Hydromax_Passenger Crowding

Discussion in 'Stability' started by mvd535, Jul 30, 2012.

  1. mvd535
    Joined: Jul 2006
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    mvd535 Junior Member

    1. I was trying to use Hydromax software at the University to demostrate to the students the passengers crowding effect on a small ferry boat.
    2. I was trying to do it by using the Hydromax Criteria tool for an specific loadcase, but as I am not too familiar with this software, I was not able to understand how the passengers weight and transversal location data filled at the loadcase table will or will not be in conflict with the same passengers data at the criteria.
    3. So I was wrongly thinking that if I am using the criteria tool, where the passengers weight and transversal location must be included, then I should erase these passengers data from the loadcase to avoid any conflict.
    4. After I had done the above, I found out that the passenger weight used at the criteria was never added to the final loadcase displacement.
    5. Because of the above, I modified the loadcase back to the original having the passengers weight and transversal location data in it again.
    6. Question is,...Do we have to use cero value for the transversal passengers arm at the loadcase table to avoid any conflict with the same transversal arm data at the criteria, which must be obviously not cero ??.
    7. Passengers vertical arm from the baseline it was kept with no change at all.
    8. The number 6 question it was submitted from the students themself.
    Many thanks
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    I don't have or use Hydromax.

    However, if you are teaching students, then surely the best thing to begin with is set up a simple weights and centres table with the varying TCG as passengers are moved further and further outboard.

    Then using the intact GZ data, just overlay the righting arm created by the pass crowding that you calculated in the W&C table.

    Once you have done this, then use Hydromax to ensure that the program is giving you the correct data, or better still, after showing how it is done traditionally (manually) let the students use Hydromax to find out how to arrive at the same, or close enough, results as calculated the "old fashioned" way.

    Never trust the results from a program until you can verify it manually.
     
  3. mvd535
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    mvd535 Junior Member

    Hydromax_Passenger Crowing.

    Ad Hoc, Many thanks for your quick reply, i am totally agreed with your suggestion. In fact, I discussed that with my students, and they were not too happy with the old fashion way, however they understood my position as this way will allow them to check their "lovely" program. As a teacher, it is actually my responsibility to show to them "learn to do sums by hand first and then you can trust calculator". High technology sometimes put breaks in their minds.
     
  4. abcdefg
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    abcdefg Junior Member

    To use the passenger criteria in hydromax, keep your passengers in the loadcase table on the centreline.

    Within the criteria dialogue add in the no of passengers, weight of passenger and a mean distance off centreline. Hydromax then computes the resultant angle of heel by converting the information to a heeling moment ie Number X Mass x distance off centreline. This moment (Tonne.metres) is then divided by the loaded displacement to give an upsetting lever (units metres) which is plotted onto the GZ graph (Righting lever) The point at which the two lines intersect is the equilibrium position. This value will be listed in the criteria results page after running the large angle stability function.

    If you were to simply move the persons transversely in the loadcase table, the equilibrium function will give the angle of heel directly.

    Typically when doing stability analysis, heeling moments from wind, passengers, rudders and combinations thereof are analysed using the large angle stability routine all at once.


    Make sense?
     
  5. mvd535
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    mvd535 Junior Member

    Hydromax Passenger Crowing

    To abcdfg,...Many thanks for your help, it is make a lot sense, actually students were thinking to do it in that way, so we will keep the passenger at the loadcase table at center line while applying the passenger crowing criteria, excellent !!!.
     
  6. naserrishehri
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    naserrishehri Senior Member

    dear friends
    i do not know how to calculate off center line distance to insert in the criteria .
    i know i have to consider 1 square meter for 4 passenger but i do not know
    which space i should consider .
     
  7. TANSL
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    TANSL Senior Member

    naserrishehri, you have to consider the REAL area where you can have passage. That is, for example, where a table, may NOT have passage.
    Of the many possible areas, you should choose the one with c. to g. further from the center line.
    See an example in the figure below.
     

    Attached Files:

  8. naserrishehri
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    naserrishehri Senior Member

    shall i consider area outside of accommodation area?i mean the edge on side without roof.
     

  9. TANSL
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    TANSL Senior Member

    You have to take into account any area where the passage can be placed, roof or without roof.
     
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