Shell plates and hull lines.

Discussion in 'Software' started by Alexanov, Oct 14, 2020.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    I wondered that myself.
    It is not easy to tell from the picture and the changes in light/colour...it could just be a 'trick' of the light or the pixel quality... who knows?

    Indeed :)
     
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  2. Alexanov
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    Alexanov Senior Member

    Most fore bulb plates, close to bottom, has very strange seam. What us the reason? I think mist of the problems comes from lines fairing quality....
     
  3. Alexanov
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    Alexanov Senior Member

    It is not easy to find pictures with clear vision of shell plates, but I think hull lines fairing also very important. Here is one hull shape faired by me. Shell plates made in Cadmatic by my collage. I may be do not understand anything in shipyard's life, but nobody from many shipyards newer complain about quality of our documentation.
    [​IMG]
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Can't really tell much from this image.
    Do you have other images taken from the side, underneath etc, and out of the water?
     
  5. jehardiman
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    jehardiman Senior Member

    Actually, to me, it looks like the thruster unit and bulb bow were two separate block fits because of the obvious seams. <shrug> I make the photo of some small intermodal ferry undergoing a refit, look at the rub fender and refitted bilge keel. Oh, the blocking looks iffy FWD of the thruster block which lends weight to a refit, not new construction.
     
  6. Barry
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    Barry Senior Member

  7. Alexanov
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    Alexanov Senior Member

    Try ti find, but it not easy...
     
  8. Alexanov
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    Alexanov Senior Member

  9. Alexanov
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    Alexanov Senior Member

    upload_2020-10-17_15-49-54.png
    some more shell plates
     
  10. Ad Hoc
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    Ad Hoc Naval Architect

    Neat.

    But this is not really the same apples to apples comparison.

    As noted, the original image, is very suggestive of the work being an "add on" and not originally designed to be part of the main hull from the beginning.
    Also the type/shape of BBow is very different too, thus creating very differently geometries...the thick stem also allows a lesser gradient of curvature than going to a single line/stem.
    The bulb as shown, the shape length and size creates a very distinct 'joint', which is absent from the original one shown.:

    upload_2020-10-18_9-51-10.png

    This makes fabrication much easier to achieve, as well as having upon appearance much more "volume" to it..which also aids fabrication.

    But I see this as an issue:

    upload_2020-10-18_9-55-58.png

    You have a plate tapering to a small triangular apex..and then it appears to finish where the other seam/butt starts/stops too.. creating a triaxial stress raiser. That is not good practice!
    In addition the regions of higher stress in cutouts are located at around 45-65 degrees (on the circle)..and you certainly don't want a welded joint in this region either...it is common practice to ensure no joints are on the circumference of these cutouts. If it can't be avoided, then they are usually placed at 0 and/or 90 degrees.

    See..it is easy to criticise the work of others... especially without knowing the full facts to hand and the reasons... why..... why it is as it is!
     

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  11. Alexanov
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    Alexanov Senior Member

    for this one I just made hull shape, but not shell plates. And actually you right in many cases.
     
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