cross curves of stability

Discussion in 'Stability' started by erdeminanc, Dec 21, 2010.

  1. erdeminanc
    Joined: Oct 2010
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    erdeminanc New Member

    i need a simple excel worksheet for calculating GZ (righting arm).

    i have the offset table of a ship and 15,30,45,60 degree offset for immersed position for transeverse stability.

    appreciate your help, thanks.
     
  2. erdeminanc
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    erdeminanc New Member

    it's really urgent, please help.
     
  3. gonzo
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    gonzo Senior Member

    It is not simple.
     
  4. Perm Stress
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    Perm Stress Senior Member

    download Freeship and hydrostatics extensions for it. It is free :)
    Hull shape import, if you do not need fairing, is a matter of "spend a few hours to read the manual and it is a job for a few minutes". Table of offsets simply has to be a text file of certain structure. All the rest is easy.
     
  5. erdeminanc
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    erdeminanc New Member

    Thanks.

    I have the program, Freeship, but unfortunately, i couldnt find the extension that you stated.

    Could you please give a link for the hydrostatic extension for freeship?
     
  6. terhohalme
    Joined: Jun 2003
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    terhohalme BEng Boat Technology

    Yet another late and desperate NA student. What do you think these home works are for? If you cant get over these exercises without forum help, how can you get over your real work in future?
     
  7. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    Again, it's not that simple. The reasonably well validated cross-curves module is a plugin for Delftship Pro, and it costs money. The built-in one in Freeship (as found on sourceforge) and Freeship+ is, shall we say, less than perfectly accurate for some hull forms.

    It certainly looks like the question is a school assignment, and as a general rule, folks around here aren't too keen on doing students' homework for them. Freeship isn't the only software that can do this, but I doubt the question is "plug in these numbers and see what happens"- more likely it's "prove that you understand how a righting arm curve is computed".
     
  8. zeroname
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    zeroname Naval Architect

    Better you should prepare it by yourself. Take the book "Theoretical Naval Architecture" By Attwood .. and start reading from page 158 there are three method is given in that chapter, i will suggest you the Barne's Method to study and prepare the excel worksheet ... take help from you teacher too.

    it's not so simple work but once you can understand for one degree , you can do it for others too. You may also need to use Autocad .
     
    1 person likes this.
  9. Perm Stress
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    Perm Stress Senior Member

    Sorry, no info on this. I use Delftship. It is not free, and my boss will not share it...
     
  10. cthippo
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    cthippo Senior Member

    I'm using Freeship 2.6 and it's in Calculations -> crosscurves. It should pop up a dialog box for the inputs.

    Maybe you can explain what the heck these curves mean
     
  11. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    See here:

    cross curves.jpg

    If you still don't understand, may i suggest you read a book on naval architecture as you're out of your depth.
     
  12. Alik
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    Alik Senior Member

    It is easy to get those curves by series of stability calculations, by any software even not having this 'cross curves' function. Just need to look at 'stability mechanism'...
     
  13. cthippo
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    cthippo Senior Member

    No question that I am. I replied because I downloaded and was playing with freeship last night and noticed that feature.
     
  14. ngyen
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    ngyen Junior Member

    yes .. i think so.. i made an excel sheet by following those rules,, but i think i need to search for that sheet again.. many days ago i did it
     

  15. adek
    Joined: Oct 2006
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    adek New Member

    Erdem contact with me .I can help ypu
     
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