testresults for EDK, TFK and DT_FK

testresults for EDK, TFK and DT_FK

Post by Brian in S » Fri, 08 Nov 2002 08:53:21


Quote:

> "Brian in SLC"

> > It actually is, if you read most knot books.

> It isn't if you read most climbing books.

Hey, its in fishin' books too (odd, that...!)...

Quote:
> > What is fun, is that there are a couple of other knots, low profile
> > like the EDK, that might be worth a look see.

> Hey - have a blast with it.  Don't forget to tell the world how great it is
> based on isolated tests and your own personal success.

Gee, I'll try knot to forget...but...maybe "isolated" tests by small
potato(e) euro rope companies like Edlerid will help refresh my
memory.

Quote:
> > Uhh, I think its "yes".  Loose knots weren't tested.

> Loose knots *were* tested in Tom's tests.  I now seriously doubt your
> crediblity as well as your reading comprehension.

Tom's tests but not Edlerid's.  Josh posted Edlerid's data.  Hank
asked if they also tested loose knots, and I think (pretty sure,
'cause that Hank feller is a smarty) it was with regard to Edlerid's
testing.  The Edlerid report stated that "all knots were tied
correctly; we didn't test carelessly tied knots.  I think Hank was
hoping for clarification.

I sleep with Tom's test report(s) under my pillow (super stuff).  I
know that sounds strange, but, I'm hoping osmosis will improve my
redding comprension.  I think you doubt most folk's credibility when
they disagree with you.  Its an easy fall back position when you can't
support an arguement with anything more substantial (snicker
snicker)...

That, or YOUR ability to comprehend is a bit off.  Naw...

Quote:
> > >The recent accident in Zion

> > May not have finished knot, or left the
> > tail too short and it rolled

> I'm stopping here.  Your post is filled with speculation and what-ifs
> showing me that you are either trying to confuse the issue, or are just
> plain incapable of producing a coherant point with merit.  The first-hand
> account was clear.

Yep.  Clear as a bell.  Lets review it here:

Scarfed from the pages of wreck climbing, the partner to the climber
whose knot failed, posted:

"Some stuff that I do know
Ross was found with the two ropes correctly through his belay device.
The ropes extended about 10feet "above" him (the other 190feet being
"below" his belay device) and the ends were not tied together.
Throughout this trip we had always been tying ropes together using a
fig-eight knot (more below). The only other abseil Ross set up that
same day (from top of pitch 3 down to the big ledge) he had used the
fig-eight knot with no back up knot on the tails. The knot was neat, I
dont remember exactly how long the tails were but they didn't
cause me a second glance. I could not see exactly what Ross was
setting up on that last abseil - he was 10ft or so to my left and was
sitting (while clipped in) so that he obscured my view of the anchor.
The fig-eight I refer to is tied as follows: The two ends you want to
join are held parallel with the ends "pointing" in the same direction.
You grab both ropes together and then tie a regular single fig-eight
knot in both ropes at once. What we did NOT use: The only other way
that might be confused is when you have the ends pointing in opposite
directions. Tie a single fig-eight in one rope then follow this
through with the other rope - we did NOT do this."

Gee, my redding comprension must be off again.  I have no credibility.
 Heavy sigh.

Quote:
> The unknown details are moot.  He attempted an EDK and
> died.

Nope, you're wrong-o.  His partner felt that he was attempting an
in-line figure eight as that was the only knot they had been using to
tie their ropes together.  Did I miss some other post were this was
recanted?

Quote:
> If he was confused and/or botched the knot, it still supports my
> point.  Why not endorse a knot with a greater safety margin both in strength
> and in how it is tied?

Is there an easier knot to tie than an EDK?  Plenty of safety margin
for a rappel (still a high and acceptable strength).  I think in any
contest, I could tie an EDK faster than a barrel (grapevine, double
fisherman's) knot.  Especially if I was tired, wearin' gloves, it was
cold, dark, snowing...or swingin' from a climbing wall on Fear Factor.

Quote:
> I do not discount the whole "a barrel knot hangs up" argument - but I do
> discount that it's a good one.  There are plenty of well known ways to make
> your rope pull clean.  In fact, I don't discount the EDK as a worthy knot -
> every test seems to prove it.  However, as I mentioned, I'm looking at yield
> in the field.

Yield in the field.  I like it.

There just isn't ANY data of substance to support that an EDK has
failed in the field.  The Teton incident?  Reread ANAM and look at the
ranger's comments.  There's doubt.

More info:

A search of the ACC site for rappelling accidents:

http://alpineclub-edm.org/accidents/years.asp

From 1896 thru 2002, no rappelling accidents involving a knot becoming
untied with regard to connecting two ropes (lot of data, lot of years,
but, it is Canada, strange brew and all...).

More info on knots and testing:

http://www.bushwalking.org.au/bushwalkingmag/mag2725.html

Fodder for thought.

Brian in SLC

 
 
 

testresults for EDK, TFK and DT_FK

Post by Nate » Fri, 08 Nov 2002 09:50:36

"Brian in SLC"

Quote:
> Nope, you're wrong-o.  His partner felt that he was attempting an
> in-line figure eight as that was the only knot they had been using to
> tie their ropes together.

No - you are incorrect.  Re-read the part where he regrets not knowing any
better.

Quote:
> Did I miss some other post were this was recanted?

Same post.  You're a waste of time.

- Nate

 
 
 

testresults for EDK, TFK and DT_FK

Post by Dan Lehm » Fri, 08 Nov 2002 10:03:33

Quote:
> Jost:  I am astounded that you have presented ... a knot that is NOT what
> you have previously shown & argued for--the "triple fisherman's knot"

Please accept my apologies for this mistaken exclamation, esp. Jost.
Now that my astonishment has had a chance to dissipate, allowing some
circumspection to take over, I see what has happened (and, had I the
sense that God gave geese and just carefully READ what Jost nicely WROTE,
I wouldn't even need this step--oh, well, sorry Jost ...)-:

   indeed, Jost's "TFK" was tied & tested; and

   the middle overhand knot has pulled through the "initial"
   overhand knot

This suggests to me that the knot wasn't properly tightened,
for it should be the case that the initial overhand draws too
snugly around the opposite SPart to enable the middle overhand
(which the opposite SPart forms) to slip through--that overhand
knot should be loaded qua stopper and hold, at that point.

But it also points out that the initial overhand and the opposite
SPart can be oriented in two main ways, which affect how well
the initial overhand closes around the opposite SPart.  In the
image shown for the (highly) tensioned knots, the more secure
orientation is the one in the righthand image, w/black'n'white rope;
in this form, the B&W SPart draws its own end around the opp. SPart ever
tighter (something like a minimal Timber Hitch; the initial overhand
could be well cinched up snug during tying).  In the other orientation,
which was how both these knots began, the SPart enters the opp. rope's
initial overhand through the natural, large space of its *belly*,
leaving the (e.g. blue) overhand in a sort of *pretzel* form (as opposed
to a half-hitch or min.timber hitch form), the blue SPart tends to draw
OUT its own end and thus keeps feeding material into this initial overhand,
leaving it vulnerable to opening and the later knots pulling through (but
this form yields the nicer, flatter profile against the surface).

The more secure orientation can be predictably tied, but it requires
that much attention to tying, and so reduces the "dummy-proof" rating.
But, as Jost's testing suggests (we must consider that his sample has
some bias of a small sample), there is safety against catastrophe.
I believe that new, slick rope, HELPS the knot draw tight and secure
(yet even so, the Edelrid testing showed deforming); older rope, with
a more frictive surface, will aggravate the opening of the initial
overhand.

---------------------------------------------------------------------


Quote:
> "Brian in SLC"

> > It actually is, if you read most knot books.
> It isn't if you read most climbing books.

I believe this "is-so","is not" argument is about the "Fisherman's knot"
being a simple overhand tied in a piece of rope.  No, is NOT:  the name
originated and has consistently been used for the pull-together line-joining
knot shown by all manner of knot books--angling (orig. use), general, and
climbing.  The "double Fisherman's" is thus aka the "grapevine", and so
the "triple fisherman's" is (as e.g. in _On Rope_) the next in that series
of progressively more rope-consuming knots.  In slick fishline one can see
the multiple turns draw quite tight ("welded"); in increasingly heavier
angling line, into cords, and ropes, recommended and helpful turns are
pretty much less than four.

Quote:
> I'm quite certain the possiblities are endless.  However, none have been
> tested quite like the traditional fisherman's knot.

> > > The recent accident in Zion ...
> > May not have finished knot, or left the tail too short and it rolled ...
> The first-hand account was clear.  ...  He attempted an EDK and died.

NO:  he tied exactly what the pair had long been accustomed to using,
a Side-Oriented FIGURE 8 bend (the EDK is a S-O Overhand, not Fig.8),
and perhaps with some haste & concern for reach of rap. line he this
time left shorter tails and maybe didn't so well pre-tension it, and
the knot failed.  And Tom Moyer's and others' tests have shown the
S-O Fig.8 to be a dangerous knot, quite vulnerable to flyping/capsizing.

Quote:
> Why not endorse a knot with a greater safety margin both in strength
> and in how it is tied?

He IS--the EDK is that:  it's easier to tie largely because it is so
short'n'sweet simple that one has less chance to go wrong (any crossing
--"non-parallelism"--will be more apparent, if it occurs, even), and
the behavior is still better even if one does.
BUT, there are ways to bolster this simple knot.  E.g., one can do so
by casting an initial overhand around the *throat* of the EDK to resemble
Jost's TFK structure.  (Note that the EDK then is loaded purely qua stopper,
not pried apart; it will be thus a tad harder to untie, but no bigger under
normal abseil loads.)

--dl*
====

 
 
 

testresults for EDK, TFK and DT_FK

Post by Tumblema » Fri, 08 Nov 2002 12:43:57

Gee, Nate, I'm having a hard time understanding what you're getting
at. There are a number of lab tests (none exactly identical) done by
competent people all over the world and every one seems to say that
either the EDK is to be recommended or that it more than adequately
meets the requirements for a rappel knot. Here's another:
http://www.bwrs.org.au/research/documents/1%20main%20paper.pdf. They
do a careful, elaborate test and end up recommending the EDK in
comparison to a (true) TFK, Fig-8, and side loaded Fig-8. Read: IT
MEETS SPEC, Nate, better than the competition. I haven't seen you come
up with lab tests that reach a contrary conclusion.

OTH, you want to cling to anecdotal evidence to try and suppport your
point. Two specious and disputed reports of failures of purported
EDS's, while ignoring all other anecdotal objections that claim that
the most serious problem is having the ropes hang up on retreival and
the EDK is superior in that respect. That's not how a careful engineer
reaches a conclusion. Even so, what IS your conclusion? That you don't
care for the EDK despite the evidence? That's fine. That others are
wrong because they like it and are supported by the evidence? Hmmm...

Your analogy about designing disk drives is apt. An engineer who
focuses on manufacturing yield may become self-congratulatory, but if
the product doesn't satisfy customers, nobody's buying it. I think
that's the case with your arguments, too.

 
 
 

testresults for EDK, TFK and DT_FK

Post by Jost Gudeliu » Fri, 08 Nov 2002 12:56:07

Dan,
Thanks for the "compliments" ("Thanks for the work, but, hey, this is a
pretty surprising discrepancy to arise from those who should be intimately
familiar and focused with/on this knot"). I am a guide (UIAGM), perhaps like
you?
Excuse me, but I think you misunderstood my bad English explaining  the TFK
acting under a load more than 700daN.
I try it again:
- the knot was tied correctly and side-oriented
- there were three overhand knots, one behind the other - red,blue,red in
the mock-up or blue, black, blue in the test
- up to a load of around 700 daN the TFK kept its form
- than the knot lost its original form
- the first overhand knot (A) was teared open and slipped partly over the
second (B)
- B and A kept together and held each other
- B, now in the first position, pulled C against A
- A and C had a close connection by their form
- the TFKmade it to the highest load of between 2500 and 3300 daN
- with that new form th TFK is not practicable for rapping, OK
- but in practice (or field) you will not have this load of 700 daN
- therefore I recommend the knot  as an easy to tie and safe knot to combine
two ropes for rapping

Quote:

> > EDELRID, the famous German company for alpine ropes, tested the three
knots
> > which are used to combine two ropes for abseiling.
> > You will see the results on my homepage www.gudelius.de on the site
"Jost's
> > Alpine Seite".

> No, they did NOT!!!

They did.

Quote:

> Jost:  I am astounded that you have presented on your own WWWeb site
> results for a knot that is NOT what you have previously shown & argued
> for--the "triple fisherman's knot" [sic--this is a name already attached
> to a known knot, like the grapevine, but w/1 additional wrap]!!!???

I dont know all American knots and their names, of course. Do you know all
German, Austrian, Swiss names of the knots? I only translated my German term
in English. Maybe, that was a mistake.

Quote:
> How can you look at these photos and write that you don't tie knots
> carelessly--when in fact the tested "TFK" is quite different from what
> you elsewhere have shown!?  --i.p., from what this very WWW page shows
> at the bottom.

See above, the form changed under a load of around  700 daN.

Quote:

> NOTE THAT THE LOADED ENDS DON'T BOTH PASS THROUGH THE FIRST-ENCOUNTERED
> OVERHAND FORM, BUT INSTEAD ONE SIDE TURNS AROUND THE PAIRED ENDS.

see above again;

Quote:
> Further, NOTE THAT THE EDELRID VERSION HAS EFFECTIVELY NO *FLAT* PROFILE

I saw it and explained it above, but it is without relevance for the
practice as I wrote above.

Quote:
> This is truly amazing, and sheds some light on how well folks (don't) pay
> attention to knots!  Egads, ... !  (I'll have to hurry up and meet my vow
> to provide to you images of some real side-oriented bends, including a
> simply improved EDK and a couple of versions of your "TFK" (the initial
> overhand can assume a couple of forms).)

I am most interested in  images of your versions, without load and under
load.

Quote:
> > We did not test any carelessly tied knots

> Well, see above on that:  you tested not what you alleged & aruged for!
> Surely this Edelrid revision/version wasn't intentional; it appears as
> though not a fly, but maybe a(n Alpine) "Butterfly" got into the ointment!

Excuse me again, please;  you only looked at the images without reading or
understanding the text.

Quote:
> To respond to the question about "Aren't all knots tied carefully?",
> no, they aren't, really.  So climbers and other life-critical users
> have some that are dummy proof in other ways--i.e., that work in different
> forms.  Just scrutinize the many images of the ubiquitous fig.8 loopknot,
> and you'll see what I mean.  (E.g., the book _On Rope_, 1st ed., p.33,
> which is the cover page for the chapter on Knots, shows a non-symmetrical
> form of the knot, and beside it a slipped-out-of-orientation Yosemite
Bowline!

> Abseil bends are occasionally tied by tired climbers in dim light at the
end
> of a trying day; it is helpful then that the knots used are in some ways
> dummy-proof (possibly with use of a back-up).  The EDK & Side-Oriented
Fig.8
> work poorly if the parallel parts slip out of *parallelism*, and in hasty
> tying, esp. of the latter knot, this can easily happen.  "Leave ends long"
> is a tacit admittance of that, and of the fact that the behavior of the
knot
> depends on how tightly it is drawn up before loading.  (Anglers knots,
e.g.,
> require specific, pretty severe (e.g. approx. 40-60% strength) tensioning
> before use, to get into proper/strongest form).

well roared, lion, but how will you compare and test knots which are tied
carelessly?

Jost Gudelius
www.gudelius.de

 
 
 

testresults for EDK, TFK and DT_FK

Post by Mike Swan » Fri, 08 Nov 2002 18:38:43



.  The casual reader should observe that his triple

Quote:
> > fisherman's isn't.

> It actually is, if you read most knot books.  A fisherman's knot is an
> overhand tied onto a standing piece of cord.  Josh's triple
> fisherman's is just that, three overhand knots tied in a row on
> alternating standing strands which just happen to be parallel and not
> opposed.

No it isn't.  Any knot book I've read describes overhands tied against each
other as a fisherman's knot, AKA grapevine.  A double fisherman's uses
double overhands, triple uses triples.

Using 3 overhand knots in a different configuration does NOT make it a
triple fisherman's.

Mike

 
 
 

testresults for EDK, TFK and DT_FK

Post by Brian in S » Sat, 09 Nov 2002 01:43:56

Quote:

> "Brian in SLC"

> > Nope, you're wrong-o.  His partner felt that he was attempting an
> > in-line figure eight as that was the only knot they had been using to
> > tie their ropes together.

> No - you are incorrect.  Re-read the part where he regrets not knowing any
> better.

> > Did I miss some other post were this was recanted?

> Same post.  You're a waste of time.

Well, I'll burn a bit more bandwidth to make my point.  Nate, feel
free to skip this as I'm sure its just a further waste of your time.

And Jost (not Josh, sorry!), thanks again for posting the data from
the Edelrid testing.  I know some of us really appreciate it.

First, here's the more salient points of the Teton "incident"
involving the EDK:

Teton details, from the 1998 ANAM:

"Fall on Rock, Rappel Ropes Knot "Unraveled"
"Wyoming, Grand Teton, Guide's Wall"

The interesting points:  ropes used were 10.5 and 10mm in diameter.
MG tied the ropes together with an overhand knot, leaving 6 to 8
inches of tail.  The party rapped twice, then MG "started to untie the
knot by loosening it (for a single rope rappel) and then decided to
keep the ropes tied together...".  MG "re-secured the knot by pulling
on all ends to tighten, which he demonstrated."  MG rappelled 80 to 90
feet to the next ledge.  When he finished, Dagher "said that she and
Turk moved the knot about twelve inches forward, but did not adjust
it.  Turk then proceeded to rappel.  When Turk was approximately 300
feet above the ledge, Dagher states that she watched the knot
"unravel", causing Turk to fall".  A phone interview with Turk stated
that "she could offer no additional information surrounding th nature
of the accident, but added that Dagher had made a comment about the
knot, to the effect that "it looked pretty weird" and she wasn't clear
how it could hold.  This comment was made at the last rappel station."
 Turk stated that she was aware that MG "had adjusted the knot at this
station but did not see him do so."    Thankfully, Turk's injuries
were limited to a soft tissue wound (exposed spine) which was cleaned
and sutured.  They initiated the rescue with a cell phone.

So, there it is.  I'm glad the "EDK" didn't live up to its namesake.
But, I think there's enough ambiguity in the story to at least make me
wonder what really transpired.  Selective amnesia?  I happens.  I've
seen first hand at an auto accident, where the driver couldn't
remember being the driver.  His friends were hurt pretty bad and we
had a hard time trying to figure out how many people were in the car.
He was the only one that wasn't hurt.

What is clear is that these folks were at least attempting to use an
overhand knot, ie the EDK, for their rappel.  I chatted with two
rangers in the Tetons at the time, and neither one had a clear picture
of what really happened.  I don't casually discount this incident
either.  Its a data point.

Regarding the Zion incident this past May involving an apparent knot
failure during rappel, its pretty clear to me, and has been restated
(see below) that the knot they were using was an in-line figure eight
and not an overhand (EDK) knot.

I scarfed the following from the supertopo website.  I think worth
reading.  The author makes some good points in general and worth
reposting in its entirety (my belated condolences).

Have fun, be safe (not necessarily in that order!)...

Brian in SLC

Posted by Richard Connors on the climber's forum on the Supertopo
website:

From: UK This is Richard again - as at the beginning of this thread.
First of all, thanks to all those who posted kind words - it really is
appreciated.
I am glad that my post created a few replies - my only thought was to
get other people to think about this issue, since I do not have a
clear solution and I never have been a ropework guru of any sort. I
think it goes like this:
Using a Fig-eight (like we did) or an overhand (EDK) does not snag as
easily when retreiving you ropes - this is not too subjective a claim:
lots of people will attest to this, it makes sense when you watch the
knot as you pull your ropes AND it has been shown (albeit in a lab) in
some of the many "rope testing" articles on the web. Rope snagging is
not just an inconvenience. Accidents do occur from people trying to
retrieve stuck ropes (talk to guys who do canyoning aswell!). The
double/triple fishermans is a strong knot and doesn't have the
"rolling" issue of the fig-eight/EDK but it is more likely to get
stuck.
I dont know how definitive we can be in talking about knots failing
when improperly tied. In this case, I don't know if the knot was tied
neatly, or if it was pre-tensioned, or how long the tails were. I *do*
know that the fig-eight is a very easy knot to tie and it seems
unlikely that Ross tied it completely wrong. I can believe the tails
were too short, and maybe it wasn't all super-neat but I did not see
this. The worrying thing in my mind is that I reckon Ross thought he
had tied a good knot, he always checked his own setup, he liked it
enough to set off, and then he died.
So what's my point...a couple of things: The guy who said you should
check things all the time - damn right. No one is going to argue with
that. We usually did, except in this case I was standing 10ft away and
we were each getting on with stuff. Sure Ross could have called me
over or whatever and maybe I would have seen a crappy knot and given
him a slap, or MAYBE I would have seen a neat knot with only 6inches
of tails and thought it looked fine...because I didn't know about the
rolling issue.
So I got thinking about how I started using this fig-eight method and
liked it, but I never actually sat in my back garden thinking "I
wonder how close you can tie this to the ends" or "what are the
failure modes of this knot". I just got on and used it. How many
people are like this - just starting to use a new nifty way of doing
things, without really exploring all it's weaknesses? Now I have taken
that time and tied this knot and pulled it apart a number of times in
different ways and I have learnt something. I guess some of the point
of posting is to say just that - it's not just me that "learns" new
techniques in this way and gets on using them without really thinking
through all the limitations, without testing (in however shoddy a
fashion) what might happen in the margins. I am not telling anyone how
to go about their climbing, just saying be aware of these things that
you have not fully tested and explored. Don't just assume it'll all be
fine.
None of us climbs perfectly, you tie these knots a zillion times in
your life, you set up a zillion belays (are they all perfectly
equalised, multidirectional and with redundancy?). We all have had to
wing-it in various situations when things were getting hairy....this
wasn't one of them. Please don't***up the easy stuff - as much as
you can, know the necessary margin of safety for whatever method you
prefer. There are guys have been using the EDK for years and will
continue to do so safely, and no doubt there will be guys die using
this knot sometime in the years to come.
Enough already. Like I said I am not the guy to tell you which knot to
use, but DO know your systems and that means knowing how and where
they might break.

Richard.

 
 
 

testresults for EDK, TFK and DT_FK

Post by Nate » Sat, 09 Nov 2002 01:57:33

"Brian in SLC"

Quote:
> What is clear is that these folks were at least attempting to use an
> overhand knot, ie the EDK, for their rappel.

Thank you very much - next.

Quote:
> its pretty clear to me, and has been restated
> (see below) that the knot they were using was an in-line figure eight
> and not an overhand (EDK) knot.

Brian - pull your head out of your ass.  You have the reading comprehension
of a drooling retard.  It is clearly stated in the first post what they were
using.  Go find someone to read it and slowly explain it to you.  It was a
figure-8 tied to look like a EDK.

- Nate

 
 
 

testresults for EDK, TFK and DT_FK

Post by Michael Boo » Sat, 09 Nov 2002 02:46:24

For what you have contibuted materially to this thread, you make
too much noise, dude.

Quote:

> [quite a lot, snipped]

--
*********************
L. Michael Boos
CH-8001 Zuerich
*********************
to e-mail remove 4 dots from left to right
 
 
 

testresults for EDK, TFK and DT_FK

Post by Brian in S » Sat, 09 Nov 2002 03:27:24

Quote:



> .  The casual reader should observe that his triple
> > > fisherman's isn't.

> > It actually is, if you read most knot books.  A fisherman's knot is an
> > overhand tied onto a standing piece of cord.  Josh's triple
> > fisherman's is just that, three overhand knots tied in a row on
> > alternating standing strands which just happen to be parallel and not
> > opposed.

> No it isn't.  Any knot book I've read describes overhands tied against each
> other as a fisherman's knot, AKA grapevine.  A double fisherman's uses
> double overhands, triple uses triples.

> Using 3 overhand knots in a different configuration does NOT make it a
> triple fisherman's.

> Mike

I have a knot book (can't recall the title) that defineds as I've
mentioned above, but, your right Mike, A fisherman's is tied with
overhands on opposing strands.  For the sake of clarity.

But, what the heck do we call Jost's knot then?  The, three
alternating overhands on alternating strands all in a row knot?  Lets
see, the TAOOASAIAR knot?  Or, gotta play with this a bit, ILTAOAS
knot.  Gotta be something nifty here...AOIL, ILAO.  Hmmm...

Yeah, not what we in the states normally call a triple fisherman's.
But very clear on his website what he's referring to.

The "in line" fisherman's knot is interesting too...as a rappel knot
for joining two ropes together.  I wonder if someone knows, in knot
parlance, how to technically describe the "in line" version of an
overhand, figure eight and fisherman's knot.

Anyone?

Brian in SLC