Author Topic: Knots for 3-strand twisted polypropylene ropes  (Read 3780 times)

mcjtom

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Knots for 3-strand twisted polypropylene ropes
« on: May 03, 2023, 03:22:52 PM »
What are the most fruitful knots on stiff polypropylene ropes?  This fellow has some practical advise, but I'm not that convinced:

https://youtu.be/SVXMqZYVp9o

For loops I had some success with the Angler's loop and for bends with the Double Fisherman. How do others deal with such ropes?  What best to use for a hitch, stopper, or a friction loop?
« Last Edit: May 04, 2023, 05:27:57 AM by mcjtom »

Dennis Pence

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Re: Knots for 3-strand twisted polypropylene ropes
« Reply #1 on: May 03, 2023, 11:29:56 PM »
A very simple answer I often give for this question is to try some fishing knots.  For example, in the Uni Knot Family, most recommend 5-6 wraps (although one saltwater site recommended 10-12 wraps).  For polypropylene you might only need 3-4 wraps.  {ABoK #1121, which Ashley calls a Gallows Knot is really a 3-wrap Uni Loop knot.}

This stuff is stiff and slick like most fishing lines, so other fishing knots might be appropriate.  (The Angler's Loop, which fishermen call the Perfection Loop, is no longer considered adequate for modern fishing lines.)
« Last Edit: May 04, 2023, 11:57:07 PM by Dennis Pence »

Dan_Lehman

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Re: Knots for 3-strand twisted polypropylene ropes
« Reply #2 on: May 04, 2023, 12:55:51 AM »
What are the most fruitful knots on stiff polypropylene ropes?
...
For loops I had some success with the Angler's loop and for bends with the Double Fisherman.
For an eye knot, the Mirrored BWL is designed for
such difficult material --stiff, unbending kernmantle;
springy, bending-but-eager-to-spring-free, and slick,
and sometimes hard (read : limited contact patch) PP.
The Mirrored BWL isn't a knot that is set snug-tight,
just well-formed and close,
and its conglomeration of parts upon parts serves
well to arrest further loosening.

(( I should remark that once I got some 3mm? soft-laid
PP cord from someone who was quite frustrated trying
to use it (so, ha, Send It To Dan!).  I struggled (with
only 2 hands, and a mouth) to set the End-Bound Dbl.BWL
snug; but at last I succeeded.  Victorious, I looked at the
knot and thought to it "Let that learn ya!"; then, after
perhaps 30 seconds?, the knots loop-binding-loops
all just relaxedly opened into looseness !!!  HUH ??

The photo'd knots mostly all have their "back-door"
states with a HARD bend in the Outgoing Eye Leg;
this isn't so keen to expand but wants to scissor-like
open, and that's easily impeded by surrounding parts;
though for the stiff rope, a hard such bend isn't going
to work, and thus (2nd from left) I found the version
making a softer bend for that. ))


Now, for a set-tight knot,
use a Locktight EK.

https://forum.igkt.net//index.php?action=dlattach;topic=3888.0;attach=7199;image


The main variations I like are
the 2nd-from-RIGHT one (for the springy PP),
and the 2nd-from-Left one (for unbending rope
--note that the outgoing eye leg isn't bent quite
so hard.
The design goal was simple :: get strangle-knot-like
security, but with a BWL-like opening "back door"
so it can be untied.

--dl*
====

ps : Sorry, but I'm in time pressure,
and so don't cannot here now give a nice
verbal description.
« Last Edit: May 05, 2023, 09:06:25 PM by Dan_Lehman »

Dan_Lehman

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Re: Knots for 3-strand twisted polypropylene ropes
« Reply #3 on: May 04, 2023, 08:57:21 PM »
What are the most fruitful knots on stiff polypropylene ropes?
 This fellow has some practical advise, but I'm not that convinced:

https://youtu.be/SVXMqZYVp9o

Hmmm, to my eye, HIS ropes were rather unstiff, but springy,
which matches my experience with PP stuff, for the most part
--although, reflecting on this point, I do have some that are
rather firm.

For an e2e joint, the multiple Lapp bend should work well
(= a Reverse sheet bend but then w/added wrapping of
the hitching line's tail through the U-fold and around the
one leg & its own S.Part).  It gives Strangle-like binding
but w/help for loosening of pulling the U-fold's legs apart
to prise out enough of hitching S.Part to enable loosening.


--dl*
====

 

anything