|
deleted
Deleted
Aug 21, 2003, 9:45 PM
Post #51 of 70
(5904 views)
Shortcut
Registered:
Posts:
|
very nice, clyde.
|
|
|
|
|
sittingduck
Aug 21, 2003, 11:43 PM
Post #52 of 70
(5907 views)
Shortcut
Registered: Aug 19, 2003
Posts: 338
|
Apply enough force on a single bowline and the curl will untwist and the result is a sliding knot, how strong this sliding knot is I dont know. The harder the knot is tied the more force have to be applied for this to happen and tied hard it might be impossible.
|
|
|
|
|
mesomorf
Aug 22, 2003, 1:55 PM
Post #53 of 70
(5907 views)
Shortcut
Registered: Feb 3, 2002
Posts: 397
|
In reply to: I know of one climber that got killed because he used the bowline. He had to be rescued by helicopter and the rescue team clipped a carabiner to his bowline loop and lifted him off the wall. The bowline untied and the climber died. This would not have happened if the climber had used the figure of eight.
Please cite the date and area where this happened. A reference to a print resource, heck, even an online resource, would give this some credibility.
|
|
|
|
|
neadamthal
Aug 22, 2003, 2:06 PM
Post #54 of 70
(5907 views)
Shortcut
Registered: Dec 2, 2002
Posts: 245
|
In reply to: Apply enough force on a single bowline and the curl will untwist and the result is a sliding knot, how strong this sliding knot is I dont know. The harder the knot is tied the more force have to be applied for this to happen and tied hard it might be impossible.
got a reference for this?? i really don't see how the 'curl', or the single loop, could straighten out. if the knot is set properly, there's no way a load on it could straighten it out. just tie one and jump on it and you'll understand.... :?
|
|
|
|
|
cracklover
Aug 22, 2003, 2:56 PM
Post #55 of 70
(5907 views)
Shortcut
Registered: Nov 14, 2002
Posts: 10162
|
In reply to: In reply to: Sorry you saw my response as being that of a raving lunatic. I saw yours as being that of someone who poo-poo'd my question as meaningless. That wasn't my intent. My purpose in pointing out that accident data would likely be unavailable was to dispell the fallacy that lack of data showing one knot to be safer than the other tacitly supports the alternative; ie, that the two knots are equally safe. It is common for people to mistakenly believe that lack of data contradicting the null hypothesis is support for the null hypothesis.
If you thought I was implying that, then thanks for the correction. Mine was an honest request for information.
In reply to: In reply to: Just because you don't see how something can be done, doesn't mean it can't be done. As a scientist, I am aware of that, which is why I questioned how such data could be collected, rather than stated that it could not. -Jay
I appreciate you spelling this out. If you look back on your first post, I believe you'll find that the question comes across as a rhetorical one, implying that such data could not exist. I'm sure you didn't mean to portray yourself as the voice of ultimate authority. Um, right? Anyway, I believe I've spelled out a couple of places where I think such information might have been produced, but there may be others.
Regarding the curl-straightening issue. I too am skeptical on how this might happen. Sure, if somehow the force was all on the side of the rope where the curl enters the main loop, it could probably happen at a fairly low force. I'm not sure how, in the standard practice of tying in with a bowline, you could possibly get a force on just that one strand. And with the force on both strands of the loop, this "uncurling" can be produced?
GO
|
|
|
|
|
jt512
Aug 22, 2003, 5:09 PM
Post #56 of 70
(5907 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: In reply to: My purpose in pointing out that accident data would likely be unavailable was to dispell the fallacy that lack of data showing one knot to be safer than the other tacitly supports the alternative; ie, that the two knots are equally safe. It is common for people to mistakenly believe that lack of data contradicting the null hypothesis is support for the null hypothesis. If you thought I was implying that, then thanks for the correction. Mine was an honest request for information.
I wasn't sure whether you were implying that or not, but there is always someone around who will make the wrong inference from lack of data. I was trying to head that off.
In reply to: In reply to: In reply to: Just because you don't see how something can be done, doesn't mean it can't be done. As a scientist, I am aware of that, which is why I questioned how such data could be collected, rather than stated that it could not. -Jay I appreciate you spelling this out. If you look back on your first post, I believe you'll find that the question comes across as a rhetorical one, implying that such data could not exist. I'm sure you didn't mean to portray yourself as the voice of ultimate authority. Um, right?
The "final authority"? No. But you are asking an epidemiologic question, and I'm an epidemiologist. Consequently, I understand what is required to collect valid data on the relationship between purported risk factors and rare outcomes, and so I can say with a fairly high degree of confidence that such data would be unlikely to exist for the question at hand.
In reply to: Anyway, I believe I've spelled out a couple of places where I think such information might have been produced, but there may be others.
I'm talking about accident data, not anecdotes or lab tests of tensile strength, neither of which are likely to be useful in answering the question about whether one knot is safer than the other.
-Jay
|
|
|
|
|
sittingduck
Aug 22, 2003, 5:55 PM
Post #57 of 70
(5907 views)
Shortcut
Registered: Aug 19, 2003
Posts: 338
|
In reply to: In reply to: Apply enough force on a single bowline and the curl will untwist and the result is a sliding knot, how strong this sliding knot is I dont know. The harder the knot is tied the more force have to be applied for this to happen and tied hard it might be impossible. got a reference for this?? i really don't see how the 'curl', or the single loop, could straighten out. if the knot is set properly, there's no way a load on it could straighten it out. just tie one and jump on it and you'll understand.... :?
I know this because I did read an article about it in Norsk Klatring (Norwegian climbing mag), other climbers have told me this (maybe the best source if one wants to learn) and I have tested it myself on a loose knot. I am not able to test this knot to its maximum so I dont know how it would react.
|
|
|
|
|
neadamthal
Aug 22, 2003, 6:15 PM
Post #58 of 70
(5907 views)
Shortcut
Registered: Dec 2, 2002
Posts: 245
|
[quote="sittingduckI have tested it myself on a loose knot. I am not able to test this knot to its maximum so I dont know how it would react.
well, a loose knot isn't to be used to protect your life.
i've fallen on a single with a df backup... it holds fine. i implore you to try the same in a controlled situation. i'm not saying it couldn't 'uncurl', but i really don't understand how it ever could (but i defer to the law of improbability)
|
|
|
|
|
cracklover
Aug 22, 2003, 6:31 PM
Post #59 of 70
(5907 views)
Shortcut
Registered: Nov 14, 2002
Posts: 10162
|
In reply to: The "final authority"? No. But you are asking an epidemiologic question, and I'm an epidemiologist. Consequently, I understand what is required to collect valid data on the relationship between purported risk factors and rare outcomes, and so I can say with a fairly high degree of confidence that such data would be unlikely to exist for the question at hand.
In reply to: I'm talking about accident data, not anecdotes or lab tests of tensile strength, neither of which are likely to be useful in answering the question about whether one knot is safer than the other. -Jay
As you wish. Either way, climb safely and joyfully.
Peace,
GO
|
|
|
|
|
jt512
Aug 22, 2003, 7:04 PM
Post #60 of 70
(5907 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: In reply to: The "final authority"? No. But you are asking an epidemiologic question, and I'm an epidemiologist. Consequently, I understand what is required to collect valid data on the relationship between purported risk factors and rare outcomes, and so I can say with a fairly high degree of confidence that such data would be unlikely to exist for the question at hand. Actually, no. Read it again "Anyone know of any data (personal experience included) showing that a single bowline with a Yosemite backup is any less safe than a double bowline with same?" The epdemiological inference was yours alone. As you're involved in the field, I can understand why you would focus in on this one aspect, but there are many reasons why one knot might be demonstrably worse than another.
Baloney. All reasons boil down to exactly two: whether there is an important difference in strength between the two knots, and whether one could come untied more easily that the other.
The answer to the first question is obviously "no." If either knot weakened the rope to the point where it broke in a fall, it would be well known. However, it is well known that ropes don't break in falls. Therefore, both knots must be strong enough, and thus, tensile strength tests unnecessary. Therefore, the question comes down to whether the knots are equally secure, and the only way to answer that is with data. A pull test isn't going to inform you if one knot is more likely to come undone during a climb, and anecdotes are worthless.
In reply to: You don't think that lab tests or anectdotes have anything to teach you about knot safety. To the best of my knowledge, there are fewer than half a dozen deaths attribuatable to using the fig-8 version of the EDK recorded. How many more before you have a valid sample size? The answer, my friend, is blowing in the wind!
I have no idea what you are talking about, and neither do you, apparently. I would consider a single death from a failure of a knot as reason to investigate that knot's safety.
In the case of the EDK vs the death-8, you are comparing a safe bend with a dangerous one, so you're going to see a marked difference in accident rates; that is, a large effect size. Large effect sizes are detectable with small sample sizes. Hence 6 accidents with the death-8 vs, probably 0 with the EDK is a meaningful difference.
However, you don't have a large effect size with a single vs a double bowline. Accident rates are nearly zero for both these knots. If that were not the case, we'd know about it. Since the effect size, if any, is small, you'd need a huge sample size to make meaningful comparisons. But accident rates for these knots are way too low to produce large enough numbers of incidents to make meaningful comparisons. Get it now?
-Jay
|
|
|
|
|
dirtineye
Aug 22, 2003, 9:50 PM
Post #61 of 70
(5907 views)
Shortcut
Registered: Mar 29, 2003
Posts: 5590
|
Holy knotweed batman,
I can't believe anyone really thinks a proper bowline will pull into a slip knot with enough force. IF that were so, it would have been branded as unsafe a LONG time ago by sailors.
I mean, if that is not enough, it's been tested as having 75 % the strength of the rope for gods sake, and they get those results by pulling til the rope breaks. That is, the knot does not fail, the rope breaks, usually right outside the knot.
To say that you can have trouble with a loose knot is like saying you can have trouble starting a car if you don't put gas in it. Knots are not complete til they are set and dressed. Knots that are not complete are not safe, that's very basic knowledge. The EDK will roll right off the ends of the rope if it is not set for example.
About data from tests or anecdote, I'd rather see tests, for the control aspect. In reports you have no way of knowing if the knot was tied properly. (I'm accepting that modern ropes don't break, so the knot would have to screw up some other way)
To test the "coming undone during a climb"-ness of a knot, I guess you'd have to have a machine to shake and rub the crap out of the knot tied into a harness, huh? Just a thought.
|
|
|
|
|
sittingduck
Aug 22, 2003, 11:20 PM
Post #62 of 70
(5907 views)
Shortcut
Registered: Aug 19, 2003
Posts: 338
|
A LOOSE bowline will turn into a slipknot, that is easy for anyone to test. When I think of all the bad tied fig.8's I have seen I dont think it is unlikely that there have been and will continue to be badly tied bowlines. Hope is that climbers allways back it up one way or the other. For beginners I think the fig.8 is a better choice because it is easyer to learn and more forgiving if uncorrectly tied.
|
|
|
|
|
neadamthal
Aug 23, 2003, 12:27 AM
Post #63 of 70
(5907 views)
Shortcut
Registered: Dec 2, 2002
Posts: 245
|
for sure... i only use a bowline for times when i think i'll actually fall and tighten the knot. i think beginners should use the figure 8 retrace as well.
but why would you ever leave your knot loose and undressed? if you have any sense about you, you wouldn't. :? but there's always distraction i guess...
|
|
|
|
|
dirtineye
Aug 23, 2003, 1:01 AM
Post #64 of 70
(5907 views)
Shortcut
Registered: Mar 29, 2003
Posts: 5590
|
LOOSE IS NOT RIGHT.
I guess you could say the same thing about gear placements and bolts too, hey, look guys, a loose nut is not as safe as a well set one, it could fail! Gee, this bolt spins and wiggles in it's hole, why, it is not as good as a tight one!
IF YOU CAN'T TIE A PROPER KNOT STAY HOME.
A bad figure 8 is still bad, debating what knot is still the best when it's done wrong is just ludicrous. Tie em right, it's not rocket science. Gimme a break.
|
|
|
|
|
sittingduck
Aug 23, 2003, 9:50 AM
Post #65 of 70
(5907 views)
Shortcut
Registered: Aug 19, 2003
Posts: 338
|
If a piece pops there is always the previous pieces and the belay anchor. If the tie in pops thats it. Up til one point I did not know how to tie in until someone teached me, sorry to say that the one teaching me did not know all there is to know about the fig.8 ... dude this is the bomber knot, period. So I did belive this and treated it as a bomber knot and did not try to find out for myself. If you cant tie a proper knot then learn to tie one, and learn all there is to know about the knot.
|
|
|
|
|
jt512
Aug 25, 2003, 4:50 PM
Post #66 of 70
(5907 views)
Shortcut
Registered: Apr 12, 2001
Posts: 21904
|
In reply to: IF YOU CAN'T TIE A PROPER KNOT STAY HOME.
Somebody said that to me yesterday at Williamson.
Dirtineye, you've been quoted in SoCal.
-Jay
|
|
|
|
|
dirtineye
Aug 25, 2003, 5:06 PM
Post #67 of 70
(5907 views)
Shortcut
Registered: Mar 29, 2003
Posts: 5590
|
I don't know what to say.
Maybe the guy thinks he said it first? This will probably lead to litigation or something. That line does have a ring to it, doesn't it?
SOome are born to greatness, others have it thrust upon them, I stepped in it. Oh wait, that was sh!t.
:P :P :P
|
|
|
|
|
vertical_reality
Aug 25, 2003, 5:20 PM
Post #68 of 70
(5907 views)
Shortcut
Registered: Jun 19, 2002
Posts: 2073
|
In reply to: Apply enough force on a single bowline and the curl will untwist and the result is a sliding knot, how strong this sliding knot is I dont know. The harder the knot is tied the more force have to be applied for this to happen and tied hard it might be impossible.
Wow, did this really happen? You'd think the rescue team would have enough common sense to clip into the belay loop, or is it standard practice for S&R to do this?
Why would they clip into the tie-in knot knowing that this just adds another point of possible failure into the system?
|
|
|
|
|
full-time-climb
Deleted
Aug 25, 2003, 5:33 PM
Post #69 of 70
(5907 views)
Shortcut
Registered:
Posts:
|
Thanks for this topic everyone.
John
|
|
|
|
|
dirtineye
Aug 25, 2003, 6:54 PM
Post #70 of 70
(5907 views)
Shortcut
Registered: Mar 29, 2003
Posts: 5590
|
The reason these finishes for bowlines became popular for climbing is that rescuers did find that clipping into a bowline loop could cause it to pull out.
I don't know the details but I've been told that by more that one rescue guy.
When I said a proper bowline will not pull out I was talking about using it as a tie in loop, where the forces on the knot are in one direction, coming from the belay end of the rope.
Pulling on loop knots by taking the loop and pulling it at 180 degrees apart at the knot is not a good idea, this is forcing the knot to act as a bend, which is a different situation altogether. A loosely tied figure 8 can fail in this test just as well as a plain jane bowline, and this has been demonstrated before, in the bend tests where a figure 8 rolls down the rope and off the ends.
The moral is, Choose an appropriate knot, dress and set your knot and use a backup.
|
|
|
|
|
|
|
|
|
