Two by Four knot (or what knot is this)

[roo]

Average load at failure:

If you have the data still, would you be willing to post the minimum loads at failure?

[X1]

   Great !  Congratulations, J.P.

   Let me make some suggestions.
   1. It would me much better if you use solid braid rope - otherwise the "helicity" of the laid rope can interfere with that of the knot, and the result could become unreliable. Also, if you could use thicker ropes, with more stands, which generate more consistent results. Take a big breath, and go to the 1/4 inch ! 
   2. It would be useful to publish some more characteristics of the rope, as diameter and weight per unit of length.
   3. You should calculate and publish the standard deviation of your results.
   4. It would be very useful if you classify the exact point of rupture at each knot, and publish the relevant statistical results for this parameter, too.
   5. It would also be very useful if you refer to the specific temporal pattern of loading. How slowly or quickly was it applied on the standing end ? How much time elapsed between the start of the loading and the moment of rupture ?
   6. The Water bend can be dressed in a number ways. You should specify the exact way you used. ( I have conjectured that the way shown at the first attached picture would lead to stronger knots). I suppose you dressed the fig.8 bend in the most "common" way, shown at the second attached picture, because it can also be dressed it in a number of different forms.

   Thank you J.P. This is the only article I have seen in this Forum that has NUMBERS on it ! Thank you too, KnotGod. Please, help me, too, write such articles, when I will grow up !

[kd8eeh]

How did you measure the weight it could hold to hundredths of a kg?  What type of device did you use to get the numbers?

Also, could you get data for a triple fisherman's knot?  That is the only bend I have ever seen used by climbers, and I'd like to see if it is really so strong as they say...

[James Petersen]

Average load at failure:

If you have the data still, would you be willing to post the minimum loads at failure?

twine                   ALAF...34.98 kg  MLAF: 33.00    SD: 1.52
zeppelin bend            ALAF...26.98 kg  MLAF: 24.00    SD: 1.86   SOK: 77.13 %
2x2-round-turns bend    ALAF...25.12 kg  MLAF: 23.10    SD: 1.44   SOK: 71.80 %
figure 8 bend           ALAF...31.10 kg  MLAF: 28.00    SD: 1.78   SOK: 88.91 %
water/tape bend         ALAF...24.25 kg  MLAF: 18.90    SD: 2.38   SOK: 69.33 %

Key to abbreviations:

ALAF    Average Load At Failure
SOK     Strength Of Knot
MLAF    Minimum Load At Failure
SD      Standard Deviation

How did you measure the weight it could hold to hundredths of a kg?  What type of device did you use to get the numbers?

The scale I used measures weight to 1/10 kg. After testing, I entered the numbers in a spreadsheet, which calculated to  two decimal places. Rather than round or those numbers, I simply left them alone. I apologize for any confusion this may have caused.

[kd8eeh]

Still, did you just weigh a bunch of objects and attach them to the twine?  Do you have a spring scale attached to the rope?  Also, how did you get the twine to attach to the weight?

In short, what exactly would i do to mimic your test?

[James Petersen]

        While experimenting with ways of tying a bowline I somehow ended up with a loop tied with a whatknot -- ABOK 1406. This simply seems to be a round turn around a round turn. I doubled the knot and dubbed it the two by four (2x4) -- two round turns around two round turns.

How very embarrassing. First I say (accurately, BTW) that it consists of a round turn around a round turn. Then in the next breath, I say it is (it isn't!) "two round turns around two round turns." Either nobody noticed it -- not highly likely --, or you were all to polite to mention it. Thanks. I think I'll just start calling it the "lazy dog loop/bend," since it just goes round and round.

Today I began some testing on the loop forms of the knot, both two round turns around a single turn, and two round turns.. Still using Z-laid nylon with 30 filaments for the sake of continuity.  X1 suggested that I test the bend form of the knot as well as at the same time testing several other knots for comparison, including the water knot/bend, the figure 8 bend, and the Zeppelin bend, since these are "the golden standards of bends", which I have done. Thanks for the guidance, X1.  Now my question. What are the golden standards for end of line fixed single-loop knots? I have started testing along with the overhand loop(ABOK 1009), the bowline (ABOK 1010), the round-turn bowline (ABOK 1013), the figure-8 loop (ABOK 1047). What other knots would make good comparisons. Once again, any guidance will be much appreciated.

Thanks all,, and Happy Christmas!

[X1]

I say it is (it isn't!) "two round turns around two round turns.[/i

   There was a lengthy thread in this Forum, about what is "a round turn". To me, a round turn is a 360 degrees turn of the one leg of the loop relatively to the other. When we have one and a half round turn ( 540 degrees ) we sometimes call it - inadvertently - "two round turns". If you want to be precise, mention the number of degrees, not the number of "round turns".

What are the golden standards for end of line fixed single-loop knots? 

  The "king of knots", of course, the bowline. The retraced fig.8 loop comes second, because, although it has some shortcomings, it is still used by the majority of climbers, and its security and strength have been tested and are reported to be superb. If I would have to choose a third one, well known to most knot-tyers, I would have picked the Anglers/Perfection/Tugboat loop(s) (?). I do not believe that the overhand loop (ABoK#1009) you mention is used very often by knot-tyers, because it may be difficult to untie, but, as the most simple loop of all ( a double line overhand knot ), it, too, can serve as a standrd.

[James Petersen]

I say it is (it isn't!) "two round turns around two round turns.[/i

   There was a lengthy thread in this Forum, about what is "a round turn". To me, a round turn is a 360 degrees turn of the one leg of the loop relatively to the other. When we have one and a half round turn ( 540 degrees ) we sometimes call it - inadvertently - "two round turns". If you want to be precise, mention the number of degrees, not the number of "round turns".

Actually, the reason I went back and looked at my original post was that while perusing ABOK I happend onto page 13, knots 40, 41, and 42. Ashley seemed pretty clear on "loop, round turn, and two round turns." But I guess those who used that particular vocabulary/semantics have for the most part died, and the language continues to evolve.  But for pure brevity in speech, Ashley still wins. "360 degrees" (seven syllables) -vs- "a loop"(2), or "720 degrees" (8 syllables) -vs- "a round turn (three). Perhaps if we wanted to use smaller numbers, I guess we could use radians.

[X1]

http://igkt.net/sm/index.php?topic=710.msg4811#msg4811

Cast your vote here...

[Bob Thrun]

        Has anyone seen this knot described or tied anywhere?

I made a 3x3 version when I wanted to make a bend based on the Monkey's Fist. It jammed up solid. I removed turns and rearranged coils and eventually re-invented the Rosendahl Bend 9 years before the publication in Boating. There are a lot of variations of where the ends go into the coils. Do the coils of one rope go toward  the standing  part of the other rope or away from it? One of the 1x1 variations is a Granny Knot. Graumont and Hensel, in The Encyclopedia of Knots and Fancy Rope Work, page 24, call a 2x2 variation the Jam Bend and say it "is of no proctical value."

[James Petersen]

...There are a lot of variations of where the ends go into the coils. Do the coils of one rope go toward  the standing  part of the other rope or away from it?

In the version of the bend I have been testing the coils have been made with the lay. The way that if you tighten the lay  a loop will form. I guess that would mean that the coils move away from the standing end of the rope. (In this configuration it can be dressed to look very much like a two-strand Matthew Walker and exactly like X1's strangle bend). In the nylon twine I have been testing it on, it runs every time if any of the coils are made against the lay. This might not be an issue in natural cordage. I am currently doing some testing on the loop form(s) of the knot, in the same Z-laid nylon twine.

One of the 1x1 variations is a Granny Knot...

Sure enough. I had noticed the whatknot form but hadn't pursued it any further. The granny knot turns out to be the version with the coil moving away from the standing end of the opposite rope and the whatknot (ABOK 1407) is the variation where both coils move toward the standing end of the opposite rope..

The Encyclopedia of Knots and Fancy Rope Work, page 24, call a 2x2 variation the Jam Bend and say it "is of no proctical value."

Finally, a reference to it. A seized version, no less. Thank you. I can see where if this were tied in natural fiber rope and loaded, it would be impossible to untie, especially after becoming wet. I can't imagine such a knot actually being used in the days when sailing ships ruled the seas. But times change. Someone in a fairly recent post asked for a loop knot that is very hard to untie.

[X1]

   This bend is evidently much "simpler" than the Zeppelin bend - iff by simplicity we mean things that are related to its topology, or its structural mechanism, or the conceptual image we have to memorize/remember in order to tie it. However, if we measure the simplicity of a knot according to how much convoluted is the path the working end(s) follow in space going around and into its nub (1), we will see that, in fact, the difference between this bend and the Zeppelin bend is very small. Having said that, I proceed to my next point : 
   Although I have to admit that I am seduced by the maximal simplicity of the Symmetric Sheet bend, I do not believe that knot tying is some "competition", with "winners" and "losers" - and that we should not explore a knot which is less simple, less strong, less secure, less easy to tie and untie , or "less" whatever, than another... The same happens with any artefacts, so we are watching movies and reading novels that may be "less" something than the ones we have already seen or read - to say nothing about the most beautiful artefacts of this world, women... Knot tyers are exploring all the interesting knots that might exist, within some very broad limits, which are put so to keep their total number reasonable - not infinite or huge, but not ONE either !  We are collectors : even if a collector can not collect all the butterflies of the world, he would not manage to continue to live a creative, fruitful and interesting life if he reduce his collection too much. Of course, knot users, in general, and knot consumers, in particular, will always wait in the line to acquire the "#1", the "best","simplest", "strongest", "safest", "most easy to tie and untie", etc. knot - i.e., the cheapest one ! I suspect that our tendency to dismiss some knots is a consequence of the fact that our human brain is not evolved to remember convoluted paths of 1D curves in 3D space. Then, we COVER this limitation of ours by various excuses, the easiest and "a la mode" one being " practicality". When I listen that a knot "is of no practical interest" , I immediately, automatically, become very suspicious... and I also become interest in this knot right away !  One can simply say " I do not like this knot, because...", "... so I am not interested in this knot". That is OK, and it is the natural thing to do. No collector would be satisfied if his collection would be exactly the same as that of another s - if all the items of his collections had been already collected, so his collection itself is not but a copy!
   There are more than 200 bends already known, and I reckon that the total niumber of interesting bends would be somewher in between, say, 500  and 1000 ( I have recently became aware of the large number of the asymmetric bends, so I inflate the number a little bid to remain in the safe side...). So what ? We have watched many more than 500 or 1000 movies, but we are still watching new ones... An average chess player knows many more variations of openings, and when I was a kid I had a much larger collection of ( printed cards with ) cars than that ! 

   1. A measure of the simplicity or complexity of a knot
    http://igkt.net/sm/index.php?topic=3740.msg21722#msg21722

[Dan_Lehman]

J.P., can you answer X1's question above about the
particular orientation/form of the fig.8 & overhand knots?

Looking at X1's photos, there, the overhand is in a form
unlikely to obtain, though proposed by Heinz Prohaska
for joining tape ends so that each tail would finish
lying *interior* --to preclude being snagged loose,
and also should avoid slippage in low-force cyclical loading.
The fig.8 knot is in what I have called "the perfect form",
and if one loaded the what rope from the left and orange
from the right, ... "the strong form" --"weak" is vice versa.
(In my "strong form", the loaded strands bear into their
traced twins; in the "weak form" they pull away, *interior*
to them, and bear into other parts.  My terms arose from
one tester's assertion of about an 8 %-point difference
in strength between the loadings --which is something
I now regard as yet to be verified, and esp. across different
materials, and so on.  But it spawned those monikers.)

But for pure brevity in speech, Ashley still wins. "360 degrees" (seven syllables) -vs- "a loop"(2)

But that brevity is (a) in sounded reading and (b) at the cost
of clarity.  It's better to avoid ambiguity (and I think we can
find that Ashley is inconsistent, here (just as "bight" can mean
"without ends, somewhere along the rope" or otherwise
"a folded ('doubled'/'halved') ('loop') part of rope").

I do not believe that knot tying is some "competition", with "winners" and "losers"
--and that we should not explore a knot which is less simple, less strong, less secure,
less easy to tie and untie , or "less" whatever, than another...

Haven't you noticed Knot4U's .sig?  --"Winners / Losers" write large,
for the lorry lashings!   

But in regarding the history of knots in the wild, one can
put their evolution, their appearance & use, in such terms of
competition, as a perspective to view in trying to understand
how certain things came to be.  Not to say that it's decisive,
inevitably determinant, but it might have influence ... .

the Jam Bend and say it "is of no practical value."

Finally, a reference to it.  A seized version, no less. Thank you.
I can see where if this were tied in natural fiber rope and loaded, it would be impossible to untie,
especially after becoming wet.
I can't imagine such a knot actually being used in the days when sailing ships ruled the seas.

Beware of Hansel & Gretel and their world of make-believe!
I really believe that they just tossed into their big batch of
"knots" things they dreamed up, for who-knows-why!
Their frequent use of "of no practical value" begs the question
"Then, WHY do you present it?!" --to which I know of no good
answer given by them, hence my belief above.  (To have a seized
end-2-end knot be "of no practical value" really begs the question!)


--dl*
====

[X1]

the overhand is in a form unlikely to obtain

  It needs a careful, perhaps difficult dressing, yes - but it is not "unlikely" to obtain ! It is not as easily obtained as the "common" form. The crossing of the standing parts at the belly of the knot is meant to help the first curves remain wider than they would have been without it. It has its price in the easiness of tying the knot, sure, but what counts is if it has any significant effect on the ultimum strength, or not. Has it ?

Haven't you noticed Knot4U's .sig?  --"Winners / Losers" write large, for the lorry lashings!   

   I thought it was quite evident where I was referring to. Although my intentions were misunderstood repeatedly, I do not believe that "success" dictated by natural or social evolution has anything to do with value. In particular, the "survival" of some knots "in the wild" does not mean that they are the "best" possible, and the absence of some others ( for example, most members of the interlocked overhand family of knots, as you had mentioned - such as the Zeppelin knot ) does not mean that there is anything "wrong" in them.

   

[X1]

   The fig.8 knot ... if one loaded the white rope from the left and orange from the right, ..."the strong form" --"weak" is vice versa.
...one tester's assertion of about an 8 %-point difference in strength between the loadings --which is something
I now regard as yet to be verified

  Although one can understand a slight difference - in the "weak" form the second collar of each link is neither very tight nor is it utilized very much - I wouldn't even imagine an 8%! So, I am afraid that I have to see it to believe it ... On the other hand, that means that all knots, and all their variations, however similar to each other, should be tied, examined and tested. The knot tyers paradise !