12' Cedar Strip Hull Design. Would this work?

Discussion in 'Wooden Boat Building and Restoration' started by GSardone, Jun 26, 2007.

  1. GSardone
    Joined: Jun 2007
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    GSardone Junior Member

    I have never built a boat before but I have recently wanted to build my own. I will be using a stich and glue-like method and the hull was designed using SolidWorks.

    I borrowed some lines from traditional italian speed boat designs. I had to tone down the curves since it's such a small boat and I don't know the torque tolerances of 1/4" x 3/4" or 1" cedar strips. The transom has a 15 degree rake. The hull will be glassed and the stern will be reinforced to fit a 40 hp outboard.

    My question is: Is it feasible to use cedar strips with this design? I could use however many forms I want since I could easily get the cross-plane dimensions from the program I'm using. I coud even get the forms AND planks cnc'd for a fairly cheap price since I could save it to their program file.

    Thanks for looking!

    Deck:
    [​IMG]

    Keel:
    [​IMG]

    Bow:
    [​IMG]

    Stern:
    [​IMG]
     
  2. frosh
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    frosh Senior Member

    An ambitious hull shape.

    Hi, this is a pretty big project for a very first boat build due to the hull shape shown in your posting. The curves, particularly the concaves which are present as well as considerable convex curvatures will make life challenging even for an experienced builder. Stitch and glue works generally for simple flat panels bent in one plane only and this is most often marine plywood. It can't be done in my opinion for that hull shape. Then you mention cedar strip which is completely different to stitch and glue. This is possible but another method which can achieve the result is cold molding very thin plywood layers. Another way is foam coring using structural foam (Airex, Klegecell, etc.) in strips and laying a glass skin inside and out. Personally I won't recommend any of the above methods to anyone who has never built a boat before except maybe cedar strip on a simple hull shape such as a basic canoe hull. You should really buy plans for a boat suitable for a novice builder.
     
  3. GSardone
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    GSardone Junior Member

    Well I'm a pretty hardcore do it yourselfer so this is right up my alley. I won't be stitching so yeah I guess I shouldn't really call it that at all. I like the idea of structural foam to use as forms. I could (hot) glue the strips to that and grind it off the interior after I glass the exterior.

    I'm going to get some foam panels and waterjet cut a bunch of forms. Hopefully that'll take care of the funky curvature, that and using thinner strips.

    Ambitiousness aside, does it look like a good design? Is there some rules I'm not following concerning hydrodynamics?
     
  4. frosh
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    frosh Senior Member

    Hi, I cannot comment on the hull shape as I am hard core sailing and windsurfing based. It seems hugely more complex than a simpler shape that will perform as well in a 12 footer with a small outboard. Why punish yourself? Is it for aesthetics only? Did you know that you need an accurate mold as well to lay up the foam or wood etc. This is then discarded after the hull is built unless you are building another identical one. The mold can be as expensive and time consuming to make as the hull or even more so. The only way out of the mold is the stitch and glue method.
     
  5. GSardone
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    GSardone Junior Member

    Ahh well that's the thing.

    I can get the form made for less than $100 if I get them cut using a waterjet. A waterjet is a cnc machine that uses a 50,000 psi beam of water and abrasives to cut through anything as thick as a foot of steel. It costs me $5 a minute.

    The program I used to design the hull has an option to save it to the same program the waterjet uses so it's actually a very easy process.

    And yes all the hassle would pretty much be for aesthetics. What can I say?!

    Thanks for the insights. Keep em comin!
     
  6. frosh
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    frosh Senior Member

    When you talk abot the "form" you probably mean Mold? OK so you can get it cut for free almost, but it is not about cutting, it is about constructing a male or female rigid form that looks like the boat itself out of real materials. No machine or robot can yet do this for you no matter what computer program you might have access to. And there is the cost of the materials for the mold, not to mention the time required to accurately put it together. I fear that we are not really communicating on this concept! Check out boat molds on Google to see what I mean.
     
  7. GSardone
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    GSardone Junior Member

    Oh I see what you mean. Well I was just going to make several cross sections to bend the strip around, perhaps a perpendicular piece at the bow where the strips meet.

    You gave me an idea though, I could conceivably make a whole mold by cutting many cross sectionsthat butt up against eachother all the way up the hull. Then grinding out the curves and possibly bondo'ing at the end. That may take some more effort but I don't mind spending the time.
     
  8. frosh
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    frosh Senior Member

    It is not that easy!

    Rather than do a lot more talking about the building of the mold, I will refer you to an excellent link showing how a 14ft. racing yacht mold might be constructed. If you think that building the mold is easier and cheaper than building the final hull then you do not understand the whole process.
    http://www.javelins.org/Technical/virtualJavelin/sailingNZ/d82_SNZaugust.html
     
  9. GSardone
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    GSardone Junior Member

    Of course I don't understand the whole process. It's my first time! Thanks for the link. ;)
     
  10. PAR
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    PAR Yacht Designer/Builder

    As a general expectation, your first attempt at yacht design shouldn't vary very far from well understood concepts, principles and known shapes of accountable craft. There isn't enough information provided in the drawings you supplied to understand your hull shape, other then a guess, based on some shadowing, which isn't particularly conclusive. Just from this, I can see several issues that will likely need addressing. Since you're unfamiliar with the principles and concepts, not to mention the engineering necessary, it would be difficult to offer more assistance, then to suggest there's considerably more to developing small craft shapes, then a surface model rendering. Check out the book store on this site or your favorite book seller, looking for titles on yacht design and construction. There are many good ones to choose from, with most truly interested in the subject, having a substantial library of them. I don't mean to offend you GSardone, you can do it, but first you'll need an education in several disciplines, which is difficult to get in this format.
     

  11. GSardone
    Joined: Jun 2007
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    GSardone Junior Member

    I started fiddling around with this whole thing because I haven't found any plans Iliked. I'm going to push this back until I find something or if I ever get the chance to sit down with an engineer with experience to put together something that would fit my needs. Thanks for the help!
     
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