Full-length keel

Discussion in 'Boat Design' started by daiquiri, May 21, 2009.

  1. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    PAR, thanks for these considerations. All of them are very resonable and true. But, as I said before, the goal is to have a boat simple to build, with a look and appeal of a traditional workboat with a full-length keel.
     
  2. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    @Alan White:

    Perfect! This is exactly the kind of info that I was hoping to get. :)
    I'm glad to hear that I'm not the only one here who likes the looks and lines of those oldie nutshells. :)
    Do you have some pics of your boat to show?
     
  3. alan white
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    alan white Senior Member

    I should have some pictures. Gotta go now, but I'll post a couple later.
     
  4. philSweet
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    philSweet Senior Member

    Daiquiri, I'm interested in what you had in mind for mixed stitch an glue construction. Attached is a sketch of a craft I drew specifically to explore such a build before trying it on a bigger boat. I wanted to figure out how to build heavyish stitch and glue style craft single handed. Came up with the idea of joining five stitch and glue panel pairs and assembling them on frames. Each component light enough to be handled by one person easily. The round bilge gets strip-planked last. The five panel pairs are the hull bottom, port and starboard fordeck/topsides, and port and starboard aft deck/topsides. king planks join deck centers. Butt blocks join Fore and aft. Seems easy to pattern and kit if the build method works.

    The test boat- a 21' Hampden type. Sorry the second image is inverted, I can't flip it and save it with my software.
     

    Attached Files:

  5. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    I think that the method you have described can work, but it will require some very precise woodworking, imho. Otherwise the transition area between the fore and aft pre-assembled shells could look all but smooth.
    It might also allow you to pre-assemblate and install all the interior joinery and plumbing before enclosing everything with fore and aft modules. It should make the cabinetmaking faster and much more comfortable. The problem again is that it requires a very precise job, in order to make all the modules fit well.

    My idea was different... It was driven by the necessity to have a reinforced keel, so that I can insert properly shaped lead bricks into the cavity formed by the side plates. So I was thinking about making the boat's bottom (keel plus first row of port and starboard strakes) with ply-on-frame method, while the upper strakes would be added with stitch and glue technique. The frames would therefore extend vertically only till just above the first chine, and would act as a support for the floor grating.
    All above that would be essentially clear from frames - though I will know that only after I've performed proper scantlings. Apart the area around the mast, which will be generously reinforced, of course.

    P.S.
    It's been quite a while since the last time I saw drawings entirely made by hand. I find it very proper for boats of this type. :)
     
  6. philSweet
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    philSweet Senior Member

    Terminating the frame ends as you described is tricky. both the frames and the hull are very rigid entities and there will be a great concentration of stress at the nib ends. For a boat like you've described, I would cut a 4", 5", and 6" square of 5 oz dynel and epoxy them over each nib, small to large. Works for me. I'm guessing frames from 12mm ply and a skin of 7-9mm stuff?. I should probably mention I tend to build things as if they will survive forever. I managed to crack two rib ends on one of my boats when it fell four feet onto concrete. The cracks showed up two years later.
     

  7. Gilbert
    Joined: Aug 2004
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    Gilbert Senior Member

    I would recommend drawing your sailplan first and then configure the keel to balance it. Perhaps everyone is assuming that, but I don't recall that anyone mentioned it.
     
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