Hull design

Discussion in 'Multihulls' started by Jussi_2, May 18, 2014.

  1. Jussi_2
    Joined: Jan 2014
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    Location: Finland

    Jussi_2 Junior Member

    What U think about these dimensions at the photos? It is quite big. If I end up to build this, I were thinking to use 25mm M-Corecell, and Triaxial fiberglass skins over it, 4mm outer and 3mm inner skin, and good internal structure.

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  2. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Sailboat, powerboat ????
    Displacement ????
    Type and size of rig???? Engine ????
    What will it be used for ????
    Where will it be used ????
    Weather conditions ????

    In general, what are the requirements and objectives?
     
  3. Jussi_2
    Joined: Jan 2014
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    Location: Finland

    Jussi_2 Junior Member

    Lot of question marks.. heh.. I understand it as I didn't really add much of an information as I were more likely asking what U think about the length / width ratio etc. But anyway. It will be Sailboat, with 2 diesel engines. My plan was to make it big enough, that I can live inside of it while visiting in different countries. Type and size of rig is not decided. I will need a professional help for it. Basically it will be used for sailing and living the sailing time. I was thinking first (B)offshore class. but maybe better do (A) ocean class. I have professional resin vacuum infusion machines, as i build sport car panels. Also I own a big CNC milling machine, what I can use for making a male mold for the hulls. I have only build smaller boat what was solid fiberglass. I have experience of making fiberglass and carbon fiber products, also Pre-Preg products.. But to be honest, Not experiences of building big boats. I have also a cabin design for this. as now only the hulls are visible in the photos.

    I just finished reading: The Elements of Boat Strength: For Builders, Designers, and Owners. It was quite nice book. But it was made for monohulls, not for multihulls.
    Is there a good book for building a multihull?
     
  4. petereng
    Joined: Jan 2008
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    Location: Gold Coast Australia

    petereng Senior Member

    Hi Jussi, skins are too thick and the hulls have too much rocker. But you seem to have all the right toys to build a good boat. keep at it and yes answering Davids Q's would be good. What CAD system did you do this in? Peter S
     
  5. Jussi_2
    Joined: Jan 2014
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    Location: Finland

    Jussi_2 Junior Member

    Hi! Thanks for the reply. This hull design is not made by me.. I am only thinking to produce it. It is made with Rhino program. I have a good designer who have a lot of experience of using rhino 4. He can easily modified this model.

    I have talked to two catamaran builders, who build 10 meter catamarans, and they are using 25mm corecell + 2x 600gr triaxial fiberglass for both side as a skin. For my ears, it is sounding very thin. Also 20meter is quite long catamaran. I know U would need lot more details, but what kind of skin thickness U would suggest?
     
  6. petereng
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    petereng Senior Member

    25mm core and 1200gsm cloth either side is a common combo in australia for cats. Can go thinner on some lightweight designs. The skin thickness is determined by the puncture resistance which you want or the panel spacing. If you are building to ISO or Lloyds there is a prescriptive minimum thickness unless you can prove by test that your proposed skin has the same puncture (impact) performance. The longer the panel spacing the thicker the core needs to be to meet deflection limits if designed to a code, also the longer the spacing the more shear is on the core and most lightweight designs become core shear limited vs stress limited in the skins . Cheers Peter s

    The 4mm would be in areas along the keel and impact prone areas. Also can be thicker up front in regularly impacted areas. In areas prone to impact it should be solid laminate not cored anyway.
     
  7. Jussi_2
    Joined: Jan 2014
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    Location: Finland

    Jussi_2 Junior Member


  8. Jussi_2
    Joined: Jan 2014
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    Location: Finland

    Jussi_2 Junior Member

    Gurit says this in their website?
    "Gurit® Corecell™ S can also replace other materials, such as plywood, when creating high strength inserts for through-bolting in composite laminates."

    So what do U think? Could this be used in the places where I would need just normal solid fiberglass because of mounting?
     
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