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Thread: Second thoughts on snap shackles

  1. #1
    Curator of Broken Parts toddster's Avatar
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    Second thoughts on snap shackles

    Another revelation from Captain Obvious.
    Yesterday, I found this odd object laying on deck, at the base of the mast. Looked ominously like something important.
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    It took an embarrassing amount of head-scratching before I realized that it is the locking pin from a snap shackle. From the boom vang to be precise.
    (The rest of the evidence was all laying around on deck too, but I was looking upward...)

    Looks like something (stray reefing line?) snagged the split ring that holds the shackle together, and it just fell apart.
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    Obvious in hindsight, but I did not realize that the split ring, which you yank on to release the shackle, is all that holds the mechanism together. Now that has me pondering whether these things are a good idea for critical applications. Looking at other snap shackles on board, I see that some of them have split rings on the pin and some have riveted loops, which presumably are immune to snag-failure.
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    Confession - there were so many things to do at launch time that I haven't taken the time to sit down and eye-splice the shackles onto the new rope halyard ends anyway - I've just got them tied on with bowlines. But... the snatch blocks that I use for preventers and bridles all have this same type of snap-shackle.

    Hmm...
    s/v arcturus E29 #134

  2. #2
    Contributing Member II 67rway's Avatar
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    More Shackle Failures

    I too have had a couple of shackle failures recently; both holding mainsheet 8:1/4:1 block to the traveler. First was the snap-shackle, lazily put on for convenience. Then the Harken shackle that came with the high speed/low speed blocks.

    We sail her pretty hard, but no crash or loose block gybes... Sheet in hard, gybe, then ease it. Do find ourselves flogging the main to weather in strong gusts though, which is hard on all sorts of gear.

    My guess is the Harken shackle lost it's threads with a side load, as if the shackle rotated at some point, but don't know.

    Scary to have the boom un-tethered while under sail with blocks swinging wildly through the cockpit, to say the least.

    Using a Wichard HR D-shackle there now... wish the blocks could fit a larger one!
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  3. #3
    Principal Partner steven's Avatar
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    I really do not like this style of snapshackle and have removed them from Indigo. In addition to the ring letting loose, a line can snag it and cause it to open Also, the swivel is prone to corrosion and an unexpected twisting load can (as I can attest) break the shackle at the swivel. Especially bad for halyards because among other things you will need to climb the mast. But no matter where it is being used, breaking under load will probably to cause something bad to happen.

    I prefer knots. For halyards, knot of choice (I routinely use a stunsail tackbend, also sometime called a buntline hitch - which ties fast, is reliable, doesn't take up much room, and can easily be undone when tight and wet). For sheets, I find a bowline ties faster than a hooking a snapshackle (though a snapshacke can release faster, but I am not racing).

    --Steve
    Last edited by steven; 10-08-2019 at 12:27 PM.
    Steve and Paula
    Indigo E35-2 #446
    Annapolis

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