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Brummel Splice failures at lock? (synthetic rigging)


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Hi, 

Has anyone experienced brummel splices in dyneema/spectra failing at the lock?  Colligo recommends the brummel splice, but I've been told by another person versed in synthetic rigging that it has failed at the lock. 

Would this be because of the distortion of the fibers at the lock (straighter is stronger), some of the fibers that are un-coated with resin from the center of the line get exposed, or the lock taking the load before the buried tail?

I'm going to make up a new forestay and trying to decide if I should use a brummel, straight burry with stitching, or something else?

 

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Marlow have always claimed that a straight bury is stronger than a brummel in their testing.  Advantage of a brummel is that it can never pull the splice, but it is akin to putting a knot in it, which as we all know reduces the load carrying capability.  

Maybe contact the manufacturer of whatever you are using to see if they have some test data.

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I was under the impression, there was a big thread on it here a few years ago, that since the the throat of the spice has double the line it's starting from a base of 200% of the line strength.  So even through a straight bury and brummel weaken the line, and so does the angle of the throat, it'll still be stronger than 100% if it's done right.  The weak point will be where the bury ends.  At this point there is only a single diameter of line, so it's down to 100% strength, and the change in the thickness creates a stress riser, concentrating forces at this point.

In short, make sure the bury is long enough and make a nice smooth taper to get the strongest splice and don't worry about brummel or straight bury.  

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Each line manufacture is different, New England Ropes measures the breaking load of the line spliced so if it's a 12 strand dyneema it's measured with the direct bury splice. I believe Marlow measures the breaking load with the line around bollards though it could have changed in the past few years.  Most of the time, the splice fails where the taper begins and because there was a lack of taper. Generally I give a full fid of taper and a strand cut at at time instead of the recommended 3 or 4. If your concerned about a direct bury pulling out you could always lock stitch it I suppose or whip the throat. 

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Don’t forget you size synthetic for stretch, not strength. Synthetic sized that way has so much extra strength the splice loss doesn’t matter. Or so say the testers.

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That stuff is so incredibly strong and stretch free that by sizing it for hand you are virtually guaranteed to have a huge reserve of strength.

3/8" is about the minimum for reasonable hand on a heavily loaded line and that gives about 10 tons of breaking strength so.......

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I used to brummel everything, but direct bury with a lockstitch is just about as fast and I don't need to do mental gymnastics to plan for hardware.  I'll still use a brummel in small stuff, but don't see the point in 3/16" or larger.

As an example it is a lot easier to trim the end of a stripped halyard with a shackle if it has a direct bury vs a brummel.  You just snip the lockstitch, trim the line, and redo a new splice.  With a brummel I need to pull the whole halyard off of the boat and do the brummel with all 125' of tail attached.

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The problem with a lock stitch, is the line/splice stretches and the lock stitch does not.  When we are doing pull tests, you can hear the lock stitch ripping it's way through the line.  And the splice almost always fails at the lock stitch.

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9 hours ago, lamorak said:

The problem with a lock stitch, is the line/splice stretches and the lock stitch does not.  When we are doing pull tests, you can hear the lock stitch ripping it's way through the line.  And the splice almost always fails at the lock stitch.

It would be interesting to see a video of your pull test.

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The trick is that you don't want the brummel lock to load up in normal conditions. Rather you want the splice to behave like a direct-bury and the brummel is only there to prevent accidental pull-out of the buried tail under no-load conditions. To ensure that the brummel doesn't load up, don't tighten up the lock before you bury the tail. Leave in loose and leave a bit of a gap between the locks and the entry point for the bury. Then when filing down the bur, make sure that the locks are still separated. Doing it this way allows the splice to slip and settle a bit while it beds in without the brummel locks getting loaded up and breaking.

I hope this makes sense...

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22 hours ago, lamorak said:

The problem with a lock stitch, is the line/splice stretches and the lock stitch does not.  When we are doing pull tests, you can hear the lock stitch ripping it's way through the line.  And the splice almost always fails at the lock stitch.

But isn't this true for a brummel too - that the brummel will load up and break? It would be interesting to see tests comparing brummels and buries with lock stitches. I have also given up on brummels and use buries because they are so much easier to get right lengthwise.

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On 8/21/2019 at 1:21 PM, lamorak said:

The problem with a lock stitch, is the line/splice stretches and the lock stitch does not.  When we are doing pull tests, you can hear the lock stitch ripping it's way through the line.  And the splice almost always fails at the lock stitch.

Does changing the line you use for the lock stitch impact this at all? Recently I have gone to dyneema stitching for the lock, with the assumption that it will stretch at roughly the same rate as the splice.

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On 8/21/2019 at 8:18 AM, Alex W said:

I used to brummel everything, but direct bury with a lockstitch is just about as fast and I don't need to do mental gymnastics to plan for hardware.  I'll still use a brummel in small stuff, but don't see the point in 3/16" or larger.

As an example it is a lot easier to trim the end of a stripped halyard with a shackle if it has a direct bury vs a brummel.  You just snip the lockstitch, trim the line, and redo a new splice.  With a brummel I need to pull the whole halyard off of the boat and do the brummel with all 125' of tail attached.

I can whip up a one-ended brummel in just a couple minutes. Is it as fast as a simple bury, not quite, but it's pretty darn quick. It's a great party trick as well when you're in a drifter.

 

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55 minutes ago, Raz'r said:

I can whip up a one-ended brummel in just a couple minutes. Is it as fast as a simple bury, not quite, but it's pretty darn quick. It's a great party trick as well when you're in a drifter.

 

I can too doing the inside-out trick, but not with a shackle installed in it.

 

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41 minutes ago, Raz'r said:

Yeah, all my shackles are luggage tagged

That still requires you to pull the halyard out of the mast. I'll stick with direct bury and lock stitch. 

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3 hours ago, Alex W said:

That still requires you to pull the halyard out of the mast. I'll stick with direct bury and lock stitch. 

No, it doesn’t. You can put a Brummell in the end of a line with just one end free. Once you learn it, it’s simple even for me. But I’m not advocating a switch, I think either is fine. 

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Two things in this thread have me scratching my head..

Why is the  brummel lock under  load. It sounds like the bury is just not deep enough.

I am also stumped by the need to pull the halyard out of the mast. 

A Raz'r stated you only need one end of the line to do the splice and after some practice it can be done quite quickly. 

You  can't do the splice through a hole in a fitting but if it is just a shackle would you just remove the pin? 

 

 

 

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On pulling the halyard: How do you luggage tag hitch a shackle onto an eye splice without having access to the tail?   Or how do you make a brummel around a shackle without having access to the tail?  

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26 minutes ago, Alex W said:

On pulling the halyard: How do you luggage tag hitch a shackle onto an eye splice without having access to the tail?   Or how do you make a brummel around a shackle without having access to the tail?  

It's possible!

And you can luggage tag by passing the eye through the shackle, then around the shackle if the eye is large enough. I hope this is clear.

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ah cool, I hadn't thought I'd doing it that way.  I have to admit that I never leave my eye splices that large. 

I have done tons of mobius brummels, and said that earlier (maybe not clearly enough). 

I'll still probably stick with direct bury when hardware is involved. 

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Having just done this, luggage tagging a Tylaska T-12 to 3/8" line, the eye only needs to be about 2" long to fit around the shackle to one-end luggage tag.  It can fit widthwise over the shackle rather than the longer lengthwise.  However, at this length the bury of the splice will need to curve around the bail of the shackle when luggage tagged.  I.e., it takes more than the length of the eye portion to bend around the bail and back through.  The bury is somewhat stiffer and doesn't bend as well, so I didn't like this.  A 3" eye is needed to get the bury to start just after the bail.

After doing this, it was still possible to get the stopper ball adjacent to the bail.  So no hoist length was lost vs a non-luggage tagged eye with the same sized stopper ball on the line.  The extra 3/8" from the luggage tag wrapping around the bail is all that is extra longer, and it fits in the ball.

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