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  1. #1
    Moderator Christian Williams's Avatar
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    Alternatives to cotter pins in turnbuckles

    When I get the answer to this I will finally know everything.

    What is the purpose of cotter pins in rigging turnbuckles?

    They don't prevent the turnbuckle turning or set the adjustment. (Are they supposed to?)

    They provide nice sharp edges often covered in tape. (A side benefit?)

    I guess they prevent a bored child from taking the mast off your boat ("See, Timmy, that's why the cotter pin is there...")

    No doubt I have missed the obvious explanation for 70 years or so.

    Click image for larger version. 

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    Last edited by Christian Williams; 03-14-2019 at 07:50 PM.
    Thelonious II, E381 hull 513 (1984) Universal 5432
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  2. #2
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    I venture that the cotter pin stop the threads completely disconnecting and therefore prevents a catastrophic failure.

    I put a ring instead of a cotter pin in place to prevent unwanted adjustment.
    Mike Field
    "Jenny" E35-3 #251
    San Francisco

  3. #3
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    They Prevent the turnbuckle from turning. The Rings do the same thing..I guess if the cotter pins are so short, then the turnbuckle would be able to turn
    Josephine, E381 hull 505 (1983) Universal 5432

  4. #4
    Advanced Beginner bgary's Avatar
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    Yes, they're supposed to stop the turnbuckle from turning. But that's dependent on choosing a pin - and bending it in such a way - that it "interferes" with the turnbuckle body. I'd say probably 90% of the pins I see at the marina are too small and, when bent flat, accomplish pretty close to nothing. It's an ancient catch-22: if the ends stick out far enough to do their job, they are also sticking out far enough to poke holes in sails, hands, etc....

    I'm one of those apostates who uses rings instead of pins. Partly because they don't have sharp ends, and partly because I can remove and replace them without tools. Bonus point for "knowing" that the turnbuckle won't turn, because it can't when the "hole" in the ring is captured by one side of the turnbuckle body.

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
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  5. #5
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    In the old days of biplanes and flying wires, safety-ing the turn buckles was a big deal because the vibration would back them off and in aviation we have to use safety wire.

    If you really want to create a cut hazard, safety wire is a GREAT answer for you.
    Last edited by Tin Kicker; 03-14-2019 at 11:58 AM.

  6. #6
    Moderator Christian Williams's Avatar
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    I approach understanding, but grumpily.

    The photo in the initial post is from Harken. Those cotters will not stop anything turning.

    This photo is my boat. Large cotters, installed by me. Even so, they are pathetic ineffective mechanical means of preventing uncommanded unscrewing. "Uncommanded unscrewing"--hard to wrap your mind around, and probably unconstitutional.

    Bent tails on "correct" cotters do not stay lined up, either. In order to fulfill their unconstitutional opposition to uncommanded unscrewing, they have to splay a little. Into your leg. Or expensive sheet. It is their nature.

    OK, I guess I will go around and replace them with rings, as Bruce does. I don't recall seeing anybody else with rings, though.

    So--are we eccentrics?

    Really?

    Cotters through turnbuckles have been around since I was a kid. Standard practice. Tape good for 10 months, then starts flapping. Tape not effective in covering sharp stainless ends, anyhow. Tape a ritual, like shaving. Stuff grows back. Sharp cotter grows back.

    Purpose of tape: to keep cotter splits lined up with threaded rod.

    Tape therefore mandatory part of turnbuckle system. Huh? Tape is part of a "system"?

    If the simple answer is a ring, why just us?

    If a better answer is Monel wire lashing (Tin Kicker), the standard for shackle pins, how come nobody does it?

    Are we smarter than everybody?

    Click image for larger version. 

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    Last edited by Christian Williams; 03-14-2019 at 12:08 PM.
    Thelonious II, E381 hull 513 (1984) Universal 5432
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  7. #7
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    Christian - The answer is that this is a time consuming pain, especially if a quick pin or clip is available. Try doing a bunch of these through one handed access holes.
    Last edited by Tin Kicker; 03-14-2019 at 01:28 PM.

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