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  1. #1
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    Eliminating the Weak Spot - Whoopie Slings

    I'm new to the forum, but I've dived headfirst into hanging and diy'd my whole set up so far. The one piece that's stuck in my head is the whoopie sling. It's simple, but manages to do something that could easily be overcomplicated with other methods. That being said I do see that it could be improved slightly by eliminating the weak spot that lies between the two buries. It's the only part on the sling that isn't doubled up in some way.

    My idea is simply to overlap the buries. The adjustable bury would simply come out of the line some distance past the end of the bury for the eye. The two inner lines run beside each other not through one another.

    I've just done this with some mason line, and it's still easy to adjust. I don't see any issue with this on small line. The thing I'm most curious about is if two pieces of amsteel will fit inside the other part and still function. There's also the possibility that this much material will weaken the line to the point that this isn't a useful method.

    If this were to work in theory it may be worth trying on smaller line than usual since it will increase the breaking strength. That might eliminate some of the issues with the larger line.

    I also think that if I can figure out how to bury part of the adjustable bury inside of the fixed bury(don't ask me how) it may work better and possibly eliminate the need for the locked-brummel at the eye splice. That will be a bury in a bury. We'll call it whoopie-ception or something.

    I think that's all I had to say. Chime in with comments and whatnot. The one I've already made is going to stay that way. Another is on the way for some unscientific testing.

    Oh, if this doesn't make sense then let me know. It's late.

  2. #2
    GrizzlyAdams's Avatar
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    I understand the idea, I think.

    Tension is what keeps the fixed eye bury from moving when under load. The locked brummel keeps it from pulling out when not under load....but, significantly perhaps, under the assumption that the buried line is left alone inside the cord.

    If you overlap the buries, then as you shorten the whoopie sling, the sliding of the sling loop against the the fixed eye bury will....I dunno. Seems like it would encourage that bury to back out a bit. Not liking that prospect.

    I don't overlap the buries, but I do have the exit point of the adjustable line right at the point where the fixed eye bury ends, not so much as to "minimize the weakest point" as to minimize the shortest length the whoopie sling can span.

    just my $0.05 on the question...
    Grizz
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  3. #3
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    Quote Originally Posted by GrizzlyAdams View Post
    I understand the idea, I think.

    Tension is what keeps the fixed eye bury from moving when under load. The locked brummel keeps it from pulling out when not under load....but, significantly perhaps, under the assumption that the buried line is left alone inside the cord.

    If you overlap the buries, then as you shorten the whoopie sling, the sliding of the sling loop against the the fixed eye bury will....I dunno. Seems like it would encourage that bury to back out a bit. Not liking that prospect.

    I don't overlap the buries, but I do have the exit point of the adjustable line right at the point where the fixed eye bury ends, not so much as to "minimize the weakest point" as to minimize the shortest length the whoopie sling can span.

    just my $0.05 on the question...
    Thanks for your input and your videos! Those videos really pulled everything together in my initial state of confusion.

    I don't disagree with your concern about the adjustment messing with the fixed eye bury. I had thought about it and decided it would make it self evident at some point before I start doing this on a scale that would risk my butt.

    I also made another from mason line, and broke it. It certainly felt more difficult to break, and broke in the loop. Seems as though it works to some extent.

  4. #4
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    Quote Originally Posted by jrh065 View Post
    ...by eliminating the weak spot that lies between the two buries. It's the only part on the sling that isn't doubled up in some way...
    By my understanding, the area of single line is not the weakest point in a whoopie. It is the distorted area of the constrictor where the free end of the adjustable bury exits the constrictor. Overlapping the buries would further stress this area making it even weaker.

    Again...this is my understanding, but I am fairly confident it is correct.

  5. #5
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    FWIW...

    "Test samples were consistent for breaking strengths and exhibited a single failure mode. The Whoopie Sling broke at the exit point of the adjustable tail with the butt splice."

    Quoted from this paper.

  6. #6
    Senior Member GrayDog's Avatar
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    If break strength is your concern, why not go with a larger diameter amsteel?

    Just moving from 7/64" to 1/8" increases break strength from 1600# to 2500# with weight only increasing from 4.8oz/100ft to 8oz/100ft.
    hammock [ham-uhk] noun
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  7. #7
    Senior Member JerryW's Avatar
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    I believe you are over-thinking the whoopies. Even using Dynaglide, the single portion is strong enough to support a huge load. If you're really worried, just follow GrayDog's suggestion above.


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  8. #8
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    What Grizz says...

  9. #9
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    Quote Originally Posted by GrayDog View Post
    If break strength is your concern, why not go with a larger diameter amsteel?

    Just moving from 7/64" to 1/8" increases break strength from 1600# to 2500# with weight only increasing from 4.8oz/100ft to 8oz/100ft.
    Many of us do just that. Matches the safety margin professional riggers go by. 10-to-1. With no weight cost to speak of.

    Quote Originally Posted by gmcttr View Post
    By my understanding, the area of single line is not the weakest point in a whoopie. It is the distorted area of the constrictor where the free end of the adjustable bury exits the constrictor. Overlapping the buries would further stress this area making it even weaker.
    You beat me to it. I also think it might actually make the whoopie weaker to overlap those buries, not stronger.

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  10. #10
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    The weak point is the exit of the adjustable bury, as documented in an email to me by a Samson Rope R&D Engineer.

    Overlapping the two buries may create an uneven transition area, which will weaken the rope at that point. That's why the fixed bury has to be tapered. Cutting it off flush creates a localized load.
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