around in pocket, I I think so

Discussion in 'Projects & Proposals' started by WindRaf, Oct 2, 2014.

  1. WindRaf
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    WindRaf Senior Member


    sorry...I was in a hurry
     
  2. WindRaf
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    WindRaf Senior Member

    Angélique
    about yur opinion, thanks
    i think that you are a naval architect with 30 years of experience in yacht designe
     
  3. Angélique
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    Angélique aka Angel (only by name)

    You're welcome, but no thanks !

    No, this is so obvious that anyone with a general interest and just a little knowledge in boat design can draw this conclusion.
     
  4. WindRaf
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    WindRaf Senior Member



    OK, i see, you're convinced that the cat-boat can not exist, and that the boats with the bulbous bow can not be built.
    Of course I respect your personnel concerned general columnist, thanks.

    Excuse my English

    ah, I forgot, this is a tapered development


    sviluppo conico.png
     
  5. Jamie Kennedy
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    Jamie Kennedy Senior Member

    Clearly this thread is getting us all frustrumated.
     
  6. Angélique
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    Angélique aka Angel (only by name)

    I didn't respond to any cat-boat, here you can see some Catboat sail-plans . . .
    I didn't say bulbous bows can't be built, this is what I said about your bulb . . .

    Don't worry, I'm just a member of the ‘‘ peanut gallery ’’ - :p

    That's no problem at all, I can understand you, and otherwise I would ask . . :)

    Good Luck !
     
  7. Angélique
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    Angélique aka Angel (only by name)

    I'm just responding to some nonsense* here, sorry if someone gets frustrated by it . . :eek:

    * which is also twisted in WindRaf's last above post . . :eek:
     
  8. Jamie Kennedy
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    Jamie Kennedy Senior Member

    Not frustrated, Frustrum-ated. ;-)

    see #169
     
  9. Angélique
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    Angélique aka Angel (only by name)

    Ah, (in post#170 now :confused:) I didn't understand ‘‘frustrumated’’ and thought it was a slip for something like ‘‘frustrated’’ . . :)

    Now I know you mean ‘‘Frustum-ated’’ without the 2th ‘‘r’’ . . :idea:

     
  10. Jamie Kennedy
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    Jamie Kennedy Senior Member

    It was meant to be a pun, but that's all right.
    In my heart I know I'm funny.

    [​IMG]
     
  11. WindRaf
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    WindRaf Senior Member

    The foolishness is to believe that the directional stability is determined by the ratio of length to width.
    There are wide boats with excellent directional stability.
    And there are narrow boats with directional stability catastrophic.
    Directional stability is given by the interaction between the dynamic zone of metacentre - center of drift - dynamic sailing centers
     
  12. Angélique
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    Angélique aka Angel (only by name)

    That's why I didn't mention only the length to width ratio but some other subjects as well . . :idea:

    This is what I said about the directional stability, you've abbreviated it a little too much in your twisted conclusion . . :eek:

     
  13. Jamie Kennedy
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    Jamie Kennedy Senior Member

    This is true, but I think you will agree that it does become increasingly difficult to realize good directional stability for displacement-length ratios over say 600, when even with everything else as good as you can get it, you really just gotta stretch that sucker out some.

    It is very hard to find examples of sailing vessels with length-displacement ratios over 600. The highest I have been able to find, including sailing barges and fishing smacks and even the medieval carracks and so on, are the beloved West Sail 32 and perhaps the Santa Maria, excluding our beloved Tens and their predecessors. I don't think beam alone is the problem, or depth, or the sail plan. It is simply the lack of length relative to everything else. You even lose stability at some point when you go too big for the length. I think the answer in a successful AIT is to reduce the loaded displacement to a minimum, and of course still get everything else right, not just for longitudinal stability but for pretty much everything else as well, including comfort.

    So for L/D = 600, roughly 600kg.
    perhaps...
    100kg for passenger (smaller would be better)
    200kg for boat (possibly through better materials)
    300kg for consumables (including gear that creates consumables)

    Not saying it can't be done heavier, I just think it gets harder over 600.

    p.s. Santa Maria largest of the 3 ships, possibly 150 metric tons displacement over 60 feet = L/D of 682
    (It had a beam of 18 feet and a draught of 10 feet, which seems very unstable to me)

    [​IMG]
     
  14. Angélique
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    Angélique aka Angel (only by name)

    That's about lofting a "slant frustum-ated right cone" in general and not specific about your boat, the picture is widely spread over the web.

    I've looked it up in Italian for you, study it well, you might learn something from it . . :idea: - -- link -- link --

    Just for info for English readers, in the quote a Google Translation of the part about the lofting of this "slant frustum-ated right cone", but beware automatic translations make mistakes especially when it comes to jargon . . .
     

  15. Jamie Kennedy
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    Jamie Kennedy Senior Member

    Just for fun if we did model a TEN from a Carrack like the Santa Maria, with a cods head and mackerel tale and a block coefficient of about 0.5 ...

    length = 10 feet
    beam = 3 feet
    draught = 1.5 excluding external ballast keel for stability
    Displacement = 1500 pounds = 681 kg
     
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