Hydrostatics software - comparison of accuracy

Discussion in 'Software' started by Alik, Dec 17, 2014.

  1. Alik
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    Alik Senior Member

    Interested in comparison of accuracy of hydrostatics software from different suppliers and formulas for basic geometrical shapes. I have seen such tables, but now cant find... Does anyone have a link?
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    I think it is more about who accepts the results than how accurate they are, per se.

    I use Wolfson Suit of programs. Not the most user friendly to get new 3CAD lines into the software, but once it, very robust. But, it can't be all bad if the MAIB use it too:
    http://www.wumtia.soton.ac.uk/news/maib-chooses-wolfson-software

    We have tested different ones ourselves in years gone by - don't have the data to hand now. I too did see a comparison years ago, but not recently.. These days i think they are all pretty robust and as accurate as we need them; considering when I was a student it was all done by hand.

    Thus if it is a mere academic exercise in one software versus another, you'll always get one better than other, but how much variance from each other and the "correct" result and its importance only you can say.
     
  3. Alik
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    Alik Senior Member

    Thanks AdHoc, we use Wofson Suit as well.

    The question is not about 'what is most accurate soft?''. The issue is that we want to demonstrate RRR (Russian River Register) that formal certification of stability software is not important.

    I have seen such comparison for RhinoMarine on their website, but now it is gone.
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Then I suggest your route is to ask RRR how many Flag authorities do they know that have done as they are requesting. Since they are all part of IMO they should know, ego, there must be a Flag approved list circulated within IMO. If they have no answer..that is the answer! There is none.

    Historically it is always been the case that Flag authorities do their own independent checks against the software one is using. If the results tally closely enough to their own, they accept your results forthwith. If RRR has not done that themselves, independently, then I don't see how RRR has the ability to say what is correct or not, in the absence of their own data.
     
  5. Alik
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    Alik Senior Member

    This is well understood; but they (not themselves, but the research institute developing rules for them) just wrote again this requirement to certify software in the new Rules. We are to show that in terms of accuracy it is not an issue and 'unapproved' soft gives results within 1%. The same refers to other soft, such as FEA.

    Actually, exactly what I wrote is: 'If one wants to reach technological advance, should apply up to date modeling methods and predictions, not waiting to get the software formally 'approved'. This is specially true because software is updated on regular basis, and no one will run the re-approvals once in few months; the software developers are not interested to approve their products for Russian market. No IACS class society is asking for such approval (excerpt RS). If someone does not understand this and does not want to look at world's practices, should concentrate on pumping resources to the West and not to attempt building hi-tech products such as boats and ships.
     
  6. TANSL
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    TANSL Senior Member

    Comparison of the results obtained with different software is very difficult because, among other reasons, as we all know, getting the models created with each application are equal is almost impossible. If the model is not exactly the same (and can not assess to what extent they are unequal), the results are not comparable.
    My experience with government is that they do not want to approve any program. For reasons that are far from my understanding, they trust or do not trust on certain programs, but not "homologate" then.
     
  7. valber
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    valber Naval Architect

    There is some info from MaxSurf Stability Manual.
    Good luck!
     

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  8. valber
    Joined: Feb 2006
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    valber Naval Architect

    Look here...

    Rabah had made the comparative stability calculations by means of different software for the same hull of a tug.
    As I know he has much more calculations then published at the forum.
    May be now it's a time for them...
     
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