# Two by Four knot (or what knot is this)

**URL:** <https://discourse.igkt.net/t/two-by-four-knot-or-what-knot-is-this/4623>\
**Category:** Knotting Concepts & Explorations\
**Created:** [4 December 2012 17:18 UTC](https://discourse.igkt.net/t/two-by-four-knot-or-what-knot-is-this/4623 "2012-12-04T17:18:28Z")\
**Posts on this page:** 1\
**Showing post:** 98

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**Author:** ![Dan\_Lehman](https://discourse.igkt.net/letter_avatar_proxy/v4/letter/d/7ba0ec/32.png) [@Dan\_Lehman](https://discourse.igkt.net/u/Dan_Lehman)\
**Post date:** [14 January 2013 20:17 UTC](https://discourse.igkt.net/t/two-by-four-knot-or-what-knot-is-this/4623/98 "2013-01-14T20:17:33Z")

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> [@X1 post:95](#):
>
> > [@Dan\_Lehman post:94](#):
> >
> > I’m talking about the eye-within-eye structure, where the eye legs flow to a hard turn of this connection, and so an imbalance of tension could arise --way too much friction AND resistance to bending impediment to provide for equalization.
> 
> If you are/were talking about the friction around the point/area the two eyes meet/embrace each other - those hard turns, those two linked opposed U-turned segments- you are/were not telling anything else/more than what has been said already many times now - and which points to a possible severe reduction of the naively supposed “sum-devided-by-two” of the average strengths of each link / eyeknot, considered sepatetely.

More hyperbole. While the old test results I cited suggest  
that the point of interlinking eyes was the break point  
–at least, there were differences between differently  
joined (mere reeving vs. square-knot-like joint) eyes–,  
we’re not seeing that point as a break point here.

And what I’m saying above is in response to something  
I thought you’d insisted re “bight” legs in always being  
of equal load : no, if an imbalance is introduced by how  
the knot compresses and feeds material into each leg,  
the friction at the joint of eyes will inhibit equalization  
of forces on the legs.

On the other hand, we’re still talking about roughly half  
of the force that is borne by the SParts, so the eyes should  
not be critical points. (But it sure would be nice to under-  
stand how that old test data came to be different --maybe  
it just was of few cases and not so much difference to be  
explained as normal variance? Rope was relatively thick.)

> The results of the average strengths of each "summed" eyeknot will be lowered quite a bid, when this weak link/point/area will be taken into account in theory, or when it will be included into the compound bend in practice. This was one of my arguments against the validity of the general statement of J.P., right from the start ! I even predicted an as high as 50% reduction of the system of two linked eyes, in relation to a system of two unknotted lines - just because of those sharp U turns at this point/area, that are completely "naked", unprotected by any deflexion (in their vicinity) that could possibly absorb/dissipate the loading .

And here I completely reject this opinion : again, the tension  
in the eye legs is half (roughly) of that in the SParts  
–it should not be a weak point unless the knot is strong.  
J.P., I think, is not finding it so in his material & knots.

> So, my gut feeling told me to bet at a 50%,

That's a good feeling, but, again, it's 50% OF 50% ! --i.e., the force delivered here is half that to the SParts.

> [quote="Dan\_Lehman post:94, topic:4623"] The essence is the proposition that, given the seen-here test results for several eye knots and some end-2-end knots, eye knots [b]are sufficiently stronger[/b] that [u]it would be stronger to join lines with a pair of them than a single end-2-ender[/u]. [/quote] That proposition is wrong because of many reasons, so it is of no use whatsoever to [u]conceal[/u] it as if it is "deduced" from / forced by the experimental data -- because [i]unperformed experiments have no results[/i]. The "given" ( performed) experimental data were only for the one-member links ( the [end-2-end] knots /bends and the eyeknots/loops ), not for the two-member links ( the linked eyeknots).
> 
> The phrase “given the…” - " it would be…" connects performed to un-performed experiments   
> –and I had already lost many of the few remaining segments of my life line arguing that this is WRONG !

Yes, there are unperformed experiments; but there had been  
unanalyzed-fully results of the data at hand --which I have now  
laid bare with statistical analysis. (And I should say that the  
volume of experiments etc. certainly is limited; but we do have  
at least some analysis to make from what has been done,  
beyond merely looking at the averages.) The implications  
of the particular values of mean and standard deviation  
support the proposition, at this stage of data --nothing more,  
but nothing less, either.

> [quote="Dan\_Lehman post:94, topic:4623"] I have remarked that this also can be done with the [i]"twin"[/i] eye knots end-2-end joining, as well as with the direct interlocked eyes : that the loading profile is the same [/quote] Yes, indeed, the loading profile is the same... BUT THE KNOT IS NOT ! In comparison to "twin" "eyeknots" ... , [u]ex-eyeknots where each of the two legs of each former eye has now been [b]"cut and pasted"[/b], in order to be connected to its twin )[/u], the genune linked eyeknots have ONE MORE WEAK LINK --and this link is very weak, indeed : [u]the point/area the eyes are linked together I was talking about above[/u].

Whoa, you’re well off the track, here. Please confer [ABOK](https://discourse.igkt.net/t/9845) #1454  
–which seems to be the sole instantiation of the “twin” concept–  
for what is meant; there is no “cut and pasted” part (whatever  
that could mean), and in fact the inter-reeved-eyes point is gone  
–just pure _knots_ loaded the same as “eyeknots” are (we should  
think).

> ..., sorry, I am knot going to calculate the reduction of strength we should expect due to the "weakest-link" situation in the case of three links !

No one's sorry about skipping this gratuitous exercise, although it could be edifying for one who has so far so eschewed applying statistical methods to the data --except that, here, so far, the data for the inter-eye points has been a clean 100% non-failing.
# –dl\*

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