Author Topic: Aligned Double Loops  (Read 7266 times)

vagary

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Aligned Double Loops
« on: December 27, 2012, 08:13:12 PM »
I'm looking for a double-loop knot with aligned loops (not splayed like a Spanish bowline) that is secure and doesn't jam. Ideally, it can be easily taught to people who aren't familiar with bowlines but I can practice to tie it quickly and smoothly. The Portugese bowline is the standard knot in this category:


But I find the Portugese bowline a bit clumsy to tie and hard to teach. The fisherman's/anchor bend (ABOK 1723) is easy to explain but has to be dressed perfectly or it'll slip:


Lately I've been trying (but have not yet tried teaching) a knot that I've seen called a reverse French bowline. It has also been criticized as not being secure:


Finally, I have seen suggested a loop based on ABOK 1445 (the myrtle hitch?), but in my experience it jams more than any of the other loops:


Any thoughts on the best knot in this category?
« Last Edit: December 27, 2012, 08:41:06 PM by vagary »

SS369

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Re: Aligned Double Loops
« Reply #1 on: December 27, 2012, 09:03:11 PM »
Hello vagary and welcome.

The loop that fits your request the best, in my mind, would be the Bowline on the bight. Very easy to tie and the loops are aligned and don't slip individually. I hope that is something that is not a requirement (the slipping)?

http://www.igkt.net/pdf/KnotChartsWeb.pdf Page #8

Hope this meets your needs.

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vagary

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Re: Aligned Double Loops
« Reply #2 on: December 27, 2012, 09:47:46 PM »
Thanks. I should have added that I'm tying this around a "spar". I'd have to play around with the bowline on a bight tied using a single end, but I think it won't be elegant for that. I use the term "loop" rather than "hitch" because I don't want the loops to tighten around the spar.

An application is tying a hammock to a tree: I don't want to cut into the bark so I want to distribute the load of the hammock over multiple wraps that won't tighten.

Sweeney

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Re: Aligned Double Loops
« Reply #3 on: December 27, 2012, 10:14:46 PM »
You can tie a bowline on the bight by starting from an ordinary bowline then following it round again (some climbers use this as a tie in knot to a harness).

Barry

SS369

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Re: Aligned Double Loops
« Reply #4 on: December 27, 2012, 11:31:53 PM »
Two strands going around the tree is not very much protection if that is the main concern.

I would use a tensionless anchor/hitch, very simple and will spread the load very well. Give it as many wraps as you like and tie the tail around the standing part with any configuration you want.
Or carabiner for that matter.

This will work with webbing as well.

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roo

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Re: Aligned Double Loops
« Reply #5 on: December 28, 2012, 01:36:22 AM »
An application is tying a hammock to a tree: I don't want to cut into the bark so I want to distribute the load of the hammock over multiple wraps that won't tighten.
A midline loop like the the Butterfly Loop or Span Loop may be employed as a self-equalizing system instead of learning a separate sliding double loop knot.  First, you tie your Butterfly Loop a reasonable distance from the tree.  Then run the free end of the rope around the tree, then back though the Butterfly Loop, then around the tree again (etc.), and then finish by attaching a Bowline (or some end loop) to the Butterfly Loop.  There are no rarely-used knots to learn this way.

Or you could just use separate protective measures like a piece of hose or a length of webbing if reducing pressure on the bark is important to you.
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roo

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Re: Aligned Double Loops
« Reply #6 on: December 28, 2012, 08:19:34 AM »
Or you could just use separate protective measures like a piece of hose or a length of webbing if reducing pressure on the bark is important to you.
To expand on this thought, you could just place a Sheepshank (or some variant) in the belly of a single loop knot of your choice to effectively widen the bearing area.

http://notableknotindex.webs.com/sheepshank.html
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Sweeney

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Re: Aligned Double Loops
« Reply #7 on: December 28, 2012, 01:38:57 PM »

This will work with webbing as well.


Thinking about this I would separate the anchor around the tree from the hammock and definitely use webbing/climbing tape. For ease of removal make a long webbing sling joining the ends with eg a water knot and wrap the doubled webbing around the tree from front to back and around to the front (giving 4 tape widths at the back) attaching the hammock by passing its rope through the 2 loops as well as behind the webbing wraps at the front. This is then easy to take down and put up with minimal damage to the tree.

Barry

Bob Thrun

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Re: Aligned Double Loops
« Reply #8 on: December 29, 2012, 05:08:35 AM »
A tensionless hitch concentrates the force in the first turn around a tree.  Even worse, it does it by tightening the first turn and sliding the rope around the tree. The rubbing could damage the bark.  I would make a continuous loop of webbing, the wider the webbing the better, and use a basket hitch.  The one inch (25 mm) webbing used br climbers can be tied or sewn. Knots are bulky in 2 or 3 inch webbing. The wide webbing should be sewn.

Dan_Lehman

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Re: Aligned Double Loops
« Reply #9 on: December 30, 2012, 07:58:33 AM »
Two strands going around the tree is not very much protection if that is the main concern.

I would use a tensionless anchor/hitch,
very simple and will spread the load very well.

Give it as many wraps as you like and ...

Specious reasoning, however fair,
is like missing a link in the chain of thought;
and when, by praxis, that chain's pulled taut,
it becomes apparent what isn't there.

--Anon., II


This is far from the first time I've seen such an assertion.
Care to go through this chain link by link?
 ::)

Quote
The fisherman's/anchor bend (ABOK 1723) is easy to explain
but has to be dressed perfectly or it'll slip

?!  The said knot is a hitch and so of course should
bind to the hitched object; it isn't merely being "dressed
perfectly", but some happy circumstance of materials
that is seeing it not slip, if indeed you have that!
But, tie off its tail into a bowline and you have then
a twin-eye structure.

But the simplest thing to do, with rope, is to just run the
line around and through the preformed loop part of the
bowline --i.e., its central nipping loop, the so-called "rabbit
hole", "gooseneck"-- until you have the number of eyes
wanted, and then finish in the usual manner; alternatively,
one can achieve the Portuguese bowline form, aka "bowline
on a coil"
by just wrapping, and then forming the nipping loop
and so on.

Still more kind to the tree, as others have said, is to build
a bridle from tape and to tie to that with the rope.  Two
eyes of rope put 25% of the load on each strand; three
put 16%; maybe this is fine, overall, even if tape covers
a broader surface.


--dl*
====

SS369

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Re: Aligned Double Loops
« Reply #10 on: December 30, 2012, 03:24:52 PM »
Two strands going around the tree is not very much protection if that is the main concern.

I would use a tensionless anchor/hitch,
very simple and will spread the load very well.

Give it as many wraps as you like and ...

Specious reasoning, however fair,
is like missing a link in the chain of thought;
and when, by praxis, that chain's pulled taut,
it becomes apparent what isn't there.

--Anon., II


This is far from the first time I've seen such an assertion.
Care to go through this chain link by link?
 ::)

Quote
The fisherman's/anchor bend (ABOK 1723) is easy to explain
but has to be dressed perfectly or it'll slip

?!  The said knot is a hitch and so of course should
bind to the hitched object; it isn't merely being "dressed
perfectly", but some happy circumstance of materials
that is seeing it not slip, if indeed you have that!
But, tie off its tail into a bowline and you have then
a twin-eye structure.

But the simplest thing to do, with rope, is to just run the
line around and through the preformed loop part of the
bowline --i.e., its central nipping loop, the so-called "rabbit
hole", "gooseneck"-- until you have the number of eyes
wanted, and then finish in the usual manner; alternatively,
one can achieve the Portuguese bowline form, aka "bowline
on a coil"
by just wrapping, and then forming the nipping loop
and so on.

Still more kind to the tree, as others have said, is to build
a bridle from tape and to tie to that with the rope.  Two
eyes of rope put 25% of the load on each strand; three
put 16%; maybe this is fine, overall, even if tape covers
a broader surface.


--dl*
====

Reasoning is not quite specious, just based on personal usage. That said, I do use a layer of protection between the rope and anchor regardless.
I think of the "tensionless" anchor as a hitch where in the wraps the force is diminished around the hitch to item thus leaving very little remaining at the tie off and so this means (to me) that the load is lessened overall.
It is a workable suggestion based on using the single rope, if one is not prepared with additional means.
The stated usage was to be  hammock suspension and not necessarily life support.

Dan, your suggestion will work as well though a bit more involved.

Quote
The fisherman's/anchor bend (ABOK 1723) is easy to explain
but has to be dressed perfectly or it'll slip

Please attribute other's quotes to them.

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Dan_Lehman

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Re: Aligned Double Loops
« Reply #11 on: December 31, 2012, 05:10:52 AM »
Two strands going around the tree is not very much protection if that is the main concern.

I would use a tensionless anchor/hitch,
very simple and will spread the load very well.

Give it as many wraps as you like and ...

Specious reasoning, ...

This is far from the first time I've seen such an assertion.
Care to go through this chain link by link?
 ::)

...

--dl*
====

Reasoning is not quite specious, just based on personal usage.
That said, I do use a layer of protection between the rope and anchor regardless.
I think of the "tensionless" anchor as a hitch where in the wraps the force is diminished
around the hitch to item thus leaving very little remaining at the tie off and
so this means (to me) that the load is lessened overall.
It is a workable suggestion based on using the single rope, if one is not prepared with additional means.
The stated usage was to be  hammock suspension and not necessarily life support.

Rather, reasoning has been omitted.
Bob put it succinctly, but w/o effect?

Let's try it:

problem) rope bearing full load it to meet the tree,
so how to lessen its potential harmful effect?


a) tensionless hitch brings full loaded rope
around tree, lessening not one bit, at this point.
Furthermore, the length of rope w/o definite
arrest (i.e., movement is slowed by friction, but
not definitely arrested by some hard turn --the
ultimately clipped 'biner or knot to SPart)
implies that there can be considerable movement
of the fully loaded strand as friction builds.

Tree cries "OUCH, you're cutting into my bark!!!"

a') load on wrap #1+P is small consolation to the
cut by wrap #1.  (Apparently, where T.H. is most kind
is to itself!   ;) )

b) Other user ties a bowline around the tree,
which brings 50% force to each side,
about 1/2 of "ouch" force, thus.  Moreover,
there will be little movement of the rope,
which is "arrested" at the point around the
tree opposite to the load (unless the eye were
long, in some "wrap N times, pull one" form).

c) Multi-eye knot further reduces load per strand
bearing into tree, with 1/4 load for two eyes,
1/16th for 3 eyes, and so on.


--dl*
====

SS369

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Re: Aligned Double Loops
« Reply #12 on: December 31, 2012, 02:28:45 PM »
Thank you Mr. Lehman, for the illumination.

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James Petersen

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Re: Aligned Double Loops
« Reply #13 on: January 31, 2013, 08:08:36 PM »
I have used ABOK 465 both to suspend children's swings from trees and to tie hammocks. In my experience with swings and hammocks, the damage to the bark of the tree/limb comes when a loose loop is used and then slips when the swing or hammock swings back and forth, chafing (actually, effectively sawing) the bark with the rope.

A relative simply threw a single line over a large maple  branch about 25 feet off the ground to make a tire swing for his children. The swing was simply a bight thrown over the limb with both ends secured to a tire. The swing was there a couple of years and then removed. The branch rotted off a few years later. At approximately the same time, I made a swing for my children in a large maple tree outside our house, using two lines secured to the limb with this hitch (ABOK 465). That swing is still there and still fully functional, although the branch has grown completely around the hitches where they are tied.

This hitch makes a nice "hinge," if you will, where the working end changes direction and is passed back under the turns (on the left side of the picture in ABOK.) It is easily tied on a branch, limb, or horizontal spar, but can be somewhat challenging on a vertical post or tree, depending on its size.

This is not a double loop as mentioned in the OP, but it has proven very effective for me. YMMV.
« Last Edit: January 31, 2013, 08:27:56 PM by James Petersen »

Benboncan

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Re: Aligned Double Loops
« Reply #14 on: February 01, 2013, 03:52:50 PM »
Vagary, search for "Cambium Saver" and make your own.