Clevis Pins

Discussion in 'Sailboats' started by SuperPiper, Nov 12, 2020.

  1. SuperPiper
    Joined: Jan 2003
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    SuperPiper Men With Little Boats . .

    The shrouds on my trailer sailor are attached at the hounds with pins and split rings. I'm considering using bolts with nylock nuts for convenience (damn, those split rings can be challenging). One rationalization is that the nuts and bolts may add a little bit of support to the fork terminal (see photo).

    Thoughts? Experiences?

    Clevis Pin.JPG
     
  2. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    I have not seen distortion like your top drawing.

    Be sure to size the bolt so only the should (no threads) is contacting the terminal forks. Threads may act as a file and wear away the forks.

    Cotter pins might be easier to use than split rings.
     
  3. jehardiman
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    jehardiman Senior Member

    All the rigging and handling specs and requirements (CFR, OSHA, ASME, NAVFAC P-307) say not to do this and it is a USCG citable safety item. Off the shelf bolts are considerably weaker than pins because: a) they have less area and/or strength, b) the stress riser caused by the threading, and c) they improperly constrain the bending load. If you are going to do this you will need an engineered custom made and hardened bolt. Check the manufacturer, they may already have one.
     
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  4. wet feet
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    wet feet Senior Member

    Two thoughts;how often do you remove the shrouds from the hounds and why don't you switch to R clips with your clevis pins? I agree with the sentiments in post #3 and wouldn't use bolts at all as the time taken to ensure the thread engages is also a bit challenging.
     
  5. Barry
    Joined: Mar 2002
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    Barry Senior Member

    upload_2020-11-12_11-57-33.png [​IMG][​IMG]

    A $20 pair of split ring pliers is an easy fix for the split rings. You can get stainless ones for fishing, though usually 304 stainless. I imagine that wet feet meant these? hairpins, probably available in stainless though depending on where they are located, the pointed end might be an issue with snagging things
    Or these clevis split rings which are easy to start
     
  6. gonzo
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    gonzo Senior Member

    I disagree with your statement. None of those regulations apply to a small sailboat. A 316 stainless steel bolt will be equivalent to the 316 pin as long as the threads are completely out of the fork. Further, to address your other statements:
    a) A 1/4" bolt will have the same diameter at the shoulder as a 1/4" pin. As for strength, the same alloy will have the same strength.
    b) A bolt or pin will fail in shear. The threads will not cause a stress riser, since all the stress is on the shoulder which does not have threads
    c) I can't visualize how a bolt can improperly constrain the bending load. If there is a bending load on the fork, it means that the chainplates are not aligned, which has nothing to do with whether he is using a pin or a bolt.
     
  7. messabout
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    messabout Senior Member

    Agree with Gonzo that 316 stainless does not care whether it is a pin or a bolt. The problem with using a threaded fastener is that the threads extend a certsin distance from the beginning end. In common practice the formula for thread length is 2D + one quarter. So a quarter inch diameter bolt will have 2 times one quarter plus one quarter inch of thread.........three quarter inch of thread. Get that threaded part out of any stress condition. If your clevis end is three quarters wide then the bolt must have three quarters of plain shank and be at least one and a half inches long. Now you will want to cut off the excess threaded part and use a wrench to fasten the nylock nut to the bolt....................you did not want to trust a common nut to hold that bolt shank in place did you? Naaah! you need the security of a Nylock or other type of nut that cannot spin itself off the end of the modified bolt. . Best use the standard pin with an R clip or circlip. It is kind of important for that shroud, forestay, or lower remain in its' assigned position.
     
  8. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    For additional security drill a hole thru the bolt and use a cotter pin.

    I use D-shackles thru the terminals. They make great attachment points for a hoisting sling. For a day trip mousing the pin with a zip tie.

    Re-read the op

    Leave shrouds and stays attached to the mast with pins and rings. Use shackles at deck end
     
  9. Ike
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    Ike Senior Member

    Agreed. There are no USCG regulations concerning small recreational sailboat rigging. Big commercial passenger carrying sailboats, yes.
    However, I have been this route and frankly clevis pins and split rings are the better option.
     
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  10. gonzo
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    gonzo Senior Member

    When I am rigging or reinstalling a mast, always carry a few undersize bolts and nuts in my pocket. I use them to temporarily hold the standing rigging. Later, I can install whatever pins with rings or cotters.
     
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