stability critaria

Discussion in 'Stability' started by pavel915, Jan 18, 2007.

  1. pavel915
    Joined: Nov 2006
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    pavel915 Senior Member

    dear all,
    my knoledge about stabilty is confined to GZ curves, cross curves etc and I know the hydrostatics as good; but I have to know about the term " stabilty critaria" from u!
    specially when I use the demo of hydromax , i see that for Large angle stability analysis or limiting KG analysis ,a stability critaria is to be selected , there are many list of critarias,
    would you please give me a bit knoledge about these critaria and if u can provide me any link which is describes that critaria which are given in hidromax ?

    I think you have understood my question and hope u will reply to me to about that!
    thanks!
     
  2. mflapan
    Joined: Oct 2005
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    mflapan Junior Member

    Dear Pavel915

    The stability criteria will vary depending upon the nature of the vessel, the types of hazards that it will be exposed to, the types of operation and the nature of the testing method.

    You might like to download the draft standard that we are working on for intact stability criteria at http://www.nmsc.gov.au/documents/NSCV_Subsection_6A_2nd.pdf

    This should explain the variations in criteria.

    The file might take some time to download so please be patient.

    Best regards
    Mori
     
  3. knowme
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    knowme Junior Member

    Thanx for the document
     
  4. knowme
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    knowme Junior Member

    In fact I forgot to add that there is a NES document for stability criteria for ships and submarines. Pse google. It is publicly available.
     
  5. mflapan
    Joined: Oct 2005
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    mflapan Junior Member

    The stability criteria vary from vessel type to vessel type, jurisdiction to jurisdiction, vessel operation to operation. The stability criteria will be specified in the applicable standard against which the vessel's compliance is measured. For commercial vessels, it is normally a standard specified by the flag authority. For recreational vessels it might be a standard such as ISO, or Yachting Federation standards. Sometimes there is no specified standard but you will still need to check stability to fulfil your duty of care obligations. In such cases, you might need to refer to ISO or commercial vessel standards, assess which criteria are the most applicable and apply them to your vessel.

    As an example of stability criteria, have a look at the current Uniform Shipping Laws Code in Australia for commercial vessels that can be downloaded at: www.nmsc.gov.au/documents/USL/usl-section8-sub-sectionC.pdf

    I hope this helps.

    Regards
    Mori
     
  6. dincerd
    Joined: Aug 2004
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    dincerd Junior Member

    Dear All,

    i need to get both intact and damaged criteria file depends on mca rules ( same as Rina Classification of Charter Yachts) for Hydromax. Anyone can help me??
     
  7. alan white
    Joined: Mar 2007
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    alan white Senior Member

    A new method for finding the center of gravity of a yacht. Takes into account the precise position of something as small as a bottle of whiskey being removed from a shelf, or a plastic bucket slowly sliding across the cabin on the end of a fishing hook.

    http://www.boatdesign.net/gallery/showphoto.php?photo=1439
     
  8. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    :D :D :D
    The definitive 'No Inclining Test, Please'

    (question: photoshopped or real?)
     
  9. alan white
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    Location: maine

    alan white Senior Member

    Might be a fake. Probably. I saw such a scene once though. A worried crew waited out the requisite six hours, their approx. 35 ft sailing yacht sat on a small rock, and the tide was 11 ft. It's like being ordered to stand with your pants down in a dunce cap for all the world to see. Everyone sailing by saying, 'There but for the grace of God go I!"

    Alan
     
  10. asfekar
    Joined: Jun 2007
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    asfekar New Member

    iso 12217-1 in hydromax

    hi. i have been designing 9 meter non sailing boat. i have to pass iso 12217-1 criteries in hydromax. but i dont know some terms mean. for examole A n .
    please help me. its very important for me.
     
  11. Guillermo
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    Guillermo Ingeniero Naval

    askefar,
    I'll try to get back to you on monday from the office, with the ISO 12217:1 in front of me. In the mean time please clarify your question: do you want to know what "A" and "n" are....? :confused:
     
  12. hmattos
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    hmattos Senior Member

    If it helps at all the Stability criterion required for RIBs (or RHIBs in some countries) to be sold in the European Union area requires that the specified load must be fixed in the boat and then ALL the specified people ( passengers and crew) must ALL be able to walk to the edge of the deck without the boat heeling enough to ship any water.

    Hope this helps
    Hugh Mattos
    Chartered Engineer
    www.explorermarine.co.uk
     
  13. asfekar
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    asfekar New Member

    i am explaining my problem..
    i have been building between 6 and 9 meter zodiac rib boats.and i think i must use iso 12217-1 criteries. iif i use wrong criteries please inform me about it. and please tell me which criteries i must use.
    well. if i have to use iso 12217-1 criteries i dont know how to use it.
    i will order :
    1) in ofseet load test heeling arm= A*cos^n(phi) what is A and n.
    2) in rolling in beam test
    Wind arm: a v^2 A (h - H) / (g disp.) cos^n(phi)
    constant: a (0.5 rho_air Cd) = 0 kg/m^3
    wind model Velocity
    wind velocity: v = 0,000 kts
    area centroid height: h = 0,000 m
    total area: A = 0,000 m^2
    additional area: A = 0,000 m^2
    height of lateral resistance: H = 0,000 m
    H = mean draught / 2 m
    H = vert. centre of projected lat. u'water area m
    H = waterline m
    cosine power: n = 0
    gust ratio 1
    Area2 integrated to the lesser of
    roll back angle from equilibrium (with heel arm) 0,0 deg
    roll back to equilibrium (ignoring heel arm) deg
    Area 1 upper integration range, to the lesser of:
    spec. heel angle 0,0 deg
    angle of first GZ peak deg
    angle of max. GZ deg
    angle of max. GZ above heel arm deg
    first downflooding angle deg
    angle of vanishing stability (with heel arm) deg
    Angle for GZ(max) in GZ ratio, the lesser of:
    spec. heel angle 0,0 deg
    angle of first GZ peak deg
    angle of max. GZ deg
    first downflooding angle deg
    Select required angle for angle of steady heel ratio: DeckEdgeImmersionAngle
    Include GZ reduction: GZ' = GZ - B cos^m (phi)
    B = 0,000 m
    m = 1
    Criteria:
    Angle of steady heel shall be less than (<) 30,0 deg
    Angle of steady heel / Deck edge immersion angle shall be less than (<) 80,000 %
    Area1 / Area2 shall be greater than (>) 100,000 %
    GZ(equilibrium) / GZ(max) shall be less than (<) 60,000 %
    Area 1 shall be greater than (>) -1,#QO m.deg

    how will i define height of lateral resistance.
    roll back angle from equilibrium
    spec heel angle ( it is written twice :S )
    and others.


    3) in resistance to wawes part. how will i define them:
    heel angle at which required RM is constant =
    required value of RM at this angle is=

    4) in heel due to wind action how will i define terms . for insteance roll back angle from equilibrium etc.

    theese informations very important for me. please inform me about it.
    really very important. my msn : sultanfatihkar@hotmail.com
    thank you very much.
     
  14. Guillermo
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    Guillermo Ingeniero Naval

    askefar,
    for inflatables and RIBS you have to use ISO 6185-1, ISO 6185-2 and ISO 6185-3, not ISO 12217.
    Cheers.
     

  15. asfekar
    Joined: Jun 2007
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    asfekar New Member

    i thank you so so so much guillermo. but my hydromax does not have theese criteries. can you give me a link??
     
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