life lines dyneema tension turnbuckle substitutes?

Discussion in 'Boatbuilding' started by Charlyipad, Sep 2, 2018.

  1. Charlyipad
    Joined: May 2014
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    Charlyipad Senior Member

    Hi folks, I am upgrading my life lines (finally). Bought a mess of 7/64ths amsteel to use. the stanchions are 1" fiberglass rods. Holes will be drilled on a 4" layout for each horizontal run. then at the end of each I have to tension and adjust somehow. OK, I know I've got to pre stretch the am steel first, but then, if I use small turnbuckles, I only have about 2-3 inches to play with. PLUS, for a 36 ft boat with a gate on each side that means about 32- turnbuckles! ouch. Theres got to be a better way. whatever I use, it has to stay secure. Any ideas? Thanks
     
  2. JamesG123
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    JamesG123 Senior Member

    Are you saying you are running horizontal lifelines at 4" intervals on (I assume) 26" to 36" stanchions? Why?
     
  3. Charlyipad
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    Charlyipad Senior Member

    Hi James, the stanchions are 39 1/2 inches high. Per coast guard regs. With 7/64ths am steel , I wonder if turnbuckles are even necessary. I will have a diamond stopper knot on one end, and have to cinch them tight on the other somehow.
     
  4. gonzo
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    gonzo Senior Member

    Make an eye at the end and use lashings.
     
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  5. JamesG123
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    JamesG123 Senior Member

    But why are you running 8 wires thru them as I understand you?
     
  6. Charlyipad
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    Charlyipad Senior Member

    regs.

    More I think about it, a stopper knot on fwd end threaded through the stanchions back to the companionway gate, There, maybe put an eye thimble between the last stanchion and the gate stanchion. then at the gate, run a line through with an eye splice thimble on the fwd end, with the lashing between the two thimbles. Inside the gate have another stopper knot with a loop, for hanging the gate courses on, with hooks of some kind. ?
     
  7. JamesG123
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    JamesG123 Senior Member

    If you mean 46 CFR 177.900? This is a charter boat? I was thinking private boat...

    What Gonzo said. The easiest way I've seen it done is to use a small(ish) come-along to tension the cable for a crimp fitting.
     
  8. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Like Gonzo said

    Lashings

    No need for come-alongs.

    Hardest part is preventing chafing at stantions.
     
  9. JamesG123
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    JamesG123 Senior Member

    A come-along makes it easier to one person to do.

    Yeah, deburring and chamfering the thru holes in the stanchions will minimize the wear from wind and window-lickers leaning on them.
     
    Last edited: Sep 3, 2018
  10. Blueknarr
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    Blueknarr Senior Member

    There are lashing procedures which include multi-purchase tensioning so no separate come along required.
     
  11. Blueknarr
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    Blueknarr Senior Member

    More I think about it, a stopper knot on fwd end threaded through the stanchions back to the companionway gate, There, maybe put an eye thimble between the last stanchion and the gate stanchion. then at the gate, run a line through with an eye splice thimble on the fwd end, with the lashing between the two thimbles. Inside the gate have another stopper knot with a loop, for hanging the gate courses on, with hooks of some kind. ?

    Knots and dyneema don't mix well. Fortunately, dyneema's slipperyness prevents most knots from holding at all. Dyneema looses FAR more than the 25% loss of strength often quoted for knotted rope. I have been assuming a 50% loss for high tech lines. A quick Google query, to validate my assumption, gave results of others claiming up to 85% loss. I am confident in my policy of no knots in loaded dyneema. End of tail warning knot permitted as no load.

    One characteristic of high tech lines is that they don't like sharp bends. Especially those found in many knots. Your lifelines should end in thimbled eyesplices. The mobius brummel splice would be my choice.

    Eventhough it has a very low initial elastic stretch, dyneema suffers from slow permanent stretch. Pre stretching does not fully eliminate creep. Plan on retentioning your lifelines every couple of months. When the tensioners bind up, brummel splices can be undone and repositioned.

    Heat shrink tubing protects against stantion post chaf.
     
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  12. Charlyipad
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    Charlyipad Senior Member

    Did a test run today. It is a lot of work! Had trouble splicing the 7/64ths w/o a proper fid. Do they even make such a fid?? I tapered the end by unraveling some of the fibers and trimming etc, then taped a point with duct tape. It worked OK, but would I think the tape adhesive works against the slickness of the line as it worms through the core to make up the splice. Like the shrink tube idea. I was thinking of putting a rubber tube over the lashing just to make it look neater.
     
  13. Blueknarr
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    Blueknarr Senior Member

    What type of splice are you doing?
    Amsteel is one of the easiest lines to splice. I usually don't bother with a did at all. Sometimes I'll use a pencil or ball piont pen if one happens to be in breast pocket. Try bunching up the line before slpicing. 1536202704006991891439.jpg
    Didn't have amsteel on hand. See how fat this single braid gets when pushed together. Push the rope over the tail instead of the tail into the line.
    Electrical tape works better than duct tape.
     

  14. Charlyipad
    Joined: May 2014
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    Charlyipad Senior Member

    It is 7/64ths am steel. I'll try electrical tape. I think it will all fall into place once I find something to wrap up the taper so it stays stiff and slick.
     
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