Autohydro - Intact Stability IMO MODU Criterion

Discussion in 'Software' started by hprajaya, May 28, 2012.

  1. hprajaya
    Joined: May 2012
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    Location: South East Asia

    hprajaya New Member

    Dear,

    I'm working in ship stability using Autohydro. In subject of Intact Stability implementing IMO MODU code, I have difficult to write my RUN file for Autohydro.
    I've done in IMO General & IMO Wheater criterion n succes.
    Can someone help me to write RUN file for IMO MODU code criterion??
    Attachment file are the criteria. I need to to solve {Area (A+B)/Area (B+C)} >= 1.4

    Thx.

    View attachment IMO MODU Code.doc
     
  2. Jort
    Joined: Sep 2012
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    Location: Rotterdam

    Jort New Member

    IMO intact stability

    Dear Hprjaya,

    I have also recently started to use Autohydro. It is quite hard to get started. From the Autohydro helpdesk I got the following answer to a similar question when we were trying to calculate dropload criteria for a crane vessel:

    I thought I would try sending the attached in case it makes any sense to you. This is for the DNV application of the loss of load. I noticed that the BV wants the angle between the second intercept and max roll angle to be > 20, while I think in the DNV rules it's 15. You'll see at the bottom of the cll.run file a check for 15 degrees.

    Notes:

    1) In the test.run you'll see two moments. Pay particular attention to the sign - one has to be positive and the other negative. The sign controls which way each load heels the vessel.
    2) The eighth line in the macro is " `report off ". The little character in front, " ` ", is the 'comment out' character and means don't process this line. I've commented out this line in order for you to evaluate whether the results are correct. Once you are satisfied the macro works remove this " ` " character and that will avoid all that extra/confusing/useless information in the report.
    3) You might notice there are two puzzling ra's, the second and third to last, I believe. Autohydro won't evaluate an area when there are only a few data points so to get around this for A1 I find the area from gz0 to 90 and then the area from 1st intercept to 90 and subtract one from the other to get the area from gz0 to 1st intercept.
    4) I believe this macro works for both directions of heel, but...
    5) There is no way to draw vertical lines on the plot or otherwise denote where 2nd intercept, gz0 and 1st intercept are other than by the note following the last righting arm.


    I have attached the files that come with it.

    Would you be able to share your IMO intact stability code run file with the limits with me?

    Regards,

    Jort
     

    Attached Files:

  3. hprajaya
    Joined: May 2012
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    Location: South East Asia

    hprajaya New Member

    Hi Jort,

    Below are text for IMO General Intact stability criterion (limit). Just copy and paste to your run file at autohydro. Then you can add command for RA limit.

    `add limit criteria by IMO
    LIMIT OFF
    LIMIT TITLE GENERAL CRITERIA (IMO A749)
    LIMIT AREA FROM 0 TO 30 > 0.055
    LIMIT AREA FROM 0 TO 40 OR FLD > 0.090
    LIMIT RA AT 30 > 0.200
    LIMIT ABSOLUTE ANGLE AT MAX > 25
    LIMIT GM > 0.150

    For IMO weather and MODU code, there a bit different, since for those criterion preassure and wind velocity are applied. You have to give particular attention to windage area for those criterion.

    Regards,
     
  4. Jort
    Joined: Sep 2012
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    Location: Rotterdam

    Jort New Member

    Dear Prajaya,

    Did you manage to solve your MODU criteria where you needed to solve {Area (A+B)/Area (B+C)} >= 1.4? If yes, I would be very interested to see how you did this.

    I am still struggleing as how to check the criteria of 0.03 mrad from 30 to 40 deg or from 30 to downflooding from the 2008 intact stability code. Have you done any calculations with this criteria yet?

    Regards,

    Jort Brouwer
     
  5. sameedck
    Joined: Apr 2006
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    Location: d

    sameedck Senior Member

    Sameed

    Try this.

    for Intact stability

    "

    Limit off
    Limit title MODU INTACT STABILITY
    Limit (1) Abs ratio from equil to ra0 or fld > 1.4
    Limit (2) Rar @ ra0 > 0.9

    "
    ----------------------------------
    for damage stability

    "
    variables thetas (ANGLE)
    set thetas = [1.5*{Heel}]
    set thetas = [{thetas}+7]

    If {thetas} < 10 Then set thetas = [10] Else set thetas = {thetas}

    Limit off
    Limit title MODU DAMAGE STABILITY

    Limit (1) Angle from Equil to fld > 0
    Limit (2) Angle from Equil to RA0 > {thetas}

    "

    ---------------
     
  6. salvatorejmz
    Joined: Feb 2015
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    Location: naples

    salvatorejmz New Member

    crowding of passengers

    Hi, I have a problem with the Crowding of passengers criteria.
    Can you help me with the command on autohydro for this criteria???
    the angle of heel on account of crowding of passengers to one side may be not exceed 10°.
    thank you so much ;)
     

  7. liuquan
    Joined: Aug 2015
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    Location: singapore

    liuquan New Member

    Hi,

    I think it should be the following correction for modu intact stability:

    Limit title MODU INTACT STABILITY
    Limit (1) Abs ratio from 0 to ra0 or fld > 1.4
    Limit (2) Rar @ ra0 > 0.9

    if from equil to ra0, means from first interception point to second, but A+B is from zero heel. thanks


     
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