Analysis of Bowlines paper uploaded for review and comment (PACI website)

[Dan_Lehman]

The image you show is one I regard as absurd :
[and I explain in detail why!]

My bad, the fig 8 is simply an illustration from KM007.
Such a harsh statement towards the founding members of Knotting Matters Dan!!!

Where is a founding member, here?

Well an illustration is what it is "an illustration"!

... of what?!  It's supposed to convey
information.  Please (re-)read my explanation
of my charge(s) --I give a rationale for the judgement.

the point is, Bill Marsh in his book "Modern Rope Techniques in Mountaineering" -
advises: ".....always ensure that the main rope lies on the outside of the first bend in the knot (see Point "X" in the diagram). If this is
on the inside, the knot is weakened."

To which I pointed out that this statement
and associated image are ambiguous; different
geometries can result if that illustrated structure
is loaded.  If some dressing is applied, well, then
please show me where this dressing has been
specified (and where "on the outside" lies, then)!
Point is : it is NOT.
How do you not understand this?

Alan WALBRIDGE has tested this for fig 8 and confirmed based on limited experience.

Which sadly leaves Alan as one who has just
glossed over the ambiguity w/o notice or comment.
My surmise, btw, is that the "on-the-outside" part
gets drawn more naturally than not into the spot
I explain as reaching less far and pulling away from
the twin part; it is thus the form/loading of the knot
that Chisnall found to be weaker (and Lyon found
to be insignificant --i.e., either way, roughly equal).

(Alan tested knots for me --one time--, and I'm grateful
for that, preserving the partially broken specimens for
continued reference/study.  The rope was 1/4" laid/twisted
nylon, and the breaks were in either 1 or 2 strands (I think
an eye splice --for getting rope strength-- broke in ONE;
usually, though, to Alan's remark in km007:03, it was
stronger knots breaking two, weaker one strand). )

The interesting thing is that you never find a Fig8 (or other variations of it) in ABOK where the Spart is inside! Ashley has always managed to magically draw the Spart curve outside! in this world of internet this information has been lost and every other site and book illustrates this in a random in- or out- manner with no care!

I think I see the problem now : you need to improve
your eyesight!   
#531 (eyeknot) doesn't fit the image above,
and will more likely give the bears-against-twin
orientation I define, partially --kinda looks to be
what Dave Merchant suggested, which is awkward
to do (as it entails the twin parts crossing).
#1047 is more typical of the presentation of such
tie-with-a-bight knots : the SPart/end distinction
is left to the imagination!  His flat, unrealistic drawing
at least settles into a well-dressed final one, albeit
still w/o hint of SPart/end difference.  Tell me, of
this illustrated well-dressed knot, which part lies
"outside" ?!  That inner/outer relation simply
doesn't obtain!  One can see which reaches farther
along the axis of tension.  (And in many photos of
loaded fig.8s, one can see that this part is slack
and so must not be loaded.)
#1411 (end-2end knot) is misdrawn of upper ends
--the SPart should be shown going UNDER the tail--,
but the lower ends are clear enough and in that state
will set into the bears-against-twin orientation rec'd
by Chisnall.  MAYBE Alan got that, but it's not at all
a given from the darn-lame "flat" illustration so often
presented!

I think the hypothesis holds for the [double] bowline too.

I think it holds as well --not "also", but "no better
than"!   

I'll have to check what KM#007 (or nearby) says and who

Did you get one in its time?

Yep.

... don't find the EBSB+Y very practical since the tail is not easy to pass through the both loops]
As you know this is of major importance for sport climbing, which consists of repeated tries of the crux and thus Repeated falling and loadings!!

Forgetting the fundamental Rule of Climbing:
Don't Fall!
You can I think search and find "Lehman8" on this
site, which was my attempt to bring bowlinesque
push-the-collar-back easy untying to the fig.8 base
(for its security & strength).  IMO, the 8 might get much
strength from the bearing/gripping of the tightening
double collars and so my Lehman8 looses that, going
for the "bears-against-twin" cushioning.  At which
point I then bring up the point that all of the knots
are amply strong (as shown by historical usage).


--dl*
====

[Dan_Lehman]

The most convenient way to observe the nature of the Scott's Lock Bowline capsizing event is to tie the knot in bungee or shock cord.  Elasticity seems to play a role.

Here's are some pictures with the standing part shown on the top of each picture.

But there are TWO parts on top ... --which
is which?

It would help to have some words as to what
the images show, how it was got, et cetera.
(E.g., "This resulted from ring-loading.")

--dl*
====

ps : I will leave it to X. to say which is "pretty/ugly".

[Dan_Lehman]

ANY one of the many knots that have a sharp bend in its nub ( while it could well had avoided it ), is an ugly knot. 

  A nice example of such an ugly knot is offered
by Dan Lehman in this very page : See the first/at
the left of the two spring-based-shock-absorber-looking loops,
shown in his recent post.

That sharp bend where the tail-side eyeleg
enters is worrying to firm/stiff rope, but a
help for flexible-but-springy rope such as
common laid polypropylene can be, as the
rope won't *flow* 'round this hard bend
and loosen, but will want to open it like
scissors but fail --i.e., the difference I told
above between the EBDB's round, 3dia.
turns and the Janus bowline's bights.

( By this, I do not wish to convey the false impression,
that the second/at the right loop, is much prettier !  ).

You wouldn't be, for it's true not false
--a beautiful knot!


--dl*
====

[xarax]

That sharp bend ... is worrying to firm/stiff rope, but a help for flexible-but-springy rope

   I think that we should try to tie knots that can be tied, and be at least not-ugly ( if they are not pretty ), in any "ordinary" material.... Perhaps this is not but a hope, a wishful thinking, of somebody who believes that "knots" are mostly knotted structures, tied on materials, not knotted materials - i.e., that geometry is the most important property of any knot, not composition.
   

[Dan_Lehman]

That sharp bend ... is worrying to firm/stiff rope, but a help for flexible-but-springy rope

   I think that we should try to tie knots that can be tied, and be at least not-ugly ( if they are not pretty ), in any "ordinary" material....

Beauty is in the eye of the beholder
(but then why are those curators filtering
all the new rubbish at us as *art*?!).
Spring PP rope is quite common.

 

[xarax]

   I think that we should try to tie knots that can be tied, and be at least not-ugly ( if they are not pretty ), in any "ordinary" material....

Spring PP rope is quite common.

   My English attempts are much worse / uglier than my knots ! 
   Perhaps I should had written " in each and every "ordinary" material ". I mean, a knot should not be ugly if tied in any one of those materials. PP included...

[knoeud]

I think the hypothesis holds for the [double] bowline too.

I think it holds as well --not "also", but "no better
than"!   

I'll keep this one
I need to check out those knots. a contrario, it suggests that only few drawings of Ashley don"t fit the absurd image, most do

Playing with all these variations of bowline when climbing, I completely agree that only one modification to the original DB or B is good but more than that is just not very practical.

I cam up with this one the other day, which has the same 3 dia as EBDB and EBDB+Y. However, it secures the tail in the same move when we are making the 3 dia thanks to the collar. I have a good feeling about the overall structure. Dan what you think of this? (it is not a lee lock, but a DB with a new secured tail or say an EBDB where the turn is more secured by the collar)

[Dan_Lehman]

I need to check out those knots. a contrario, it suggests that only few drawings of Ashley don"t fit the absurd image, most do

Not so fast : it suggests that there were
only a few drawings of the fig.8 and that
none that I found fits the absurd image.

Playing with all these variations of bowline when climbing, I completely agree that only one modification to the original DB or B is good but more than that is just not very practical.

I'm not sure what you're saying here,
but I'll agree that knot users in most applications
will prefer to have a lesser than greater set of knots
to know.  But there are differing demands and
circumstances, which might call upon different
knotty solutions, so we should explore ... .
AND we must hope to gain an understanding
of the knotting, so that we can *invent* what
we need, in uncommon cases.

I came up with this one the other day, which has the same 3 dia as EBDB and EBDB+Y. However, it secures the tail in the same move when we are making the 3 dia thanks to the collar. I have a good feeling about the overall structure. Dan what you think of this? (it is not a lee lock, but a DB with a new secured tail or say an EBDB where the turn is more secured by the collar)

The knot that you show omits the binding
of the extension (tail wrap) of the SPart,
so I think your knot is suspect in that regard.

Yes, I have oriented the tail of the EBDB to lie
sort of "within the collar", but I think I favored
it otherwise --maybe only as being easier tied?

--dl*
====

[knoeud]

Thanks Dan, preciate your insight.

I finally got a chance to do some limited tests on the knot I showed (which I refer as RDB in the table). I have summarized the results in the attached table.

Since my first concern is to replace the infamous fig8 with a variation of bowline, I compared the Fig8 vs RDB using two climbing cords of 4mm and 7 mm. The cords were Beal brand new, where 4mm has a breaking load of 400 daN (kg), and 7mm is at 1170 daN (kg). I used a pull mechanism with two identical ends, tying one knot at one end, and the other knot at the other end of the rope.

To my surprise in both ropes, the fig8 failed and not the RDB! the fig 8 fail was the classical one, where the standing part fails where it enters the knot. (repeated tests and changing the ends for these two knots gave same results. (My theory was that fig8 should win against any bowline variation, so I used all my new cords to retest and retest! at the end, I was like, oh man, a bowline variation may be stronger than fig8! (?) )

Next, I thought of comparing with EBSB+Y, which may in theory protect the tail better with the Y part. Tests performed using the 4mm rope, in each case the EBSB+Y failed and not the RDB. (as a side note, it is a very different situation when a bowline fails, since nothing of the knot is left behind, no structure. However, when a fig8 fails, half of its structure is still there!)

My resources are limited, so I will appreciate it if someone could test these results to a better extend and confirm or dismiss my observations.

Next, I would like to perform tests on RDB, EBDB, and Prohaska Bowline (Janus). I need to buy new rope!

[Dan_Lehman]

Since my first concern is to replace the infamous fig8 with a variation of bowline,

Please state your reasons --i.e., what is it
of the one knot that you sought improvements
for, and that the other might provide?  (There
are many differences, and not all of these might
be of issue.)

To my surprise in both ropes, the fig8 failed and not the RDB!
the fig 8 fail was the classical one,

Could you specify the precise form/dressing
by reference to an image --here's a clear one
with what I regard as (for a name) "the perfect
form" (in terms of dressing).  It is loaded via
the right end entering the knot, the left one
being tied off in a strangle knot to that.
(This might be the most common version, but
sometimes the strands of the eye legs take a
different path, with a subtle crossing.)

where the standing part fails where it enters the knot. (repeated tests and changing the ends for these two knots gave same results. (My theory was that fig8 should win against any bowline variation, so I used all my new cords to retest and retest! at the end, I was like, oh man, a bowline variation may be stronger than fig8! (?) )

Craig Connally asserted that he found his favored
Yosemite bowline stronger than a fig.8, and had some wierd
position that contrary test results weren't the right
way to compare  --huh?  In any case, when someone
gets the results they want, expect X. to offer the sage
circumspection to not bet the farm (or boat) on that!   
But I take your feelings.

Tom Moyer once had such a result, in a single test; he also
had some test in his high-mod-cordage examination in which
his fig.8 eyeknots broke --ALL 5-- at >90% of his tested
rope strength (nb: tested, not vendor-stated).
Now, there just isn't enough *room* >90% to make
a fuss over (unless you consider some angler's testing
of the Bimini twist in which --to his shock-- he got >100%
of his tested strength (and was honest enough to think
"this can't be right" and to re-test!)).

I will also recall that years ago, reporting to this forum,
a fellow was testing end-2-end knots by breaking line
with two such knots anchored by fig.8 eyeknots to some
tree & his truck : the eyeknots never broke!
--even vs. an end-2-end twin fig.8 knot which is essentially
the same thing (2 fig.8 eyeknots) !?

So, you had an intact broken fig.8 to examine?
(Any chance of photos?)
With knots testing, one might try marking the rope
pre-test (maybe after some loading, to set the knot)
in a couple places, and then see where those positions
lie in the broken knot.  (Having a photo at some state
of heavy loading, near-full stretch, to see positions
would be best, of course.)

Next, I thought of comparing with EBSB+Y, which may in theory protect the tail better with the Y part.

Why would one care about protecting the tail?
(--unless a woman walking certain parts of Europe.    )

Next, I would like to perform tests on RDB, EBDB, and Prohaska Bowline (Janus). I need to buy new rope!

Realize that your testing is suspect in having
no good measure of force, just A-vs-B results,
and w/o a LOT of that, you can be too easily
misled.  (Suffice it to say that if you have good
results vs. a knot that is reasonably known to
be pretty consistently strong --yes, the 8--,
you can at least conclude that a victor over
that will have done well.  But there remains
the prudence of seeing strength as largely
irrelevant to rockclimbing : history just doesn't
show knots breaking.)

I'd rather see a more different knot tried,
such as the mirrored bowline, in which
I see the "difference" being multiplicity
of loaded parts coming out of the main
nub --vs. just the eye legs for above.

Also realize that results of DYNAMIC LOADING
might differ from what we're seeing here;
and that is more relevant to tie-in knots.
HERE, I wonder if the mirrored bowline offers
significant advantage for a test of, e.g.,
repeated "FF1" (fall-factor 1 : drop = length
of line in system) drops.  That might be a test
you and some friends could do, expecting to
see knot conditions on a couple-few drops
before there is a final one.  (Pick straws to
see which "friend" is dropped.  No, drop
something inanimate!  --or drop Xarax,
but at LEAST 20-25 times : use a good knot
and rope (maybe a zeppelin loop).)
 
)


--dl*
====

[agent_smith]

But there remains the prudence of seeing strength as largely irrelevant to rockclimbing : history just doesn't
show knots breaking.)

I agree with this comment from Dan.

Strength is irrelevant.

Security and stability are of far greater concern.

Case in point:
An offset overhand bend (aka offset water bend) is perfectly adequate as an end-to-end joining knot in preparation for performing an abseil descent where you want to retrieve the rope(s) post descent. The load is 1 person. In a worst case scenario - the load can be 2 persons (rescuer + patient both descending on a shared belay device). The knot will not fail - it never fails (unless human error causes it to 'fail'). And in my opinion, the so-called 'EDK' is actually the offset figure 8 bend. This is the unstable/insecure form that has caused fatalities (again - this is my theory - witness accounts are sketchy because the surviving party members are typically inexperienced and suffering from shock - and can only try to recollect what they think they witnessed).

I just dont understand why there is so much attention given to knot strength?

The ability of a knot to resist cyclic loading (aka 'slack shaking' as some term it) is paramount. Also, off-nominal loading profiles - ie the knot is loaded in a way that wasn't intended - is also something that the knot must must withstand.

Of course, my context herein is mountaineering / rock climbing / abseiling activities where human life is literally on-the-line. That is, knot failure would lead to death - so you have to choose knots that wont fail. And strength is irrelevant.

...

I'm getting ready to update my Bowline paper soon and will be calling for assistance from people such as Dan and Xarax and other notable IGKT members...

Mark

[xarax]

   Hi Mark. It has been a long time since your last appearance in the Forum. We are glad you are back ! 

   For what concerns me, I believe I should try to repeat a few things, and I will try to do this as concisely as I can.
 
   1.
   A "secure" bowline may include a double nipping structure ( = two nipping turns on the path off the Standing Part before/ante the eye ), or not - but, IMHO, it should also include a double collar structure ( = two collars, two 180-degrees U turns on the path of the Standing Part after/post the eye ). Most knot tyers - Ashley included - believe that, in order to secure the common, Standard bowline from the danger of any accidental slippage of the Tail End, the most simple and efficient way is to grip this End in more than one points along its path, by more than one nipping turns. The most well-known applications of this idea are the "Double bowline" ( two turns - based ) and the "Water bowline" ( Clove hitch-based ). Perhaps these knot tyers suppose that a double nipping loop becomes, somehow, tighter than a single one, so it grips the penetrating Tail End harder, so the friction forces becomes greater, and the Tail can not slip through the nub any more. I happen to disagree. The main function of a more complex nipping structure is to improve its stability, not its gripping power - because the greatest danger in a common bowline is that, under heavy loading, the nipping loop can "open up", and degenerate into an open helix. A well-balanced, more tightly closed around itself nipping structure, will not suffer from this danger. THAT is the main reason which may justify the use of a double nipping structure ( like a Clove hitch, a Girth hitch, a Pretzel hitch (= reversed Girth-hitch) or a Constrictor ). The hypothetical enhancement of the gripping power of those complex nipping loops on the Tail End has not been proved by any detailed experiment, as far as I know.
   Even if one has not made up his mind on this matter, I believe he should always classify the secure bowlines according to this fundamental distinction : The first class will include all the bowlines with a simple, single collar, and the second class will include all the bowlines with a more complex collar ( like a double or a braided one ). My opinion is that you should better re-organize the order of the presentation of the bowlines in "Analysis" according to this criterion.

   2.
   If we do decide that, in order to avoid any slippage of the Tail End, we also need a more complex collar structure, the simplest and easiest way to do this is to make the Standing Part follow a second U-turn, this time "upwards", by making it turn around an eye leg, and/or around the "lower" part of the rim of the nipping loop. The most well-known applications of this idea are  the many possible "Janus" bowlines, Standard or "Eskimo"-like ones.
   Now, we have seen that, when the Standing Part has made a second, "lower" U- turn, and it is oriented "upwards", towards the Standing End, it is a most easy and straightforward thing to re-tuck it through the first, "upper" collar - and that, when this happens, we may end up with a TIB bowline (1). Many such cases have been demonstrated, and the method those TIB bowlines can be tied in-the-bight has been described ( the "haltering" collar method ).
   What I came to believe this last year, is that, if we have already decided to use a second collar, =  if we have already made the Standing Part be re-oriented towards the Standing End, then to make it pass through the first, "upper" collar, too, is only a very small price we should pay, in order to acquire a TIB bowline. To me, it seems not-so-clever to lose the great versatility a TIB eyeknot can offer, for just an easy tuck less. Moreover, it turns out that many of those TIB bowlines can be tied by this "haltering" collar method in-the-bight even easier and quicker than in-the-end ! If the satuation allows it, (  and it allows it many times, when I do not have a closed ring, but a pole or a bollard, around the accessible end of which I can pass my eyeknot...), I always tie such a TIB bowline in-the-bight.
   Even if one anticipates he will never want or need to tie his eyeknot in-the-bight, I believe that he can not deny the fact that a TIB eyeknot is a more versatile knot than a non-TIB one - so I believe that you should better include more TIB bowlines in your collection. In particular, I believe that you should include the TIB variation of the Scot s locked bowline, the TIB variations of the "Janus" bowlines, like the Alpineer s bowline, and the very simple TIB variations of the Clove- and Girth-hitch based bowlines. (2)(3)(4)(5)

   3.
   Although we can only speculate about its value regarding security or strength, when the nipping loop of a bowline encircles three ( or more ) rope diameters it becomes noticeably rounder and wider - and I do not believe there is any reason a segment of the rope inside the nub that passes near the nipping loop, should not pass through it as well. On the contrary, I believe that such a wider nipping loop, at the very core of the eyeknot, distributes the tensile forces along a more extended area, and I presume that this can not be but beneficial to the overall security and strength of the knot.
   So, I believe that this should be a third characteristic according which you should re-organize the order of the bowlines you present in "Analysis".

   4.   
   Recently, I had tied and tried a new secure bowline, which obeys all the three criteria I have pointed out above : It is a double/two-collar one, a TIB one ( which can also be tied in-the-bight very easily and quickly ), and a wide-nipping turn-based one. I call it Ampersand bowline, from the shape of its collar structure (6). I have also found ( not immediately !  ) that the Ampersand bowline and the Scot s TIB bowline are re-arranged "reversed" eyeknots ( where, by "reversion," we mean swapping the Standing and the Tail Ends ). It had happened to me to tie and try dozens of "new" bowlines, simply by systematically exploiting all the available options, and then submitting the outcomes to all the tortures I could imagine...( although my work can not be compared to that of Alan Lee, who has proven to be such a prolific, indeed, knot tyer...). So, I believe I am not mistaken when I claim that the Ampersand bowline is a notable member of the family of the secure bowlines, and that it deserves a place in the "Analysis".
 
1.   http://igkt.net/sm/index.php?topic=4695.0
2.   http://igkt.net/sm/index.php?topic=4517.msg30269#msg30269
3.   http://igkt.net/sm/index.php?topic=4697.msg30344#msg30344
4.   http://igkt.net/sm/index.php?topic=4695.msg32103#msg32103
5.   http://igkt.net/sm/index.php?topic=4695.msg31708#msg31708
6.   http://igkt.net/sm/index.php?topic=4877.0

[enhaut]

This "Analysis" (in progress) is a formidable study, many thanks to Mark Gommers and his contributors. The service gived to the community is immense.
 IMHO,the only thing lacking in the document, is"exploded views" of the bowlines. Alan Lee in this forum present sometimes his creations is this manner, it's a great time saving learning tool.
 For many reasons the Xarax's ampersand bowline deserves to figure in the "Analysis". His overall security seems solid and one of them is the astute way to tie it the the bight.
 Let me tell you Xarax that I had to work hard to figure it out! I think I have found a way of presenting the tumbling over (the verb) part.
 I think some TIB bowlines must be presented in this study but IMHO the paramount quality of a useful bowline is the fact that it's Post Eye Tiable.

[knoeud]

... a test of, e.g.,
repeated "FF1" (fall-factor 1 : drop = length
of line in system) drops.  That might be a test
you and some friends could do, expecting to
see knot conditions on a couple-few drops
before there is a final one.  (Pick straws to
see which "friend" is dropped.  No, drop
something inanimate!  --or drop Xarax,
but at LEAST 20-25 times : use a good knot
and rope (maybe a zeppelin loop).)
 

back from an intensive 3 days of climbing and may I say hard fallings! I decided to perform your test Dan, and prepared a fall factor 1 situation (I had a back-up rope and a back-up harness in case anything go wrong. Don't try this unless you know what you are doing!).  The only small detail was then to do the 20 FF1  falls.  I couldn't find Xarax nearby, so I dropped me! scary  .  It was very fun in the beginning and natural, but after the 15th fall, you just don't want to deliberately let go and take a FF1 faaaall !! But we did it anyways

I used a new 5m long, 10 mm dynamic climbing rope, which I tyed to an anchor point with a Janus bowline and tyed back to my first harness with a RDB (the close variation of EBDB that I am testing these days).

After 20 FF1 falls (see the photos), I could clearly observe that
* The knots kept their initial from (no dramatic change of form as it may happen with fig8).
* It was easy to untie them with tired climber' hands (after 20 climbs and falls)
* One other interesting observation was that the tail ending did not move on the RDB knot (not observable by eyes anyways). You can see this in the 3rd figure, where the U turn was left kind of loose and stayed like that after 20 falls. This point I will re-test with the pull system to the breaking point and take measures.
* the fact that in RDB the tail end was back inside the loop made a more compact knot (compared to the Janus) and enhanced the lead climbing experience (a matter of personal opinion I think).

I am done falling for now (pewh!), and going back to the pull system tests.

Appreciate any comments.

PS. from the last test results:

So, you had an intact broken fig.8 to examine?
(Any chance of photos?)

yes, I have to organize the photos and post a summary here very soon.

With knots testing, one might try marking the rope
pre-test (maybe after some loading, to set the knot)
in a couple places, and then see where those positions
lie in the broken knot.  (Having a photo at some state
of heavy loading, near-full stretch, to see positions
would be best, of course.)

I am organizing new experiments with 10mm climbing rope to perform a closer test. I will consider these points.

[zoranz]

So, I believe I am not mistaken when I claim that the Ampersand bowline is a notable member of the family of the secure bowlines, and that it deserves a place in the "Analysis".

This is new lock, very interesting. For us non-experts in the world of knots it would be desirable that X presents end-loop in a loose form.
 


For now I can not switch to TIB variant. (Every journey begins with the first step.)

Best regards,
ZZ