Small catboat design review

Discussion in 'Boat Design' started by mbowser, Dec 29, 2015.

  1. mbowser
    Joined: Nov 2015
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    Location: Canterbury NH

    mbowser Junior Member

    Over the past month I have been spending a lot of time trying to get up to speed designing a small raid type sailboat here: http://www.boatdesign.net/forums/boat-design/first-time-poster-seeking-advice-54650.html
    and think I've come up with a reasonable design that will probably suit my needs, but circumstances dictate that I can't realistically begin building this design for at least a year (I am building a new, bigger shop this upcoming summer).

    So in the meantime I'd like to get some experience building a design of my own doing, and after measuring my current shop space I can get away with building a 12' boat. My body size (6'5" 230lbs) doesn't lend itself to well trimmed small boats so I thought I'd take a crack at something along the lines of a beetlecat that I spent a lot of time on when in college. They are wide and stable and I always like the sensation of being so close to the water while sitting on the floorboards.

    I want to do a stitch and glue plywood version which will have hard chines so it's not even close to an exact copy, but the general dimensions are there. I am going to build up a model first, but I have a few concerns regarding the forefoot area and whether or not there is too much twist to get plywood to bend.

    I'd much appreciate some advice as to the following:
    1. Can I even get the panels to come together at the bow (assume 6mm okume 1088 plywood)?
    2. Would you expect the underwater profile to behave as a catboat would? There is a lot of wetted area and while I know catboats are not known for speed, I'd like something fun to sail. I would use a gaff beetlecat rig for this boat (~110 ft/sq).

    Thanks for any input.
     

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  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Catboats are known for speed and most well designed ones, get up and scoot pretty easily, assuming you can hold them down. This boat will be as sensitive to trim changes as your other, narrower boat, though this one has much more bearing area and wetted surface. This just means she'll need more power to get up and it'll offer more resistance to heeling moment from the rig. The buttock angles seem a little steep for real performance, but it'll sail, if this is all you're trying to prove.

    As previously mentioned, you can build a boat that you'll dislike to sail, just as easily as one that you'll enjoy. Trying to learn yacht design through the hunt and peck method, is a rather tedious way to go. You could get a set of plans, make some modifications to the sheer sweep, stem shape, transom angle, rig, etc. without having to learn the subtleties of small craft yacht design.
     
  3. mbowser
    Joined: Nov 2015
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    Location: Canterbury NH

    mbowser Junior Member

    I guess I've been in the wrong catboats, but regardless, I have a great fondness for the beetlecat and given that my current shop dictates something 12' and under, it seems like a good learning opportunity.

    If it sails like a dog, then I'm not out a huge chunk of change and I move on. If I learned a bit about boat design in the process then it is worth it to me. Maybe it will teach me once and for all that I shouldn't try designing my own boats :)

    On the other hand, I just came across the Bolger Bobcat this afternoon and thought it was similar to what I had envisioned and might be a good place to start.
     
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There are lots of Beetlecat like plans available. I have a slightly larger one at 15'. Bill Garden's Tom Cat is another. The Bolger BobCat is one uglyass boat (below).
    [​IMG]
    [​IMG]
     
  5. SukiSolo
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    SukiSolo Senior Member

  6. mbowser
    Joined: Nov 2015
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    Location: Canterbury NH

    mbowser Junior Member

    Tom Cat is lovely, but right now I'm looking specifically at plywood construction. Unfortunately, my current shop really has a hard stop at 12' if I want to be able to move around. That will be changing this summer, but until then I'm looking for a short term project that I can do.

    Agreed.
     

  7. mbowser
    Joined: Nov 2015
    Posts: 23
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    Location: Canterbury NH

    mbowser Junior Member

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