Numerical/mathematical methods for hullform lines to Modern Vessels

Discussion in 'Boat Design' started by robert.drag0n.95, Sep 7, 2024.

  1. robert.drag0n.95
    Joined: Sep 2024
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    Location: Spain

    robert.drag0n.95 New Member

    Good afternoon. I am new to this forum and a master's student in Naval and Ocean Engineering in Spain.

    And I wanted to ask about modern mathematical models to generate the shapes of a ship since, in my studies, we only teach how to model through CAD programs such as MaxSurf or Rhinoceros, with parametric transformations and control point adjustments.

    It is something that I would like to learn, apart from interacting with programs, to go deeper into how the shapes of a hull are really drawn, such as waterlines, buttocks and sections.
    I only know David Taylor's mathematical model from the MNVDET website. I researched this model and, although it is effective, it is a somewhat outdated criteria.
    I would like to know more models apart from the aforementioned Taylor. And how to find documents regarding them. Since I am not very convinced about playing with boat preforms in Maxsurf.

    This question is motivated by curiosity and the desire to learn more about my studies, since what I am asking is not usually given in my educational center. I sincerely hope to be taught how ship hull forms are actually made.

    Greetings and a good autumn from Spain.
     
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Welcome to the forums Robert.

    Yes there are many more model series than the original Taylor, generally every design firm or shipbuilder will have their own preferences.

    Are you wanting to know how to design a hull from first principles or how it is normally done commercially?

    I will tell you right up front there is no "magical" mathematical formula that will turn out the "perfect" hull form; and any CFD just integrates your (knowingly or unknowingly) selected biases. This is why most ship's underwater form is based on just a handful of model series. The percentage performance gain over the vessels operational lifetime is rarely worth the up-front design and build costs; more so if infrastructure (channel width or depth, lock size, etc.) is involved.
     
    Ad Hoc and bajansailor like this.
  3. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    In addition to JEH's wise words above.

    There are ostensibly two issues at play in your question.
    1. How to create the lines, mathematically in a 3D environment.
    2. Why have the shape it is and varying as such.

    In no.1 it is maths that is used in "isolation" from the purpose of the Design.
    In no.2 the absence of a systematic series to investigate, one is left with - creating the shape from ideas/thoughts/knowledge...etc.

    Understanding Design (naval architecture) and how shapes influence the hydrodynamics of a hull's performance (speed and statical stability) are all integral with "the shape".

    So are you more interested in defining shapes using mathematics in 3D, or, defining shapes for a purpose, which then uses mathematics to create it?
     
  4. robert.drag0n.95
    Joined: Sep 2024
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    Location: Spain

    robert.drag0n.95 New Member

    Good afternoon.

    Answering your question: I want to define the shapes, with a hydrodynamic purpose (Speed and Resistance), and then use mathematics to create the 3D shapes.

    Regards.
     
  5. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Today, extremely few hulls are designed solely for maximum speed or minimum resistance because the compromises of the other factors (seaworthiness, range, carrying capacity, arrangements, etc.) are so reduced as to make the vessel useless except for a very small niche (i.e the golf quandary...if the idea is to make the lowest strokes why hit the ball at all?).

    If all you are looking for is to tie minimum resistance/maximum speed to a mathematical method of lines development and formulation; then Lamb's Hydrodynamics is a good place to start (actually.... it was the book where it all started in 1879). Otherwise, for overall hydrodynamics in the development of useful ship lines see SNAME's Hydrodynamics in Ship Design by Saunders. While there are newer texts, these two provide the firm foundation that almost all modern ship hydrodynamic development work is based on.

    Additionally, you might want to investigate The Principles of Naval Architecture Series: The Geometry of Ships by John Letcher and the rest of his papers if you are interested in how to smoothly transform developed parent hull shapes into daughter hull forms by computational methods.
     

  6. Cory
    Joined: Nov 2020
    Posts: 19
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    Location: Sedro Woolly Washington

    Cory Junior Member

    I design and build many types of boats without AutoCAD

    And I'm the controlling information when I hire people that do AutoCAD
    The AutoCAD projects are at my website Tyler ltd.com
     
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