Power prediction : Holtrop-Mennen

Discussion in 'Boat Design' started by TANSL, Dec 17, 2013.

  1. TANSL
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    TANSL Senior Member

    I attached a spreadsheet with the Holtrop-Mennen method.
    If anyone finds it interesting it can be downloaded and, if anyone thinks of any modification or improvement, I would greatly appreciate that tell me.
    Thank you
    NOTE: See you next posts. There may be program updates (see post #21)
     

    Attached Files:

    • H-M.zip
      H-M.zip
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    Last edited: Dec 19, 2013
  2. Olav
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    Olav naval architect

    Nice one, TANSL! Thanks for sharing.

    Some comments:

    It would be nice if users were able to change the water density and kinematic viscosity.

    The user is asked to enter the prismatic coefficient, although this could be directly calculated by the spreadsheet, since cP = cB * cM = (V/LWL*BWL*T) * cM. The best (read: most comfortable) solution in my opinion would be to enter one of the values and have the spreadsheet figure out the missing ones.

    What is the definition of "transom wetted area"? I cannot remember such an input value from when I dealt with the Holtrop-Mennen method some time ago, but judging from the data from the example case the transom wetted area is not identical to the submerged area of the transom.

    Anyway, nice effort! Thanks again!
     
  3. TANSL
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    TANSL Senior Member

    Olav, thanks for your comments. I will keep that in mind and, when given any more, I will include them in a new version, which will uploaded in the forum.
    The term "wetted transom area" may not be adequate. Meant the submerged area of the mirror: ATR
     
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  4. Olav
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    Olav naval architect

    Thanks, I'm looking forward to it!

    Ok, but then it means the same thing. I was confused because there are two different transom areas in your example case (16.0 m² in the Main Particulars and 4.6 m² where the stern shape is specified).
     
  5. TANSL
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    TANSL Senior Member

    Yes, there is a mistake. The program does not use the second area, it calculates with the 16 m2.
    You can change wáter density as desired.
     
  6. rxcomposite
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    rxcomposite Senior Member

    Is the program working? I was expecting output and a graph plot when I press calculate.
     
  7. TANSL
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    TANSL Senior Member

    The results should appear on the second sheet.
    See attached program with some corrections.
    NOTE : please, go to post #21 to download file.
     

    Attached Files:

    Last edited: Dec 19, 2013
  8. Olav
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    Olav naval architect

    Two possible sources of error:

    1. Did you allow macros to be executed in Excel?
    2. Did you have zero knots as your lower limit of the vessel's speed range?

    It worked perfectly fine on my PC and gave the same results (within expected round-off errors) as my own Holtrop-Mennen spreadsheet.
     
  9. rxcomposite
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    rxcomposite Senior Member

    TANSL, Olav

    I downloaded the second version and still the same. What am I doing wrong?

    I enabled editing and enabled content as instructed by Excel, loaded the sample inputs then pressed the calculate button. Nothing!

    I am interested as I have tried programming this before but was not so confident.
    1. The wavemaking formula (Havelock) has 3 speed ranges
    2. The Wetted Surface Area (WSA) formula for bulbous bow, has 3 different versions from 3 different sources. One from PNA, one from Tupper, the third one I could not remember at the moment. I do not know which one is correct as it gives different values.
     
  10. TANSL
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    TANSL Senior Member

    rxcomposite, I do not know what could be causing the problem. If anyone has experienced the same situation and resolved it would be very helpful if he could explain how he did it. Thank you.
     
  11. rxcomposite
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    rxcomposite Senior Member

    I have Olav's Holtrop- Mennen downloaded from the spreadsheet library and the links provided by Quequen, Spanish & English at -http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/holtrop-mennen-method-excel-spread-sheet-49058.html

    All working perfectly as downloaded from the forum so there must be something that is preventing TANSL's version. Sent you a PM TANSL.
     
  12. daiquiri
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    daiquiri Engineering and Design

    Hi Ignacio,
    I have used the "Load example" button in your spreadsheet, and then clicked on "Calculate".
    Got this error message:
    Holtrop error.jpg
    Apparently, there is a non-defined variable called "fila" in the script. Hope it can help you in debugging.

    Cheers
     
  13. TANSL
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    TANSL Senior Member

    daiquiri, thanks. The variable "fila" is not declared and therefore can fail. My computer does not generate this error but in fact may occur.
    You can declare the variable "fila" as a integer, in the subroutine "calcula" or download the file again from post # 37, I've already changed.
    Cheers
    Ignacio
     
  14. daiquiri
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    daiquiri Engineering and Design

    Thanks Ignacio.
    I have downloaded the updated version and have run it. No error messages this time, but unfortunately I have to confirm Rxcomposite's observation. The "output" sheet remains blank after the calculation is performed. The spreadsheet visibly does some iterations for a fraction of the second, but doesn't write the output to the "output" sheet.
    Cheers
     

  15. TANSL
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    TANSL Senior Member

    This is a major problem. I must investigate why it happens. I'm working with Windows 7 and Office 2010. Thank you.
     
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