Looking for some more stability advice from you clever people

Discussion in 'Stability' started by jimmymc90, May 1, 2011.

  1. jimmymc90
    Joined: Apr 2011
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    Location: glasgow

    jimmymc90 Junior Member

    I have posted a couple of times for some help on here already and have got some good advice.
    Im basically redesigning a ro-ro ferry to comply with regulation 12a. I have currently removed 300 tonnes of fuel and replaced this with a double hull under the six fuel tanks. The total added steel was approx 50 tonnes. From this I have worked out the ships new deadweight, lightship and draft however im not sure how to go about proving the ship is still stable. I have all the parent ships data and have done been taught a bit of nav arc before Im just getting abit confused from having to work backwards from the fugures I have.

    im assuming I will have to calculate the fuel tanks new centres LCGs and the free surface effect etc but Im not sure what else.

    as always thanks for any advice
    James
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Can you add ballast to equal the fuel you removed?
     
  3. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    James

    Do you have the stability booklet?..ie do you have the cross curves of stability?
     
  4. jimmymc90
    Joined: Apr 2011
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    Location: glasgow

    jimmymc90 Junior Member

    cheers for your replies guys,
    Gonzo, I have been told to try keep away from simply adding ballast to replace the fuel.
    Ad hoc I have the statical stabilty curves of each load condition but obviously these conditions have now changed slightly, is this what you are talking about?
     

  5. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    From the weights on and weight off table....if you make sure you do this with the VCG and LCG too, you end up with the new displacement, VCG and LCG.

    From the curves of stability, you can calculate the stability using the KN data, at the new displacement and LCG, VCG.
     
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