deterministic damage stability analysis maxsurf

Discussion in 'Software' started by Edolyi, Apr 26, 2014.

  1. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    I'm now doing deterministic damage stability analysis in maxsurf, I've created the damage cases, have runned the large angle stability and floodable length analysis. But to be honost I'm not quite sure to carry out a deterministic damage stability analysis what I should exactly do with the software. Can anyone give me some hints? Thank you!
     
  2. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I do not know how far you've advanced you on your own but I will tell you the procedure I follow. If there is something you already knew, or is obvious to you, sorry.
    I attached file with the explanations. I hope it helps
     

    Attached Files:

  3. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    Thank you TANSL! Yeah I have already done these steps and carried out the large angle stability analysis for each case. Is it like if in each damage case the ship can pass the perticular criteria then the deterministic stability is done? I have used just one criteria used for the analysis, and I think maybe thats not enough, the requirement for the criteria I also think is set too low, the attained screenshoot is the criteria I've used. Could you help me have a view?
     

    Attached Files:

  4. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I use IMO criteria A.749(18), not SOLAS II, 1-18. May be there is the problem.
    Any way, I would need to know your ship, and the model you've done in MaxSiurf to review.
     

    Attached Files:

  5. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    I've tried that criteria mate, but maybe it is code for intact stability, it always shows not analysed when I study other damage conditions, just like the screenshoot I attainded. Is that the only criteria you use? My ship is a trimaran vessel, the model is in the attached file
     

    Attached Files:

  6. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The criteria I have listed are the ones I always use, adding the specific criteria of the type of boat I'm studying, if any: fishing, passenger, container, ...
    There are special criteria for multihulls because the criterion of maximum GZ at 25 ° or more, they can not keep.
    It is necessary to investigate why it says "Not Analysed". The program can not decide what analyzes and what not.
    Let me examine the model to see, in a quick look, if I find something wrong with it.
     
  7. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    Cheers mate. It's a dwt type file, have u opened it successfully?
     
  8. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Actually what you have uploaded is a DWG file but AutoCAD tells me it's an invalid file. Neither accepts it as DWT.
    Put a file in dwg format or the actual file you use in Maxsurf. I prefer the latter.
     
  9. NavalSArtichoke
    Joined: Oct 2013
    Posts: 431
    Likes: 9, Points: 0, Legacy Rep: 83
    Location: GulfCoast

    NavalSArtichoke Senior Member

    You haven't said what type of vessel you are analyzing: passenger, product carrier, bulk carrier, tanker, what?

    There are specific residual stability (= stability after damage) standards for certain vessel types. You must consult the various SOLAS and IMO codes for a particular vessel type, because not all residual stability standards are identical. There may also be national standards to meet as well, depending on the flag state. If you seek a reduced-freeboard load line for your vessel, the ICLL includes damage standards which must be met before such a load line can be considered.

    Using IMO A.749 for assessing residual stability is not recommended, however, since these standards are clearly intended for intact stability, and it is not common practice, to boot. The residual stability standards for damaged vessels may include criteria which intact vessels are not required to meet, such as the maximum equilibrium heel angle after damage.

    In my opinion, applying intact standards to damage cases produces an ultra-conservative curve of allowable vessel VCG.
     
  10. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I am not a scholar of stability after damage or a researcher in this area, but I've done these calculations in some projects , especially in passengers boats and I think the following (talking on passenger vessels )
    • Stability after damage does not include additional or more strict criteria. The criteria are the same. In both cases you have to check the effects of the passage at a band.
    • The residual stability is not measured at an angle of heel. In the deterministic method all that is required is that the margin line is not submerged.
    • No need to consult or SOLAS and IMO: the vessel must comply with the regulations which is applicable to it, either international or local authority .
    • You can´t say the implementation of IMO A.749 it is not recommended because in many cases it is mandatory to apply .
    • Certainly stability after damage have requirements that are not asked in the intact stability . Whew!
     
  11. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    I couldnt upload the maxsurf file mate. it only accepts dwg file, you can try open the trimaranWITHSS model in the sample of maxsurf package:)
     
  12. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    My vesssel is a trimaran container, I was looking for specific criteria for trimaran container, but its quite hard to find. I'll try to do what u said. Cheers mate!
     
  13. NavalSArtichoke
    Joined: Oct 2013
    Posts: 431
    Likes: 9, Points: 0, Legacy Rep: 83
    Location: GulfCoast

    NavalSArtichoke Senior Member

    I'm afraid they do, especially for IMO and SOLAS. IMO A.749 specifically states that it is to be applied for assessing the stability of intact vessels, and to me that does not also imply that one applies these standards to vessels in a damaged condition.

    It's not clear what the phrase 'passage at a band' means.

    I never said 'Residual Stability' was measured at an angle. 'Residual stability' encompasses characteristics like minimum metacentric height, maximum righting arm, and range of stability after damage.

    For vessels operating on an international voyage, applicability of SOLAS and IMO may not be optional, depending on the characteristics of the vessel and the regulations of the flag state. This is why the OP needs to disclose something about the vessel for which he is doing the deterministic damage stability analysis.

    I never said that IMO A.749 did not apply, only that it applied to vessels in the INTACT, not DAMAGED, condition.

    Which contradicts your first item above.

    Passenger vessels are not the only vessels for which damage stability requirements may apply. Margin Lines were developed at a time before computers were available, and damage stability studies could not be carried out in depth like today. Margin Lines are used, in conjunction with a floodable length calculation, to assess the proper spacing of transverse bulkheads in order to provide a crude degree of survivability after damage.

    Certain flag states, like the US, still require the use of margin lines to determine acceptable subdivision of a passenger vessel, but this does not also preclude the simultaneous application of other standards to assess the residual stability of a passenger vessel after damage.

    For small US passenger vessels, the equilibrium angle of heel is not permitted to exceed 7 degrees, and no part of the margin line can submerge. The metacentric height must exceed 0.05 m. This heel may be increased to 15 degrees if certain residual stability requirements are met, such as area under the residual righting arm curve and range of positive residual righting arms.

    In the US and other countries which are signatories to the MARPOL conventions, vessels which carry oil or other noxious substances must meet certain stability standards in the damaged condition. For these vessels, in the final stage of flooding,

    1. the angle of heel must not exceed 25 degrees for off-center flooding (which may be increased to 30 degrees provided no part of the deck edge is submerged)
    2. the range of positive righting levers after damage must extend at least 20 degrees beyond the equilibrium angle of heel, and
    3. the maximum righting lever in this range must be at least 0.1 meter.

    Likewise, tankers and product carriers which transport hazardous chemicals have a certain set of rules which they must meet in the damage condition, along with certain minimum damage extents to be considered.

    These various rules have been written so that it is clear what stability standards must be applied to certain damaged vessels.
     
  14. TANSL
    Joined: Sep 2011
    Posts: 7,506
    Likes: 747, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Hydromax gives me the following error message and I do not know why it occurs.
    As for the stability criteria, I do not know, sure NavalSArtichoke can help you with that
    You should raise any loading condition.
    That boat has littel buoyancy. At the depth of 4m has a displacement of 1000 tonnes, which is probably less than its structure weight.
    A trimaran with so thin hulls can´t be good for carrying large loads.
    Study load conditions to see how the ship holds and reconsiders the ability of the ship to carry large loads
    But I leave you with NavalSArtichoke because I know you'll be in good hands. Surely he also knows how to handle the boat with Maxsurf.
    I will not go into speculations.
    Cheers
     

    Attached Files:


  15. Edolyi
    Joined: Mar 2014
    Posts: 26
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Newcastle University

    Edolyi Junior Member

    Cheers mate! But how could you find it's 1000t at the depth of 4m? To be honest I'm new to the software and can only find it's 508t at the draft of 2.599m by running uphydrostatics?and the structure weight showed in the loadcase is 231.487t. Is there anything wrong when I'm doing vessel particular check?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.