Carbon fiber davit design.

Discussion in 'Multihulls' started by svquintana, Jun 28, 2016.

  1. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    Have you thought about asking over at DIY-Yachts forum? I'm guessing that someone over there would have done carbon davits and can give some pointers on a solution that has worked for them?

    https://diy-yachts.com/forum/
     
  2. svquintana
    Joined: Mar 2012
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    svquintana Junior Member

    Thanks for that link. I'm going to spend some time over there and see what I can learn.

    Thanks to all, for your comments.

    Paul.
     
  3. daiquiri
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    daiquiri Engineering and Design

  4. UpOnStands
    Joined: Nov 2015
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    UpOnStands Senior Member

    sorry, got busy for a bit.
    now back to the design
    I've been looking at a lot of SS davits and here is question for the community.
    How many would trust existing tubular SS davits to support the tender half full of water?
    How many would trust the lifting points/tender to support the load?
     
  5. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    If your dingy is full of water, lift one side first to flush the water out.
    Make sure your transom can handle the loads, the plate has to be wide enough.
    I was playing with the idea of mounting an A frame on the top of the transom rather than on the side of it. This way the downward force can be spread better.
     
  6. UpOnStands
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    UpOnStands Senior Member

    the op appears to have his main sheet traveler running along the top of the transom
     
  7. svquintana
    Joined: Mar 2012
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    svquintana Junior Member

    Well, reviving, and concluding another thread of mine.

    I've designed and built the davits. They are built with 1.2 mm carbon fiber on either side of 20mm foam, 250mm wide, and nearly 300mm thick at the corner. The dinghy is lifted using two 1000w captive line winches, by Quick. One line for each end of the dinghy.

    The winches are hidden in the hulls, and the line runs through the back beam, through the bulkheads using friction rings (Antal), and turning the 90 degree corner into the davit using a proper block. They go through the back beam, through Antal friction rings, and into the davits. They then make a 90 degree turn, through another block, and go through a friction ring on the bottom of the davit, which you can see in the photo, and attach to the dinghy.

    There will be a limit switch adjacent to the friction ring, to prevent the winches from over running the stop.

    There will also be a "work light" mounted half way between the friction ring and the access plate, and an Antal Deck ring mounted on the bottom of each davit, at the outer end. These will be used to mount a dinghy cradle, for offshore work. It'll just be a safety feature, in case something happens to the lift lines.

    I've just bolted them on temporarily today. The 3/8 bolts will stay, and deal with the peel force at the top of the davits. The davits will also be coved and glassed to the transom. When that's done, the "roots" will be faired and painted. As you can see, the sides of the davits are not yet faired, the white is only overspray, and waiting for glass.

    The pads on top, are backing pads for the lift block. The pad is 2mm carbon at 90 degrees to the carbon on the davit.



    Cheers.
    Paul.
     

    Attached Files:

    Last edited: Oct 18, 2018
    UpOnStands likes this.
  8. UpOnStands
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    UpOnStands Senior Member

    Congratulations. Looks better than Pro-built. Just need to remember to remove the drain plug when stowed. ;)

    What tender do you have in mind?
     

  9. svquintana
    Joined: Mar 2012
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    svquintana Junior Member

    Thanks for the compliments.

    The tender is a Caribe c12, with a Suzuki, fuel injected, 20hp outboard. We built the davits to fit the dinghy.

    And we'll try to remember to remove the plug, and keep out the baggies. :)

    Though I think these davits could hold the dinghy, even filled with H2O, though I'd prefer not to try.

    Cheers.
    Paul.
     
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