Splicing and the Locked Brummel

[MacEntyre]

In the first post you stated that the Locked Brummel is weaker than a plain bury splice.

That was Nacra533 who made that statement.

[nacra533]

wow, I didn't know that at all. Well shoot, does this mean I should redo my whoopies??

No need. Just be aware there is a reduction and the safety factor is not as high. As I mentioned, I use them primarily on hammocks and sailing rigging.

...

Didn't that McDonald splice come off of a sailing forum? Is it not loaded the same way we load the hammock suspensions?

Sailors (which I am) use it frequently. There are several reasons. Spectra is primarily used on contol lines and running rigging (the stuff that gets adjusted alot) Often on control lines, the line is PLENTY strong and it becomes a function of block/pulley /sheave size and strength vs. handling ability/how easy is it to pull it. Also, control lines tend to flog, which can shake a plain buried splice loose. That's the reason for stitching at the beginnning of the bury., but stitching stiffens the line and whipping the bury fattens it. Both impede the smooth flow of the line around a block. Another reason is they are frequently loaded, then unloaded.

On a whoopie, the locked brummel is not the weak link. So for that application at least it doesn't help to use a standard spliced eye.

I totally agree with Knotty. It is not the weak link in a whoopie. He has done a lot of research in to whoopies.

Knotty - do you have a reference for this?? Brion Toss rates the Locked Brummel with bury at as close to 100% of virgin rope as you care to get.

Toss is a rigging guru and he should be believed as long as you know terminology he is referring to. See below on terminology differences. My reference, which may be outdated, is OSHA, arborist, and rigging standards prohibit or discourage a locked brummel in 8 or 12 strand class II line for life support or load support overhead. The also prohit or discourage the "weaveing" the line before the bury. I've seen data that prohibits it (by demonstrating the allowed splices with dimensions) and I've seen data that discourages it by causing the line to be derated to the point it does not make sense to do it.

Terminology differences
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.

http://www.jamestowndistributors.com...+Eye+Splice%29

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.
http://www.jamestowndistributors.com...Lock+Stitch%29

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.

Some add

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.

[BillyBob58]

.........If you're doing it the small stuff, I suggest derating the line. You're probably still fine depending on sag angle and your weight. Remember, at a 30 degree sag angle, the tension in EACH line = your weight (not half of it). As sag angle decreases, tension increases significantly, at 15 degrees sag angle, tension in EACH line is almost double your weight. There is a great chart on HF that shows loading as a function of sag angle. I have no idea of how to find it.......

Thanks for the heads up on derating the line.

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.

[goodcaver]

thanks for the responses. Guess I'll keep hanging and watch my whoopies with a keen eye!

[GrizzlyAdams]

Thanks for the heads up on derating the line.

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.

dang right you should know this BB58!

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?

[opie]

-A Locked Brummel is LESS strong than a regular buried splice. It looks more secure and handles better in no or low loading situations, but the breaking strength is less than a regular buried splices. For Hammock usage, most are not getting that close to the BS of the line so there is some margin of safety there. I use locked brummel in the majority of my splices when loading is less of a concern than the no/low load situation. It saves me from stitching the bury. Locked brummels cause a shearing stress in the line instead of tension which line is rated for. If you're doing it the small stuff, I suggest derating the line. You're probably still fine depending on sag angle and your weight. Remember, at a 30 degree sag angle, the tension in EACH line = your weight (not half of it). As sag angle decreases, tension increases significantly, at 15 degrees sag angle, tension in EACH line is almost double your weight. There is a great chart on HF that shows loading as a function of sag angle. I have no idea of how to find it.

I pulled 2 slings apart, 1 with a locked brummel and 1 with a stitched bury. Both gave out at the same point. Not to pick nits.. But I cant see how the marlin splice derates the line any more than the actual entrance for the bury.

I also believe Samson stated that the Locked Brummel derates the line no more than a plain bury.

[Knotty]

Thanks for the heads up on derating the line.

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.

What's important is the final angle, after loading it. At 30deg each suspension line will carry a load equal to your full weight. What angle it started at doesn't matter.

Also, the 30deg thing isn't a rule...just a guideline.

[TiredFeet]

That was Nacra533 who made that statement.

Thanks MacEntyre - I need new glasses, but I'm so cheap I keep telling myself that there's still plenty of wear left in the current pair.

[TiredFeet]

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:

1. Samson Ropes method, which is probably the easiest, but requires both ends of the rope
2. 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
3. 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.

Toss is a rigging guru and he should be believed as long as you know terminology he is referring to. See below on terminology differences. My reference, which may be outdated, is OSHA, arborist, and rigging standards prohibit or discourage a locked brummel in 8 or 12 strand class II line for life support or load support overhead. The also prohit or discourage the "weaveing" the line before the bury. I've seen data that prohibits it (by demonstrating the allowed splices with dimensions) and I've seen data that discourages it by causing the line to be derated to the point it does not make sense to do it.

Terminology differences
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.

http://www.jamestowndistributors.com...+Eye+Splice%29

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.
http://www.jamestowndistributors.com...Lock+Stitch%29

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.

Some add

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.

[nacra533]

nacra - ...
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.

It sounds like we are.

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.