need help in Damage and Probailistic stability

Discussion in 'Stability' started by sudhir0201, Aug 22, 2010.

  1. tahtoh25
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    tahtoh25 Junior Member

    could you please give me any document say how to make it even manually because i need it urgent
     
  2. sudhir0201
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    sudhir0201 Junior Member

    @tahtoh25

    no i don't have any document, i only know how to do in software(Tribon),but i myself have certain doubt, thats why i m asking here to help me ., wel as far as document is concerned , PNA volume -1(Principles of Naval Architect)is a good book
     
  3. sudhir0201
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    sudhir0201 Junior Member

    can anybody help me to download NAPA software through internet??. plz its urgent
     
  4. ontwerp
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    ontwerp Naval Architect

    Download NAPA

    Sudhir,

    Why don't you contact their sales department? Their website is www.napa.fi

    If you are actually saying that you want an illegal copy...do you think that is how a naval architect should act?
    In my opinion there is a code of ethics that a professional should follow, and using stolen software to do your work is not ethical.

    But if you are just saying that you want to download a trial version or something like that, then I think you can best contact their sales department.
    ;)
     
  5. sudhir0201
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    sudhir0201 Junior Member

    @ ontwerp,
    yap ur right....., but i want to use this software for personal use, not for public. and it is very expensive .so i m unable to afford so much money. thats why i m looking for if its is available in internet.
     
  6. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    Sorry sudhir0201, but discussion of illegally obtaining software is not allowable on the forum here. We're seeing more and more companies greatly increase the accessibility of top software to students in the last few years; and sometimes with enough effort unique (legal) possibilities can happen. But discussing any illegal software distribution is not within our TOS.
     
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  7. sudhir0201
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    sudhir0201 Junior Member

    Damage Stability in NAPA

    dear friends,
    i m doing damage Stability in NAPA. I want to clarify how can we consider any room/space as a free flooding space in NAPA. for Example in case of aircraft carrier , we have some sea chests which is always filled with water so that can be consider as free flooding space. and It is required to use any opening as a unprotected opening which belongs to a free flooding space/ zone.

    and if any body having any study material, manual, PPT and pdf file of NAPA. plz share with me , i need that. thanks in advance.
     
  8. ontwerp
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    ontwerp Naval Architect

    seachests in napa

    Hi Sudhir, so you have decided to start using Napa? That is nice to hear, in my opinion it is the best stability package out there.

    A seachest, or other negative volume such as bowthruster tunnel, should be reduced from your stability hull (stabhull and damhull). They do not contribute to the bouyancy and do not need to be flooded for damage stability.

    Sometimes seachests will have a deaeration pipe, but since the opening of the pipe leads to the sea (and not an internal compartment) it is not necessary to include it in your model as a flooding point.

    If you are using napa to do damage stability, try using the managers - they will walk you through the calculation. In the help files there is additional walkthroughs on how to use the manager and the calculations. You should also login to the napanet (from the website) to download workshops and papers and presentations from the various user meetings.
     
  9. sudhir0201
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    sudhir0201 Junior Member

    ontwerp. Thanks for reply. u are right, now i m using NAPA for intact and damage Stability. but it is not as user friendly as Tribon. because it is command based. I m using damage command for damage stability, rather then using from manager. as u said we can remove the seachest from damhull as it is having -ve buoyancy . what about for a compartment just above the bulkhead Deck having unprotected openings in hull side ?, can we also consider that space as a free flooding space (-ve Buoyancy).

    I m using the help file to clear my doubts. but it is very difficult to understand. and more over i am facing certain errors during my calculation which is not available in help file. although may be it is there but it is difficult to search.

    wel u are having vast knowledge of Naval Architect. can u help me in NAPA , how to take maximum benefit from it. and how to proceed. I know basics of NAPA but i stuck when i faced any error. it is difficult for me to resolve that error.

    wel as I m basically a mechanical engg. So What is my future in Ship design line??. and how can i grow myself in this field??
     
  10. sudhir0201
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    sudhir0201 Junior Member

    ontwerp and friends, Pls give me some reply........
     
  11. Pascal Warin
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    Pascal Warin Junior Member

    Actually, it makes sense to apply to naval vessels the probabilistic regulation for Special Purpose Ship (i.e. considering that persons on board are well trained for evacuation not like regular passengers).
    Basically, the calculation process is same as SOLAS one but required index is different (RESOLUTION MSC.266(84) adopted on 13 May 2008)

    Modification of our software VeriSTAR Stability is underway(due in April) to change required index calculation but you may immediately use it for calculating attained index.

    This software is free for educational academic and non-profit use.
    In other cases I can provide limited time fully functional demo.
    www.veristar.com
     
  12. ontwerp
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    ontwerp Naval Architect

    Hi sudhir,

    Yes command based is not as user friendly, but once you get the hang of it it is a lot faster than mouse based programs (similar to using keyboard commands in Autocad is faster than mousing).

    For probabilistic damage stability you should use the manager, it will walk you through the calculation and has many help notes built into it. Additionally there is a detailed probabilistic damage stability manager workthrough in the online manuals.

    What sort of compartment is it? In general if it is above the waterline and not watertight - you cannot include it in your stability model.

    If you want help with napa, maybe you should do an introduction course at Napa. Otherwise you can just do it, and read the manual to help with your questions. That is how we do it at my company. However, the learning curve is about 6 months, and with every new IMO regulation there are new things to learn and new ways to do calculations. That is what makes our work interesting and annoying.

    Here is a tip that might help when you are trying to figure things out at the command level: use the command !COM to see what commands are available and then use the command !EXP xxx (where xxx is the command you are interested in) to see an explanation of how to use that command.

    Many guys in my office are mechanical engineers by training, but none of them work in stability or basic design, they all work in structural design and project management. So in my experience, a mechanical engineer can better specialize in ship structure rather than stability.

    Depending on what you learned in school and how much self study you are willing to do, it could be possible for you to do stability, but maybe it's better to specialize in what you know, or go back to school and study naval architecture, or work with a mentor in the stability department of a company.

    Or you can send me your stability problems and I will take care of them at our consultants rate ;)
     
  13. ontwerp
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    ontwerp Naval Architect

    SPS Damage Stability

    When you say the calculation process is the same as SOLAS, but only required index is different, I think you are comparing with a passenger vessel?

    It is think it is worth noting that if you are comparing with a cargo vessel damage stability calculation, SPS requires you to increase your required index AND include escape routes in the calculation, AND include intermediate flooding via non-watertight A class bulkheads - which can affect your attained index quite a bit.

    Another thing is that most countries who have navies have their own codes and SOLAS may not apply. Navies do use classification rules for design, but more as a guideline - in the end the navy decides what it will apply. There is the naval ship code (ANEP-77), which was developed by NATO, but it may or may not be used by the flag state. So the first step in design of a navy ship is to find out which standards they want to use, and it will probably not be as stringent as SOLAS.
     
  14. Pascal Warin
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    Pascal Warin Junior Member

    Yes. Please refer to regulation.

    As regards, regulations you are right that some navies may have their own but when there is not such, proposing them to apply SPS makes sense.
     

  15. ontwerp
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    ontwerp Naval Architect

    Pascal, I assume you work for BV, (so you approach this from the point of view of classification society) but coming from the point of view of a designer I would not design a navy ship for SPS (passenger) unless expressly required. It would limit the ship incredibly. (by requiring all the pesky escape routes, etc. ;) )

    Actually the navy designs I have worked on always came with their own regulations provided by the flag state, with some reference to SOLAS, but not nearly as stringent.

    What do you think of the proposed NATO code that I mentioned in my comment above?
     
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