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  1. #1
    Senior Member hutzelbein's Avatar
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    Splicing - length of bury?

    When I started splicing, I read a couple of tutorials (mostly by Opie) and copied the spliced gear I had. But recently, I have tried to make sure I have it right. Especially the bury lengths. On my whoopie slings, the bury of my fixed eye is 5.9" (15cm) long, including the trimmed part. The bury of the adjustable eye is 9.5" (25cm) long. The bury on my dog bones and locked continuous loops is 3.2" (8cm) long. I don't know why the buries on the original items had these lengths. I simply assumed that the makers knew what they were doing. On Dutch's Amsteel 101 it says

    What size bury for Amsteel 7/64? Samson specifies that a fid is equal to the diameter of the rope x 21, and that an effective bury for Class 2 rope should be three and a half fids. The diameter of Amsteel 7/64 is 0.11 inches, so for this rope, one fid is equal to 2.31 inches. So the recommended bury would be about 8 inches. Bury = fid x 3.5 = 2.31 x 3.5 = 8.01 inches Note that the length of the bury is dependent on the diameter of the rope. Counter-intuitively, the smaller the diameter of the rope, the shorter the bury needs to be. For example, a whoopie made with 1.75 mm Zing-it would only need five inches of bury (if following Samson specs), while one made with 1/8 inch Amsteel would need nine inches.
    Since I have never seen a dog bone, a continuous loop or a fixed eye of a whoopie sling with 8" buries, I'm not sure that understood the text correctly. I assume that "bury" in this case means the constricting part of the whoopie slings, is that right? What are the other "buries" then called? And is there are rule on how long they should be? If I don't lock my continuous loops, would I need to make each end 8" long, or only 4" because both share the load?

  2. #2
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    Samson has whoopie sling instructions right on their website. They also have lots of other useful splicing instructions. This has been my go-to for most my splicing needs (along with Grog's Animated Knots).

  3. #3
    Senior Member jcksparow's Avatar
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    Quote Originally Posted by hutzelbein View Post
    When I started splicing, I read a couple of tutorials (mostly by Opie) and copied the spliced gear I had. But recently, I have tried to make sure I have it right. Especially the bury lengths. On my whoopie slings, the bury of my fixed eye is 5.9" (15cm) long, including the trimmed part. The bury of the adjustable eye is 9.5" (25cm) long. The bury on my dog bones and locked continuous loops is 3.2" (8cm) long. I don't know why the buries on the original items had these lengths. I simply assumed that the makers knew what they were doing. On Dutch's Amsteel 101 it says



    Since I have never seen a dog bone, a continuous loop or a fixed eye of a whoopie sling with 8" buries, I'm not sure that understood the text correctly. I assume that "bury" in this case means the constricting part of the whoopie slings, is that right? What are the other "buries" then called? And is there are rule on how long they should be? If I don't lock my continuous loops, would I need to make each end 8" long, or only 4" because both share the load?
    My (potentially flawed) understanding is that when you're making a locked brummel, the bury will not need to be as long as it can't be undone by applying force on the eye loop. In the case that you were splicing a simple eye (burying one end of the line into itself with no locked brummel) the bury has to be long enough to function like a whoopie sling and hold the load applied to the eye. I usually use buries of 3-4" for thin cordage like zing-it and 5-6" for amsteel.
    "Now and then we had a hope that if we lived and were good, God would permit us to be pirates." -Mark Twain

  4. #4
    HandyRandy's Avatar
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    Splicing - length of bury?

    Something to note that I remember reading somewhere. The bend that you must make in a locked brummel will weaken the line somewhat. Does anyone know by how much?

  5. #5
    Senior Member kitsapcowboy's Avatar
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    FWIW I typically use a 5" to 6" bury behind the locked brummel in a 7/64" fixed eye, and my constrictor sections are a minimum of 8" (marked prior to threading the core).
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  6. #6
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    Quote Originally Posted by dscotthep View Post
    Samson has whoopie sling instructions right on their website. They also have lots of other useful splicing instructions. This has been my go-to for most my splicing needs (along with Grog's Animated Knots).
    Add this one for an eye splice and we have the best answer for the OP's question.

    Quote Originally Posted by jcksparow View Post
    My (potentially flawed) understanding is that when you're making a locked brummel, the bury will not need to be as long as it can't be undone by applying force on the eye loop...
    Yes, your understanding is flawed. The proper bury length for an eye splice would be the same with or without a locked brummel. During destructive testing the bury of a proper eye splice will not pull out even without a locked brummel or lock stitching. The intent of the brummel is not to add extra holding power but only an alternate to stitching as a method to prevent the bury from backing out under no-load conditions.

    Keep in mind that eye splices are used in testing to determine the tensile strength of amsteel blue so a proper eye splice provides the full rated strength. The reason we get by with shorter than recommended buries is because we are not coming close to stressing the bury's to the ropes full tensile strength.

  7. #7
    Senior Member jcksparow's Avatar
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    Quote Originally Posted by gmcttr View Post
    Yes, your understanding is flawed. The proper bury length for an eye splice would be the same with or without a locked brummel. During destructive testing the bury of a proper eye splice will not pull out even without a locked brummel or lock stitching. The intent of the brummel is not to add extra holding power but only an alternate to stitching as a method to prevent the bury from backing out under no-load conditions.

    Keep in mind that eye splices are used in testing to determine the tensile strength of amsteel blue so a proper eye splice provides the full rated strength. The reason we get by with shorter than recommended buries is because we are not coming close to stressing the bury's to the ropes full tensile strength.
    Fair enough. Learn something new every day.
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  8. #8
    Senior Member hutzelbein's Avatar
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    Quote Originally Posted by gmcttr View Post
    Add this one for an eye splice and we have the best answer for the OP's question.
    [...]
    The reason we get by with shorter than recommended buries is because we are not coming close to stressing the bury's to the ropes full tensile strength.
    Thanks, so you're saying that it doesn't really matter if I'm splicing a dog bone, a whoopie sling or a continous loop, the bury with 7/64" Amsteel should always be 3 fids = 8.01" if I want maximum strength?

    • For whoopie slings this would mean increasing the fixed part by more than 2", which would require even more distance between the trees.
    • For dog bones this would mean a minimum length of 16" plus the size of the fixed eyes. Currently, mine are about 12" long, which is already longer than what I would like for many applications.
    • For continuous loops this would mean a minimum length of about 9", with the buries going through most of the loop, making the diameter of the rope pretty big.

    Since no hammock gear manufacturer seems to use the bury length officially recommended, what is the unofficial rule that applies to hammock uses?

    And how does bury length translate into capacity? If I understood it correctly, a dog bone made from 7/64" Amsteel with 2 x 8" buries would have a minimum strength of about 650lbs? If manufacturers shorten the buries to 2 x 3.2", how much does this decrease the strength? If using a safety factor of 5, 650lbs means a safety limit of only 130lbs - which is less than even I weigh! This sounds scary.

  9. #9
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    At some point, the shortening of buries will cause the failure mode to change from breakage of the rope to the pull out strength of the bury.

    The only way to definitively answer your questions would be by break testing submitted samples of splices with varying bury lengths.

    Since we have all had success with shorter than recommended buries for our hammocking uses, I'm comfortable with that. On the other hand, if I'm splicing for life support for tree climbing I go strictly with manufacturer's recommended splices.

  10. #10
    Senior Member hutzelbein's Avatar
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    Thanks. Maybe I'll devise a break test.

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