I read with some interest Ron's experiments on the locked Brummel found here:
http://www.treeclimbercoalition.org/phpbb/viewtopic.php?t=638&sid=13aed69e29e31524656da726410cabf7

I took a slightly different tack in my experiments, as described below.

The locked Brummel is a very peculiar creature. It has characteristics of both a knot and a splice and seems to confuse just about everybody, myself included. It is never used by itself (see picture below); the tail, often much longer than the one shown, is stuffed into the rope to make a proper buried splice. Since the Brummel can't come apart or unroll like a knot, it offers absolute protection against a splice that comes apart--the eye is still there, still holding the load, because of the Brummel.

How good is this protection? How does the Brummel behave when it is pulled to failure?

The photo shows my test Brummel tied in 5/16 inch Samson Tenex Tec. This rope has a published average break strength of 4700 lbs. The tail is 3.5 inches long and tightly taped at the end to make sure the Brummel would break before the tail could unravel. At the other end of the test piece I spliced an ordinary eye with a tapered bury.

Even though I was certain the Brummel would break long before the splice, I needed baseline data for comparison: I needed to know the break strength of a similar piece of rope with two ordinary splices but no Brummels. Altogether I did 4 tests: 2 break tests on control ropes, and 2 break tests on Brummels.

All four test ropes came from a single piece of new Tenex. The results are as follows:

Controls: 4400 4460
Brummels: 2742 2594

The first picture shows the first Brummel test at 1004 lbs. tension. It has already become so tightly knotted that it is nearly unrecognizable as a Brummel. It only gets worse from there.



The first strands snapped at 2742 lbs, which I took to be the point of failure. Interestingly, most of the strands are still intact. The second Brummel test followed this exact same pattern. Note also that strands have broken on BOTH sides of the Brummel. Considering that the eye side of the Brummel has the load divided between the two legs, it seems remarkable that anything would break on that side. Again, both Brummels showed this same pattern of failure.



The controls broke, as expected, at the very end of one or the other of the two buries.

The last photo is a closeup of the first Brummel test after more pulling had broken most of the remaining strands. The tension never again rose to 2742 lbs, and I did not bother to break the last few strands. Note in the photo the broken strands on BOTH sides of the Brummel.


Readers will draw their own conclusions from this. To me, the Brummel is like a parchute: it is not nearly as good as the plane that just ejected you, but it will get you to the ground safely. If you have a splice whose bury is so short you don't trust it, by all means put in a Brummel. If the splice bury is actually 100% bomber, whether you trust it or not, then the Brummel is just a waste of time and rope.

I like to use a locked brummel in my splices to prevent my splice from pulling apart during no load conditions. When I do one I know that that tail bury is going to stay right where I left it. I much prefer them to stitching. Under loaded conditions they certainly aren't doing anything to add to the strength of the splice. I have never thought of a locked brummel as something that is intended to make a splice safer under load. It is pretty cool to see how much they do hold if a tail bury were to slip.

If I recall correctly when Ron broke some of the splices I did they failed where they were stitched rather than at the end of the tail bury. Since I saw that I quit stitching them. That's just me though I doubt I would discourage anybody from stitching if that's the way they like to do it.

I disagree that doing a brummel is a waste of time, for me. I don't splice for a living so I can spend as much time on my splices as I care to. (Just ask Moss ) I don't feel like it is a waste of rope either. It serves a very good purpose, especially in a single braid application like Tenex, Ice Tail, or even Zing-it. When I do 8mm Bee-Line splices I whip the cover down so tight on each end that I think it would prevent no load pull out. But I still have a locked brummel under there. It takes about an extra inch of cord per splice. I can spare that.

I splice the ends of my zing it. I have had those eyes fall apart under no load if I didn't do something to prevent it. I haven't felt like pulling 180' of zing-it through itself yet so I stitch those.

I really enjoyed seeing your results Moray. I find this stuff very interesting. More please!

A full review is forthcoming, I've been climbing on an 8mm Beeline split tail with spliced eyes by Hunab and the preliminary report is: most excellent!
-moss

Hunabku, thanks for your thoughtful comments. Since the purpose of my experiments, beyond my own amusement, is to demystify some of the issues around knots and splices, I want to respond to a couple of your comments.



This is perhaps one of the most pernicious misconceptions about the locked Brummel, and one you can easily debunk yourself. Give me one of your freshly made splices protected by a locked Brummel; I will bend the thing back and forth a few times, and, presto!, the splice core starts to work its way out. The mechanical interference of the Brummel may prevent it from working out very far, but it will start coming out.



I really want to see the evidence for this!!! Since the stitching is right at the throat of a splice, where you have two full-diameter ropes (core and cover), and only the cover is in any way distorted, the idea that a few stitches are going to so weaken that area that it becomes the weakest part of the whole system, weaker than a single rope, seems incredible to me.



I did an experiment about 6 months ago in response to a claim someone made that repeated load cycles would cause an unsecured buried splice to come apart. I carefully marked the splice and then put it through 500 cycles from 0 to 150 lbs. There was no detectable creep in the splice. On a hunch, I took that same splice and bent it back and forth about 40 times. I was prepared to go 500 times, but I took a quick glance at the thing after 40 just to see if anything was happening. To my surprise and horror, a full half inch of the core had already pulled out!

Clearly the straight bury splice is vulnerable under no-load conditions. The Brummel is not a remedy for this, but stitching is. All 3 of these assertions can be easily verified by anyone at home with a little rope and a needle and thread.

The unceasing rain here in Maine has stopped all my break tests cold, but I have some early knot test results I may write up while I am waiting for the weather to clear...

A brummel does everything I need it to do. Nothing more, nothing less. I like em.

Here is a video of a brummel doing what I need it to do...

http://www.youtube.com/watch?v=_3BadTAv-ig


Go with what you like. I'll do the same.

I have no interest whatsoever in being the one who is "right". I just prefer brummels to stitching.

I'll gladly send you one of my splices to fiddle finger with...

For 20 bucks that is.

Good luck getting it apart. Yes there is a locked brummel under there, and no stitching.



Best regards, Hunabku

Well, your photo tells the story: the bury of your splice is secured by the cover and by the gorgeous whipping. It looks rock solid to me.

Here is a picture that demonstrates what I am talking about.



The two eyes on the left belong to the same hitch cord--a piece of Ice Tail that I have used for the last couple of years. Both eyes have locked Brummels, but everything is so fuzzy they are hard to make out. Both are stitched.

That slight crook in the middle one is real; that is its relaxed position. The red arrow points to the tail where it exits the Brummel just before it is buried in the splice. Out of a combination of ignorance and incompetence I must have flexed the throat area right after finishing the bury, and the result is what you see--a small bulge of core pulled out. I didn't know any way to push it back in, so I stitched it as you see it. It is easy to see how this works. If you were to take the bad splice and bend it much more severely at the crook, the area indicated by the arrow, being on the outside of the bend, wants to get longer. Everything on the Brummel side of the bend is locked up, so there is no rope to be had there. But the unstitched core is an easy source of more rope, and the bending action levers it right out. So much for the idea that a locked Brummel prevents the core from creeping out.

The splice on the right, also Ice Tail, is one I made a few days ago. I am not worried about the old one, nor am I retiring it, but I wanted to have a slightly shorter one on hand. I also ditched the Brummel since I know the bury is much longer than necessary.