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Thread: Attaching Blocks to Boom

  1. #1
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    Default Attaching Blocks to Boom

    Just looking for some feedback on this setup to attach Blocks to Boom. I've just used a Boom Hitch with a U-Bolt included whilst tying it. The ends have been taken to the opposite side and tied with a reef knot. This for my small catboat.

    Note that the spar shown is just a sample and is approximately half the diameter of the real thing.

    P8120967-1.jpg P8120968-1.jpg

  2. #2
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    Default Re: Attaching Blocks to Boom

    Two things I come to think of right away:
    Shafe, the schackle will be moving back and forth a lot, eating up the line and perhaps the boom too.
    Because of this and for other reasons, you really need to secure the bolt of the schackle (usually done with a thin cupper thread), and perhaps turn it upside down so the bolt is at the block side of the arrangement.
    Over all, I really don't like the system you've developed. Sorry.

    /Mats

    Elected Swedish Yourneyman of the Year 2019

  3. #3
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    Default Re: Attaching Blocks to Boom

    Webbing, two wraps arranged in a "V" configuration, block suspended from the apex of the V. 1" is fine for most small boats, easy to sew. Doesn't tend to move, can be easily secured with a couple of small screws if needed.

  4. #4
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    Default Re: Attaching Blocks to Boom

    Whether you use line or webbing the strops need to be longer. We have rope stropped blocks, located with bees screwed to the yard.
    finished 003.jpg
    It really is quite difficult to build an ugly wooden boat.

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  5. #5
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    Default Re: Attaching Blocks to Boom

    I've used similar lash ups, including lashing a shackle exactly as you show. Not beautiful, but very functional and no chafe issues to date. Give it a whirl and keep an eye on it. You'll know soon enough if it is going to work out ok.

  6. #6
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    Default Re: Attaching Blocks to Boom

    Just a thought. You could ditch the shackle entirely. Pass an end of your line through the blocks becket, middle it, and tie a rolling hitch round the boom with the doubled line. Or a rolling hitch with both single ends going in opposite directions.
    It really is quite difficult to build an ugly wooden boat.

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  7. #7
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    Default Re: Attaching Blocks to Boom

    I was thinking the same with ditching the shackle. It is just adding a way for the block to fall off when the pin drops out.

  8. #8
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    Default Re: Attaching Blocks to Boom

    Yup, the shackle is defenitely a weak point. But as Nick points out, there should also be a bit of slack in the line holding the block.
    I can think of numerous solutions, a line around the boom with eye splices in each end, one eye inserted into the other. Or a constrictor knot (many other knots would work too) around the boom with a line with eye splices.
    However, I don't really see the point, unless it's to test various points on the boom to see where it works best to attach the block before using a conventional solution to attach it permanently.

    /Mats

    Elected Swedish Yourneyman of the Year 2019

  9. #9
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    Bellingham, WA, USA
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    Default Re: Attaching Blocks to Boom

    Quote Originally Posted by Slacko View Post
    I was thinking the same with ditching the shackle. It is just adding a way for the block to fall off when the pin drops out.
    To add to this; it's not 'if', it's 'when' the pin falls out. Especially when you have the pin at the top like in the pictures.

  10. #10
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    Default Re: Attaching Blocks to Boom

    Ditch the shackle, frap it after wrapping it.
    How many blocks on the boom ? Room for a bridle ?

  11. #11
    Join Date
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    Default Re: Attaching Blocks to Boom

    Here is the set up of the Boom and Mainsheet in the book.

    P8130969-1.jpg

    I do not wish to add Bee Blocks to the top of the Boom but rather tie the blocks on.

  12. #12
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    Default Re: Attaching Blocks to Boom

    It'll work fine.

  13. #13
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    Default Re: Attaching Blocks to Boom

    If you're concerned about chafe add a sacrificial leather wrap...but do lash the pin

  14. #14
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    Default Re: Attaching Blocks to Boom

    If you figure-8 around the shackle, then the lashing will isolate the shackle from the boom. Use an even number of wraps(either 2 or 4, not three as in your photo) and tuck under alternate turns to cancel any twisting tendency. If you don't understand what I am saying, picture a single turn of figure-8 wrap...it will just un-twist and be slack. So you make alternate turns try to twist it the opposite way.

  15. #15
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    Default Re: Attaching Blocks to Boom

    Quote Originally Posted by wizbang 13 View Post
    Ditch the shackle, frap it after wrapping it.
    How many blocks on the boom ? Room for a bridle ?
    Meanwhile at the night club, everyone got on the floor for the 'wrap 'n' frap'.

  16. #16
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    Default Re: Attaching Blocks to Boom

    Hey Sean, read my post again. I didn't use the word if.
    I've had the experience of seeing the pin drop out of the mainsheet block 1/2 way through a tack.
    At least I wasn't gybing at the time.

  17. #17
    Join Date
    Aug 2008
    Location
    Corvallis Oregon
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    Default Re: Attaching Blocks to Boom

    Soft shackle, prusik, lashing, all currently in use on my boat for main sheet block, halyard attachment to yard, and downhaul, respectively.

    Don't overthink it, rig something up and try it. Easy to change until you figure out what you prefer.

    Bill

  18. #18
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    Default Re: Attaching Blocks to Boom

    The use of a prusik or other kind of lashing on a small diameter boom saves drilling holes which become weak points.
    Ben Fuller
    Ran Tan, Liten Kuhling, Tipsy, Tippy, Josef W., Merry Mouth, Imp, Macavity, Look Far, Flash and a quiver of other 'yaks.
    "Bound fast is boatless man."

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