SOS (Stability about a high speed ship)

Discussion in 'Stability' started by yuyewuyuconan, Dec 5, 2009.

  1. yuyewuyuconan
    Joined: Nov 2009
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    yuyewuyuconan Junior Member

    HI,every one!
    Lpp=30m ; B=6m ;D=2.5 m;d=1.9 ,displacement =150 t;"V"HULL,speed=25kn
    The ship only have water tanks and fure oil tanks ,they are lowest . The angle of maxGZ is not enough (other criteria is OK)。How can i get enough angle whit changing body line ,or other method .Thank you!
     
  2. gwboats
    Joined: Sep 2005
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    gwboats Naval Architect

    Stability - high speed ship

    yuyewuyuconan,

    Looks like you have a freeboard problem (i.e not enough of it).
    0.6 metre on a 30 metre boat is not nearly enough in reality.
    You could do with a touch more beam as well to help stability and hump speed.
    Hope this helps.

    Graham Westbrook
    Naval Architect
     
  3. yuyewuyuconan
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    yuyewuyuconan Junior Member

    HI gwboats
    Yes , freeboard of the ship is not enough ,but if it becomes more than 0.6m(The VCG of the light ship rise high than before ) . lf/lq ↓ --!.Are you sure more beam can help this ship stability?(More beam can hlep stability but i don't sure it can help the angle of the maxGz) .I tryed add appendage on the both sides of the ship .The result of calculation is that the maxGZangle become smaller 。。。
     
  4. gwboats
    Joined: Sep 2005
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    gwboats Naval Architect

    Stability

    yuyewuyuconan,

    You should see a significant increase in GZ value and angle by adding more freeboard.
    My guess would be about 50% better in both values by increasing freebard to 1.25m. (a more realistic value for this size of ship).
    An increase in beam of say 1.0m will also give a large increase in GZ value but probably only increase angle by around 10%.
    It would appear you have a ship of slightly strange proportions, is it restricted for any particular purpose?

    Hope this helps.
    Regards,
    Graham Westbrook
    Naval Architect
     

  5. yuyewuyuconan
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    yuyewuyuconan Junior Member

    Thank You Very Much !
     
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