Calculation of resistance

  • Nobody/Anonymous


    I have routines for calculation of resistance of deplacement-ships.
    They are however written in Matlab. Are there anybody that can implement
    theses routines into freeship ?

    If you can, send a note to

    Btw, we are now finishing the Norwegian translation.

    Haavard Holm

    • gianlisi

      gianlisi - 2006-11-16

      hi Haavard

      I'm writing a VPP (I just have to make order in the output files actually) in Matlab.
      I wrote a post here:

      Are your routines useful for sailing yacht? Have they something to do with the Delft Series?

      May I eventually include them in the VPP? So far it uses the DSYS as presented in 1999 at the CSYS symposium


    • Nobody/Anonymous


        I have put the matlab-code at
      The method gives good results for ships like tankers and containerships.

      According to Professor Sverre Stenn (working with propulsion, resistance amd experiments),
      this is the best method based on empirical data for the above mentioned ships.

      The method should not be used for planing hulls, sailing yachts swats catamarans.

      Haavard Holm

      • gianlisi

        gianlisi - 2006-11-17


        thanks a lot for the link.
        I had a look at it but, as you said, I don't think it's suitable for sailing yachT!

        Thanks all the same...


      • Marven

        Marven - 2006-11-17

        Hi Haavard,

        I've take a quick look at the code, and it seems like a very simple method. I could implement this in FREE!ship very easily. How do the results compare to those of Holtrop & Mennen?
        If you could send me a PDF of the original publication I'll try and add it to the program.

    • Nobody/Anonymous

      Hi Marven,
      Here is PDF file from journals with statistical method Holtrop 1984, formulas and samples.

    • Nobody/Anonymous

      Please give me a hint, if you want code for Holtrop.

      Haavard Holm

    • IanM

      IanM - 2006-12-18

      Be careful, Holtrop calcs need verifying.  There is a missing minus sign in the published paper calculation for m1 in the third term.  The example for c15 also.

      If this could be implemented operating in real time, i.e. the resistance curve automatically updates with form change, this would become most powerful.

      Thank you


    • Nobody/Anonymous

      Hi all!
      I have modul Freeship v2.6 with Holtrop method 1982-84 calculation of resistance (writed on Fortran) and can be send of all for your e-mail. I am from Russia and translate interface on Russian language and i have russian.ini. My e-mail is Archive is 1.5 Mb.

    • Nobody/Anonymous

      Hi All!
      All of interested statistical method Holtrop-Mennen 1982-84 of resistence calculation in Freeship2_6 and Russian.ini can load from:
      Archives are 1.5 Mb. AS IS and without garanties. About problems write me .

    • Nobody/Anonymous

      Hi Stefan!

      Я имею более 10 причин, из-за которых не могу дать исходники программы.
      Одна из них - Delftship на 90% базируется на Freeship2.6 и стал платным. Код, который я разрабатываю с минимальными изменениями интерфейса может быть легко импортирован в платную версию DelftshipPro. Поэтому исходники я выложу только тогда, когда аналогичный и более лучший код расчетов гидродинамики судна будет в версиях Delftship. Кроме того, часть кода написан на фортране мною и моими соавторами, которые пока против опубликования кода. А перевод на Delphi слишком трудоемкая задача.

      I have more than 10 reasons from which can not give source program codes.
      One of them - Delftship on 90% is based on Freeship2.6 and became requiring payment. Code which I  develop with the minimum changes of interface can be easily imported in requiring payment version of DelftshipPro. Therefore I will lay out source codes only then, when similar and more the best a code of calculations of hydrodynamics of ship will be in the versions of Delftship.
      In addition, part of code written with on Fortran me and my coauthors which while against the publication of code. And translation on Delphi too labour intensive task.



      • Stefan Probst

        Stefan Probst - 2007-04-04

        Dear Victor,

        may I friendly suggest that you read the license that allows you to use, modify, and re-distribute FREE!ship, i.e. the GPL ....

        It says, that without offering also the source code, you are not allowed to redistribute the original or any modified version, whether it is free of charge, or paid for.

        Martijn holds the copyrights of FREE!ship and he is the only one who can use that code also for non-Open-Source purposes.

        "Funny thing is", that you kept Martijn's copyright even in the versions that you released. Means: He would indeed be allowed to use your code. You should clearly mark your contributions as released under your copyright, which would mean that he is not allowed to use it.

        See e.g.

        Best Regards,

    • Nobody/Anonymous


      By not releasing the sourcecode you are clearly violating the GNU license that came along with the sourcecode of FREE!ship. You  are not acting in the common interest of the open source community but merely using the software for your own name and fame. I cannot imagine that this is what Martin intended when he released the sourcecode. Your argument that the code has been written in Fortran makes no sense at all, it should be released all the same.

      I suggest you read the GNU license too, because you're violating the following parts:

      For example, if you distribute copies of such a program, whether gratis or for a
      fee, you must give the recipients all the rights that you have. You must make
      sure that they, too, receive or can get the source code. And you must show them
      these terms so they know their rights.

      Meaning you must distribute the code under the same license WITH the sourcecode
      Do you also distribute the GNU license with your version, because that's obligated too.

      If the software is modified by someone else and passed on, we want its recipients to
      know that what they have is not the original, so that any problems introduced by
      others will not reflect on the original authors' reputations.

      This means you must indicate clearly (for example on the welome screen of freeship) that the modifications are yours, not Martins!

      a) You must cause the modified files to carry prominent notices stating that you
      changed the files and the date of any change.

      This speaks for itself

      b) You must cause any work that you distribute or publish, that in whole or in
      part contains or is derived from the Program or any part thereof, to be licensed
      as a whole at no charge to all third parties under the terms of this License.

      This part explains again that all software derived from the FREEship project automatically falls under the same terms of GNU license.

      I could go on, but I think I've made my point. You cannot take an open source program and distribute it on your own terms. There are licenses involved that can have legal implications if you do not stick to them.

      So why don't you act like a grown up and just stick to the terms of the license. Or if you don't like what's in the license I suggest you do not use the software at all.


      John Jenkins.

    • Nobody/Anonymous

      Stefan and John Jenkins.

      Thank you for references.
      In order to execute all terms - required heap of time, which not have.
      I am a not professional programmer and I not need a fame.
      You convinced me - I halt development of Freeship+.

      This is last release :



      • Stefan Probst

        Stefan Probst - 2007-04-04

        Dear Victor,

        in your previous post, your two given argements were:
        1) you don't want to disclose your source code, so that Martijn cannot use it for his closed-source SW.
        2) Parts are written in Fortran.

        John Jenkins wrote already, that there is no problem to publish the Fortran sources. If somebody wanted to compile your code, (s)he had to compile also the Fortran parts ... his/her problem.

        To prohibit somebody not to exercise his rights is clearly against the license. That this is directed mainly against the holder of the copyright himself, is "interesting" ... to use careful words.

        Now you give a lack of time as your reasons.

        First, I think there is not much time involved. This is how I would do it:

        1) You change one time the splash screen from "copyright Martijn van Engeland" to something like: "copyright Martijn van Engeland, unless otherwise noted. See Whatsnew.txt for details."
        2) You add a similar line in the header of each source file that you edit.
        That takes one time a few minutes.
        3) You mark each part of the sources that you change. Should be easy, e.g. a comment line with "start changes by TVF" and somewhere later "end changes by TVF".
        Adds a few seconds per incidence.
        4) For each release you take the sources of the last release and replace all the files that have changed meanwhile, then zip everything up and upload it next to your binaries. Should also take a few minutes only.

        Bottom line:
        The only thing that might need some time, is to "clean up the code". Fair enough.
        What, if you publish your code not as "release", but only as "nightly build" for "people to test"? Then everybody would understand that the sources might not be that "tidy". Every few versions you make an official "release" with cleaned up code.

        With a bit of luck, you might even find somebody to help with all this stuff.
        Bottom line: You make everybody happy, with only little additional time needed.

        What you wrote the last time was more like "if I can't make my own rules, then I won't play with you". I hope that was not your last word.


    • Nobody/Anonymous


      That's very interesting...
      But You will be determined in the beginning, that initially, and that the second time. Following rules or development of necessity to majority of software product. I think that majority will choose the second. Or not?

      And for the calculation of hydrodynamics of ships the Free!ship not needed...
      As time will be freed I will develop the program of calculation of hydrodynamics free of any licenses of type GPL and other.

      Best regards.


      • Stefan Probst

        Stefan Probst - 2007-04-05

        Dear Victor,

        you wrote:
        But You will be determined in the beginning, that initially, and that the second time. Following rules or development of necessity to majority of software product. I think that majority will choose the second. Or not?

        I am sorry, but I don't understand what you write. Can you explain a bit more?

        Also, what are your main concerns regarding Martijn taking your contributions into his DELFTship? Is it about the calculation formulas, the algorithms, .... or is it just about the lines of code?

        Martijn is naval architect. He knows about Holtrop-Mennen (spelling?). Actually, some time ago, he sent me some "tools" to do a Holtrop-Mennen estimation. So, the only thing are the lines of code. You know what? If you think, that your lines of code are of value to Martijn, then why don't you contact him and offer your code as so-called "dual license"? Means: you publish your code like requested under the GPL for everybody, but if Martijn wants to include it in his non-open, for-pay version, then he would have to pay some fees to you. This would be perfectly legal. He would have to think how much time it would save him versus own coding, and then you agree on a price. Martijn is an honest man. If he'd make much money with his DELFTship, then I am sure he would pay you a reasonable sum - or you could negotiate that you get some of his pay-for SW for a reduced price. If he doesn't make much money: What's the problem if he gets the code without much payments to you? You can even negociate with him, whether your contributions should be mentioned at some place in DELFTship... those lines would be under your copyright, after all....

        So, as you see, I'd rather have you "inside the boat" of fair, GPL'ed FREE!ship development. I don't want to push you "over board" ;)


        PS: just out of curiosity ... where in Russia do you live?

    • Nobody/Anonymous

      Hi Stefan!
      Beautifully in a theory - will look on practice.
      There is link on source Free!ship release version 2.7+ accoding to requirements GPL 2:
      Read first Whatsnew.txt


      • Stefan Probst

        Stefan Probst - 2007-04-07

        Dear Victor!

        Thanks very much! :))

        You are a champion!


    • Nobody/Anonymous

      is this still available somewhere?

    • Nobody/Anonymous

      If you needed in this source, link here is:

      If you have a problem - mail me  Or


    • Nobody/Anonymous

      The files exe, source and manuals(2.6) of FREE!ship 2.7+ you can download from site now:



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