Author Topic: Double Bowline ( ABoK#1013) : the "Right" or the "Left hand" form ?  (Read 7198 times)

X1

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   Ashley in ABoK and Mark Gommers in (1), show the "right hand" form. However, in the "left hand" form, I think that the tail is nipped by the standing-part s and by the eye-leg s  first curves in a more direct and effective way. Therefore, I believe that the "left hand" form is more secure - and this argument has nothing to do with the argument about the relative resistance of the two forms to ring loading ( as it happens in the case of the two forms of the common, single nipping loop bowline - this is not an issue in the Double Bowline s case ). There is also another factor that we should take into consideration : In this "right hand" form, the tail is located at the "soft point" of both nipping loops, near their crossing points, where it can not be squeezed by their rims, but only by their crossing legs. We always wish to utilize the tensile forces coming from the standing end and the eye legs in the most effective way, in order to obstruct and prevent the slippage of the tail ( the part of the working end after the collar), rather than the slippage of the continuation of the returning eye leg...
   Of course, in the absence of any proper laboratory measurements, ( for the time being, the only experimental instruments I have been able to use were my fingers  :)), all those "theoretical" arguments do not matter much. ( See also a similar case, at (2)). We want/need experiments, otherwise we can not proceed any further !

1. http://www.paci.com.au/downloads_public/knots/Bowlines_Analysis.pdf
2. http://igkt.net/sm/index.php?topic=3994.msg23760#msg23760

Dan_Lehman

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Re: Double Bowline ( ABoK#1013) : the "Right" or the "Left hand" form ?
« Reply #1 on: April 04, 2013, 06:02:21 PM »
As you note, you're just howling into the wind devoid of any
factual indications of relative security --and one might surmise
that the "relative" aspect is the only place that one might see
a difference : as in being "more dead" from being hit by a truck
vs. a car.   ;)

Further, you seem fixated on the securing of the tail --i.e., its
last-segment-in-the-nub-- : but one might prefer security to come
earlier, on the tail-side eyeleg's passage into the nub ; more grip
here should result in less of that leg's delivered tension to the
collar (and therefore less pressure upon the SPart, depending
on how on sets the knot --lightly or SSnugly!

(Recall that in the Brion [sic --it's an "o"] Toss video of Spectra
12-strand 5/16" line pulling out of the dbl. bowline it was the
SPart-side flowing through the double turNip and not the (stoppered)
tail that proved its undoing --a difference of nip of the tail, one
must guess, would be academic to this problem!)


--dl*
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X1

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Re: Double Bowline ( ABoK#1013) : the "Right" or the "Left hand" form ?
« Reply #2 on: April 04, 2013, 06:39:15 PM »
   As you note, you're just howling into the wind devoid of any factual indications of relative security

   However, I have to note that exactly the same happens to you !  :)

   one might prefer security to come earlier, on the tail-side eyeleg's passage into the nub ;

   I guess I should not repeat my argument about the "last line of defence" here, again. I prefer the greatest portion of security ( if we can envision such a thing... ) come at the last part of the working end ( the tail ) rather than at the first .

... more grip here should result in less of that leg's delivered tension to the collar 

   That is another thing that requires experimental evidence... I do not worry about the collar ! :) I believe that the collar is the most important element of the bowline - after the nipping loop - just because it is such a miraculously efficient mechanism of absorbing the tension delivered by the eye leg. It seems to me that nothing can serve as a reliable substitute to the collar - so I am not sure that we should "waste" any gripping action of the nipping loop on segments of the eyeleg before its U turn around the standing end ( or around the eye leg of the standing part, in the case of the "Eskimo" (-)bowlines ). However, I did try knots where the collar is relieved by an intermediate half hitch / "secondary" nipping loop around the rim of the "main" nipping loop ("Link bowlines "). I can only hope that the issue would be resolved some day - and that I would be ALIVE till then... :)
« Last Edit: April 04, 2013, 06:40:33 PM by X1 »