drawing midship section of catamaran

Discussion in 'Boat Design' started by shrijeet mishra, Apr 1, 2020.

  1. shrijeet mishra
    Joined: Feb 2020
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    shrijeet mishra Junior Member

    hi everyone

    hope you all are doing good and are safe in this pandemic.

    actually am trying to learn to draw midship of a catamaran in soft copy to give a print out
    my vessel if grp based high speed vessel
    i have done the calculation for thickness and lamination sequence
    but then am not sure of how to start and end it with.

    please if anyone can help me doing it.

    it is urgent.
    im uploading the calculation excel
    offset excel and body plan (stn 5 being midship)
    also the word document.
    please help me
     

    Attached Files:

  2. shrijeet mishra
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    shrijeet mishra Junior Member

    sir
    anyone if can help
    will be much obliged.
     
  3. gonzo
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    gonzo Senior Member

    I would suggest you upload the drawing as a pdf. Many people may not be able to access a dwg file. You should contact your instructor for clarification. The instructions give you already assumed values. I only gave a quick look at HSC-LC rules of IRS, but there are tables with assumed values you can enter. The dimensions are kind of odd, considering it is a catamaran. Usually the freeboard is several times the draft. This has a draft of 2.16 m and freeboard of 0.340 m. It seems like you need to arbitrarily pick a deadrise between 10 and 30 degrees. Also a running angle of 3 degrees or more. Have you read chapter 7 of HSC-LC?
     
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  4. shrijeet mishra
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    shrijeet mishra Junior Member

    Yes sir
    i went through all the rules.
    and the excel prepared is as per rules
    i have written and noted down each rule.

    im requesting if anyone can help me draw it in autocad
    with the given values of thickness and stiffners dimensions

    i have written the rules

    ill upload the pdf of my bodyplan
    but sir i am actually not able to visualise and draw in autocad what is where and how to mark it.
    i have attached the files and calculation i could understand the max
    hope this is enough and help in drawing it out.
     

    Attached Files:

  5. TANSL
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    TANSL Senior Member

  6. shrijeet mishra
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    shrijeet mishra Junior Member

    sorry sir but i can only see the drawinf of body plan which i had attached earlier in my reply.

    i am in need to draw the midship section of this catamaran
    ive done the calculation but not able to draw it like where to draw what transverse or girders and how to label them
    hope u get my query.
    i have understood and done the calculation rest part is to draw. which am unable to do.
     
  7. TANSL
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    TANSL Senior Member

    So you need somebody to do your job in doing scantlings drawings. That's another matter.
    You draw it on a paper and I'll draw it on Autocad.
     
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  8. shrijeet mishra
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    shrijeet mishra Junior Member

    no no sir not actually wanting that someone else to do my job
    is drawing on autocad so easier than on paper.?
    i just got paper drawing of someone with same kinf od hull and drawing of midship of GRP.
    if that can be made for my dimensions as found in excel is that possible to do in autocad.
    am new to autocad and stuff.
    tbh this is my degree project work. im learning and trying to apply.
    hope u understand and help me out.

    on lighter note sir if you actually give me that final drawing with the dimensions calculated in excel there is nothing more i can ask for right now and would be so grateful forever. :D
     

    Attached Files:

  9. TANSL
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    TANSL Senior Member

    When calculating the stands of a ship, you must proceed in two stages.
    - first define the structure, number of elements it carries, its position, and its approximate separation
    - once this is done, the scantlings of the elements defined according to the previous point are calculated.
    If you have not done step # 1, it is impossible to go to step # 2. Where are you at the moment?

    By the way, you should forget about those drawings of the last century and project the structure of a modern ship.
    If the only thing you lack is knowing how to use AutoCAD, what you should do is spend your time learning to work with that software instead of wasting it writing in this forum. Writing here is not going to teach you how to solve your problems.
     
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  10. gonzo
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    gonzo Senior Member

    Just by looking at it, the deadrise appears to be more than 30 degrees. You could make your life easier by making a chine hull. That would make the sections mostly straight.
     
  11. TANSL
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    TANSL Senior Member

    A chine hull could make his life easier (it will be difficult to find out), but for his boat it could be total nonsense.
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    It is much easier than you think. You have done all the hard work already, like this:
    upload_2020-4-4_8-6-35.png

    So, all you need to do, is place this data onto your dwg with the assumptions in the calculations that you have made.

    For example, this is basically the same as your hand calculations, but shown on a dwg:

    upload_2020-4-4_8-7-41.png

    And is is referenced here:
    upload_2020-4-4_8-8-19.png

    So the section is shown, the layup is noted and spacing , on the hull lines, is also shown.

    You supplement the assumptions by stating what materials are being used, such as:

    upload_2020-4-4_8-9-31.png

    And you can do a detail line by line dwg of the hull layup, or just list it as shown:

    upload_2020-4-4_8-10-25.png

    You then add further details for the connections, like the frames such as this:

    upload_2020-4-4_8-11-6.png

    Again, just direct from your hand calculations, but shown pictorially.

    Or combinations of them such as here:

    upload_2020-4-4_8-12-34.png

    Or a combo showing frames/layup regions:

    upload_2020-4-4_8-21-26.png

    So it is really up to you how you wish to show this data.

    No idea what "stands of a ship" means... and how does this assist the OP?
     
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  13. shrijeet mishra
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    shrijeet mishra Junior Member

    i hope by stands you meant stiffeners and plates scantlings.
    i have done the calculations of parts like bottom frames girders beams transverse and cross structure.
    just wanting to draw it

    yes sir posting wont help me drawing but i am learning many things which i would have not. from you and others
    instead of posting and scrolling instagram spending some time here is worth i feel.

    i have started working or autocad and engineering drawing basics so that i get to understand what to draw and how and where.
     
  14. shrijeet mishra
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    shrijeet mishra Junior Member

    sir chine hull only advantage i know is ease of construction also no such specified rules and model work was done i suppose.
    i chose NPL ROUND BILGE displacement hull series
    it satisfies my required condition of high speed and also provides me with offset table and other basic required methods by NPL models.

    i would like to know and understand the differences and advantages or disadvantages chine hull has over round bilge.
    your experience and knowledge would help me too knowing the basics of hull design and selection.
     

  15. shrijeet mishra
    Joined: Feb 2020
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    Location: india

    shrijeet mishra Junior Member


    sir
    thank you so much
    this was actually i am try to understand and learn that how to label and what is calculated in excel the scantlings where are those placed and it drawings respectively.
    if not autocad ill try first on A2 sheet and then try over it.
    if such problem comes in autocad ill request you again
    i hope u dont mind helping me over.

    thank you sir.
     
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