Euro Death Knot Testing
Tom Moyer
actually have some information (not that that's really a requirement for
posting on rec.climbing), here goes ...
I learned this weekend at the International Technical Rescue Symposium
that the figure eight version of the Euro Death Knot is being actively
taught to climbers in Canada. I had thought that only the overhand
version was in widespread use and that everyone pretty much recognized
the figure eight to have the potential to be a really quick trip to the
bottom of the crag.
For those who don't know what this knot is, check out the drawings at
http://www.petzl.com/FRENG/tech/techframe.html
Failure of the figure eight version of this knot has already caused a
fatality in1994 at Seneca Rocks and an accident in 1995 in Salt Lake.
Both of these knots would politely be called "mis-loaded" and impolitely
would be called, well - the "Euro Death Knot". The failure mode for the
figure eight version is to flip/invert/capsize, which then becomes the
identical twin of the first knot, just with shorter tails. After enough
of these events there are no tails left and the knot fails. Leaving at
least a foot of tail is recommended.
I spent a few hours yesterday in my front yard with a come-a-long and a
load cell to try to get some decent information on this. The results
still leave room for plenty of argument. People who don't like the
figure eight will say, "See, it slips at really low loads!" People who
do like it will say, "See, if you dress it right, pretension it well,
and leave long tails, it doesn't fail. Besides, I've been using it for
years and I'm still alive!"
If you're too impatient to wade through the results below, the short
answer is that if you do all those things, you should be ok. My question
is - why would you take the chance? If you're in a situation where a
stuck rope would be catastrophic, use the overhand. It has all the same
advantages and not nearly as much risk.
Be safe - the body we have to scape off the rock may be yours.
- Tom Moyer
Salt Lake County Search and Rescue
Rope A: Mammut 11 mm static - used
Rope B: Unknown manufacturer red 11 mm dynamic - used
Rope C: ABC/Sterling 11 mm static - new
Rope D: Blue Water II+ 11 mm static - new
Rope E: ABC 8mm static - new
Rope F: 1" Tubular Webbing
Test #1: RopeA/RopeA - figure 8 - well dressed and pretensioned
Capsized at 750 lb, Rope broke at 2520 lb
Test #2: RopeB/RopeB - figure 8 - well dressed and pretensioned
Capsized at 590 lb, Capsized at 2280 lb, Rope broke at 2560 lb
Test #3: RopeB/RopeB - figure 8 - well dressed, pretensioned loosely
Capsized at 290 lb, Stopped Test at 2800 lb
Test #4: RopeB/RopeB - figure 8 - sloppy, crossing strands and loose
Capsized at 110 lb, Capsized at 140 lb, Capsized at 340 lb,
Capsized at 420 lb, Capsized at 530 lb, Stopped Test at 2500 lb
Test #5: RopeB/RopeB - overhand - well dressed and pretensioned
Capsized at 1400 lb, Capsized at 1940 lb, Capsized at 1990 lb,
Rope Broke at 2070 lb
Test #6: RopeA/RopeA - overhand - well dressed and pretensioned
Stopped Test at 2540 lb
Test #7: RopeC/RopeC - figure 8 - well dressed and pretensioned
Stopped Test at 2500 lb
Test #8: RopeD/RopeD - figure 8 - well dressed and pretensioned
Capsized at 2170 lb, Stopped Test at 2550 lb
Test #9: RopeB(11mm)/RopeE(8mm) - figure 8 - well dressed and
pretensioned
Capsized at 1330 lb, Capsized at 1550 lb, 8mm broke at 2700 lb
Test #10: RopeB/RopeB - figure 8 - well dressed and pretensioned - WET
Capsized at 470 lb, Rope broke at 2790 lb
Test #11: RopeB/RopeB - figure 8 - well dressed, pretensioned loosely -
WET
Capsized at 290 lb, Rope broke at 2470 lb
Test 12: RopeF/RopeF (webbing) - well dressed and pretensioned
Webbing broke at 2070 lb
Clyde Soles
> If you're in a situation where a
> stuck rope would be catastrophic, use the overhand. It has all the same
> advantages and not nearly as much risk.
Yep, your results confirm mine that I posted here several years ago.
There is NO advantage of the fig-8 version. Pity people don't listen.
Both the AMGA and CMGA are guilty on this.
--
DISCLAIMER: Unless otherwise indicated, this post is personal
opinion and NOT an official statement of my employer.
Karl Lew
and ... I'm still for the overhand EDK.
--Karl
Tom Moyer <tmo...@alum.mit.edu> wrote in message
news:382A0475...@alum.mit.edu...
> is - why would you take the chance? If you're in a situation where a
> stuck rope would be catastrophic, use the overhand. It has all the same
> advantages and not nearly as much risk.
>
Bob Harrington
Tom Moyer <tmo...@alum.mit.edu> wrote:
Wow, thanks.
>Test 12: RopeF/RopeF (webbing) - well dressed and pretensioned
>Webbing broke at 2070 lb
What knot?
Bob
Tom Moyer
- Tom
Michael Riches
> Test #5: RopeB/RopeB - overhand - well dressed and pretensioned
> Capsized at 1400 lb, Capsized at 1940 lb, Capsized at 1990 lb,
> Rope Broke at 2070 lb
>
> Test #6: RopeA/RopeA - overhand - well dressed and pretensioned
> Stopped Test at 2540 lb
Tom...Thanks! I have often wondered how this knot would handle itself under
load. It's recommended, but with the name of the Euro Death Knot, it has
always had me slightly worried...This alleviates a lot of my fears and
hopefully some of the fears of those out there that have been tempted to use
it but backed off for the same reason...only to tie something twice as big
and bulky and then jammed it real good...
--
The Rockrat (Convert)
Bob Harrington
Thanks, now please post a summary and highlights of the the ITRS.
And if it's not too much trouble, could you put that comealong and
load cell on an overhand tied with an 11 mm and 8 mm, soaking wet?
:^)
Bob
Al Black
Clyde Soles <cso...@rmi.net> wrote:
>Tom Moyer <tmo...@alum.mit.edu> wrote:
>
>> If you're in a situation where a
>> stuck rope would be catastrophic, use the overhand. It has all the same
>> advantages and not nearly as much risk.
>
>There is NO advantage of the fig-8 version. Pity people don't listen.
>Both the AMGA and CMGA are guilty on this.
Nod, and thanks to both of you for your testing!
Perhaps they are changing, in the AMGA and CMGA instruction manual just
published (1999), here's what they say:
Flat overhand:
Common uses: Connecting ends of similar diameter rope for low load
scenerios (e.g., rappelling). Less prone to inverting than the flat
figure 8 but harder to untie after being loaded.
Flat figure 8
Common Uses: Connecting ends fo a similar diameter rope
rope for low load scenerios (e.g., rappelling).
Just my opinion, but they should be doing a bit better than this given a)
that Clyde's (and others) data has eben out there for quite a while, and
b) that according to the damn manual guides are supposed to be current on
the recent techneques.
Oh well back to the regularly scheduled flame fest.
al
--
david_h...@my-deja.com
> I learned this weekend at the International Technical Rescue Symposium
> that the figure eight version of the Euro Death Knot is being actively
> taught to climbers in Canada.
I'm a little curious about who's teaching this as over the years I have
yet to meet a teacher (in the southern Ontario region) who does.
>
> For those who don't know what this knot is, check out the drawings at
> http://www.petzl.com/FRENG/tech/techframe.html
Here's the exact URL:
http://www.petzl.com/FRENG/tech/knots.html
>
> Failure of the figure eight version of this knot has already caused a
> fatality in1994 at Seneca Rocks and an accident in 1995 in Salt Lake.
>
It was a Toronto-area climber killed in the Seneca Rocks accident.
However, the story I heard is that he had been taught the figure-eight
setup by a guide in the Adirondacks.
Cheers,
David Henderson
Toronto
Sent via Deja.com http://www.deja.com/
Before you buy.
Michael Just Hansen
Thanks,
Michael
benc...@my-deja.com
Why are the numbers all over the place with similiar type ropes but
different brands?
Does the either have an advantage with small diameter, static, mixed
diameter ropes?
Has any one every died from marking their rope with a sharpie pen?
What does a loosely tied or wet fishermans break at?
Rope B seems a little funky. Even with the overhand it still inverted
at 1500lbs. What's up with that rope? Was it old and fuzzy?
Steve Miller
Nice job! Very useful information, thank you! The setups with repeated
inversions are especially scary. One question though - when the ropes broke,
was it always at the knot? Thanks. ...Steve
Dave Andersen
> I am new to this so could someone tell me what "The Euro Death Knot" is?
An overhand knot in two strands of rope to join them together.
(ends)
(rest of rope) ------------- <-- rope 1
^^^^^^^^^^^^ <-- rope 2
Place 'em parallel to each other, leave *lots* of tail (I usually go for
a minimum of a foot) and tie an overhand in them both.
Works very well for joining ropes for a rappel or other low-load
situation. Works far better than a figure-8. As Tom's data pointed out
very effectively, tighten it well before rapping on it, and make sure the
tails are long, and you'll be peachy fine.
-Dave
--
work: dga - at - lcs.mit.edu me: angio - at - pobox.com
MIT Laboratory for Computer Science http://www.angio.net/
Nate
> Yep, your results confirm mine that I posted here several years ago.
> There is NO advantage of the fig-8 version. Pity people don't listen.
> Both the AMGA and CMGA are guilty on this.
I also seem to recall you driving home how safe and practical this knot
was - the overhand that is.
I mean, come on, Clyde - did you bother to actually read this data??
> Tom Moyer <tmo...@alum.mit.edu> wrote:
> Rope B: Unknown manufacturer red 11 mm dynamic - used
> Test #4: RopeB/RopeB - figure 8 - sloppy, crossing strands and loose
> Capsized at 110 lb, Capsized at 140 lb, Capsized at 340 lb,
> Capsized at 420 lb, Capsized at 530 lb, Stopped Test at 2500 lb
>
> Test #5: RopeB/RopeB - overhand - well dressed and pretensioned
> Capsized at 1400 lb, Capsized at 1940 lb, Capsized at 1990 lb,
> Rope Broke at 2070 lb
Duh! A well dressed overhand is inverting! How about a sloppy one,
like for the figure 8 in test #4? Too bad Tom did't take data for a
sloppy overhand, but I wouldn't exactly call it a reach to infer ...
especially when a well dressed figure eight seems to hold.
How about hundreds of people tieing this knot with several different
qualities of rope - like a nice smooth new one - or a wet one??
No thanks! I'll stick with something well proven and familiar - and
safe.
Let's not forget the accident in the Tetons where the client reported
the knot (overhand) "untied before my eyes" or some such comment with
similar meaning.
> Be safe - the body we have to scape off the rock may be yours.
Nice job on the testing, but why is it all you rescue types speak the
same line?
- Nate
--
Nate Beckwith - Boulder, CO
http://www.netone.com/~nate
Kyle Rudnick
Karl Lew <ka...@climerware.com> wrote in message
news:80d0h0$9ml$1...@news.intuit.com...
> Wow! Real science! Thanks for all the work.
> and ... I'm still for the overhand EDK.
> --Karl
>
> Tom Moyer <tmo...@alum.mit.edu> wrote in message
> news:382A0475...@alum.mit.edu...
> > I know this has been the subject of lots of flaming already, but since I
> > actually have some information (not that that's really a requirement for
> > posting on rec.climbing), here goes ...
> >
> > that the figure eight version of the Euro Death Knot is being actively
> > version was in widespread use and that everyone pretty much recognized
> > the figure eight to have the potential to be a really quick trip to the
> > bottom of the crag.
> >
> > http://www.petzl.com/FRENG/tech/techframe.html
> >
> > fatality in1994 at Seneca Rocks and an accident in 1995 in Salt Lake.
> >
> > would be called, well - the "Euro Death Knot". The failure mode for the
> > figure eight version is to flip/invert/capsize, which then becomes the
> > identical twin of the first knot, just with shorter tails. After enough
> > of these events there are no tails left and the knot fails. Leaving at
> > least a foot of tail is recommended.
> >
> > I spent a few hours yesterday in my front yard with a come-a-long and a
> > load cell to try to get some decent information on this. The results
> > still leave room for plenty of argument. People who don't like the
> > figure eight will say, "See, it slips at really low loads!" People who
> > do like it will say, "See, if you dress it right, pretension it well,
> > and leave long tails, it doesn't fail. Besides, I've been using it for
> > years and I'm still alive!"
> >
> > If you're too impatient to wade through the results below, the short
> > answer is that if you do all those things, you should be ok. My question
> > stuck rope would be catastrophic, use the overhand. It has all the same
> > advantages and not nearly as much risk.
> >
> >
> > Salt Lake County Search and Rescue
> >
> >
> > Rope A: Mammut 11 mm static - used
> > Rope D: Blue Water II+ 11 mm static - new
> > Rope E: ABC 8mm static - new
> > Rope F: 1" Tubular Webbing
> >
> > Test #1: RopeA/RopeA - figure 8 - well dressed and pretensioned
> > Capsized at 750 lb, Rope broke at 2520 lb
> >
> > Test #2: RopeB/RopeB - figure 8 - well dressed and pretensioned
> > Capsized at 590 lb, Capsized at 2280 lb, Rope broke at 2560 lb
> >
> > Test #3: RopeB/RopeB - figure 8 - well dressed, pretensioned loosely
> > Capsized at 290 lb, Stopped Test at 2800 lb
> >
> > Capsized at 110 lb, Capsized at 140 lb, Capsized at 340 lb,
> > Capsized at 420 lb, Capsized at 530 lb, Stopped Test at 2500 lb
> >
> > Test #5: RopeB/RopeB - overhand - well dressed and pretensioned
> > Capsized at 1400 lb, Capsized at 1940 lb, Capsized at 1990 lb,
> > Rope Broke at 2070 lb
> >
> > Stopped Test at 2540 lb
> >
> > Stopped Test at 2500 lb
> >
> > Capsized at 2170 lb, Stopped Test at 2550 lb
> >
> > pretensioned
> > Capsized at 1330 lb, Capsized at 1550 lb, 8mm broke at 2700 lb
> >
> > Test #10: RopeB/RopeB - figure 8 - well dressed and pretensioned - WET
> > Capsized at 470 lb, Rope broke at 2790 lb
> >
> > Test #11: RopeB/RopeB - figure 8 - well dressed, pretensioned loosely -
> > WET
> > Capsized at 290 lb, Rope broke at 2470 lb
> >
Karl Lew
Thou must do due penance and slog over to ye olde tome,
www.petzl.com, where thou must seek the wisdome therein
round about rappeling. Give up hope not, lest ye fall
into despair, knot knowing thy overhands from thy death
knots.
--Karl
Kyle Rudnick <imam...@actcom.co.il> wrote in message
news:80esb2$oat$1...@lnews.actcom.co.il...
david_h...@my-deja.com
> I am new to this so could someone tell me what "The Euro Death Knot" is?
>
direction and tie a figure-eight-on-a-bight with both (two half twists
and then poke the tails through the eye). As indicated by the data, this
knot distorts as low weights and can untie.
The safe version involves tying a figure-eight-on-a-bight on *one* rope
and then rethreading the second rope through the figure-eight -- from
the OPPOSITE direction. If done properly, the tails should be pointing
in opposite directions.
Though strong, this version has a bulky profile and is likelier to snag
when you're pulling your ropes.
Cheers,
David Henderson
Toronto
Tom Moyer
double fisherman's knots for comparison. I'll post them next - but first,
some answers to Ben's questions - just my opinions & happy to hear others.
- Tom
benc...@my-deja.com wrote:
> What kind of numbers make you guys happy in a normal non-rescue rappel?
In my experience, knots that fail by breaking are fairly predictable. Knots
that fail by slipping (like prusiks for example) vary with the type of
rope, the diameter, how well the knot is dressed, how hard it's preloaded,
how long the tails are, whether pulled against an object, whether clean or
dirty, wet or dry, icy, etc etc etc. If a knot/rope breaks repeatedly at
500 lbs, I'd be fine rapping on it. If it slips at 1000, it makes me
nervous. There's a reason we don't use either EDK for rescue loads.
> Why are the numbers all over the place with similiar type ropes but
> different brands?
That's the way that knot's gonna behave. You have to believe there are
combinations I haven't tried that go at a lot lower forces.
> Does the either have an advantage with small diameter, static, mixed
> diameter ropes?
From the numbers (see my next posting for the overhand numbers) they look
about the same for mixed diameter ropes. Keep in mind that this is one
sample only. There's *no one* I know that recommends either version of the
EDK for mixed diameter ropes. Double fisherman's is the recommended knot
for this situation.
I was surprised to see that the EDK looks *better* in static rope than
dynamic. Gotta try more ropes before saying that's always true.
> Has any one every died from marking their rope with a sharpie pen?
Don't think so - but if they have, I sure want to know about it.
> What does a loosely tied or wet fishermans break at?
See tests in next post
> Rope B seems a little funky. Even with the overhand it still inverted
> at 1500lbs. What's up with that rope? Was it old and fuzzy?
Yep - old, fuzzy, and retired. Now in lots of little pieces. Chris H
offered to give me some pieces of new BD dynamic rope in various sizes for
testing. When he does, I'll post the results. Until then, I'm not pull
testing the ropes I still climb on.
Tom Moyer
fire...
Some comments:
When the overhand inverts, it doesn't really do the same thing as the 8 does.
The 8 flips completely around and it's really obvious. It also eats a huge
chunk of the tails when it does. The overhand kind of twists a little, some
more rope goes through the knot, and the force goes down. Any time I pulled on
the come-a-long and the force went *down* a few hundred pounds or more, I noted
the peak force before it happened. I'm going to change my terms and call it
"rolled" to differentiate it from way the figure-eight behaves.
As before, all rope breaks (with one exception noted below) happened at the
knot being tested.
Tests 18, 19, and 20 are on double fisherman's knots, pretty much the gold
standard for comparison. As before, the load is on a single strand, with a
figure eight on a bight at each end. For #19 and #20, the double fisherman's is
loose and mis-tied in every way I can think of that you could still sort of
call it a double fisherman's knot. Definitely the worst excuse for a DFK I've
ever seen.
A friend of mine (a Canuck) talked this morning to a director with the
Association of Canadian Mountain Guides and he told me that they have stopped
recommending the figure 8 version. The accepted practice now is the overhand
version, although some folks continue to use the figure 8 style.
It's pretty clear that both versions of the EDK suck if you don't tie them
cleanly and pretension them well.
Again -
Rope A: Mammut 11 mm static - used
Rope B: Unknown manufacturer red 11 mm dynamic - used
Rope C: ABC/Sterling 11 mm static - new
Rope D: Blue Water II+ 11 mm static - new
Rope E: ABC 8mm static - new
Rope F: 1" Tubular Webbing
Rope G: Mammut 8mm static - new
Test #13: RopeB/RopeB - overhand - well dressed, pretensioned loosely
Rolled at 1070 lb, Rolled at 1120 lb, Rolled at 1470 lb, Rolled at 1870 lb,
Rolled at 2000 lb, Rope broke at 2100 lb
Test #14: RopeB/RopeB - overhand - sloppy, crossing strands & loose
Rolled at 200 lb, Rolled at 370 lb, Rolled at 1400 lb, Rope broke at 2100 lb
Test #15: RopeB(11mm)/RopeG(8mm) - overhand - well dressed & pretensioned
Rolled at 1230 lb, Rolled at 1610 lb, Rolled at 1930 lb, Rolled at 1840 lb,
8mm broke at 1770 lb
Test #16: RopeB/RopeB - overhand - sloppy, crossing strands & loose (again)
Rolled at 300 lb, Rolled at 420 lb, Rolled at 1440 lb, Rolled at 1520 lb,
Rope broke at 1830 lb
Test #17: RopeB(11mm)/RopeG(8mm) - overhand - well dressed & pretensioned - WET
Rolled at 950 lb, Rolled at 1300 lb, Rolled at 1160 lb, Rolled at 1130 lb,
Rolled at 1070 lb, Rolled at 1110 lb, Rolled at 1200 lb,
Rolled and 11mm sheath broke at 1460 lb, Rolled at 1230 lb,
Rolled at 1450 lb, End of tail pulled through knot at 1410 lb
Test #18: RopeB/RopeB - double fisherman's - well dressed & pretensioned
Rope broke at double fisherman's at 2880 lb
Test #19: RopeB/RopeB - double fisherman's - sloppy, mis-tied & loose
Rope broke at the figure-8 on a bight at 2580 lb
Test #20: RopeB/RopeB - double fisherman's - sloppy, mis-tied, loose & WET
Rope broke at double fisherman's at 2620 lb
Tom Moyer
> > Be safe - the body we have to scape off the rock may be yours.
>
> Nice job on the testing, but why is it all you rescue types speak the
> same line?
>
> - Nate
I dunno. Sick sense of humor, probably. <grin>
- Tom
shya...@my-deja.com
Thanks for all the info.
I was taught a nice variation of the fisherman: tie
a reef knot and _then_ a fisherman's at the two ends.
Really close to the reef knot on both ends and solidly
pre-loaded.
The advantage is that the fishermans doesn't get
loaded as much and hence easier to remove.
Ever used/tested this setup?
thanks
krishnan (shyam)
Bangalore, India
mike_...@my-deja.com
Tom Moyer <tmo...@alum.mit.edu> wrote:
> Ok - here's the next round of tests. Should add a little more fuel to
the
> fire...
>
> As before, all rope breaks (with one exception noted below) happened
at the
> knot being tested.
Ashley, in The Ashley Book of Knots, asserted that ropes break where
they enter the knot, not inside it. Is that what you're seeing?
Read with great interest, thanks Tom.
Cheers,
Mike
Lisashifra
why not just use the double fisherman's knot and blow off the rest of this?
Clyde Soles
> I mean, come on, Clyde - did you bother to actually read this data??
Yeah, I did. What part are you still clueless about?
Karl Lew
--Karl
Lisashifra <lisas...@aol.com> wrote in message
news:19991112110052...@ng-fa1.aol.com...
Nate
> Yeah, I did. What part are you still clueless about?
Ah, Clyde, that would be part where you tried to convince everyone that
this was a safe knot. Then, you got on here a few days ago to reiterate
the validity of your past comment - despite the data suggesting, IMO,
otherwise. You are correct, I am clueless as to the contradiction.
- Nate
Keith Jewell
lisas...@aol.com (Lisashifra) wrote:
> So, maybe i'm missing something huge and obvious here (and I probably
> am), but why not just use the double fisherman's knot and blow off the
> rest of this?
>
partner who insisted on using the double fisherman's with overhand
backups on each end. After we broke a sweat from freeing the ropes and
dragging the knot around horns and knobs, my lips turned blue as I
struggled to dis-join the ropes in the thirty mile an hour wind. My
curses were loud.
K
Chris Wegener
itself along the rock reducing the possibility of catching or jamming when
the ropes are pulled. Large knots like the double fisherman or the figure
eight follow through are easier to hang-up.
Chris
Lisashifra <lisas...@aol.com> wrote in message
news:19991112110052...@ng-fa1.aol.com...
Gary Clark
> So, maybe i'm missing something huge and obvious here (and I probably
am), but
> why not just use the double fisherman's knot and blow off the rest of this?
Good question, not obvious from the discussion.
Double fisherman knots are quite prone to hanging up in any crack they
encounter, or over an edge. The knots being discussed tend to stand up in
the air, so that only the ropes are against the rock (see the diagram at
the Petzl web site). These knots will have much less tendency to catch on
an edge or in a constriction. Also, they untie much easier after loading
than the double-fish knot.
I've always used the double-fish, but a guide in Canada showed me the
fig-8 version, now apparently being called the Euro-death-knot in this
thread, so I find this all very interesting. I haved since used it to rap
a couple times, but I wasn't real comfortable with it. However, I am not
dead. Thanks much to Tom Moyer for getting some data, rather than just
spewing unfounded opinions, as is an all-too-common tendency in this
group.
--
Gary Clark
North American Classics on the Web
nacla...@usa.net
http://www.sunrisemtsports.com/naclassics/
Dave Andersen
> In article <19991112110052...@ng-fa1.aol.com>,
> lisas...@aol.com (Lisashifra) wrote:
>> So, maybe i'm missing something huge and obvious here (and I probably
> am), but
>> why not just use the double fisherman's knot and blow off the rest of this?
> Good question, not obvious from the discussion.
> Double fisherman knots are quite prone to hanging up in any crack they
> encounter, or over an edge. The knots being discussed tend to stand up in
> the air, so that only the ropes are against the rock (see the diagram at
> the Petzl web site). These knots will have much less tendency to catch on
> an edge or in a constriction. Also, they untie much easier after loading
> than the double-fish knot.
> I've always used the double-fish, but a guide in Canada showed me the
> fig-8 version, now apparently being called the Euro-death-knot in this
> thread, so I find this all very interesting. I haved since used it to rap
Careful there. I believe that when most of us say the "EDK", we mean
the *overhand* knot, and not the true death knot, the figure 8. The EDK
nomiker is a bit of a joke, because the knot, if used properly (see test
data) is quite safe for low-load situations.
Clyde Soles
> Ah, Clyde, that would be part where you tried to convince everyone that
> this was a safe knot. Then, you got on here a few days ago to reiterate
> the validity of your past comment - despite the data suggesting, IMO,
> otherwise. You are correct, I am clueless as to the contradiction.
Nothing in his data suggests that the overhand is unsafe for the
intended purpose. Can't help your failure to comprehend.
Nate
> Nothing in his data suggests that the overhand is unsafe for the
> intended purpose. Can't help your failure to comprehend.
Clyde, the overhand inverts, and a loose figure eight fails at an
unacceptably low load, yet held when dressed, etc.
I'm sure you feel vindication by the nice numbers accociated with well
tied and prim knots, but the data also shows that things deteriorate
unaccebtably fast if the knot is loose, wet, etc. If this doesn't at
the very least catch your attention, then your brain is numb.
- Nate
Karl Lew
Nate, to rephrase, are you saying that careless climbers
who weigh 600lbs or more shouldn't rap in the rain
using the OEDK?
--Karl
Nate
The margin of safety an overhand provides is unacceptable to me,
especially when a real knot takes so little additional effort.
Clyde Soles
> If this doesn't at
> the very least catch your attention, then your brain is numb.
Before you keep talking out your butt, perhaps you ought to do the tests
yourself sometime.
Nate
> Nate <nate_b...@maxtor.com> wrote:
>
> > If this doesn't at
> > the very least catch your attention, then your brain is numb.
>
> Before you keep talking out your butt, perhaps you ought to do the
> tests yourself sometime.
Spare me. Admit it Clyde, you're an uneducated, inexperienced hack.
You doing those tests is akin to a 4 year old staring into a tropical
aquarium. In this case, you are wrong. If you are okay with those
safety margins, then go for it.
Crack Boy
Getting back to the bar in safely is beauty.
Crack "gone double fishermans" Boy
Karl Lew wrote:
>
> Because the EDK is prettier.
> --Karl
>
> Lisashifra <lisas...@aol.com> wrote in message
> news:19991112110052...@ng-fa1.aol.com...
Dave Andersen
>> Nothing in his data suggests that the overhand is unsafe for the
>> intended purpose. Can't help your failure to comprehend.
> Clyde, the overhand inverts, and a loose figure eight fails at an
> unacceptably low load, yet held when dressed, etc.
> I'm sure you feel vindication by the nice numbers accociated with well
> tied and prim knots, but the data also shows that things deteriorate
> unaccebtably fast if the knot is loose, wet, etc. If this doesn't at
> the very least catch your attention, then your brain is numb.
The inversion of an overhand is a much less serious event than the
inversion of a figure 8. Furthermore, if you actually look at the test
data, you'll note that after one inversion, the next inversion occurs at a
considerably higher level of force. If you leave 12" of tails on a pretty
poorly tightened overhand, you're still not going to die until the force
on the ropes gets to over 1200 pounds or so. Sure, I'll give you that you
could do this if you really put your mind to it, rapping on the rope and
then constantly taking huge falls on it, but what in the world are you
doing taking factor one falls on your rap rope?
The safety margin in an 8 is much reduced; the knot both inverts more
easily, *and* eats up a lot of rope when it inverts. Thus, you can suffer
fewer inversions on an 8 than you can on an overhand. The difference is
significant, and makes up the difference between a safe knot and an unsafe
knot *FOR LOW LOADS*.
But if you do take whippers while rapping, please do use a double
fishermans. :)
Ken Cline
> The margin of safety an overhand provides is unacceptable to me,
> especially when a real knot takes so little additional effort.
I think, we've finally nailed this issue, boys and girls. There's no
longer a need to beat this dead horse (n.b. I have other dead horses
to beat). The bottom line is Nate doesn't like using the overhand, so
let's not make him use it. Everyone else can go back to climbing as
usual.
Ta, ta.
Ken
Oops, I almost forgot the manditory force analysis!
A worst case fall on a dynamic rope generates 2000 pounds of force on
a climber's harness. Apply this load to a rappel system and each rope
feels half. Now recall that the worst of Tom's tests shows an
overhand capsizing at 1400 lbf (and Tom's numbers are the lowest I've
seen reported), so
[drum roll, please...]
An overhand knot won't capsize, much less fail, even if you take a
hard fall onto your rappel line! Rappel device slippage and friction
will reduce the forces even further.
[technical detail: a factor 1 fall on two ropes generates about the
same force as a factor 2 fall onto one. As a general rule, try to
avoid high ff falls while rappelling.]
Clyde Soles
> Spare me.
Oh puhleeze. If you can't flame better than that -- or even defend your
illogic -- don't bother.
Karl Lew
Ken-1 Nate-0
The crowd goes wild....
--Karl "reporting from the AstroDome"
Ken Cline <cl...@cline117.dsl.frii.net> wrote in message
news:m31z9vj...@cline117.dsl.frii.net...
Mike So
succesfully hold their own with the Chief Inspector of the
Climbing Physics Police? Will Karl "Marv" Lew get caught up
in yet another kinky sex scandal? Only time will tell.
Tune in next week, same bat time, same bat channel.
-mike
Nate wrote:
> Spare me.
Clyde wrote:
> Oh puhleeze.
Ken Cline wrote:
> The bottom line is Nate doesn't like using the
> overhand, so let's not make him use it. Everyone
> else can go back to climbing as usual.
Michael Riches
<an...@shell.aros.net> wrote:
> The inversion of an overhand is a much less serious event than the
> inversion of a figure 8. Furthermore, if you actually look at the test
> data, you'll note that after one inversion, the next inversion occurs at a
> considerably higher level of force. If you leave 12" of tails on a pretty
> poorly tightened overhand, you're still not going to die until the force
> on the ropes gets to over 1200 pounds or so. Sure, I'll give you that you
> could do this if you really put your mind to it, rapping on the rope and
> then constantly taking huge falls on it, but what in the world are you
> doing taking factor one falls on your rap rope?
>
> The safety margin in an 8 is much reduced; the knot both inverts more
> easily, *and* eats up a lot of rope when it inverts. Thus, you can suffer
> fewer inversions on an 8 than you can on an overhand. The difference is
> significant, and makes up the difference between a safe knot and an unsafe
> knot *FOR LOW LOADS*.
>
> But if you do take whippers while rapping, please do use a double
> fishermans. :)
>
> -Dave
You fall and generate the force necessary to invert the overhand, it
inverts...the fall has held. I can't see where you would continue to
generate the type of forces necessary to invert it farther, am I wrong? What
kind of a fall would a person have to take that would keep the force high
enough to keep inverting this knot to failure??? To me it looks like the
initial shock load would have to be high enough to snap the ropes at the
knot. The instant the knot inverts it dissipates enough force to slow the
climber down enough to keep the rest of the fall below the inversion limit,
With the dynamic principals of the rope and the limited weight of a climber
the fall would have to be an extremely hard and fast fall to sustain the
forces necessary to keep inverting either knot. I know a climber can
generate forces in excess of 2000 lbs on static gear, but on dynamic gear???
On say an average fall of 10 to 20 feet just what would the force of a
falling climber be? Say the climber weighs around 165 lbs, the ropes are
both 10.5mm conditions are dry and completely overhanging, so that the rope
has to absorb the lions share of the shock of the falling climber???
--
The Rockrat
Nate Beckwith
Dave Andersen wrote:
> If you leave 12" of tails on a pretty
> poorly tightened overhand, you're still not going to die until the force
> on the ropes gets to over 1200 pounds or so.
How do you come to this conclusion when there is no data for a poorly
tightened overhand?
There is, however, data showing that both a figure eight and overhand
hold pretty well when "dressed". The figure eight starts inverting at a
mere 100 lbs when not dressed. What does the overhand do? How about
when wet? How about when not perfectly "dressed"? How about on a large
variety of rope qualities? The data clearly shows these all
contribute. Unlike you, I am not assuming anything. Do you know
something we don't? What I'm reading is pretty much telling me no way.
- Nate
--
Nathanial Beckwith - Boulder, CO
http://www.netone.com/~nate
Nate Beckwith
Ken Cline wrote:
> (n.b. I have other dead horses to beat).
I've got serious issues with your linear equations, man. Way bogus
stuff. Next physics thread though...
> The bottom line is Nate doesn't like using the overhand, so
> let's not make him use it. Everyone else can go back to climbing as
> usual.
I don't really give a rat's ass about what other people use to rap
with. But when someone who tries on cloths and operates a word
processor for a living gets on here and makes pompus technical claims,
I've just gotta post something.
Until I see test data from overhands tied in other than "dressed"
conditions, and/or more information about the accident in the Tetons -
over and out...
Karl Baba
use it.
How many folks have died when their death knot came undone, (if any, it
was a freak accident)?
How many folks have died or had a horro epic when their rap ropes got
stuck and they had to bivy or do something slow and/or desparately
dangerous to free them, I'm sure we will never know but I bet there
are plenty.
The zero profile of an overhand is a truly significant advantage that I
have personally experienced significantly helping in rope retrieval.
When I KNOW there is no sweat pulling the ropes, I use a double
fishermans, just to keep my partners from getting nervous, but when
there is a doubt, it is the oEDK!
Peace
Karl
In article <80i3g9$e1m$1...@nnrp1.deja.com>, Nate
<nate_b...@maxtor.com> wrote:
>
> The margin of safety an overhand provides is unacceptable to me,
> especially when a real knot takes so little additional effort.
>
>
> - Nate
>
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
http://extra.newsguy.com/~climbing/
Rockclimbing Guide (remove NOSPAM from the return address)
Ben Craft
What knot do you use in alpine climbs, low angle raps, or in areas like
Red Rocks that can catch the rope?
#######
#####\_O -Ben Craft-
####/\/>
#### /"
### \
drift
admit it's my choice.
The EDK makes me a bit nervous, but I think I'll give it a little testing
before I discard it's
low profile advantage.
drift
Karl Baba <gu...@NOSPAMnewsguy.com> wrote in message
news:121119991731534564%gu...@NOSPAMnewsguy.com...
Tom Rogers
>
> Nate <nate_b...@maxtor.com> wrote:
> > cso...@rmi.net (Clyde Soles) wrote:
>
> >> Nothing in his data suggests that the overhand is unsafe for the
> >> intended purpose. Can't help your failure to comprehend.
>
> > the very least catch your attention, then your brain is numb.
It's good to see you guys eating each other up, rather then me.
> you're still not going to die until the force
> on the ropes gets to over 1200 pounds or so. Sure, I'll give you that you
> could do this if you really put your mind to it,
How about a person rappeling and he is hurt in the body with a none
lethal rock (1st impact) then he falls to the bottom of the rope where
each end is tied off to stop a accidental escape and he hits hard again
(2nd impact) Rope double inverts and comes un-done (soon to be 3rd
impact). This goes to show persistance will get the job done!
maohai huang
: after one inversion, the next inversion occurs at a
: considerably higher level of force.
What I could say based on the data (e.g. #14 and #16) is that the over hand
knot actually tightens itself after one or two "rolls".
Hey, want to climb some slabby stuff at Red Rock on saturday ?
"Michael Riches" <rock...@earthlink.net>
> I know a climber can
> generate forces in excess of 2000 lbs on static gear, but on dynamic gear???
> On say an average fall of 10 to 20 feet just what would the force of a
> falling climber be? Say the climber weighs around 165 lbs, the ropes are
> both 10.5mm conditions are dry and completely overhanging, so that the rope
> has to absorb the lions share of the shock of the falling climber???
Information at your finger tips! See Hal's drop tests:
http://www.dtek.chalmers.se/Climbing/Hardware/DropStats/index.html
Generating 10 kn force on dynamic gear seems well possible (see the
last figure).
Mad Dog
> The margin of safety an overhand provides is unacceptable to me,
> especially when a real knot takes so little additional effort.
That's your personal decision and I respect your right to make that
choice. The first time I rapped on an overhand, it scared the living
shit out of me, but we were on a route that ropes snag on easily and my
partner was much more experienced than I so I blindly trusted. A couple
of nights later, four of us talked about it in camp. Since an
overhanging boulder with a couple of bolts on top was just a short walk
away, we decided to do a little test. We tied a 7mm to an 11 with an
overhand, extended to bolt anchor with slings to make the anchor free in
air. We then tied on about 500 pouinds of gear. The knot tightened and
moved maybe an inch. I then climbed onto the packs holding the gear.
No more knot movement. Then I bounced. Then Jim, Wes and Wendy
sequentially climbed on. We bounced hard and the knot moved another
centimeter. This must have been a humorous sight and it was difficult
to accomplish. I was convinced that it was safe enough. These were
mid-life ropes with some fuzz. Newer, slick ropes might creep more.
Decide for yourself. It is the UIAA recommended rap knot, right?
Clyde Soles
> Will Clyde get the last word? Or will Nate?
He can have it. Nate's still angry because I rejected his article
proposal on bed wetting.
Ken Cline
> What kind of a fall would a person have to take that would keep the
> force high enough to keep inverting this knot to failure??? ... I
> know a climber can generate forces in excess of 2000 lbs on static
> gear, but on dynamic gear???
We're drifting into angels and pins territory here. Above 2000lbs,
the climber breaks. Rappel ropes just aren't subjected to loads like
this.
Ken
Ken Cline
Nate, have you stopped taking your Thorazine?
Anyway...
Nate Beckwith <na...@netone.com> writes:
> Ken Cline wrote:
>
> > (n.b. I have other dead horses to beat).
>
> I've got serious issues with your linear equations, man. Way bogus
> stuff. Next physics thread though...
Well, then maybe you should take this up with Dr. Joseph W. David,
Associate Professor of Mechanical Engineering at North Carolina State
University. He and Clark Park fit a linear function to force-strain
data of real climbing ropes in order to simulate the dynamics of thge
climber-belayer system during rock climbing lead falls. If I'm
oversimplifying, at least I'm in good company.
> > The bottom line is Nate doesn't like using the overhand, so
> > let's not make him use it. Everyone else can go back to climbing as
> > usual.
>
> I've just gotta post something.
Nobody had to rebut Clyde's wisdom. Sometimes, even if you think
you're smarter of more qualified, it is better to keep quiet.
Ken
Nate Beckwith
Clyde Soles wrote:
> He can have it. Nate's still angry because I rejected his article
> proposal on bed wetting.
Without a few flames, reading and participating in this group is about
as interesting as staring into a goldfish bowl. Hence my lack of posts
as of late. I still respect you, Clyde, but disagree with you on this
one. Don't take it personally - because I'm not.
Thanks to Tom, especially for the second round of tests. I've got some
toys here if you want to catch some higher frequency peaks.
>Test #16: RopeB/RopeB - overhand - sloppy, crossing strands & loose (again)
>Rolled at 300 lb, Rolled at 420 lb, Rolled at 1440 lb, Rolled at 1520 lb,
>Rope broke at 1830 lb
> Test #20: RopeB/RopeB - double fisherman's - sloppy, mis-tied, loose & WET
> Rope broke at double fisherman's at 2620 lb
Which knot would you show to a beginner whose safety you cared about?
I've been climbing for quite some time, and have only gotten a rope
stuck at the knot once - only once! All of the other stuck ropes have
been from the line flying all over the place after it's free from the
anchor.
So, to Ben, every rap I can recall tying has been a triple fishermans
with a small tail. There must be a hundred other tricks to keeping the
lines from getting stuck, and those tricks have worked pretty well for
me.
On a side note - I haven't been climbing as long as some, but certainly
long enough to see a lot of cute tricks become fashionable, then fade.
The latest is simul-rapping.
A few years ago, Byrnes and I rapped well over 1-1.5K ft into the Black
Canyon. I recall bad anchors, bushes, flakes, the works! We used just
about every trick in the book, except simul-rapping and cute knots. We
made it down in what I recall as a pretty quick time - maybe an hour or
a little more?
Why mess around? Obviously, someone who has had knot stick problems may
feel otherwise. Of all the risks I've taken to make a route go, why
should I add risk when it is completely unnecessary?
I don't take what I would call big risks now as much as I used to. But
when I was, I felt some routes added the value to my life to justify
them. One thing, though, I've always tried to hold to, is to maintain
the highest margin possible for a given situation. I'm still here, and
I believe that's pretty much the reason why. And that would be the fuel
that drove the latest flamefest.
Later,
- Nate
Michael Riches
<cl...@cline117.dsl.frii.net> wrote:
Exactly...If you consider the kinds of forces necessary to sustain the knots
continual inverting process you more than likely will be long gone before
the rope breaks or the knot fails. I've reread all of the data points and I
can't the obvious danger that Nate is so worried about. Even the worst case
scenarios had the rope breaking before the knot failed....
> Test #14: RopeB/RopeB - overhand - sloppy, crossing strands & loose
> Rolled at 200 lb, Rolled at 370 lb, Rolled at 1400 lb, Rope broke at 2100 lb
> Test #16: RopeB/RopeB - overhand - sloppy, crossing strands & loose (again)
> Rolled at 300 lb, Rolled at 420 lb, Rolled at 1440 lb, Rolled at 1520 lb,
> Rope broke at 1830 lb
Test 17 was the only test that the knot actually failed and if you follow
the process on this test, you'd have had to totally rag doll yourself out
before the knot failed...Also given the size differences in the ropes I was
really impressed that they held up as long as they did...
> Test #17: RopeB(11mm)/RopeG(8mm) - overhand - well dressed & pretensioned -
WET
>
> Rolled at 950 lb, Rolled at 1300 lb, Rolled at 1160 lb, Rolled at 1130 lb,
> Rolled at 1070 lb, Rolled at 1110 lb, Rolled at 1200 lb,
> Rolled and 11mm sheath broke at 1460 lb, Rolled at 1230 lb,
> Rolled at 1450 lb, End of tail pulled through knot at 1410 lb
The knot rolled 9 times, all the forces involved were over 1000 lbs, with
the exception of the first one. How many of these sustained bounces will the
body be able to withstand before it kills the climber???
I think the case was very well proven for the overhand. Now if Nate knows
something we don't, I'd sure like him to post it so we can see exactly where
he's coming from. I know I've been converted...
--
The Rockrat (Especially after having fought a jammed or stuck double
fisherman's many, many times.)
Clambake
> Clyde Soles wrote:
>
> > He can have it. Nate's still angry because I rejected his article
> > proposal on bed wetting.
>
> Without a few flames, reading and participating in this group is about
> as interesting as staring into a goldfish bowl. Hence my lack of posts
> as of late.
Wow, what a complete and utter asswipe you are. The only time you can be
bothered to add anything to this group is if you can insult and piss someone
off in the process? You are a total tool who needs a good bitch slap. You even
kinda look like a little effeminate bitch! If it's all too boring for you,
then just keep yer fuckin' face shut then, bitch.
Al Black
Ken Cline <cl...@cline117.dsl.frii.net> wrote:
>"Michael Riches" <rock...@earthlink.net> writes:
>
>> What kind of a fall would a person have to take that would keep the
>> force high enough to keep inverting this knot to failure??? ... I
>> know a climber can generate forces in excess of 2000 lbs on static
>> gear, but on dynamic gear???
>
>We're drifting into angels and pins territory here. Above 2000lbs,
>the climber breaks. Rappel ropes just aren't subjected to loads like
>this.
Actually, I'm curious about the numbers here. Okay rec.climbing.physics
guys and gals, just how much force can rapelling generate. (Just
guestimates would be fine.)
cheers
al
--
Ben Craft
> with a small tail. There must be a hundred other tricks to keeping the
> lines from getting stuck, and those tricks have worked pretty well for
> me.
I think it all depends upon what type of rock you are on.
The thought of the rope catching is why I constantly use
the overhand and in my experience the overhand does perform better on the
rock that I have encountered this season on traverses in the sierras even
when you consider the hundreds of rappel tricks.
If you are on terrain that safer knot will work just as well, why use the
overhand.
>
> On a side note - I haven't been climbing as long as some, but certainly
> long enough to see a lot of cute tricks become fashionable, then fade.
> The latest is simul-rapping.
Now that's something I think is way dangerous and a quick ride to the
bottom. A recent article(s) in both mags advertise it is a safe method to
use.
Ben
Nate Beckwith
Clambake wrote:
> > Without a few flames, reading and participating in this group is about
> > as interesting as staring into a goldfish bowl. Hence my lack of posts
> > as of late.
>
> Wow, what a complete and utter asswipe you are.
Q.E.D.
- Nate
Dave Andersen
> Dave Andersen (an...@shell.aros.net) wrote:
> : after one inversion, the next inversion occurs at a
> : considerably higher level of force.
> What I could say based on the data (e.g. #14 and #16) is that the over hand
> knot actually tightens itself after one or two "rolls".
It does look that way, yes. It would make sense to argue that the
forces required to roll it compress it, but we'd probably need more data
before saying that for sure (letting it invert, completely removing the
load from it and letting it regain some of its elasticity, and then
loading it again).
> Hey, want to climb some slabby stuff at Red Rock on saturday ?
Thanks for the invite. I actually had my first introduction to the
Gunks this weekend, so I couldn't make it. Sorry!
I think I dealt with more roofs in one day of climbing than I usually
tough in a month, and I didn't actually hop on anything harder than a 5.6
today. Too much fun!
(Oh, and to tie this into the thread: I had a lovely time rapping off
the top of Madame G's free-air rappel with an oEDK today. :)
Dave Andersen
>> you're still not going to die until the force
>> on the ropes gets to over 1200 pounds or so. Sure, I'll give you that you
>> could do this if you really put your mind to it,
> How about a person rappeling and he is hurt in the body with a none
> lethal rock (1st impact) then he falls to the bottom of the rope where
Are you implying that the nonlethal rock impact is both:
a) nonlethal
and
b) places several hundred to a thousand pounds of force directly
on his rappel setup?
I hope to never see this happen. :) But let's accept it as given.
> each end is tied off to stop a accidental escape and he hits hard again
> (2nd impact) Rope double inverts and comes un-done (soon to be 3rd
> impact). This goes to show persistance will get the job done!
2nd impact: The rope won't come undone after a double inversion if
the tails are long enough. Look at the test data - even test #17 suffered
multiple inversions (and sheath breakage!) before going.
I don't think that anybody is arguing the safety of an overhand knot
with 2" tails, which very well could be demolished by only two inversions.
This would be the "Euro-begging-for-death" knot. :)
End result: One battered body hanging at the bottom of his rappel
line. Guess he should have worn a *really big* helmet, and backed his
rap setup up with an {insert favorite rap safety knot here}. :-)
Even if you consider the "many bounces" scenario, look at what happens
to the forces involved. The more the climber falls, the lower the impact
force of the subsequent falls is going to be (relative to their distance,
of course), because there's more rope out, which reduces the fall factor.
Multiple bounces would certainly be much less friendly to our hypothetical
climber, but they would actually be less stressful to the knot. ...
especially since the knot wouldn't be taking much of the force if the
climber were bouncing. :-)
Dave Andersen
> Dave Andersen wrote:
>> If you leave 12" of tails on a pretty
>> poorly tightened overhand, you're still not going to die until the force
>> on the ropes gets to over 1200 pounds or so.
> How do you come to this conclusion when there is no data for a poorly
> tightened overhand?
I think that we had a news article arrival mismatch with this message.
Tom's second message may not have arrived at your server by the time my
post showed up. Just to answer the question, though, please check out
Tom's followup post, which addressed the following scenarios:
Test #13: RopeB/RopeB - overhand - well dressed, pretensioned loosely
Test #14: RopeB/RopeB - overhand - sloppy, crossing strands & loose
Test #17: RopeB(11mm)/RopeG(8mm) - overhand - well dressed & pretensioned
- WET
In none of these tests did a "death" scenario (either rope breakage or the
knot pulling through) occur at less than 1200 lbs. Test 17 was the most
dangerous scenario - mismatched rope sizes with a wet rope, and even it
survived many inversions, and required over 1400 lbs as interim steps in
reaching the death sequence. Note that the double fisherman's is still
the recommended knot for mismatched rope sizes, but even the overhand does
well enough for *most* rappel situations.
> There is, however, data showing that both a figure eight and overhand
> hold pretty well when "dressed". The figure eight starts inverting at a
> mere 100 lbs when not dressed. What does the overhand do? How about
> when wet? How about when not perfectly "dressed"? How about on a large
> variety of rope qualities? The data clearly shows these all
> contribute. Unlike you, I am not assuming anything. Do you know
> something we don't? What I'm reading is pretty much telling me no way.
I do. I know about Tom's followup tests and message. :-)
I think that the questions you raised here are questions which do need
to be addressed before drawing any conclusions about the safety of a knot.
I would imagine, though I have no data to back this up, that before the
UIAA would recommend the knot for a particular situation, it would perform
similar tests. But even without that, Tom's performed some tests which
provide a fairly good indication that the knot is safe. We can start
arguing about the statistical validity of his results now if you'd like
to, and you would certainly make a good point by suggesting that not
enough tests have been performed to show that the overhand is _always_
going to perform as well as Tom's tests showed that it did.
To this, I can only answer with my suggestion that the knot has likely
been subjected to testing by the UIAA, but perhaps more importantly, that
even if Tom's data is off by a factor of two, an overhand knot on dry
ropes of similar diameter still exceeded the forces you're likely to place
on a rope in an ordinary rappel situation by a large margin.
If you're doing something funky (rescue work, hauling loads, climbing
on joined ropes, or rapping when it's wet or with weird ropes, etc.) then
I completely agree that the double fisherman's knot is the appropriate way
to go. But I think that for most of the raps many climbers do (certainly
myself), the oEDK has demonstrated its usefulness, and is a pretty good
tool to put in our inventory.
Karl Lew
> drift
Now you know why I think it's beautiful.
--Karl
Grant
> The only time you can be
> bothered to add anything to this group is if you can insult and piss someone
> off in the process?
What a fine example you set in your reply. Maybe you should take your own advice
when you finally pull your head out of that brown hole you keep it in. G
Dimitri
I have been convinced that the Euro-death is the knot of choice (for me)
for connecting two equal diameter lines before rapelling. I just wanted
to make sure before I kill myself trying: is it also the preferred knot
for connecting two lines with different diameters, like a 10.5mm and
an 8mm rope (which is usually what I carry in long routes)?
Sorry if this has already been mentioned before, it just seems
impossible to read all messages that have been posted on this general
topic..
Thanks for any info,
Dimitri
Hal Murray
> > Rolled at 950 lb, Rolled at 1300 lb, Rolled at 1160 lb, Rolled at 1130 lb,
> > Rolled at 1070 lb, Rolled at 1110 lb, Rolled at 1200 lb,
> > Rolled and 11mm sheath broke at 1460 lb, Rolled at 1230 lb,
> > Rolled at 1450 lb, End of tail pulled through knot at 1410 lb
>
> The knot rolled 9 times, all the forces involved were over 1000 lbs, with
> the exception of the first one. How many of these sustained bounces will the
> body be able to withstand before it kills the climber???
>
> I think the case was very well proven for the overhand. Now if Nate knows
> something we don't, I'd sure like him to post it so we can see exactly where
> he's coming from. I know I've been converted...
This sort of discussion reminds me of the knot-A is x% stronger
than knot-B stuff that pops up here all too often.
In practice, ropes don't break. The lab strength of any interesting
knot is more than adequate. The real question is can you tie the knot
correctly when it's dark out and you are cold and shivering.
The real question with the EDK is will it roll too far when you try it?
If it rolls at most x times during z lab tests, how often will
it roll y times? Are 12 inch tails really long enough?
I can't make up my mind on this mess. I'd be a lot happier if
it didn't ever roll. Maybe I'm just a Luddite. But maybe some
time I'll be more scared of the knot hanging and I'll use it.
I'd like to thank Tom for running the tests that started
this discussion.
--
These are my opinions, not necessarily my employers.
Andy Gale
> It's pretty clear that both versions of the EDK suck if you don't tie
them cleanly and pretension them well.
-------
Nate Beckwith wrote:
>
> Thanks to Tom, especially for the second round of tests. I've got some
> toys here if you want to catch some higher frequency peaks.
>
> >Test #16: RopeB/RopeB - overhand - sloppy, crossing strands & loose (again)
> >Rolled at 300 lb, Rolled at 420 lb, Rolled at 1440 lb, Rolled at 1520 lb,
> >Rope broke at 1830 lb
>
> > Test #20: RopeB/RopeB - double fisherman's - sloppy, mis-tied, loose & WET
> > Rope broke at double fisherman's at 2620 lb
>
> Which knot would you show to a beginner whose safety you cared about?
---------
Karl Lew Wrote:
*Swoosh*
Ken-1 Nate-0
The crowd goes wild....
--Karl "reporting from the AstroDome"
Ken Cline <cl...@cline117.dsl.frii.net> wrote in message
news:m31z9vj...@cline117.dsl.frii.net...
> An overhand knot won't capsize, much less fail, even if you take a
> hard fall onto your rappel line! Rappel device slippage and friction
> will reduce the forces even further.
--------
Hey Karl, Care to modify your previous statement?
Ken?
Just curious.
(He shoots! He scores!!.....)
Andy
--
******************************************************************
Andrew Gale The Scripps Research Institute
ag...@scripps.edu La Jolla, CA
******************************************************************
Ken Cline
> > >Test #16: RopeB/RopeB - overhand - sloppy, crossing strands & loose (again)
> > >Rolled at 300 lb, Rolled at 420 lb, Rolled at 1440 lb, Rolled at 1520 lb,
> > >Rope broke at 1830 lb
> Ken Cline <cl...@cline117.dsl.frii.net> wrote in message
> news:m31z9vj...@cline117.dsl.frii.net...
>
> > An overhand knot won't capsize, much less fail, even if you take a
> > hard fall onto your rappel line! Rappel device slippage and friction
> > will reduce the forces even further.
Andy Gale <ag...@scripps.edu> writes:
>
> Hey Karl, Care to modify your previous statement?
>
> Ken?
>
> Just curious.
Sure - I'll modify my statement:
If you rappel on a loose double overhand with really short tails, it
just might be possible to cause it to capsize and fail. Evolution
in action. On the other hand if you tie it even a little bit
carefully, the double overhand is safer because it won't fail and it
is less likely to get stuck or pull down loose blocks when being
retrieved.
> (He shoots! He scores!!.....)
Let's think about this, shall we? You seem to be implying that
because an improperly tightened overhand can slip a little, it is
unsafe. Well, Tom's data appears to prove just the opposite - a
sloppy loose overhand tightens itself pretty quickly when it capsizes.
Besides which, it took 300 lbs to capsize the knot which is a 600lb
rappel load (there are two strands). Apparently you must tie the knot
loosly, leave no tail, and bounce hard to get the thing to fail.
Ken
P.S. there was an error in my earlier analysis. I said worst case
falls generate at most 2000 lbs, when a UIAA drop test is acceptable
up to something like 2700 lbs and real falls on old ropes might be
even worse. What I should have said is that typical hard lead falls
generate up to 2000 lbs (this according to a paper on climbing anchor
safety).
Bob Harrington
Hal Murray <mur...@pa.dec.com> wrote:
>I can't make up my mind on this mess. I'd be a lot happier if
>it didn't ever roll. Maybe I'm just a Luddite. But maybe some
>time I'll be more scared of the knot hanging and I'll use it.
Yeah, I've used the overhand a lot, but I know what you're saying.
It's not the mean failure that worries me, it's the standard
deviation.
Bob