Bulkhead design

Discussion in 'Boat Design' started by saeedfa, Jul 15, 2020.

  1. saeedfa
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    saeedfa Junior Member

    Ad Hoc you say as a general regulation we can use the pressure at 1/3rd from the base of any vertical girder ?
    this is my important question.

    if i do the calculation for a tank, so TANSL said right, we must consider the height of ventilation pipe on deck, so the hydro static pressure on the top of the bulkhead were not zero, but in my case this is a bulkhead that separate the engine room from steering room so in this case ad Hoc say correct there is no need to consider the height of ventilation air above deck so the pressure at the top of the bulkhead may be zero.
     
  2. TANSL
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    TANSL Senior Member

    If it is a watertight bulkhead, even if you are not a tank bulkhead, you must consider a certain loading height determined by regulations.
     
  3. saeedfa
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    saeedfa Junior Member

    But the attached file is DNVGL-HSLC-Pt3-CH3, and that say vertical distance in m from the load point to the top of bulkhead
     

    Attached Files:

  4. saeedfa
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    saeedfa Junior Member

    this is the reference in DNVGL-HSLC-Pt3-Ch3, for tank bulkhead
    and that say vertical distance in m from the load point to the top of air pipe or filling station.
     

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  5. TANSL
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    TANSL Senior Member

    ... or flooded waterline,....
     
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  6. saeedfa
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    saeedfa Junior Member

    yes you right
    the flooded waterline must be check in stability booklet and then if the flooded waterline upper than the top of bulkhead the pressure must be calculated according to the flooded waterline
     
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  7. rxcomposite
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    rxcomposite Senior Member

    As I read further down the thread, I get confused.

    If this is a watertight bulkhead, I would treat it the way of AH as I do not have to worry about the deck opening except possibly a manhole.

    Now if it this is is a tank bulkhead, there is a filling pipe, a breather and a sounding pipe. The appropriate rules must then be used for the height/location, which is in agreement with International Load Line and SOLAS rule for downflooding.

    There are many types of bulkheads and the construction and test procedures for them are very distinct from each other.
     
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  8. Ad Hoc
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    Ad Hoc Naval Architect

    Exactly.
    Thus one needs to understand the theory how the pressure is calculated from theory, thus provides an understanding of the mechanism at play, which has nothing to do with rules/regulations.
    Once that is understood, one can then progress to how the pressure is calculated for a WTB (theory) v how regulations interpret that structural member (theory + Class requirement).
    And the location of the bulkhead (being reviewed by Class regulation) is an import feature of that...no magic to it.. despite what others appear to be suggesting..
     
  9. TANSL
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    TANSL Senior Member

    No one is suggesting anything. It is about understanding what the DNVGL rules say. You have said something that suggests that you have not understood what that regulation says.
    Simple :rolleyes:
     
  10. TANSL
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    TANSL Senior Member

    Precisely for this reason, because there are many types of watertight bulkheads, the design pressure at the top of a bulkhead may not be zero.
     
  11. saeedfa
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    saeedfa Junior Member

    please see the picture i attached above from DNVGL rule. according to the rule, if you calculate the simple watertight bulkhead, you must consider the "h" as vertical height from load point to the top of bulkhead or flooded water line if deeper.
    if you calculate the tank watertight bulkhead, you must consider the "h" as vertical height from load point to the top of filling or air pipe.
     

  12. TANSL
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    TANSL Senior Member

    You can have a watertight bulkhead that does not reach the main deck. What would be the height h in that case?
     
    Last edited: Jul 20, 2020
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