviors by changes in any of many factors
affecting knots. (E.g., Lyon Equip. tested the Clove hitch as a ring hitch--i.e., tied
around an object w/like dia. to the rope--in several low-elongation & one dynamic ropes;
the knot held only in the latter, slipping at widely varying loads in the low-elong. ropes.
Consider a rockclimber accustomed to sure performance in climbing ropes applying
this unbounded *knowledge* to low-elongation kernmantle ropes!)

Some people have used the venerable Bowline for ages w/o trouble and thus
cannot comprehend how climbers & SAR folks et al. fault it; were those people
to work with the stiffer cordage, they'd understand.

(Incidentally, even if a Bowline loosens but remains tied, the result of loading can
be dangerous: it can capsize and become a noose.)

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