Author Topic: No-twist Portuguese bowline variant  (Read 582 times)

PolymathArtisan

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No-twist Portuguese bowline variant
« on: October 09, 2019, 01:27:53 PM »
Following my recent questions about making emergency harnesses with knots, I was interested in learning more double (and more generally, multiple) loop knots, mostly to design better ways of making such harnesses.

 I was playing around with the no-twist Portuguese bowline, which I think has some advantages for such an application (the two loops are 'side by side', not 'on top of' each other) but I didn't like how easy it is for the line to slip through the core/nub of the knot and the loops to become different sizes.

So, I added a turn in the line where it normally crosses over the top of the nipping turn . Instead, it follows the nipping turn round and then goes into the second loop (in this case on the right). This goes a long way towards securing the loop's sizes independently.



This principle could be extended to just tying a midloop in the line where it crosses the nub and tying the final bowline through that as well.

Has anyone else used or seen this variant?  Does it have a name? If not, what do people think of it?

Blue skies, Poly

Dan_Lehman

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Re: No-twist Portuguese bowline variant
« Reply #1 on: October 10, 2019, 09:22:14 PM »
Here's yet another case of presenting a bowline
from the *wrong* side --flip it over, please!

GOOD SHOW!
IMO, this is a novel bowline, and rather clever,
with double (not twin) eyes surely independent,
although I might've tied something *similar* to
what you present and ... you get credit for
inspiration!

 ;)

roo

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Re: No-twist Portuguese bowline variant
« Reply #2 on: October 10, 2019, 09:45:49 PM »
Following my recent questions about making emergency harnesses with knots, I was interested in learning more double (and more generally, multiple) loop knots, mostly to design better ways of making such harnesses.

 I was playing around with the no-twist Portuguese bowline, which I think has some advantages for such an application (the two loops are 'side by side', not 'on top of' each other) but I didn't like how easy it is for the line to slip through the core/nub of the knot and the loops to become different sizes.

So, I added a turn in the line where it normally crosses over the top of the nipping turn . Instead, it follows the nipping turn round and then goes into the second loop (in this case on the right). This goes a long way towards securing the loop's sizes independently.



This principle could be extended to just tying a midloop in the line where it crosses the nub and tying the final bowline through that as well.

Has anyone else used or seen this variant?  Does it have a name? If not, what do people think of it?

Blue skies, Poly
I notice that as I repeat a tug of the upper leg of the left loop and the upper leg of the right loop, the knot tends to gradually elongate and lose its form.
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siriuso

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Re: No-twist Portuguese bowline variant
« Reply #3 on: October 14, 2019, 07:40:58 AM »
Hi PolymathArtisan,

Your presented knot is not clear enough to show the configuration. Will you please show it by steps or in loose forms.

Happy Knotting
yChan

Dan_Lehman

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Re: No-twist Portuguese bowline variant
« Reply #4 on: October 15, 2019, 05:33:22 PM »
Your presented knot is not clear enough to show the configuration.
Will you please show it by steps or in loose forms.

I see it as:

SPart reaches down to lower turn,
turning anti-clockwise & crossing OVER itself,
out into lower leftside eye,
returning upper leftside to turn clockwise
around and lower, going out into rightside eye,
... and then to finish with the collar bight.

I think that there might be better variations!?


--dl*
====

ps : The inability to understand a given knot
can lead to discovering *new* knots!   :D
« Last Edit: October 15, 2019, 05:34:30 PM by Dan_Lehman »

siriuso

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Re: No-twist Portuguese bowline variant
« Reply #5 on: October 15, 2019, 08:29:52 PM »
Hi Dan,

Your postscript is motivational. But here we always emphasize that new knots are needed to be clearly presented.

yChan

PolymathArtisan

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Re: No-twist Portuguese bowline variant
« Reply #6 on: October 16, 2019, 12:14:04 AM »
Hi everyone, sorry I attended to this thread in a few days, I've had lots going on.

For siriuso (and confirmation for Dan Lehman) here is a loosened picture of the knot. Sorry about the awful lighting and photography, it was all I could do right now.



Roo, I was interested to test your findings and you're right. It's too late and I'm too tired to take pictures right now, but I might be able to update with photographs in the morning. For now here are some thoughts on my findings:

The problem of the knot deforming when the two lines are pulled can be solved by locking it. I tried Dan Lehman's simple lock, Lee's lock, and tying off the end as in an EBSB, and all of these significantly reduced the deformation of the knot itself to the point that it did not lose it's inherent topological structure, and did not spill. However, even with these locks in place, repeatedly tugging different combinations of the legs did make the two loops change size (both by pulling line from the standing part and between the legs of the loops themselves). I think this would be especially true in round-cross-section, slippery braided lines or stiff lines. This could be prevented by putting stopper knots in the standing end legs before they enter the nub of the knot, (though that would be very uncomfortable if the knot was ever used as intended, for an emergency harness!), or by using a fixed midloop knot instead of the second turn (the 'upper' turn) (though this would not prevent line slipping in from the standing end, which would still need a stopper).

Finally to Dan Lehman:

Quote
ps : The inability to understand a given knot
can lead to discovering *new* knots!   :D

I love this. Very true.

Thanks all!