International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: Dan_Lehman on February 02, 2018, 01:35:15 AM

Title: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 02, 2018, 01:35:15 AM
Rather than further this irrelevant discussion to the OP
of another thread, let's continue here.

Roo wrote
Quote
I'm not arguing that no force is transmitted around the object, merely that the 100% load at the standing part gets reduced to something below 100% past the entry point.

This becomes especially evident when you consider what happens to a Gnat Hitch when it is pre-snugged around an object, causing the legs to spread.  This is most easily seen by tying the hitch around a large test fixture and see at what leg angle the hitch stops contracting in free air and starts acting like a standard loop.  It's usually just shy of about 90 degrees.

So in an actual snug condition, instead of free air, we'd expect this balance point to occur even sooner.  And indeed, in high load testing of such hitches, it's not at all unusual to see the knot body to lift off the object and leave a gap, much like a loop.

And Agent_Smith reacted
Quote
The gnat hitch must not be used as a tie-in knot to a climbers harness - despite any assertion that a gnat hitch will reach a balance point (equilibrium) and stop cinching like a noose.
When tied into a climbing harness, the gnat hitch will act like a noose and cinch up tight - and so during the violent force of a free-fall, significant friction and resultant heat stress will occur to the harness textile material. The impact force of a fall is dynamic - and not a steady acting force - it is a sudden shock load.

Tie-in knots for climbing must be eye knots that do not collapse or tighten like a noose. The eye must be fixed.

The use of #409 (Poachers noose) and #1120 (scaffold noose) as termination knots for cows tails lanyard is used extensively in the rope access industry (see my previous link to IRATA code of practice). The noose is formed on a metal carabiner - not a textile harness.

To which Roo challenged :
Quote
I will take your lack of photos of the phenomenon you predict as concession that your nylon-melting hypothesis cannot be taken seriously.

If you want to be taken seriously, you need to do testing.

And I got searching.  Here is my first find, which is of rope
movement WAY more than a hitch will see,
but at forces WAY less than a fall will give --a question
of balance?!

Quote
http://www.theuiaa.org/documents/safety/Use_of_slings_when_lowering_off_and_abseiling.pdf
In 5mm cord (how thick harness loops?), of 9mm rope
only a meter of "lowering" an 80kg (standard UIAA mass)
cut through the sling.  (Hmmm, would that there were
some Kevlar slings to test!)  Thicker slings or rope (11mm)
took longer to (be) cut through.

I'm thinking that the clove hitch would fare well worse
than the less-material-to-move gnat hitch (but there might
be some other hitch to play the role I envisioned that would have
less potential movement (e.g., there's a constrictor-like oddball
in Hansel&Gretel's Encyclopedia...... (p.98#311, IIRC) !)

--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 02, 2018, 01:46:31 AM
Dan,

Can you change the title of this thread to:

"Noose versus fixed eye knot in direct attachment to harness for climbing or work at height applications"

This title more accurately reflects the precise nature of my concerns.

I would say that if any full-time climbers or rope access technicians are reading this thread - they might be inclined to chime-in and provide an opinion on why not a single training agency on Earth (our planet) recommends a noose structure as a means of rope attachment to a harness (nylon-to-nylon / textile-to-textile direct interface).

Mark
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 02, 2018, 05:18:48 AM
After doing another battery of scaled-down tests (to safely allow absurd strains) on webbing with hard repeated impacts and not the slightest hint of melting or even warming, I think this nylon-melting myth is busted.

The webbing stayed pristine, as should be expected.  The amount of squeezing and standing part movement is pretty much equivalent to what one would see in typical bends such as a Carrick Bend or Zeppelin Bend. 

This opens up several advantages for a Gnat Hitch attachment for a belay loop:

1.  Less rope usage.

2.  Knot simplicity.

3.  High security (http://igkt.net/sm/index.php?topic=6076.msg40833#msg40833).

4.  Reduced snagging risk because the gaping loop hole is eliminated.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 02, 2018, 10:27:48 AM
Quote
I think this nylon-melting myth is busted

Obviously an extensive battery of tests have been conducted and peer reviewed - which led to the alarming conclusion posted above.

The issue is not instantaneous 'melting', rather - it is the progressive damage caused by direct nylon-to-nylon contact which is exacerbated by knots that act like a noose. Obviously, at the moment of impact in a free-fall event, a 'noose' will try to cinch tight (like a hangmans noose) - and this will cause accelerated wear on the textile material of the climbing harness. Direct nylon-to-nylon contact during free-fall events is known to cause wear - a possible cause of some serious/fatal accidents (eg Dan Osman) - and a worn harness belay loop is thought to be a causal factor in Tod Skinners case. The point being that 'sawing' action of nylon rubbing against nylon is a known causal factor of accelerated harness wear.

If any novice climbers stumble across this forum and find this post - please consider this advice.
Please review the attached photos. Note the warnings on using a noose as a tie-in knot to a harness for climbing applications.
Only use knots that have a fixed eye...do not use knots that act like a noose (which collapse and cinch tight as load is applied).

I have only shown the #1047 F8 eye knot, and the #1010 derived EBSB Bowline. Another alternative is Scott's locked Bowline (which is one of the simplest locked/secure Bowlines discovered).

I repeat again my warning of not using knots that act like a 'noose' for tying a climbing rope into a harness.
Those who ignore this advice should visit this site: http://www.darwinawards.com
Darwin awards are given to people who - through acts of unbelievable stupidity - remove themselves permanently from Earth's gene pool.

Mark G

Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 02, 2018, 03:55:50 PM
I repeat again my warning of not using knots that act like a 'noose' for tying a climbing rope into a harness.
Those who ignore this advice should visit this site: http://www.darwinawards.com
Darwin awards are given to people who - through acts of unbelievable stupidity - remove themselves permanently from Earth's gene pool.

Mark G
I see you updated your photo to get the connection wrong!  Now you have the Gnat Hitch trying to catch two points ::).  You had a general noose/hitch attached to the single belay loop before (http://igkt.net/sm/index.php?topic=6075.msg40830#msg40830)! See screen grab below.  It makes it extremely hard to attribute this to a simple error on your part.

Is this what you stoop to when your theories fall apart?

I'll repeat; "the webbing stayed pristine, as should be expected.  The amount of squeezing and standing part movement is pretty much equivalent to what one would see in typical bends such as a Carrick Bend or Zeppelin Bend." 
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 02, 2018, 09:38:59 PM
Quote
I see you updated your photo to get the connection wrong!  Now you have the Gnat Hitch trying to catch two points

Oh dear.

The photos shown are typical climbing harnesses - that's how they are designed!
Your comment immediately reveals deficient knowledge about climbing in general.
Any experienced climber reading your reply would also immediately know that you dont know much about climbing in general.

Hmmmm - and you are giving advice that is bordering on negligence - that is, advising people that it is okay to tie-in with a knot that acts like a noose is negligent.

Edit Note: Highlighted the word 'negligent' to draw its attention to readers.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 02, 2018, 09:51:35 PM
Quote
I see you updated your photo to get the connection wrong!  Now you have the Gnat Hitch trying to catch two points

Oh dear.

The photos shown are typical climbing harnesses - that's how they are designed!
Your comment immediately reveals deficient knowledge about climbing in general.
Any experienced climber reading your reply would also immediately know that you dont know much about climbing in general.
Please.  You were even involved with this lengthy thread on the topic of tying into the belay loop:
http://igkt.net/sm/index.php?topic=4444.0

Also, you were showing tie-in to a single webbing point earlier.  Sorry, you can't have it both ways.  It should be fairly clear that the discussion is about a single hitch point (http://igkt.net/sm/index.php?topic=6075.msg40817#msg40817).

From the thread that spun off this discussion:

[...]
A secure hitch can be a viable option for many harnesses that have good single point tie-in location [...]

I also mentioned using the belay loop here: http://igkt.net/sm/index.php?topic=6081.msg40871#msg40871
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 03, 2018, 04:06:40 PM
Quote
Also, you were showing tie-in to a single webbing point earlier.  Sorry, you can't have it both ways.  It should be fairly clear that the discussion is about a single hitch point.

This thread is bordering on nonsense - I am almost aghast at how this is evolving into an almost oxymoron episode.

Quick educational tour is in order:
Recreational climbing harnesses come in 2 general designs as follows:
1. Single attachment point (mostly used by commercial school groups and some indoor climbing gyms); and
2. Dual attachment points (the most common type used by serious climbers - the climbing rope is fed through to capture 2 independent segments of the harness).

Now - you can try to obfuscate the crux of this matter as much as you like.
No matter which style of lower body recreational climbing harness (ie sit harness) you use - it is only advised to tie-in using a fixed eye knot. Tie-in knots that act like a noose significantly boost wear rates - via direct nylon-to-nylon (textile-to-textile) contact.
A noose will - a the moment of impact - collapse and cinch tight. A fixed eye on the other-hand, will not collapse and cinch tight.

A 'gnat' structure will act like a noose - it is not a fixed eye knot.

I an unaware of any climbing harness manufacturer in the entire world that would advise using a tie-in knot that acts like a noose. Most advise using #1047 (F8 eye knot) - which has a fixed eye. Any of the secure Bowlines can also be used (because they have a fixed eye that does not act like a noose).

I challenge you to find a climbing harness manufacturer that recommends a tie-in knot that acts like a noose. You wont find any...because it is obvious that using a noose will cause accelerated wear and tear on critical load bearing parts of the harness.

...

Now, I am trying to understand why you persist with this contest.
Any serious climbers who stumble across this thread will be stunned  by your advice that using a tie-in knot that acts like a noose is fine. They will (like me) be scratching their heads wondering why you are persisting with disseminating information that is bordering on negligence.

I think the underlying reason why you persist is deeply rooted in the fact that you don't like being challenged - you fee threatened - and this angers you. So you retaliate.
I can understand your basic human emotional need to retaliate - its sort of a flight or fight response (you choose to fight on to the bitter end no matter what the cost).

Look - it is obvious to me that you are not a lead climber. I am...I have been lead climbing (trad routes) since 1983 on a full-time basis - it is my occupation. I have personally established over 75 first ascents in Australia (ground up style - no prior top rope rehearsals or abseil pre-inspections). I have also attempted a first ascent in a satellite rock spire in the Ogre group (Karakorum Himalaya) and have several seasons of ice climbing in New Zealand south island (weather and time beat us in the end).

Search my name...Mark Gommers climbing - you will find the evidence.

I would be keen to see evidence of your lead climbing experience.

Interestingly, in all my long years of climbing experience - I have never seen anyone tie-in to their harness using a knot that acts like a noose.

I don't know if I care to reply anymore to this thread - because honestly, I'm getting bored with this child-like behaviour.

Mark G
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 03, 2018, 07:56:19 PM
Quote
This title more accurately reflects the precise nature of my concerns
Your concerns are arguably more narrow --a subset of...--
than the survey should be (as "nylon-on-nylon" warnings
come in other places).

As you note, it isn't necessarily that any single event will
be catastrophic to new rope, but some cumulative damage/wear
could result.  (There was a tragic case of a famous climber
 [Todd Skinner, yes (alas)]<-edit
--American-- whose belay loop was soooo badly worn (by
perhaps only normal events, but years of ...) that it broke
as he hung on rappel (3 years or so ago?).)

Roo's point about the cinching-upon-impact movement
being --debatably-- much like that in common knots
is worth thinking about --both from accepting as within
range the hitch, and cautioning about cyclic damage for
knots in general, and maybe esp. some that have such
"gentle curvature" of the SPart and extended interface
before a hard U-turn that ... there is much material to
elongate when heavily loaded!
(The bowline likely sees fair movement back'n'forth
through its collar, but at such low pressure as to matter
little.  But I have wondered at some of the knots I've
fiddled wrt to this issue.  E.g., I suspect that knots with
the degree of looseness of mirrored bowlines could take
multiple drops (say, FF-1 : = length of rope = of fall)
and keep *giving back* much material vs. clamping
tight, "jammed" around it; but will such giving/taking...
show with a "shiny" sheath from frictional heat, of
the SPart's first nipping loop drawing back'n'forth
over the outgoing eye leg *root* /crossing point?!)

So, if there is even a limit to degree of damage of any
single event --i.e., yes, it will hurt rope, but not nearly
to catastrophe-- , a tie-in w/a hitch MID-WAY as part
of an overall eye-knot could be reasonable (for those
liking N things to count that would have to fail ...   :D ),
as I previously mused.

--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 03, 2018, 08:00:00 PM
Quote
I think this nylon-melting myth is busted

Obviously an extensive battery of tests have been conducted and peer reviewed
 - which led to the alarming conclusion posted above.

The issue is not instantaneous 'melting',
rather it is the progressive damage caused ...

Well, where's the extensive (or even ANY, specifically noting
our issue) testing data/report for hitch-like damage?
Pitt addressed the more extended (duration) abuse of lowering.
(To which I add :: IF THE CLIMBER LOWERED HERSELF,
there's be roughly half the force on the line!  --well,
outside of a top-rope situation, there's all the clipped-in
points to deal with, but ... ).

--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 03, 2018, 08:10:07 PM
This opens up several advantages for a Gnat Hitch attachment for a belay loop:

1.  Less rope usage.

2.  Knot simplicity.

3.  High security.

4.  Reduced snagging risk because the gaping loop hole is eliminated.

I don't think that "high security" is going to sell.  IMO, I've
some doubt about something sooo simple (like the bowline,
vs. structures that are more involved.  Yes, folks groan (NEClimbing
poster remarked ...!) at the so-involved mirrored bowlines,
but that, and the DAV-rec'd BoaBight give good assurance
in having so much stuff involved that, even loosely set, they
resist further loosening, and show loosening with telltale length
of tail (i.e., upon the last tuckings undoing).

If the squeezed set[ting] of the gnat *tires* after some time,
in the firm, slick-sheathed, bend-resistant cordage, maybe
helped with some rubbing against the wall, there's nothing
but a prayer left.  (To this complaint, there are like a few
tail-tuckings --gratuitous to the Purist, but ...-- that can
come to mind.)

Then there are some who like that "gaping hole" to serve
qua belay loop; there has even been discussion re this
ring-loading of the fig.8 eyeknot's eye, apparently
tried and okay's (BMC?).


--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 04, 2018, 05:15:59 AM
Dan,

Would you be able to do me special request favor please?

Would you be able to track down a recreational climbing harness manufacturer that recommends a tie-in knot that acts like a noose?
Note: I use the term 'noose' to differentiate it from a tie-in knot that is a 'fixed eye'.

I would be most grateful if you could find such a harness manufacturer.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 04, 2018, 10:57:43 PM
... a recreational climbing harness manufacturer that recommends a tie-in knot that acts like a noose?

That's hardly answering any question, except what do
... recommend.  Softer would be whether they'd have
particular reason to warn against.  (After all, consider
that you're taking on some industry that recommends
NOT USING the bowline !)

--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 06, 2018, 12:42:25 AM
I browsed a couple of old (2008ish) gear catalogues of PMI,
Petzl, BlackDiamond, & OnRope1 --the BD one being pretty rockclimbing
centered, the others more broad or other-aimed (SAR, caving,
canyoneering, arborist).

I see a variety of harnesses.  SOME have a *clip-in* ring
of metal, which sort of concerns me re diameter (I've read
"10mm" for some separate rings, but am not sure that
what is part of the harness is as thick). Others have no
discernible means of closing --as though awaiting some
binding hitch or really snug eye to effect this (e.g., the
Goliath Expedition) !?  Some have two built-up attachment
eyes coming together, and the rockclimbing one's have a
belay loop connecting waist belt anchor point to the joined
leg-loops rather cord-like part; it seems that one will want
the looseness between waist & leg loops for activity, and
they should come together only on a fall being caught
(so a hitch would not be happy here).

It occurs to me to wonder at the compression of webbing
by the rope --esp. a hitch-- on catching a fall.  The lower
connecting point of the rockclimbing legloops is rather
rope-like, but the belay loop isn't --though I think that
it's advised NOT to tie-in to this--, nor other tape points.
Consider this one, the Fusion Climb Centar; anchor point
sure doesn't give much to hitch around (diameters, substance)!
www.amazon.com/exec/obidos/ASIN/B00J0W4Y92/ezclimbingharnesses-20 (http://www.amazon.com/exec/obidos/ASIN/B00J0W4Y92/ezclimbingharnesses-20)


 - - - - - - - -

Another tie-in-structure idea :
1) clove hitch to tie-in thread (well, if all so darn skinny!);

2) take hitch tail up and put in a bowline,

3) then bring eye-knot tail down to tuck *through*
the clove h. --i.e., run it along tie-in "thread",
which increased hitch-to bulk-- ; and finally

4) take tail --which needed to be long enough-- up
to tuck through the bowline's nipping loop,
giving a 3rd diameter and further security.

The eyeknot should be abutting the hitch,
and thereby giving what I'll call "security by crowding"
--i.e., neither adjacent knot can loosen much, because
the other is in the way!  (And yet both knots can be
moderately loose.)  (The mirrored bowline has this
sort of slack security if properly dressed --so many parts
bumping into each other.)

And, no, this isn't violating the NO HITCHES rule,
really; the clove operating really as twin eyes
and distributing force over the 4 strands leading
around the anchor point (2 eyes, i.e.).


--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 06, 2018, 12:44:16 AM
Quote
you're taking on some industry that recommends
NOT USING the bowline !

A distraction/diversion off topic.

To save a lot of wasted time - I think you and I both know that there is no rock climbing harness manufacturer on planet Earth that recommends using a knot that acts like a noose as a means of 'tying-in'. This is not a comment...it is a fact.

Perhaps another way to look at this issue is to ask "Why".
That is; Why is it that rock climbing harness manufacturers never recommend a tie-in knot that acts like a noose?
Good question!

Answer: A noose will attempt to collapse at the moment of impact in a free-fall event.
Look at this photo: http://cruxcrush.com/2015/04/01/ten-reasons-why-men-are-better-at-climbing/ (No - not Arnold, but the one underneath!)
Now imagine at the moment of impact - what would happen if the climber had tied in with a 'noose'?

We already know that nylon-on-nylon isn't good in high energy falls.
I did some experiments several years ago with 3 wrap prusik hitches subjected to a factor 1 free-fall. The prusik hitch disintegrated in a puff! (see attached photo).
If you look at the photo - you will see evidence of melting (remnants of the prusik hitch are 'fused' to the parent rope).

Nylon-on-nylon saw-through is thought to be a causal factor in the death of Dan Osman.
Link: https://en.wikipedia.org/wiki/Dan_Osman (scroll down to 'death')

And please visit this link: https://groups.google.com/forum/#!topic/rec.climbing/gW92OrNs7_o
Report from:
 Chris Harmston
Quality Assurance Manager. Materials Engineer BS, ME.
Black Diamond Equipment Ltd

His conclusions were: "What is to be learned from this accident?  NEVER LET NYLON SLIDE AGAINST NYLON!  You should already know this."

...

Anyhow, I think there is sufficient information here to put the gnat (noose) quietly to bed. It definitely has its place in the world of knotting but, that place is not as a tie-in to a rock climbers harness.

EDIT NOTE: Links should be working now.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 06, 2018, 12:57:01 AM
Anyhow, I think there is sufficient information here to put the gnat (noose) quietly to bed. It definitely has its place in the world of knotting but, that place is not as a tie-in to a rock climbers harness.
Huh?  The test results show no ill effect of the Gnat Hitch on webbing.

If you follow your blind prejudice to its logical end, you're going to have to put your Grim Reaper doodle on every knot, since the level of standing part motion, and thus nylon-on-nylon motion, is virtually equivalent.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 06, 2018, 01:03:07 AM
roo

Could you please visit this website: http://www.darwinawards.com/

If you follow your blind logic to its bitter end - and tie-in to a rock climbing harness with a gnat (noose) - I think we will find your name posted on Darwin Awards.

I personally would not like to see you remove yourself from Earths gene pool.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 06, 2018, 01:05:35 AM
roo

Could you please visit this website: http://www.darwinawards.com/

If you follow your blind logic to its bitter end - and tie-in to a rock climbing harness with a gnat (noose) - I think we will find your name posted on Darwin Awards.

I personally would not like to see you remove yourself from Earths gene pool.
Reported to moderators.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 06, 2018, 01:08:29 AM
Quote
Reported to moderators.

Thank you.

Like I said, it was a genuine feeling of remorse. I do not wish to see you injured of killed. That is a fact.
Its not an insult. Its expressed as a concern.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 06, 2018, 05:07:20 AM
Quote
Another tie-in-structure idea :
1) clove hitch to tie-in thread (well, if all so darn skinny!);

2) take hitch tail up and put in a bowline,

3) then bring eye-knot tail down to tuck *through*
the clove h. --i.e., run it along tie-in "thread",
which increased hitch-to bulk-- ; and finally

4) take tail --which needed to be long enough-- up
to tuck through the bowline's nipping loop,
giving a 3rd diameter and further security.

The eyeknot should be abutting the hitch,
and thereby giving what I'll call "security by crowding"

Trying to decipher and tie this suggested composite knot....

A close analog appears to be illustrated at #1853 (but there needs to be #1245 clove hitch formed around the harness tie-in point) - just trying to establish a mental image.
With all the routing, and re-routing of the tail + padding to the clove hitch, I think this will be hard to 'guesstimate' the correct length of rope to complete this composite knot.
Sorry - I just don't see this suggestion as ever becoming a popular tie-in knot.

And the direct clove hitch interface to the harness tie-in loop with added padding - while not acting as a noose - it is difficult to understand if any net movement would occur at the moment of impact in a free-fall (would need to be tested and verified).
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 06, 2018, 11:54:30 PM
Trying to decipher and tie this suggested composite knot....
Just Do It!
The simple scheme actually should need no particular
instructions :: connect to harness w/clove h.
(for reasons indicated); leave long enough tail so
to be able to put in a bowline
and then thread tail back through hitch,
and ... .
Frankly, as I write this, the main point is having
the eye knot snug to the hitch AND the hitch's
tail of course used in the eye (done in tying the
eye knot).
At this point --never mind the threading through
hitch, and then further, through eye knot--,
there should be that security-via-abutting aspect.

BUT, the tucking at least in the first case does
add a factor; then the last tucking added that
"3rd diameter" (but one could skip the troublesome
tucking and do this directly).

Note that in some earlier and more complicated
formulation, I had a strangle gripping the eye's tail,
being tyed first in hitch tail,
so to be a possible stopper if ... (incredible loosening occurred).
That's admittedly going far in defence for unlikely scenario.
But the binder couldn't untie/loosen so long as it was between
the hitch & eye --more of the "abutting" factor.


.:.  So, in some simpler ways, one can get hitch-wise
load distribution and maybe tail-nipping.

(And I wonder at the repeated rope movement of the
turNip of a repeatedly fallen upon (working some "sport
route") bowline?!  (Consider that with all of the
possible tucking in the most-tucked case, there'd be
3 strands in the turNip, and the outgoing eye leg
connecting eye knot to hitch :: what are the tensions
on those?  --I'm thinking that the outgoing eye leg
gets well less than usual, unless the SPart draws
heavily around into it?!  100% going to 4x25% ?!


--dl*
====
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Bipbip on February 07, 2018, 01:32:20 AM
Not a full time climber, but here is my opinion on the matter : rock climbers tend to regard new techniques with suspicion. Though I sometimes found this annoying I think it comes from a place of wise cautiousness : who would like to discover an unexpected mode of failure at their expense when failure could mean a long drop to the ground ?

Tying in to a climbing harness whith a noose seems a rather silly idea at first, but things are often more complex than our understanding of them, so maybe I'm wrong and some generation of climbers to come will adopt the gnat hitch as their standard tie in knot and fig.8 will be a thing of old timers, but that's not going to happen without solid proof of its security. Exactly for that same reason that things can really be different than what we expect them to be, it is unwise to advocate such a change in practise on mere guesses. We may not know for sure that a fixed loop is safer than a noose, but neither do we know that a noose is safe at all for this purpose ! On the contrary, though a fixed loop may not be the safest possible method of tying to a harness, we have ample evidence that it is safe enough. This alone should keep us from tying to a climbing harness with a noose and from advising anyone to do so.

What it doesn't prevent us to do, however, is discussing the pro and cons of this method, it's not likely to change the way climbers are tying themselves but it can bring a better understanding of knots and their application.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 01:44:10 AM
Quote
Just Do It!
Sounds like an slogan for Nike   :o

Ok - I did just did it.
I will be honest and state that this 'composite' structure is something that will never develop legs and gain popularity in the climbing community. People will just stick with a fixed eye knot such as #1047 F8 eye knot (or a secure Bowline). Its too fiddly and not as quick and convenient as standard tie-in eye knots.

If your main intent is to add dual eyes to the harness tie-in point - why not just experiment with a derivative of #1072 Portuguese Bowline or a derivative of #1080 Bowline on-a-bight (where no back-flip maneuver is performed) - I'll play around with these ideas and maybe snap a photo if it looks promising.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 02:10:03 AM
Quote
What it doesn't prevent us to do, however, is discussing the pro and cons of this method

Hello Bipbip, I agree about the notion that 'discussing' concepts is a good thing.
My disagreement with roo is that he made a declaration that a noose is safe to use as a tie-in to a rock climbing harness for climbing purposes. This is where I draw the line, because it progresses beyond discussion and constitutes advice.
The gnat structure acts like a noose - and we have ample empirical evidence (see my previous post about Dan Osman) that nylon sawing across nylon in a free-fall event is not good. I also posted a photo of a prusik hitch that disintegrated on a factor 1 fall (which further shows the danger of nylon-on-nylon during fall event).

Quote
though a fixed loop may not be the safest possible method of tying to a harness, we have ample evidence that it is safe enough. This alone should keep us from tying to a climbing harness with a noose and from advising anyone to do so.
Indeed. We have empirical evidence that a fixed eye knot has worked since the 1950's (Hillary used a Bowline to climb Everest in the 1950's and we can see photos of him using said Bowline). Every day around the world, hundreds of people are climbing outdoors using fixed eye knots as a tie-in.
We are not seeing mass deaths from mass failures of the fixed eye knots.
Harness manufacturers know this too - and thats why they only recommend tying-in with a fixed eye knot.

In my view, roo is taking a legal risk by openly giving advice that a noose is a safe method of tying a dynamic rope to a rock climbing harness. Although I think it would be difficult for any plaintiff to sue him - since the plaintiff doesn't know his real name or address (although IGKT could be subpoenaed/compelled to reveal these details in a court case). Furthermore, the 'plaintiff' would likely be killed or in coma from a serious fall - so it would be the family that would sue in their childs name. Litigants in a court would also have to prove that roo had a 'proximate' relationship with the plaintiff - and that his words constituted negligent advice (I am not sure if there are any existing cases which set a precedent).

roo has claimed that he has tested his gnat (noose) - and openly declares that it 'passes' his test regime. I note that his test results have not been peer reviewed nor have others attempted to reproduce his test results under strict lab conditions.

roo also has not submitted his findings to harness manufacturers to solicit their views/opinions (which act to contradict their advice and instructions). I would suggest that rock climbing harness manufacturers would not support roo's advice to use a tie-in knot that acts like a noose.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 07, 2018, 02:44:48 AM
We may not know for sure that a fixed loop is safer than a noose, but neither do we know that a noose is safe at all for this purpose
The evidence says otherwise.   The test data shows that the Gnat Hitch does not cause ill effect on the webbing, and that it is amply secure, and its security (http://igkt.net/sm/index.php?topic=6076.msg40833#msg40833) exceeds many common means of attachment.  Its use is thus actually safer.

The science of safety cannot advance if we close our eyes to the evidence.  Think of all the bowline variants that agent_smith advances in his paper.  With even less evidence of their security and lack of heat damage, he proposes them for life support use.

But the heat damage issue is rather silly.  When the amount of standing part motion is virtually equivalent for a Gnat Hitch or Zeppelin Bend, or some Bowline variant, or a Double Fisherman's Knot, it makes absolutely no sense to chase that lead expecting the rope to melt.

Now, if you want to reproduce the test results, that's perfectly fine.  I always recommend new users to test knots in the conditions and materials that they anticipate, since those conditions may be somewhat unique.  Every user has to decide which knots are the best fit for their purpose.


Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 03:00:46 AM
Quote
The evidence says otherwise.

With all due respect: Who's evidence?
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 07, 2018, 03:45:01 AM
Quote
The evidence says otherwise.

With all due respect: Who's evidence?
I'm not stopping you from doing some tests.   If you prove it to yourself, it'll make much greater of an impact than merely reading about it.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 03:59:20 AM
That wasn't an answer to my question.

So I'll ask the question again: "Who's test results are you referring to?"

And to take it a step further:
1. Have these test results been peer reviewed?
2. Have these test results been submitted to rock climbing harness manufacturers for their comment?
3. And to be 100% crystal clear - are you advising to the world at large - that a tie-in knot to a rock climbers harness can be a noose?

And for any experienced rock climbers who may be reading these posts (I feel for them) - it would be fair and reasonable of you to supply clear answers to these questions.

EDIT: Grammar edit for clarity
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 07, 2018, 04:23:46 AM
That wasn't an answer to my question.

So I'll ask the question again: "Who's test results are you referring to?"

And to take it a step further:
1. Have these test results been peer reviewed?
2. Have these test results been submitted to rock climbing harness manufacturers for their comment?
3. And to be 100% crystal clear - are you advising to the world at large - that a tie-in knot to a rock climbers harness can be a noose?
You know very well that I've been conducting the tests.  And I also know that you've been seemingly unwilling to do the same, with a deafening lack of evidence of the assertions you've been making (nylon melting, etc).
 
I also find it odd that you want me to submit my tests to manufacturers when:
I would disregard any advice to the contrary - and I stand by my advice outlined in this post. This includes any published advice even from some manufacturers - who in some cases do not have vast experience or expert level knowledge themselves. Some manufacturers have little actual field experience and some are over-populated with sales staff who are good at selling but not much else (ie spin doctors).
Mark

I notice in your Analysis of Bowlines paper, you don't even have any test results to submit to manufacturers about the knots you recommend for life support.

I wish you'd spend half of the energy you put into being so defensive with your list of "must haves" in testing into doing some actual testing of your own.   
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 04:41:54 AM
Quote
deafening lack of evidence
Yes - it is deafening lack of evidence to prove your claim.
It isn't falling on my deaf ears though. I am still listening intently for you to answer the questions.

Quote
I also find it odd that you want me to submit my tests to manufacturers
I find it odd that you try to obfuscate the issue.
Digging up old posts proves what exactly?
You are trying to apply a meaning to old words out-of-context.
Again, you are obfuscating the issue - about your claim that a noose can be used as a tie-in knot to a rock climbers harness.

Quote
you don't even have any test results to submit to manufacturers about the knots you recommend for life support
Obfuscation.
The issue is using a noose as a tie-in knot to a rock climbers harness.
The secure Bowlines in my paper are fixed eye knots - they do not act like a noose.
Secure Bowlines such as Scott's locked Bowline function well with EN892 and EN1891 life support ropes.
I routinely tie-in with the #1010 derived EBSB (secure) Bowline for lead climbing - which is a fixed eye knot (it is not a noose).
I have personally led over 100 routes using this knot as a tie-in (and fallen on it).
I have also started to use Scotts locked bowline for building anchors and also as a tie-in to a rock climbing harness. I haven't used Scotts locked Bowline as much as the 'EBSB' Bowline...but so far it is functioning perfectly well. I have not a had a free-fall onto Scotts locked Bowline yet...

Quote
I wish you'd spend half of the energy you put into being so defensive

The person who is actually being defensive is you.
Reasoning: You have made a declaration to the world at large (using the IGKT forum as a vehicle) - stating that it is safe to use a tie-in knot that acts like a noose to a rock climbers harness. This is effectively giving advice.
I challenged your assertion.
You are being defensive because you don't like being challenged - it irritates you.

I believe that the onus of proof falls upon you to prove your claim that it is safe to tie-in to a rock climbing harness with a knot that acts like a noose.

Because many climbers lives might be at risk because of your advice to use a noose, this places your claim in a high risk category - and so there is a higher burden of proof that must be applied. This is particularly so because it is also counter to what rock climbing harness manufacturers advise.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 04:50:17 AM
I think this contest is going nowhere.

I think this thread should be locked by the moderators.
I saying this not because of any ill feeling...rather, it is evident that roo will continue to infinity and beyond with his claim that a noose can be used as a tie-in knot to a rock climbers harness.

And I will respond to save lives - because it is the right thing to do.

So an impasse is reached...with neither side backing down - so this thread ought to be locked in my view.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 07, 2018, 04:56:47 AM
- so this thread ought to be locked in my view.
You don't have to keep responding if you wish, but why not at least keep the thread open in case someday you find some photographic evidence of nylon melting?

I'm willing to give you that chance.  Hell, if I find such an instance, I'll take a photo and post it.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: agent_smith on February 07, 2018, 05:14:22 AM
Quote
I'm willing to give you that chance.

I have recently been learning why 'flat Earthers' and 'moon landing conspiracy' theorists persist in their beliefs.
The reason why - I surmise - is that they firmly believe in what they are saying - and simply ignore the evidence around them.
How do you prove the Earth is a sphere to a "flat Earther" who simply ignores the evidence?

Moon landing conspirators have even gone so far as to confront the actual Apollo astronauts (Buzz Aldrin and Gene Cernan) and get them to swear on a bible on camera. Buzz Aldrin punched the guy in the face!

...

I note that roo always wants to do the following:
1. Get the last word in - no matter what; and
2. Use short, sharp combinations of words to acutely make his point.

If my predictions are correct, roo will reply again.

If I decide to no longer reply in this thread - its nothing to do with accepting roo's challenge...rather, its more of a case of not being bothered to argue with someone who cannot accept the empirical evidence of the detrimental effects of nylon-sawing-against-nylon in a free-fall event (analogy: how do you argue with a moon landing conspiracy theorist?).

Never tie-in to a rock climbing harness with a knot that acts like a noose...all else is noise.
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: roo on February 07, 2018, 05:21:08 AM
I have recently been learning why 'flat Earthers' and 'moon landing conspiracy' theorists persist in their beliefs.
Comparing me to "flat Earthers"?  Gee, thanks.   ::)  But I'm the only one providing hard evidence in this thread.  We're still waiting for your pictures of melted belay loop webbing from Gnat Hitch anchorage.

All else is noise.

(https://i.pinimg.com/originals/9a/c8/cb/9ac8cbc4657d221fd845a52b945c428c.jpg)
Title: Re: Cordage Movement & Melting Damage Risk?!
Post by: Dan_Lehman on February 10, 2018, 05:05:44 PM
Some simple, "backyard" drop tests of something
gnat-hitch'd (or other) to a rope slung mass
--the rope sling able to be chosen from disposable
stuff to stand in for the nylon harness loop-- and
a check on things made, vs. this continued nonsense
now into flat earth.  (We have a damn White House
to produce Alternative Facts --they need no help,
nor encouragement!)

Frankly, I don't wanna have to try to untie a fallen-upon
gnat hitch, but that's another matter.

--dl*
====