power cat/tunnel design

Discussion in 'Boat Design' started by ajt, Mar 29, 2012.

  1. ajt
    Joined: Mar 2012
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    Location: gold coast aus

    ajt New Member

    I'am building my dream a 8.5 mtr long x 2.4 mtr wide x 1mtr to 1.2 mtr high hull with 10 deg x 500 wide sponsons . with a 1 mtr wide tunnel running full length made of all timber ( australian hardwood strip planked tunnel hull inspired calm water powercat) .the strip planks are kiln dried hwd 18mm t x 22 mm w glued with epoxy glue the total hull weight will be 1200 kg exopy coated with resin not glassed then 3 coats non yellowing varnish . I have 2x 225 hp johnno's ( 500 kg's )which I know is over the top ? taking the total weight with fuel and water to approx 2300 kg . I was just hoping that someone with a good knowledge or a cad designer could help with a tunnel height for river and lake use not off shore as overall height of boat to top of cabin is important - possible performance of craft - planning speed - overall speed etc . would the boat be more effective using 1 motor mounted in the middle like tunnel hulls or 2 like a cat thankyou
     
  2. FMS
    Joined: Jul 2011
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    FMS Senior Member

  3. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    18mmx22mm hardwood sounds like a narrow board polished floor. :D I'd guess you'd need closely spaced frames to have adequate athwartship integrity, as most of the strength is along the grain of the longitudinal strips.
     
  4. ajt
    Joined: Mar 2012
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    Location: gold coast aus

    ajt New Member

    thanks guys the vertical sides of the tunnel are 2 layers of 20mm marine ply lapped to give strength length ways the rest like a laminated beam ...think I'll go with 1 motor in the centre ....
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    What will the transom consist of ?
     

  6. ajt
    Joined: Mar 2012
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    Location: gold coast aus

    ajt New Member

    2 layers of 18mm marine ply glued together then the whole transom area glassed in then the lot veneered over with strip planks that are 18mmx 12mm to give the same effect as the rest
     
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