Quote from agent smith:
It is jam resistant.
And, it is Tiable Without Access To an End ('TWATE').Reply from Dan Lehman:
Really ?! --it looks to be quite jammable.
Curious: Have you actually load tested the Mobius Butterfly?
Or are you speculating?
Which is it?
Reply from Dan Lehman:
(I think we can omit the "access to" bit,
something that came to rid me of "utilizing",
as that allowed in a way a need for "access".)
'TWATE' is my invention.
I prefer it in lieu of 'TIB'.
"Without access" doesn't mean without
permission (if that's your supposed interpretation?).
Tiable without access to an end nicely captures the concept.
My issue with "tiable in the bight" is that it implies a bight is required or that a bight must first be formed.
With regard to the "Wrap 3-Pull 2" knot used by SAR teams:
Reply from Dan Lehman:
But W3P2 is about security-on-the-object --that one
unpulled wrap giving the securing binding.
The wrap 3-pull 2 knot provides 3 key benefits:1. Multi-directional anchor; and
2. Resistance to jamming; and
3. Built from lightweight/compact readily available material (ie webbing).
I propose the Mobius Butterfly as a very capable alternative.
And one that is constructed from robust EN1891 low stretch rope.
That is, instead of webbing, a length of 11mm low stretch rope is used.
It can be rapidly deployed and tied around a sturdy tree.
It is easy and quick to tie (and I would argue faster than the wrap 3-pull 2).
The Mobius Butterfly is resistant to jamming (try it yourself).
...
With regard to adding the second image to aid in clarity and understanding for the casual lay reader:
The second image showed how 4 corresponding eye knots could be derived from a Butterfly bend.
It is providing context.
Reply from Dan Lehman:
Not so. You have at the top the "same" knot (not quite,
given asymmetry of Lineman's Loop), one each for the
two S.Parts. Well, you would need that at the bottom
for Mobious, no? And then you also have but one of
the implied pair for your 3rd case --need the one for
the other S.Part to complete this set.
You are not making any sense (sorry).
The image showing the parent Butterfly bend and its 4 principal
linkages is correct.
All 'bends' have 4 possible linkages that can be made between the S.Parts
and the tail ends.
To provide some context, I showed how the Mobius Butterfly can also be derived
from the 'Butterfly bend'.
In the top (upper) image, I showed a
transposition.
That is, it can also be derived by way of a transposition from the regular
#1053 Butterfly.
The sequence in which I show each of the 4 corresponding eye knots is arbitrary.
There is no required sequence/order in which I must show the eye knots.
I did not also show the further 4 eye knots that can be derived by way of transposition.
The regular #1053 Butterfly is 'EEL' (either end loadable).
The Mobius Butterfly is also 'EEL'.
And so showing the transposed knots in these cases seems to be redundant.
Quote from Dan Lehman:
As for you criterion of "same geometry",
I don't see that at all for the Mobius :: what are clearly
--and to-untie helpfully-- "proper collars" of the parent
are lost in Mobius --drawn to collapsed snugness.
The collars of a Mobius Butterfly are not 'lost'.
They are present - but simply folded inwards.
The topology is the same - its simply a compact, and very tight dressing.
I would go a little further here... the folding inwards of the 2 collars is
a natural tendency - and once achieved, stays that way.
It retains its compact dressing as a natural (unforced) state.
Of course, in very stiff rope/cordage, it may not perform as well.
My experience is that the Mobius Butterfly is effective in more supple,
soft/flexible cordage.
Some Bluewater low stretch rope has a tendency to stiffen over time.
I have some old Bluewater II rope that is virtually like steel wire rope!
Tying a Mobius Butterfly in very stiff rope would likely be difficult (I haven't tried).
Further commentary from Dan Lehman:
This is one of the problems
with analyzing/testing mid-line EKs :: establishing what
forces have acted upon them when the loading moves
from one way to another and back ... ! <sigh>
This is an opportunity to declare what your actual in-the-field
experience is with using a Mobius Butterfly.
Have you actually used and applied it?
I have - many times.
I think SAR teams will start to adopt it once they learn more
about it.
It is also quite effective for improvising a dual leg lanyard into a harness.
Rope access operators will find it very useful - not only do they have the dual
connectors, they also have a secondary 'belay loop'.
The 'belay loop' (or eye of the Mobius) - is capable of sustaining
transverse and circumferential loading profiles.
EDIT NOTE:
LOAD TEST OF MOBIUS BUTTERFLYI just tested the Mobius butterfly to
6.0kN force.
TEST 1: EN892 Beal Opera 8.5mm dynamic rope
TEST 2: EN1891 Edelrid 11mm low stretch rope
Result: No jamming -
easily untied.
No jamming in either rope.
FURTHER TEST to 8.0kNTEST 3: EN892 Beal Opera 8.5mm dynamic rope 8.0kN (approx 800kg)
Result: No jamming, super easy to untie.
Commentary:As a general rule, SAR teams do not reach
a force of 6.0kN (approx 600kg) on their anchors.
Typical loads might be in the range 2-4 kN.
In relation to my third test to 8.0kN - I know for a fact that no SAR team
will ever reach an operational load of 8.0kN.
I am therefore confident to declare that the Mobius Butterfly will
meet and satisfy all SAR needs for multi-directional anchors.