Incredible Vibration-Banque Populaire

Discussion in 'Multihulls' started by Doug Lord, Nov 11, 2014.

  1. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

  2. redreuben
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    Location: South Lake Western Australia

    redreuben redreuben

    Thats nothing short of extraordinary !!
  3. Gary Baigent
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    Gary Baigent Senior Member

    Wide platforms flex and do funny harmonic things sometimes going through waves - not unusual.
  4. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    It's not really that surprising when you think about it the majority of strength in the hull is in the vertical plane the horizontal plane is rather weak comparatively speaking and it's a long unsupported cantilever forward of the beam. Groupama3 was incredibly light for it's length and beam when built a real experiment in lightweight boatbuilding. A bit too light initially with the structural failures it experienced.
  5. redreuben
    Joined: Jan 2009
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    Location: South Lake Western Australia

    redreuben redreuben

    Modern Boatbuilding.

    If it doesn't break its too heavy
    If it breaks its too light
  6. Manie B
    Joined: Sep 2006
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    Manie B Senior Member

    Scary :eek:

  7. Jim Caldwell
    Joined: Aug 2013
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    Jim Caldwell Senior Member

    Now we know why bows break off!
  8. teamvmg
    Joined: May 2008
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    Location: christchurch,uk

    teamvmg Senior Member

    My mast bends from side to side each time I tack - is that going to fail too?
  9. 2far2drive
    Joined: Nov 2011
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    Location: Houston, TX

    2far2drive Senior Member

    it isnt just the ama. on the 2nd dive down the entire boat goes side to side. watch the main hull, windward ama and rig. just a hard impact at speed... :D
  10. DGreenwood
    Joined: Aug 2004
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    DGreenwood Senior Member

    You are seeing why carbon and only carbon could build such a structure and have it stay together. Sounds obvious, I know, but the ability to place prepreg carbon with very accurate orientation to known engineered loads, keeps the weight where it is required and out of the areas where it is not. Not scary...just the lightweight way of dealing with slamming loads. Not fun trying to sleep in there though!

  11. fastwave
    Joined: Jan 2007
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    Location: europe

    fastwave Senior Member

    From my experience this is within the norm. Carbon structures can sustain very high strain without issues.
    On an AC v5 boat the sailors were worried about a new experimental mast flexing too much and that it would come down despite the engineers saying repeatly it was ok.
    At the end after few calcs to comfort the sailors, they were told that they should start getting worried when the masthead was more than 1.5m outside the perimeter of the boat. The boat was about 3m wide.
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