Minimum Freeboard, Maximum power

Discussion in 'Boat Design' started by Velsia, Jan 11, 2012.

  1. Velsia
    Joined: Oct 2008
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    Velsia Floater

    Excuse my ignorance but I am failing to understand a statement I read recently by Marc Lombard regarding his 2nd Generation Akilaria Class 40. He says that

    "the RC2 has a new hull shape that is more powerful due to the boat having minimum freeboard (within the class rule)"

    My limited knowledge cannot let my brain explain how this works. Somebody please help or this is going to be bugging me all day.:confused:
     
  2. Perm Stress
    Joined: Sep 2009
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    Perm Stress Senior Member

    minimum freeboard mean that there is so much less weight in hull sides, and the entire deck with all deck hardware is so much lower.
    All of this reduce weight and lower the centre of gravity => more stability to carry sails => more potential to develop driving force available.
     
  3. Velsia
    Joined: Oct 2008
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    Velsia Floater

    Thanks for your reply Perm Stress.

    If I can paraphrase. By reducing the height of the topsides, the CG of the hull becomes lower thus slightly increasing the righting moment.

    I know its a long shot, and we can only give the vaguest of guesstimates but by what % would do you think the righting moment was increased by? 1,2, 5%?
     
  4. Perm Stress
    Joined: Sep 2009
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    Perm Stress Senior Member

    If was a designer of this craft I would be able give an answer. :)
    Order of magnitude you did guess well, however.
    If that reduction in VCG is followed with some hull shape mods that increase form stability, the result could be impressive.
     
  5. Submarine Tom

    Submarine Tom Previous Member

    Less windage so less wind drag as well.

    -Tom
     
  6. Perm Stress
    Joined: Sep 2009
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    Perm Stress Senior Member

    Entire rig is coming down a bit, once again lowering the CG.
    And sails are a little lower, so heeling moment became smaller as well .
    The limit is (when no rules is applied) when a boat start to be a submarine with ~20% of reserve buoyancy :D.
     

  7. Stumble
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    Stumble Senior Member

    When dealing with box rule boats like this (I believe), often there are weird measuring rules that reinforce strange compromises... For instance there could be a measure from the top of the deck to the bottom of the keel that plays a part.
     
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