Plunging chine for a micro class sailboat : your opinion ?

Discussion in 'Hydrodynamics and Aerodynamics' started by vincentg38, Sep 15, 2013.

  1. vincentg38
    Joined: Sep 2013
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    vincentg38 Junior Member

    Hello,

    I'm new to this forum, and to boat design too. I'm currently thinking on a project for building a micro class proto sailboat. Probably made of plywood, therefore a hard chined hull. My question : I drew this "plunging chine" on the side of the boat.

    http://www.boatdesign.net/gallery/showphoto.php?photo=23026&cat=501

    I find it quite aesthetic. But I wonder if, when the boat heels, this chine will alter his heading, luffing up or bearing away ? Thanks in advance for your advices.

    Vincent
     

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  2. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Better if you show a section and explain what a plunging chine is.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum Vincent. I see you've found Free/DeftShip and are busy making boat like pictures. It's important to realize there's more to it, than computer modeled shapes. It's helpful to have an grasp of hydrodynamics. How much engineering and yacht design experience do you have? If this is limited, you should start at the shallow end of the pool, learn why boats are shaped the way they are, then develop your own shapes, based on this understanding of the physics and mechanics involved. As Alan has pointed out, the profile offers very little information about the hull, except it's unconventional chine line, which has obvious flaws underway. These will become apparent once you've gained some design understanding.
     
  4. vincentg38
    Joined: Sep 2013
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    vincentg38 Junior Member

    @ Alan
    "plunging chine" is a word I invented to say a chine that starts high at the stern, and ends low at the bow. Sorry if it was not clear (I'm french and my words are not totally reliable).
    I joined new pictures.

    @ PAR
    I have no yacht design experience. And I agree, I have many, many, many things to learn. I understand that aesthetics is probably the last thing to consider if I want to design a good hull. I want to learn, I started to learn...
    You say that the unconventional chine line has obvious flaws. Can you help me and say what flaws ? I'm afraid that it acts as a brake when the boat heels.
     

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  5. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Clearly you're experiencing and you have to learn several things, not on boats, but on the reality of things.
    The first thing to learn is that things, if they are not decorative ítems, are made to achieve certain ends with them. The ships also fall into this rule. We must design a boat to work in the most correct possible way and get the goals we have planned for her.
    It may be that your ship, which you think is aesthetically perfect, afloat in a ridiculous way serving as worldwide joke. So, in addition to aesthetics, it is good that you had in mind what you want the boat to.
    It is very normal for technically advanced vessels have also very good aesthetics.
    If you want the boat to decorate your library, then everything I just said makes no sense.
     
  6. JSL
    Joined: Nov 2012
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    JSL Senior Member

    also watch your terminology........ 'plunging' may not be an encouraging term. Might give people that 'sinking feeling'.
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The wise course is to buy a few books on yacht design and construction. Once you have a handle on why thing do what they do and how to approach them structurally, you can then proceed to preliminary design studies. The book store here is a fine place to start.
     
  8. Cacker
    Joined: Sep 2013
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    Cacker Junior Member

    Why?

    Why hard chaines? Look, this is plywood hull:
     

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  9. Cacker
    Joined: Sep 2013
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    Cacker Junior Member

    Proto

    And i made cool proto design:
     

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  10. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    Before asking what others think of your model, why not explain why you did it that way and what you expect will be the result?
     
  11. vincentg38
    Joined: Sep 2013
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    vincentg38 Junior Member

    @Cacker : you're right, it's possible to build hull without hard chine in plywood. I saw here the Cox's Bay Skimmer by Gary Baigent :
    http://www.boatdesign.net/forums/attachments/design-software/26136d1223804666-predicting-plywood-bending-behavior-stitch-glue-design-img_1174.jpg
    http://www.boatdesign.net/forums/attachments/sailboats/25971d1223340048-ideal-18ft-daysailer-copy-img_1177.jpg
    http://www.boatdesign.net/forums/attachments/sailboats/25536d1222074175-ideal-18ft-daysailer-copy-img_1187.jpg
    http://www.boatdesign.net/forums/attachments/design-software/26133d1223760513-predicting-plywood-bending-behavior-stitch-glue-design-skimmer2.jpg
    http://www.boatdesign.net/forums/attachments/boat-design/26820d1226435425-trailerable-daysailor-underway-copy-img_1234.jpg
    http://www.boatdesign.net/forums/attachments/sailboats/25969d1223339969-ideal-18ft-daysailer-img_1146.jpg
    http://www.boatdesign.net/forums/attachments/sailboats/25968d1223339960-ideal-18ft-daysailer-img_1145.jpg
    Impressive work of curved plywood !

    Your 15 feet daysailer is very nice, too ! Good luck with it !

    Your micro proto hull is interesting, but I wonder if the cabin has enough room for 3/4 berth, as required by the rules of the class ? It's the great problem of these boats : to preserve a big cockpit and 3/4 berth with enough room...

    @others : thanks for your answers. I will learn now, as you have suggested. But I'm sad because nobody answered my real question...
     
    Last edited: Sep 18, 2013
  12. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    All ships in the world, if not as a shoe box, change the trim when heeling. How can you ask such a thing?.
     
  13. Cacker
    Joined: Sep 2013
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    Cacker Junior Member

    Completely! It`s know-how of accommodation in this hull. Cockpit is 3 meters long!
     
  14. vincentg38
    Joined: Sep 2013
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    vincentg38 Junior Member

    Sadly, I see that you do not know share your knowledge with a beginner without being offensive. Humbly sorry to bother you and have dared to ask a stupid question.

    I am a computer instructor IRL, and am always happy when I can help someone to grow, responding quietly and simply to his questions...
     

  15. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Dear friend, I do not want to offend anyone. I believe that with just a little thought you can figure out what I say. No need, in my opinion, have studies or do any calculations. Sorry you felt slighted, it was not my intention. Maybe I'm a bit rough with my expressions. Excuse me.
     
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