The Overhand Knot?

Will A. wrote:If the overhand is acceptable for joining cord then how come it is not also able to be used to tie into a harness for climbing. The loads seem similar.

Rappelling and leader falls result in very different forces. They also stress the knots in different ways. So far in this thread we have mostly discussed rope-joining knots, in which two strands are pulled. When you attach the rope to the harness, there is only one strand that is pulled if you fall. All this to say that extrapolation from one case to the other is not easy.

I suspect, but have no data to back up my claim, that the problem with the overhand connecting the rope to the harness has more to do with the weakening of the rope due to constriction and sharp angles than with the possibility of the knot rolling or coming unthreaded.

Will, the biggest reason we don't use it to tie in is because it's wicked hard to un-tie after you've really whipped on it. While it's not quite as strong as a fig-8 it's a moot point. You'll never develop the forces in a climbing fall that would cause that either knot to fail.
Mal

Jed Pointer wrote:Testing in the lab does not equal performance in the field. Field testing has shown a failure resulting in death. Therefore, there exists a certain statistical probablity of death by using this knot, however small. In ~20 years of climbing, I've had only a few stuck knots, every one of them cleared by by pulling the other rope to get the knot back uphill a bit, then trying again. No big deal, never an epic, plenty of ways to prevent the problem from happening in the first place. Most of my stuck ropes have been where the second line get stuck after pulling through the anchor, knot in hand. Therefore, the whole "bad knot better than stuck rope" thing doesn't fit into my head well. J

Here we go again.

Jed are you referring to the overhand knot, when used to join two ropes for rappelling?

If so, can you please provide some facts and references for the specific situation(s) that lead to death(s)?

I'm amazed that you've never had a knot-stuck rope in 20 years. That's great.

Malcolm Daly wrote:Will, the biggest reason we don't use it to tie in is because it's wicked hard to un-tie after you've really whipped on it. While it's not quite as strong as a fig-8 it's a moot point. You'll never develop the forces in a climbing fall that would cause that either knot to fail. Mal

I can't figure this post?

Are you thinking of the amount of force to roll out a two-strand flat overhand, or are you saying it's ok to tie-in to a harness with a single strand overhand, or tie-in with some other kind of overhand to overhand retrace with a single strand?

Tie-in with a simple overhand and the knot will just come apart.

The 8 retrace is one of the most difficult knots to untie when whipped on; you could go with a 9 or a double bowline, they're a little easier to untie.

The reason being for the 8 or 9 retrace instead of a bowline-type is that if you don't set it properly, the bowline doesn't hold its shape as does a 8 or 9.

Jed, I'd love to see those field testing reports, too. Are you talking actual field testing (i.e. standardized, reproducable, single variable) or anectdotes from the field. Both are valuable but it's important to differentiate.

Mark, If you tie in with a re-traced overhand, just like you'd tie in with a retraced fig-8, they show very similar strength results. It's just that you can untie the fig-8 after you really stressed it and you'll have a battle to untie the retraced overhand.

Stick with the fig-8; it's got years of great history of being the best all-round tie-in knot.

Despite all the above, I'm a bowline guy. Doubled and retraced with a backup. It doesn't make sense. It's just what I'm used to.

Mal

Jed Pointer wrote:Knot used on Guide's wall -> person died. Any other questions?

Yes: 1) what makes you conclude from that accident report that the EDK is inherently dangerous? The logical conclusion based on the statements of the people involved is that it was a poorly-tied knot. 2) where in that story does it say the person died?

JL

Jed Pointer wrote:The link is in brenta's post. Knot used on Guide's wall -> person died. Any other questions? J

Jed, we've all seen that one before -- noone appears to have died.

I still haven't seen a single article indicating a death as a result of the knot, but that would be interesting to read if one can be scrounged up.

I the words of Ranger Mark:
"It's an interesting point to note that literally millions of rappels have been done involving this knot, without incident. Information on the name "Euro Death Knot" indicates that it was named so because one's first impression of its use is generally "no way.""

Jed Pointer wrote:"Knot used on Guide's wall -> person died." I stand corrected. Knot used on Guide's wall -> failed. That's the difference between the lab and the field. You can get all scientific about it, but it still failed. I'd rather use a knot is less likely to come untied by itself, for whatever reason I can't possibly foresee, especially on paper, or in some lab, or from someone's talk on the internet. J

Jed,

Several things about that story lead me to believe that human error probably had more than not to do with the failure. The first, and most obvious, are the references to 6" tails. Two words: "TOO SHORT".

Secondly, the girls repositioned the knot after the one fastened her rappel device, at which point one mentioned that it seemed loose. Instead of carefully examining the knot and physically checking it, one of the girls admonished the other to leave it alone because nether of them were familiar with his knot. Does anyone else here see the fundamental problem with that statement?

Why were two climbers, who were inexperienced to the extent that they could not safely evaluate a rappel knot, left alone above the guide to set up their own rappels?

Mal, The info I have is second hand from Craig Leubben regarding the increased strength of the overhand with a single strand backup...sorry I do not have the actual test results but I am sure you could get them from him.

Jed...I think it is interesting that you feel that a knot used almost exclusivly by professional mountain guides is "not safe enough" for you. Considering their job is tied directly to the safety of their clients, why would they use an inferior knot to join ropes?

As for the "small minority" using EDK's, maybe in your world but I am confident that if you polled climbers worldwide you would see that it actually is used in a large majority by climbers in many different countries.

I prefer to have clients pre-rig on rappel. My take on the story is that we don't know what happened.

The most important point to my mind is that the failure, as described, could not be repeated. Cold fusion was all the rage, but was disproven because it was not repeatable. This is how the scientific method works.

I think it is far more likely that human error was involved, either on the part of the guide, or on the parts of the climbers above (which unfortunately, is in most cases reflects an error on the guide's part). For example, I consider it possible that the two climbers messed with the knot, for some unknown gumby reason, then fixed it (or tried to). We already know this is partially the case because they moved the rope. However, if they had been pre-rigged, there would be no opportunity to move the rope, because their rap devices would be attached to it. Who knows what happened up there?

There have been literally millions of safe rappels on this knot. We are not talking about a margin of error of .1%. We are talking about a margin of 10^(-4)% or less. While notably this is speculation, I am sure the order of magnitude is at least comparable. Now compare this to your 1 in 79,746 chance of being killed by a lightning blast in your lifetime (for some fun procrastination, read nsc.org/lrs/statinfo/odds.htm).