LCG and LCB for Planning powerboat

Discussion in 'Stability' started by shippro, May 16, 2008.

  1. shippro
    Joined: Jul 2007
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    Location: USA

    shippro Junior Member

    Hello everybody,

    I am trying to find LCG of powerboat. I have 3D file of the hull and actual trimmed waterline. From those data, I found displacement and actual LCB. Can I say this LCB is real LCG of this boat? I think the boat has trim so location of this actual LCB makes balance for the weight of the boat. So we can say LCB is exactly actual LCG of the boat. Please give me some idea about this issue.
  2. Olav
    Joined: Dec 2003
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    Location: Filia pulchra Lubecæ

    Olav naval architect

    Yes, LCB = LCG. If these two centres were not the same there would be a trimming moment turning the boat around its transversal axis until there is momentum equilibrium.
  3. Guillermo
    Joined: Mar 2005
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    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    It depends on the coordinates system used. If it's fixed to the 'earth' -so the vessel trims- the X coordinate of the LCB and LCG coincide at all trims, but if it is a vessel fixed system -so the water surface moves- then their X values do not coincide for trimmings other than 0 (although physically they are in the same perpendicular to the WL).

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