NACA profiles and hulls

Discussion in 'Hydrodynamics and Aerodynamics' started by laserek, Oct 13, 2014.

  1. laserek
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    laserek Junior Member

    Hello,

    I have a question: why underwater parts of hulls do not look like NACA profiles?
    More over, it looks like 'revers NACA profile' - narrow bow, and wide, round stern.

    Why?

    Marcin
     
  2. Leo Lazauskas
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    Leo Lazauskas Senior Member

  3. laserek
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    laserek Junior Member

    Thank you Leo,

    This thread is useful, but what about slow (up to 3 knots) not-planning boat?
    E.g. half submerged NACA laminar profile 64A010 as a hulls of catamaran (lets forget about stability).


    Marcin
     

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  4. TANSL
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    TANSL Senior Member

    The problem with many boats is that they need to carry things inside, ie, need space. Many designers have to work wonders to fit everything inside the boat. For reasons known to all, the engine rooms are usually put as afterwards as possible.
    Large tankers and bulk carriers have very rounded nose, but the stern can not be thin
    Some ships, such as SWATH, may have the hulls in the way you want. I am not an expert but I seem to recall that the section on "Raindrop" is the best. Thus a profile. NACA, like the drop of water, would be great.
     
  5. DCockey
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    DCockey Senior Member

  6. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Maybe it is a hot topic in the Polish-Lithuanian Commonwealth.
     
  7. DCockey
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    DCockey Senior Member

    How did Lithuania get involved? Both laserek (OP in this thread) and szlak18 (OP in previous thread) list their country as Poland.
     
  8. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I'm Lithuanian. And Poland is an old colony of Lithuania :p
     
  9. Manfred.pech
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    Manfred.pech Senior Member

    Foil shaped catamaran hull

    There have been attempts to create catamaran hulls with a special shape (not naca as I think). The results are disappointing.

    [​IMG]
     
  10. laserek
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    laserek Junior Member

    Leo, you are right: one of the most famous Polish King Jagiełło (Lithuanian) was fighting (sametime) with the most importand Lithuanian Prince Witold (personaly - his cousin :)

    I am going to use two huls of catamaran as a platform for a "houseboat" (5.5 length, 2.5width - dimentions are limited to the size of my garage) with small electric engine. No planning, no foil - just slow vessel.

    Most catamarans hulls looks like (A) - 'U' stern above the surface of water. But what do you thing about deply immesed, tapered stern like classic hulls of cargo ship? Cross-section (B) or (C) even.

    It looks like a tail of NACA profiles. Becouse of this I initiated this threat.

    marcin.
     
  11. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I can see no reason to use NACA or any other airfoil shapes for the hull
    shapes of your catamaran. You should look at the shapes of existing hulls and
    try one of them. Even if an airfoil shape worked reasonably well, you stand to
    gain very little at the speeds you are considering. The risk of creating a badly
    performing boat far outweighs the possible small benefit.
     
  12. laserek
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    laserek Junior Member

    (lost attachments)
     

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  13. TANSL
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    TANSL Senior Member

    In my opinion, (A) and (B) are the same solution. It just depends on the desired position for the center of buoyancy of the boat speed, the wave height, etc.
    Solution (C) has no meaning in traditional catamarans. Reduces tonnes per centimeter immersion which in catamarans is not good. If you want to make a Swath ship type, the solution (C), although it is closer to the concept of this type of vessel, is also incorrect.
    In general, the designer creates forms not as he likes, but to the most appropriate and effective forms for the type of vessel, and SOR, which he is working on. (I refer, of course, to the forms of the hull)
     
  14. markdrela
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    markdrela Senior Member

    Au contraire. Lithuania was a small distant province of Greater Poland. :p
    (I'm Polish) :D
     

  15. laserek
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    laserek Junior Member

    Lithuania and Poland established the first "Europa Union" in 1569 in my town - Lublin. Here is "Lithuanian Square" in the center, just 100m from my current place: http://en.wikipedia.org/wiki/Union_of_Lublin. IWelcome
     
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