Author Topic: Shape 8 Double bowline  (Read 1983 times)

X1

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Shape 8 Double bowline
« on: March 10, 2013, 06:30:07 PM »
   A simple shape 8 overhand knot (a double collar structure), interweaved within two nipping loops (a double nipping structure), generate the double bowline knot shown in the attached pictures.
   What I have found interesting - because I think that it may be beneficial to the overall security of this knot - is the "complementary" character of the two structures, in the following sense : When we pull only the two ends of the nipping structure, the knot, as a whole, tends to "fold" in one direction, while, when we pull only the two ends of the collar structure, the knot tends to "fold" in the opposite direction. So the collar structure, as a whole, prevents the nipping structure from being deformed in a way that would enable the two nipping loops to "open up", and release their grip on the segments of the two collars they encircle. I would like to watch how this knot would behave under extreme loading - if the nipping loops would be able to "open up", overcoming the resistance of the interweaved collars, before the final rupture of the rope... Where are you, J.P ?  :)

P.S. I would like to mention that if we use, as a double collar structure, a fig.8 knot ( instead of a shape 8 overhand knot that we have used here ) the result is not so satisfactory. Why ? Because a fig.8 knot collar structure is perfectly symmetric, and the segment of the rope between the two nipping loops, having to pass from the one or the other side of this structure, destroys this symmetry. In the case of the shape 8 overhand knot, which is not so symmetric, the two interweaved  structures complement each other in a more "consonant" way.

Dan_Lehman

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Re: Shape 8 Double bowline
« Reply #1 on: March 11, 2013, 07:26:58 AM »
   A simple shape 8 overhand knot (a double collar structure),
interweaved within two nipping loops (a double nipping structure),
generate the double bowline knot shown in the attached pictures.
Clearly a case of pseudocide :
"I have defined what I think a bowline is, and I follow my definition".
Really, I've looked at this intriguing structure and cannot
find your "proper collar" in any quarter!?

 ;)

X1

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Re: Shape 8 Double bowline
« Reply #2 on: March 11, 2013, 01:20:56 PM »
Really, I've looked at this intriguing structure and cannot find your "proper collar" in any quarter!? ;)

Because you have not read or understood the P.S. !  :)
This particular knot, was derived from an attempt to complete your "bowline" (1)( to turn it into a double "bowline" ( double nipping loop / double collar ), was named according to your definition - where the kind of the collar plays no role. -, not mine ! I started from tying a second nipping loop within/around the fig.8 knot collar structure, as you did, and then I have changed it to the shaped 8 overhand knot collar structure, because the fig.8 knot was too symmetric to be in a "consonant" relation to the umbilical cord between the two nipping loops... I retained the term " bowline" to denote where this knot comes from ( history/tradition...), not the essence !

1. http://igkt.net/sm/index.php?topic=19.msg26677#msg26677
« Last Edit: March 11, 2013, 02:44:13 PM by X1 »