TEST REPORT: #1033 Carrick 'loop'

Practical Knots Knot Test Reports and Reviews
1

TEST REPORT
Knot: #1033 Carrick ‘loop’

Test objective:
To determine if #1033 is vulnerable to jamming.
The scope if the testing had a very narrow focus - and that was aimed only at probing the knots vulnerability to jamming.
If the knot is vulnerable to jamming, this would cast doubt on any type of classification as a member of the ‘Bowline’ family of knots.
This author has not been able to induce jamming with ‘Bowlines’ tied in human rated ropes (for climbing and rope rescue applications - eg EN892 and EN1891 and EN564 accessory cord).
There are no practical applications for #1033 in any life critical applications in rope rescue or rock climbing. This is purely a theoretical analysis.

Type of rope material:
As identified in the attached images.
All ropes are human rated and conforming to an EN standard.

Tester: Mark Gommers
Test date: 27 August 2018
Tester classification: Hobbyist / enthusiast tester

Test rig:
Dynafor 5 ton digital tension load cell
2 ton lever hoist
Natural tree anchors in backyard
Unilateral setup - force generating machine (ie ‘lever hoist’) located on one side of knot - all force injected from one side
Lever hoist pumped by hand while observing load cell LCD display

Assumptions:
Initial (threshold) jamming is reached when it is no longer possible to loosen and untie a knot by hand (without using tools). Maximal jamming state is reached when even the use of tools will not loosen the knot.
All Bowlines are theorized as being jam resistant. NOTE: This theory is open to debate amongst knot theoreticians - and this author had never been able to induce jamming of ‘Bowlines’ in human rated ropes (ie ropes and cords than conform to an EN standard and used in climbing and rescue applications).

Observations:
At loads up to 12.0kN, I had no difficulty loosening the knot.
There was never any difficulty with any of the rope types.

Conclusion:
#1033 Carrick ‘loop’ remains jam resistant right up to a ropes MBS yield point (in EN human rated ropes).
This conclusion has been confirmed by Xarax who tested an EN 892 dynamic rope (‘Tendon’ brand) to its MBS yield point. The Carrick ‘loop’ was easily untied.
Jam resistance is an important characteristic of [a] ‘Bowline’.
At no time did the knot undergo a transformation or show signs of instability.
This knots resistance to jamming relates to the nipping structure which takes the form of a helix that is loaded at both ends.
The nipping structure is jam resistant and ‘TIB’ (which makes it topologically equivalent to the ‘unknot’).

It remains open to other testers to either confirm or refute these results (in human rated ropes that conform to an EN standard).

2

The objective IMO is rather more generally simply to see
how the knot behaves under (a range of) loading, though
I suppose here one can note that rupture wasn’t achieved (right?).

As for defining a bowline by behavior (“if it jams, it isn’t…”),
that’s pretty bogus. #1010 can become nearly jammed in
some cases, if one has a lowish threshold of loosening force.
(At least I’ve found such a knot where the collar closed tightly
around a dia-diminished (by force) SPart which unloaded
swelled and was jammed in this tightened collar.)

[u]Conclusion:[/u] #1033 Carrick 'loop' remains jam resistant right up to a rope's MBS yield point. This conclusion has been confirmed by [b]Xarax [/b]who tested an EN 892 dynamic rope ('Tendon' brand) to its MBS yield point. The Carrick 'loop' was easily untied.
You guyz tested only a couple of ropes, and the conclusion needs to be specific re that --not conjecture. Now, based on the specifics and some other observations, there might be grounds for speculation; but see that for what it is, and keep in mind that physical aspects attach to physical things, not abstract/ideal *knots*.
At no time did the knot undergo a transformation or [u]show signs of instability[/u].
[u]This is a really interesting observation[/u], one that isn't made for #1010, which can undergo quite some change via capsizing (at least w/an unsnug'd collar). And yet this tested knot even needs relaxed tying so to avoid putting the SPart into some non-*loop* crossing-knot geometry!

(For capsized bowlines found In The Wild, see posted pics
to the like-named, Practical Knotting debut thread --but pics
which for ME are not enlarging (“download failure”)?!
ici : http://igkt.net/sm/index.php?topic=1017.45
in #57 (p.4)
)

Worth putting adjacent resp. images of this vs. #1010
at the increasing loads, showing their resp. changes!
(Also interesting would be to see this knot in some
firm-laid rope which will retain its roundness rather
than compressing as kernel strands shift positions!)

This knot's resistance to jamming relates to the [i]nipping structure[/i] which takes the form of a [i][b]helix [/b][/i]that is loaded at both ends. The [i]nipping structure[/i] is jam resistant and 'TIB' (which makes it topologically equivalent to the 'unknot').
??? The resistance to jamming might be helped by the SPart's being not-a-knot, just-a-loop (not "TIB", but "PET") but it's also helped and what looms large here is the vast openness of the *double collar* <--"double" in the sense that this one part is a collaring shared by the SPart & an eye leg, and won't jam both of them (looseness might actually be seen as coming from the eye-leg side).

And in this knot the >>loop<< is well kept as just that,
and NOT so much a helix --consider how the crossing
point retains forced contact, not tending to open into a larger
helix; how SPart & outgoing eye leg sustain contact.

As a part goes increasingly helical (i.e., with larger helix angle,
ever more straight along rope), it loses nipping ability
(and puts greater demands on collars/etc. to hold in place
–consider that the sheepshank can endure sans collar!).
So don’t be harping on this technical aspect here, else the
concept of loop is pretty much lost (if even here it’s
seen as “helix” --arguable, but with such minimal/small angle).

Now, all this nice behavior is fine,
but where do we see this particular knot finding application?!
–surely, NOT as a safe way to tie in for rockclimbing, et cetera,
for I don’t think would-be users would like the openness
of the knot, arguments re stability/security notwithstanding.
Though maybe an eye knot for less-mobile use such as
a tie-once-into-a-static-position use such as setting an anchor
for cavers, where the knotted rope won’t be moving around
and jostled into things and so on. ?!

(I’m eyeing a simple tail-tuck extension,
tucking out through that double-duty broad collar over
the loop’s crossing point; that and a stopper-knob in
the tail might satisfy me, but one is consuming rope
that can thus in other ways build a maybe less-bulky
tie-in eye knot. Shake-test, Roo?! )
((2nd “what if…?” eyeing :: take tail around and tuck
again through central nipping loop --going for our 3-dia
rounding of the loop!–, and that seems to add some
slack-security, but still leave easy untying. hmmm))

I suppose those trawler folks could do with this,
but they seem okay with capsized bowlines already.

Thanks,
–dl*

3

per Dan Lehman:

Rather than a lengthy technical reply - I have edited the test report to add clarification to its intended scope and purpose.

The focus of the test was very narrow.
Aimed only at probing resistance to jamming.
It is theorized that all Bowlines are resistant to jamming. Indeed, if an eye knot is prone to jamming, this would raise suspicions as to whether it can be classified as some type of ‘Bowline’.
In my case. I have never been able to induce initial/threshold jamming with any type of ‘Bowline’ in human rated kernmantel ropes.

I did mention that Xarax had also conducted a test to the knots MBS yield point - and one of the surviving #1033 Carrick ‘loops’ was easily untied.
I would like to emphasize that in all tests, only EN certified (human rated) ropes and cords were used.

I would also like to point out that it remains open for other testers to confirm or refute my results by conducting their own tests.
Other testers should use EN certified - human rated ropes - otherwise, we have no baseline to compare against.

Perhaps Alan Lee might be willing to test #1033 Carrick ‘loop’ by pullin all the way to its MBS yield point (using a #1033 Carrick ‘loop’ at each end termination). There should be a surviving knot and this could be assessed to determine if it has jammed (or not).

4

Well, you seem to be straddling the fence between offering
a conjecture about bowlines versus giving a definition
of them. A first check coming to mind is your favorite
variation, the EBSB, where the concern is the the loop
making the “end-binding” of the central nipping loop
(which is reciprocally nipping the other) will do that nipping
so strongly as to jam. But I’m pretty sure that you count
the EBSB as a bowline.

–dl*

5

Thanks for your interest Dan.
I would like to re-emphasize that the focus of this test was very narrow.
I was looking only at #1033 Carrick ‘loop’.
I could not induce jamming - and neither could Xarax.

One could argue that all posts about knot tests are pure theory and/or conjecture.
The concept underpinning my test was to investigate the theorized resistance to jamming of all ‘Bowlines’.
If a particular eye knot is vulnerable to jamming, that would cast suspicion on whether it could be classified as some type of ‘Bowline’.
It is my belief that #1033 Carrick ‘loop’ can be classified as a ‘Virtual Bowline’ (in accord with the definition I had tendered for ‘virtual’).
The core of this knot is built upon a nipping structure that takes the form of a helix that is ‘TIB’ and loaded at both ends.

Discussion about my EBSB Bowline is another matter.
But no, I haven’t been able to induce jamming in that particular Bowline at loads up to 50% MBS (in EN564 8.0mm Sterling cord).
Perhaps I’ll revisit that particular knot soon - and try to go all the way to the MBS yield of the cord and knot.

I am hoping that Alan Lee can try to repeat my tests on #1033 Carrick ‘loop’ - and see if his results concur with mine.

6

You should attempt this with some different material;
I surmise that you’ll have the same result --unjammed.
And the reason for that is the nature of the collar as much
as the non-knot turNip.
Now, consider “myrtle”-like eye knots --loops
binding each other :: here one might have other results
(and why I suggested the EBSB (etc.)) --same non-knot
(loop) base but a different stabilizing (if not “collaring”)
structure (the tail’s loop).

One could argue that all posts [u]about knot [i]tests[/i][/u] are pure theory and/or [i]conjecture[/i].
Whoa, I'm arguing against the jump to your assertion re *bowline* from some limited testing --to which came suggested other such knots (IMO, spec'ing/defining only a turNip and allowing other stabilizing parts (to which further having a "proper collar" might be irrelevant, but for necessarily the extra rope parts in the knot)).

As you know, Xarax seems to argue the opposite in
cases of an overhand base --i.e., that such knots WILL
jam–, to which I also resist; but here, the base at least
CAN jam, whereas a loop alone cannot (even if it could
somehow magically exist vs. being a non-knot).

The concept underpinning my test was to investigate the theorized resistance to jamming of all 'Bowlines'. If a particular eye knot is vulnerable to jamming, that would cast [i]suspicion [/i]on whether it could be classified as some type of 'Bowline'.
But this is where my objection is fundamental :: i.e., that the classification that we've given (pretty much in two versions --having or without a collar) is based purely on [u]structural [/u]--not [i]behavioral[/i]-- analysis.
a [i]nipping structure[/i] that takes the form of a helix
How does a [i]helix[/i] in general at all [i]nip[/i]?! You need to see that a [i]"loop"[/i] is what is at hand, here, and not helixes in general --that's why I resist using this name here : it's both necessarily and irrelevantly the case.

(Well, a case to press on my/your thoughts in this instance
might be ProhGrip / Blake’s hitch, where nipping-gripping
is a key feature and helical vs. "loop"ing is in effect, at least
ideally at the loaded end of the coil. Some of such gripping
knots at their more helical (or maybe it’s just more loaded?)
ends put the curvature into the gripped line from the hitching
line.)

But no, I haven't been able to induce jamming in that particular Bowline at loads up to 50% MBS (in EN564 8.0mm Sterling cord).
I'd a feeling that you'd explored this. Photos? How does the material resist binding up given that tail loop / "end-binding" ?! --just not enough pull on [u]both ends[/u] of it, unlike the central one?! Might non-newish/slick rope be harder to free?

As for the carrick eyeknot, one can do some “end-binding”
extension for it and I think get a workable tie-in knot
with 3 diameters stuffed into the central nipping loop.
And maybe trawler folks making eyes sized variously
over time --i.e., that will be un- & re-tied-- will like
it in the basic version, for its easy un-/tying and resistance
to capsizing!

Thanks,
–dl*

7

Hi All,
Mark, I got the #1033 Carrick loop tested. hope you like it.
https://www.youtube.com/user/alanleeknots
謝謝 alanleeknots

8

Hi Alan,

In your testing videos, there is a yellow knotted rope in the testing line. IMO, it is not appropriate. The test line should only be placed with the test piece. In this video, you are testing three knots and two lengths of ropes.

yChan

9

I just want to thank Alan Lee for running these tests.

Peer review and follow up testing is what we need to build a picture and test the various theories and propositions advanced.
You know, given the Earth’s population - I find it truly remarkable that Alan and I (and Xarax) are possibly the only people examining #1033 Carrick ‘loop’ with the ultimate goal being to advance a working theory. I now feel very confident in declaring that #1033 carrick ‘loop’ is entirely resistant to jamming.
Maybe Dan Lehman might invest in a mechanical force generating machine and a video camera to see if he can confirm (reproduce) our test results?

From my point of view, I can’t thank Alan lee enough and I also acknowledge your personal time, effort and expense - all of which I am truly grateful.

Mark Gommers

EDIT NOTE: It appears that the break (MBS yield) is occurring in the knot closest to the force generating machine.
This appears to accord with my observations where I found that the knot closest to the force generating machine would jam before the opposite knot attached to the static anchorage point. There must be a ‘scientific’ explanation for this. In my view, a clue is the fact that the rope and knot is s-t-r-e-t-c-h-i-n-g in one direction - and that direction is toward the force generating machine. The knot is also a mass concentration in the rope.
It is interesting to observe the nipping loop cinching and compressing the rope segments encircled - you can see the ‘sawing’ action of the nipping loop - and how it compresses and flattens. Very interesting - and it is adding to our knowledge of what is going on when load is applied and increased.

10

IMO, I would have tied more relaxed knots --looser
tail collaring, which would’ve let the nipping loop pull
into the minimal-helix region, vs. its shown state of
bearing into itself at the crossing point. (Let me suggest
that looseness shown in leftmost of 3 images by
Agent_Smith’s above posted 2nd image set,
light blue rope --where the center knot already is set
with a snugger end-wrapping/-collaring.)

I don’t see this at all affecting jamming
–perhaps making the untying easier (larger collar(s))–;
maybe it could be overdone (the looseness) to the point
of leading to capsizing?! But I think that the knot has
good resistance to this, structurally, if collars are
reasonable when dressed.

Yes, in one of the four videos : what eye knot is this?

IMO, it is not appropriate. The test line should only be placed with the test piece. In this video, you are testing three knots and two lengths of ropes.
How do you think that this might affect the results?

Were there one specimen 4x longer than the short
piece Alan uses, there’d be amelioration of each bump
of pulling across the 4x-longer material, lessening the
rate on the specimen; perhaps one way to get this
without costing so much rope is to do what Alan does
(though YMMV per nature of the added-on rope).

E.g., I was offered some few tests by NERopes
and had a fixed length (perhaps it was 50’ / 15m?)
of material to make my specimens; but I was told
to have lengths that IMO wasted much cordage
between my eye knots at each end --and so would’ve
much preferred that, ahd the test device some need
for the longer piece, it be got by including some
pin-point-extention to a moving pin to which my
then-much-shorter (and thus more numerous!) specimens
would be attached (taking safeguards against flying
floating pin, in this case --shock cord-tied to sandbag?)).

I guess that one fear of (too) close knots is that there
can be some imbalance of tension across the strands,
and a short specimen can concentrate these, maybe
by chance having the higher-tensioned strands from
each knot be the same, and so avoiding the ability
for these to get force amelioration over a longer
spread of material, and actually aggravating the
imbalance by being so from both knots!

Thanks, Alan, yes!

–dl*

11

Hi All, Thanks for all the reply.

In your testing videos, there is a yellow knotted rope in the testing line.
Yes, in one of the four videos : what eye knot is this?

Recently Xarax have tie many soft chain links. I like one of them and I overlap the cross over of the middle loop,
so the two faces of the eye loop are 90 degrees apart each other. This way I have piece of light weight soft chain links,
perfect link for breaking small diameter ropes.
The yellow rope is Bluewater Ropes SAFELINE Diameter: 12.7mm (1/2″) Tensile Strength: 44.5 kN (10,003 lbf.)
if this soft chain links have 50% of MBS yield, we have 4 eye leg here, that mean this link may break at 10,000 lbf.
I only apply around 2000 lbf to it, 5 to 1 safety factor, is more than safe enough for what I am doing.
I may ask Xarax if he wants to share all his soft chain links .謝謝 alanleeknots.

12

Ah, so it’s a sort of back-2-back inferior myrtle.**

Now fiddling variations in hand, I find myself
going awry on trying to make back-2-back other
knots --such as the basic anti-bowline (just reverse
the crossing of the loop (center)), and then of a
tail-outside bowline.
.:. I’m not finding a solution yet that pleases me;
yours is holding up fine.

**But the myrtle’s (uninferior) workings are slipping
in my hand w/soft braided 3/8" nylon rope, now! (And
otherwise, jamming --great combination of attributes! :stuck_out_tongue: )

The Myrtle’s returning eye leg enters the central nipping
loop from the same side/face as for a bowline, then the
tail “coils away” from the eye;
load the tail of this knot, and you’ll have my “basic anti-bwl”
and see that the new returning eye leg enters from the
opposite side (hence my “anti-”) and coils towards
the eye.
And for either case --and for just reversing the coiling
direction–, make a 2nd tail wrap and you get 3 diameters
through the nipping loop (the better to round it)
and a more stable/secure knot.

–dl*

13

Hi Alan,

In my opinion the knotted yellow rope attached in line with the testing piece is not necessary. Just by using the tensil test device is perfect, because elongation of the knotted yellow rope and the test pieces would take place (though the elongation data is not required). If extension means are required, I prefer to use an extra metal extension bar or rod, better than knotted rope or wire/cable.

All my concern is about safety.

yChan

14

Hi All,
yChan, Thanks for the concern, I have worked in heavy construction for 40 years, hasn’t loss a fingers arm and leg yet.
Yes, I do get excited about Xarax’s soft chain link, like to try it out, I do take little risk on 1/5 safety factor.
yChan don’t you worry too much about me here. I do know how to protect myself not to get hurt.
謝謝 alanleeknots.

15

Hi Alan,

Love to share your photos. I shall be away from town for three days to China.

yChan

16

NB: the anti-bowline version shows similar geometry/behavior.

:slight_smile: