PDStrip, free strip theory program

Discussion in 'Software' started by Martijn_vE, May 10, 2006.

  1. ticotico
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    ticotico New Member

    Is there anybody who use PDStrip. I search the rel. vertical velocity of a motion point (like seakeeper can do this). Is it possible to calculate it with PDStrip?
    Have anybody some example-files for the use of motion points (e.g. the sample from gtampier) or a good manual to read the result files or an GUI?

    It is a nice program but you need many time to understand it and to use it.
     
  2. Aquilo
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    Aquilo New Member

    I'm just trying to use the pdstrip program, which seam to be a good tool - provided that the result-files could be read.
    Does anyone have a brief explanation for the output-files created by the pdstrip program?
     
  3. Martijn_vE
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    Martijn_vE Marine software developer

    PDStrip is very poorly supported.
     
  4. Aquilo
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    Aquilo New Member

    never the less, my you have found out how the sectionresluts-file has to be read?

    There are 9 complex added masses for 52 frequencies for every section.
    Is it right that these values represents a 3x3 matrix with the y,z,xx (sway heave and roll) on the diagonal (respective 1st, 5th and 9th value)?
    Do you know, if these values have to be multipied by a factor like t_ref?

    Below the added mass data the diffraction forces and Froude-Kryloff-forces are stored for every angle.

    so far....
     
  5. williamstewart
    Joined: Mar 2008
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    williamstewart Bil

    Can anybody supply me with recent information regarding PDStrip?

    I have been able to run the file with the PDSTRIP GUI (that you have to compile) available from Silversoft. However, the "responsefunctions" results files that should contain the RAO data is in a format that is ambiguous, giving 8 columns and 35 rows (8 x 35 = 280) or 280 numbers for the example problem. There are 4 wave attack angles and 5 wave length given in the input data. I would therefore expect 4 x 5 x 6 = 120 number "sets" for each of the 6-DOFs (at each heading and wave period). I would have hoped for an amplitude and phase pair of numbers in each "set", but possibly the three as descibed by gtampier, being thr real, imaginary and absolute. These two possibilities would give 240 or 360 numbers in the output, compared to the 280 I find.

    Any help would be much appreciated.

    I also would be interested to know if Martijn_vE has made (or may make) available his adaptations of FreeShip to link with PDStrip.

    Kind regards to all, Bil. bil@stewart-usa.com.
     
  6. williamstewart
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    williamstewart Bil

    Can you (Martijn) supply me with recent information regarding PDStrip?

    I have been able to run the file with the PDSTRIP GUI (that you have to compile) available from Silversoft. However, the "responsefunctions" results files that should contain the RAO data is in a format that is ambiguous, giving 8 columns and 35 rows (8 x 35 = 280) or 280 numbers for the example problem. There are 4 wave attack angles and 5 wave length given in the input data. I would therefore expect 4 x 5 x 6 = 120 number "sets" for each of the 6-DOFs (at each heading and wave period). I would have hoped for an amplitude and phase pair of numbers in each "set", but possibly the three as descibed by gtampier, being thr real, imaginary and absolute. These two possibilities would give 240 or 360 numbers in the output, compared to the 280 I find.

    Any help would be much appreciated.

    I also would be interested to know if Martijn_vE has made (or may make) available his adaptations of FreeShip to link with PDStrip. It seems that DelftShip is a slightly modified version of FREEShip. Will there be a PDStrip link to/from DelftShip?

    Kind regards to all, Bil. bil@stewart-usa.com.
     
  7. Paolo83
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    Paolo83 Junior Member

    Hello everyone! My name is Paul
    I recently joined this forum, I'm looking for a program to calculate the RAOs functions. I need these functions to do the analysis on a single buoy moored vessel.
    I think Pdstip can be the right program, but never having seen it. I have no idea how it works.

    Does anyone know a manual?
    I tried to make it run on Windows XP, but it gives me an error even though I have gfortran installed, someone can give me some help?

    Thank you!
     
  8. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Citing from sourcefoge site (http://pdstrip.sourceforge.net/):
    "PDSTRIP has been abandoned by its initiators, who do not wish to be contacted with use questions. The position of maintainer is vacant."
     
  9. Paolo83
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    Paolo83 Junior Member

    This does mean that there is no a open source seakeeping program?
     
  10. Leo Lazauskas
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    Leo Lazauskas Senior Member

  11. Paolo83
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    Paolo83 Junior Member

    Thanks it looks interesting.
    Unfortunately the link that you put on the forum does not work and now VISUAL SMP is for sale.
    The book is interesting but there are 200 pages of code to be copied by hand ...
     
  12. daiquiri
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    daiquiri Engineering and Design

    But once you've done it with no errors, it you can sell the software and earn some money. ;)
     
  13. Paolo83
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    Paolo83 Junior Member

    This was not the idea -_-' ...but okay

    Then turn the question, is there a theoretical reference for making "hand"this kind of calculation?
    For "by hand " mean with matlab or similar programs.

    Is enough for me an approximate solution, such as strip-theory by cutting the vessel in a few sections.
     
  14. Leo Lazauskas
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    Leo Lazauskas Senior Member

    The source code was available a couple of years ago but it was difficult to find within the US Navy maze.

    The theory for SMP is based on the very famous paper:
    SALVESEN, N., TUCK, E.O. and FALTINSEN, O.
    "Ship motions and sea loads", Transactions SNAME, New York, 78 (1970) pp. 250-287.

    Good luck!
    Leo.
     

  15. Tim B
    Joined: Jan 2003
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    Tim B Senior Member

    I have just e-mailed the current maintainers of PDStrip, requesting to take over the maintenance role. If they agree, this does not mean that there will be massive changes to the code immediately, but I will get the support mechanism to the same level as OpenPilot, and I will be inviting anyone with validation data to contribute it.

    For now, we must wait to see what the current maintainers say.

    Cheers,

    Tim B.
     
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