"We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
There is a difference between a locked brummell and a brummell /weave/lock stitch. Different manufacturers use different terminology.
This is what I call a Locked Brummell. Samson calls it a locked brummell. NE Ropes calls it a Brummell. Notice how one tail goes through the standing part and the other tail does as well. Look closely at the last picture. Samson's current whoopie sling shows this technique as well. I believe it to be weaker than a straight bury or a Brummell splice.
This is what I call a Brummell in Figure 2. Samson calls it a Brummell or weave, NE Ropes call it a lock stitch. I believe it to be as strong as a straight bury.
One point as to why you should follow manufacturers instructions. Samson eye splice 12 strand class II 2006 shows a straight bury, with no locked brummel nor weaving/lockstitch (which Samson and I call a brummel). In Samson's Eye and Tail splice, they use the brummel/weave splice/lock stich, but the instructions clearly state (in small print) which lines it is appropriate for. Amsteel is not one of them. The locked brummel requires you to use both ends of the line in forming the eye OR turning the line inside out. I suspect that it is easier to obtain an exact total length using this splice. It is very difficult with a straight bury. Marlow and NE Ropes both recommend a brummel/weaving/lockstitch splice for their 12 strand class II dyneema. Although, NE Ropes calls a "locked brummell" a "brummell" and a brummel/weave a lock stitch, again.
The point of my original post was not to discourage the use of the locked brummel. Like I mentioned, I use it primarily in several different arenas. My primary point was to encourage folks to pay attention to line breaking strengths and derating factors. Derating factors can be significant.
One example for knots: in double braid class 1 line, like dock lines on a boat, a bowline knot retains 55% of original breaking strength. In double braid with a specta core (Amsteel is spectra), it retains 40% of it's original strength. More than 1/2 of it's strength is gone.
Knotting small specrta/amsteel significantly reduces the breaking strength. It also does not hold knots well.
Long post to say, hang from it if your sag angle and body weight give you a margin of safety you are comfortable with. I do.
Last edited by nacra533; 08-23-2010 at 21:31. Reason: Added links
I should know this, but when discussing 30* vs 15 or 10* angles: Is it the angle before you get in and weight the hammock, or before, that gives you the useful info? IOW, your RL could be tight and straight, pretty loined up with your suspension. But after you get in and things sag, the degrees/angle will be considerably different. So you might start at 15* and end up at 30*. Or do I have that wrong? If not wrong, is it important to have the 30* BEFORE loading, or is 30* AFTER loading OK.
Or is it irrelevant? Somebody educate me please.
Apparently, signature that I used from 2006 no longer tolerated so now deleted.
thanks for the responses. Guess I'll keep hanging and watch my whoopies with a keen eye!
A good caver never loses her pack.
The angles will change as you load the hammock, and the angles to be concerned about are those of the loaded hammock. So yep, you may start with an angle that is less than 30 degrees, but after you jump into the hammock it may approach 30 degrees, depending.
ain't hammock physics phun?
(alias ProfessorHammock on youtube)
I also believe Samson stated that the Locked Brummel derates the line no more than a plain bury.
nacra - I'm taking my guidance from Brion's "Book 5 Basic Braided Splices". On pages 65 through 78 he gives instruction on making the Locked Brummel splice with illustrations. His Locked Brummel is exactly the same as Samson's Locked Brummel, just a different method of getting there - Brion's method only needs one end of the rope. Also, he specifies that the splice is specifically for "High Modulus" ropes, i.e., dyneema and spectra are what he mentions specifically, or what Samson calls Class II ropes and that "Properly done, this splice will approach 100% efficiency in strength and security."
Note that New England Ropes has another method for making a Locked Brummel using only one end of the rope, but I have never been able to really execute their method. Their method also ends up with exactly the same splice.
So we have so far 3 methods of obtaining a locked brummel:
- Samson Ropes method, which is probably the easiest, but requires both ends of the rope
- Brion Toss's method which requires only one end of the rope and, for me, is only slightly harder to execute than Samson's method
- New England Rope's method which requires only one end of the rope and which I have not been able to successfully execute.
All 3 methods will give you exactly the same splice. I find it interesting also that Brion is the only one that recommends also stitching the bury after a locked brummel. I think this is because of his background in sailing, which as you pointed out so well, loads and unloads the splice a lot and so requires securing the bury more than a hammock suspension does.
Also, I think you have to understand that Brion's guidance on the Locked Brummel splice and the strength includes the bury after the locked brummel. Without his actually stating it, I get the sense that the locked brummel isn't there to provide strength to the splice, the bury provides that, but to help manage the load/unload cycle problem. So yes, if you are going to do a locked brummel alone, no bury afterwards, then the brummel should probably not be used for life support situations. However, following the locked brummel with a bury I think changes the splice considerably.
I think that most (all??) people on the forums are following Samson's guidance in the locked brummel in the whoopie sling pdf and following it with a bury. In fact, I think if you look back over the threads, it is pretty much taken for granted that the the locked brummel splice on the forums actually refers to the combination of a locked brummel splice followed by a bury splice.
So in the end, I think after writing the above that we probably mean the same thing and that the only thing that separates us is the terminology.
I didn't mean to indicate that the crossing of the two lines without the bury was the splice if it sounded that way. I perform a locked brummel the same way samson does when both ends of the line are available. When only one end is, I use foul language and do it the NE ropes way. I'd like to see Toss' method, it's got to be easier than the NE ropes way.
As you stated, the strength is in the bury, not the locking or weaving. Those are for the low load condition.