Bruce Smith for President

From the On Rope 1 website...

Myth # 17: Knots should be backed up.

Back-up knots are often a violation of good efficiency and a waste of time . There are a limited number of knots that may require back-up. A professional should know which ones need a back-up and under what circumstances.

Making a statement like, “All knots should be backed-up” is irresponsible and shows a huge lack of knowledge about something as basic as a knot. Why would you back-up a knot? You answer, “In case you tied the main knot incorrectly.”

Backing up a knot that is tied wrong screams of incompetence. And when does it end? How do you back up a butterfly knot, a bowline on a bight or a Double fisherman’s knot? The bigger issue is the terrible waste of resources. Resources wasted includes: time, rope, throw, and/or usable operational space.

Things I wanted to accompany the above post but was too tired to type last night...


Obviously there are plenty of resources out there on the debated topics here. Still, from time to time someone makes the statement that someone else is being unsafe by doing something that is WIDELY ACCEPTED as being safe. Arguments ensue, blah blah blah.

The far bigger issue to me has nothing to do with knots however. It has to do with the Original Post. Does anyone else have any concern that NONE of the splices tested use Yale's recommended splicing procedures.

A locked Brummel as I know it is not intended to be a back up for the tucked tail. Seeing what they will hold is interesting but what does it mean when a tail tuck of the proper bury length is where the spice gets it's strength. The Brummel is there to supposedly prevent the splice from being pulled apart under no load.

Moray wrote in the Original Post "The other standard e2e, second from right, failed at 5318 lbs. when one of the splices slipped about 3 inches. There was still enough energy and tension in the system to cause the locked Brummel to cinch up tight and partially fail with breakage of one or two strands."

This is where I began to scratch my head. When did a Bee Line Eye to Eye spliced tail with 4.75" tail buries become standard? I am missing something here???

Does anyone want to go back and look at the real problem here?

The only test that has any useful data to me is the test on the tied tails. And I am very curious about that. I suspect that cover wasn't properly miked and that the knots weren't well set before the break test. I do not disagree that it broke at 3590 lbs. That sound about right for a class 2 cord with a knot tied in it. I think it is safe for me to say that a Bee Line cord with knots instead of splices still offers a much higher safety factor than a toothed cam ascender.

Anyways I though I should point out what can be missed when a thread goes directly into derailment. Irrelevant issues like the acceptance of the double fisherman's noose, and the necessity of backup knots distract people from what we should be focusing on here.

A factory made, hand spliced, Bee Line eye to eye split tail has a claimed tensile strength of 5400 lbs. That is still a fact that has yet to be proved otherwise.

A knot in any Class 2 cordage is going to significantly weaken it. That does not by any stroke mean that it will not have enough strength to be used in certain situations.

-Hunabku

Wow! I never intended to ignite such a firestorm! I would like to make a narrow comment on my own position vis-vis my experiments.



First, the word "nervous" doesn't quite convey what I really mean. Something like "uncomfortable" or "unsatisfied" would be closer to the mark. I didn't mean to imply that I consider either version of the Bee-Line split tail unsafe.

The strength reduction caused by the Brummel, just to be clear, only occurs when the Brummel deploys, not while the splice is holding. With a long enough bury, the splice will not fail and the Brummel will not weaken the rope at all. As many have pointed out, none of the numbers I observed were so low as to raise a safety alarm.

There is one safety issue that does concern me with the spliced version of the e2e. Because many people like their e2e's quite short, and don't want the thickened splice area anywhere near their knot, they use a substandard bury length. The locked Brummel lets them do this safely. The risk is they may not really understand what they are doing, may think the Brummel is just that cool twisty part right next to the eye, and forget, or never know, that the splice bury is actually the vital "lock" of the locked Brummel. All the naked locked Brummels that I tested had fully braided undisturbed tails, 4 inches long, with tight taping around the end. The test forces were unable to unbraid the tails and suck the tail through the Brummel, so they remained locked. An actual bury, on the other hand, is never taped. What's more, the last inch or two is typically unbraided so a long angled cut can be made to produce the taper. These treatments have little effect on the holding strength of the bury but they seriously compromise the Brummel "lock," the other role of this little piece of rope.

Until someone does a series of experiments on Bee-Line core to determine a minimum safe braided length for the locked Brummel tail, everyone who makes one of these things is just guessing that their buried tail will actually provide the lock function if it is needed.



I tested my spliced Bee-Line cover a couple of days ago. It was long enough that the thickened splice area was not involved in either knot that I tried. With a 5-wrap Schwabisch I found the knot worked fine for descents, but it did not always release easily on ascent. I then retied the e2e as a VT. In this case both ascents and descents worked like a dream.

I am going to resplice the cover so that the buries meet in the middle. This should give a rope physically closer to Bee-Line out of the box, and perhaps its hitch cord performance will be a little different. I'll report back.

Probably lost in yesterday's discussion is my point that an individual knot or spliced eye on an e2e split tail is only holding 1/4 of the total load in a DRT system. So for a tied eye e2e split tail (based on Moray's test figures) we're talking a whopping 7180 lb. break point. I'm fine with that, it's stronger than just about any other link in my life support system. The eye that had the core slip through it is a good reminder to properly milk the cord, set the knots and leave sufficient tail after the knots before climbing on the tail. All that said I've never had the core slip more than about 3/8" in the tail, and as mentioned that was when I first started tying them. I'm not getting any any core movement now in my split tails.
-moss

Moray, please don't think I don't appreciate your efforts in the tests. Your comments above have added a lot of context to the tests and I definitely see the relevance of the experiments better now. Thank you for posting them here. Despite all of the sidebars I believe it is collaborations like these that lead to improved products for us all.

I'd have to say that I am also quite disappointed with the performance of a Brummel in the context of a backup to a short tail tuck also. I had no idea folks were pushing the limits of this stuff that way. I'm not condemning it, but I will say that it is beyond my personal comfort level.

When Oak did an eye to eye in cover only under Nicks guidance at Boyd hill the method used was quite different than the method you describe.

You wrote "

The one done at Boyd's, if I recall correctly, had half of the strands removed from each side to be buried. The tails from each end were buried and overlapped completely within the splice. The tail from each end was pulled out on each opposing end. They were then marked and tapered before being finally drawn back up into the outer cover.

There was no "meeting in the middle".

IMPORTANT NOTE...

This was an experimental splice that has yet to be fully tested

A process is taking place to properly test the method, and hopefully eventually get approval from the manufacturer. It's going to be a process though.

I believe that the intention is to have several people make eye to eyes using a single described method. These tails will then be break tested in a laboratory environment.

The first step is to get the described method written down. I believe that effort is underway.

Perhaps a similar method would work well for a core style eye to eye. Might still be to bulky once the cover is also added on. That problem does not exist with the cover only Nick orchestrated.

Hunabku, thanks for the interesting update. Your description of the Oak splice is perfectly lucid and complete. Keep in mind I am often trying to do some sort of quick and dirty experiment in which some of the labor-intensive details can be sacrificed with no harm to the experiment. My cheap and easy "meeting in the middle" splice will be physically the same as Oak's classy splice, but it should tell me if the performance of the e2e in the tree is notably different from what I have tested so far. Mine would be a lousy candidate for a production model!

Also, even though I have made quite a lot of splices by now, I don't pretend to possess the adept artistry so clearly on display in other's work. My stuff is pedestrian at best, and I try to avoid the stuff I have trouble with, like the "overlapping-in-the-middle" splice you describe.

It is great to be part of a (mostly) high-level discussion like this!

I respliced my Bee-Line cover so that the two untapered buries met in the middle. After the line had been stressed a bit, and everything had settled down, there was an empty gap in the middle of about 1/4 inch. A careful splicer could taper and overlap the buries to avoid the empty gap.

I gave it a field test today. With the same 5-wrap Schwabisch I used before, the performance was noticeably better during ascent, as the knot was always easy to release. Since the physical properties (friction, roundness, bulk, pliability) of this full-bury all-cover rope approximate those of the factory-supplied rope, one might expect it to work about the same as a knotted e2e made from the factory cord. If this turns out to be true, then this version has a few things to recommend it. It is much easier to make than the standard spliced version; it has none of irritating bulk of the knotted version; and it is simpler than either of the other versions.

It goes without saying that anyone who experiments with this is an experimentalist; the safety or even the utility of this arrangement has not been established.