Hull shape design advice for 11.5m, 8kts, Fn=0.4

Discussion in 'Boat Design' started by ram68ocean, Jul 12, 2021.

  1. ram68ocean
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    ram68ocean Junior Member

    Thanks for pointing this out. Still the beam could be wider and the length shorter to bring down the L/B ratio. The idea behind making it slender is to reduce fuel consumption.

    I know. I was having issues with the trim at both conditions. Perhaps a water ballast tank(s) is needed.

    Interesting point. I wasn't aware of this direct relationship between wave height and beam.

    Yes a catamaran was considered but disregarded due to higher roll period.
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Obviously the round bilged version will have less wetted area per unit of volume, so that more or less mandates itself. If any differences in roll behaviour don't matter, the chined version would be a little more roll damped by the shape.
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  3. DCockey
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    DCockey Senior Member

    Any source for this?
  4. DCockey
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    DCockey Senior Member

    DWL is up to the designer, and depends on how the boat will be used. It can be useful to evaluate the vessel at several waterlines, ranging from light with minimal fuel, stores and crew to maximum displacement.
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  5. bajansailor
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    bajansailor Marine Surveyor

    No source, that is why I said 'it is something like' - I just remember reading articles where they mention this.
    I realise of course that it is not as simple as height versus beam, as some waves are steep, and others have long wave length.
    And of course it depends on the stability characteristics of the vessel concerned - if the boat has positive stability through 180 degrees then it should not be a concern. And maybe the autonomous vessel will have a watertight buoyant superstructure to give it self righting capability if a wave does knock it over.
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