Free!Ship 2.6+ vs Prediction resistance by Holtrop-Mennen started method

Discussion in 'Software' started by Victor T, Feb 16, 2007.

  1. Leo Lazauskas
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    Leo Lazauskas Senior Member

    It's a great site isn't it, Conceptia.

    I'm waiting for Goggle to take it over and rename it YouBoat. Oh, how we'll laugh then.

    Leo.
    (It's not too soon is it, Brits?)
     
  2. conceptia
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    conceptia Naval Architect

    hehe.. okay.. im waiting for da change.. Hope den dis site will be a part of ur prestige.... good luck pal..
     
  3. conceptia
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    conceptia Naval Architect

    Also before coming to this forum, I had a feeling that hydrodynamics is related to da ship motions only(cos I had only worked for wave motion study of semis n ships). But now I'm developing a liking towards da propellers, n CFD. Its all cos of yourself, victor, dalquiri etc
     
  4. masrapido
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    masrapido Junior forever

    Apologies for breaking the thread, but what is the point of a thin ship? Cannot carry any useful cargo, cannot sail except under perfect weather conditions.

    If it is about the speed, it would be a lot more practical to slap on a few wings and fly in ground effect. If it is about military applications, submarines are much better option in any respect.

    I am probably missing something, but as a marine officer, with 17 years on the sea, I am not seeing any practical use for the format...
     
  5. DMacPherson
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    DMacPherson Senior Member

    Thin-ship theory != Ships that are thin

    It is necessary to distinguish the "thin-ship theory" of wave-making prediction with "ships that are thin". The former is a calculation methodology, that as we have seen, can be applicable - if checked very carefully and with all due caveats - to ships that are not all that thin.

    Regards,

    Don MacPherson
    HydroComp, Inc.
     
  6. masrapido
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    masrapido Junior forever

    DMacPherson, my question was about the practicality of such ships, not about mathematical validity of the theories.

    I doubt that a non-thin ship can be made to behave like a thin one in a real situation, under real, random sea and weather conditions. There are some laws that will see to prevent that.

    I am not saying that certain optimisations are not possible, and not beneficial, but in reality, thin ship theories usually assume flat seas, no waves. While that does wonders for mathematical models, in real life such conditions do not exist, except in the Red Sea for better part of the year. Optimising a hull inevitably means reducing the beam, volume, or both, to gain speed.

    And that inevitably leads to thin ships. I would be happy to see examples proving to the contrary. Bear in mind that our "regular" ships are already quite slender and thin, with ratios reaching 1:10 in some categories of military ships, and even cargo ships are not far off. Just look at oil tankers.
     
  7. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Thin-ship theory requires that the longitudinal hull slope is small. Thus detroyer hulls are quite Ok, as are catamaran demihulls, rowing shells, kayaks, and many other types of vessel.

    Thin-ship theory is definitely inappropriate for tug boats, planing vessels, barges, and oil tankers.

    Oil tankers often have long parallel middle-bodies (where the longitudinal slope is zero) but the slope is large at the bow. Even that is not too bad if the Froude number is high because the wavelength of waves created by the hull are longer than the region of the hull where the slope is large. Of course, oil tankers operate at low Froude numbers, and so the wavelengths are also relatively small. That's why thin-ship theory is inappropriate.

    Hope that clarifies some aspects,
    Leo.
     
    Last edited: Jun 25, 2010
  8. ngyen
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    ngyen Junior Member

    hy

    i am trying to write a small program in VB to calculate resistance for ship which follow Holtrop Mennen.
    following this paper.

    http://www.4shared.com/document/Z-32...Vol29_1982.htm

    I want to know the formulae for calculating the following parameter.i searched but cant get any specific formula for this.
    In my program , the input is variable and they are ask the user to give ( L, B,T,H,Cb , Speed )

    please provide me formula for these

    ABT = Transverse sectional area of the bulb at the position where the still water surface intersets the stem = ???

    SAPP = the wetted area of the appendages = ??

    AT = Transom Area = ??

    hB= Centre of bulb area abolve keel line = ???



    please help
    thanks
     
  9. Jecobin
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    Jecobin Junior Member

    Ref: Freeship Plus Projects

    How do we download and use the projects that appear to be available on the website. When I try to download any of them I just get a TXT file. Am I missing something here?
    John
     
  10. Victor T
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    Victor T Senior Member

    There are NOT any TXT files. Click in your browser "Save As" and save it as FBM.
     
  11. Victor T
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    Victor T Senior Member

  12. daiquiri
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    daiquiri Engineering and Design

    Thank you for the update Victor.
    The new website is very attractive and simple to use. I see there is a "donation" button, but the webpage is still not ready. I hope it will be through PayPal system, as I find it simplest to use. I will make a donation as soon as the feature becomes available on your webpage, because I do believe that all your efforts deserve a reward.
    Cheers!
     
  13. zeroname
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    zeroname Naval Architect

    Nice work and nice new website.. you can make a mirror for download link. Downloading from http://depositfiles.com as "Free downloading" shows error and says i am already download some files.
    i will suggest for a mirror here:

    http://www.mediafire.com

    You can open free account for permanent time, it also support resume and downloading software.

    Best of luck
     
  14. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    It's quite clear that Victor's website is still "work in progress", so these things may happen...

    If you click on the "Download" menu button in the upper part of the homepage screen (and NOT the big button on the right), you will get a page with all the files ready for download directly from the Hydronship.net server. So no need to pass through Depositfiles, Mediafire or else.
     

  15. zeroname
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    zeroname Naval Architect

    oh i see... yes i clicked the right side big button.. its ok now..
     
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