Help in determining building materials requirements... please!

Discussion in 'Multihulls' started by Navy Dave, Sep 24, 2007.

  1. Navy Dave
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    Navy Dave Junior Member

    Hello,

    I am a MBA student at Southern Methodist University - Cox School of Business. I am working on a five-year business plan project for a start-up boat manufacturing company. Not only is this a required project, but also I would like to see if this is a feasible project to actually pursue.

    My question is how many layers and of what kind (mat, weave, weight?) of Fiberglass media would you recommend for a 14.5' planeing, air-entrapment hull, given your experience? I also have no idea of what type of core material to use, other than I want it to be 100% wood free. The construction method will be vacuum infusion.

    My passion is fishing and water sports, but my expertise is in finance. If anyone can fill the gap with materials needed for this project I would be very appreciative.

    This is only for forecast financials. Inaccuracies in materials requirements can have a significant impact in my financial projections. So any help would be appreciated!

    Thanks to all in advance!

    Dave
     
    Last edited: Sep 29, 2007
  2. nero
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    nero Senior Member

    You would need a boat design before you could have a material list ... before you can create your boat company.

    The horse goes before the cart. smile
     
  3. alan white
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    alan white Senior Member

    Yes, the concept (what do you want the boat to do?), then the size, shape, and weight requirement (design parameters) derived from that, then the hull material choice, then the lamination schedule to achieve the design parameters.
    What you've described is either a sailboat or a motor boat with a max speed of between 10 and 40 knots. You can get some solid advice if you nail down the design concept---- describe it, and draw it out.

    Alan
     
  4. Navy Dave
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    Navy Dave Junior Member

    Clarification:

    Hello,

    Thank you for your willingness to lend your advice.

    The boat will be a 14.5’ planeing catamaran powerboat, with a stepped hull and center pod. I expect the boat to utilize a 50 hp motor. I envision a flats boat that is patterned in part after the sleek offshore catamaran racers.

    The primary intended use is flats fishing in protected waterways.

    The target weight is 700-800 lbs.

    There will be two models:
    1) Fiberglass vacuum resin infused
    2) Kevlar/Graphite weave

    I have no idea of material weight to use, type of media (mat, weave, etc)

    The measurements are:

    14.5’ long
    6.5-7’ wide
    2.5-3’ gunwales

    I do not have any cad drawings, as the time frame is very tight on this project. If the numbers workout, I will continue to pursue this project further.

    Let me know if there are any other details that need further clarification.

    Thank you once again.
    Dave
     
  5. alan white
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    alan white Senior Member

    Out of my league, Dave, compared to some guys here. As a cat, I would foam-fill the floats, which adds stiffness by means of flotation already required, meaning the cloth schedule could be reduced relative to no foam being used. The pod would be quite stiff if somewhat egg-shaped, eliminating the need for foam-coring in that lay-up. My guess (if glass) is you'd use a combination of some specialized cloth and some woven roving, as mat makes for a resin-rich (heavy) lay-up.
    But I'd defer to the real goop artists here. Especially concerning lay-up schedules.
     
  6. rob denney
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    rob denney Senior Member

    G'day,

    For a small planing boat, the hulls below the water will be solid glass, say 600 gsm of csm with 600 gsm roving either side. Using a core for the sides and deck will save a little weight, but at great expense. I would use 4mm coremat with 600 rovings either side instead and ensure that any furniture is structural. Mould some top hat stringers under the bridgedeck to stiffen it up, maybe along the sides as well. Make the transom at least twice as strong as you think it needs to be, there are non plywood alternatives available, and make sure it is tied to the rest of the boat with frames. Make everything as curved as possible to give it stiffness.

    Glass and resin are going to be a small part of the overall cost.

    Kevlar and carbon in a boat like this have marketing value, but little else. Without a foam or balsa core they will need to be almost as thick as the glass and csm. A foam/balsa core will require a vacuum and a lot of mucking about , for a weight saving not much more than a carton of beer.

    Infusing non straight shapes can be tricky. If you do use a core, make sure the first couple are not gel coated so you can check the wet out.

    regards,
    Rob
     
  7. Navy Dave
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    Navy Dave Junior Member

    Rob,

    Thank you for the insight! I may have a few extra questions. Would you mind if I PM you direct?

    Thanks,
    Dave
     
  8. rob denney
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    rob denney Senior Member

    go ahead
    rob
     
  9. kengrome
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    kengrome Senior Member

    I would use 100% wood core, but I would treat the wood with Copper Naphthenate first before building with it. Then it will never rot even if it gets wet, and you will have a very strong hull with minimal use of expensive materials.

    Wood ... nature's low-tech carbon fiber.

    :)
     
  10. Navy Dave
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    Navy Dave Junior Member

    Thank you for your input, but one of the key marketing attributes is 100% wood free construction. I understand that your option would retain the same qualities at a lower cost, but non-the-less I'd like to stick with wood free construction.


    I am working with a rep from Diab (Robert Dyer), and he is being etreemly helpfull in regards to his products, so now I'm just looking for glass lay-up schedules.

    As an aside the boat will have foam coring in the deck and hull.

    Thanks,
    Dave
     
  11. alan white
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    alan white Senior Member

    Marketing attributes (not actual attributes). Wrong forum?
    Sorry---- maybe it's just me?


    Alan
     
  12. Chris Ostlind

    Chris Ostlind Previous Member

    Hi ND,

    There's something really strange about all this.

    You say this is for an MBA project at school which MAY turn into an actual project that could be taken into production, or at least that's what you infer.

    You have a very specific list of data specifications for this boat. You say it is intended for flats fishing in protected waterways and yet, you want to develop a plan for what amounts to an offshore racing style hull. Typically, those two things do not go together in boat design. At that, the hull will be too short for the business of comfortable fishing on the flats as it will not provide enough buoyancy either up front, where most fishermen choose to ply their trade, or from the aft section of the hull, because they are going to sink rapidly due to the stepped forms you indicate.

    From where I sit, this boat is all wrong for the stated use.

    If this is purely an exercise for the MBA professors, maybe it will fly. If it really is something you'd like to take to the next level, it needs a lot of thought before it can really work for the intended design goals. Yes, you can fish from this craft. Yes, it might just be able to plane. So from that perspective, you may have what you want. Will it be an elegant and successful solution for the goals as planned...? I don't think so.
     

  13. Navy Dave
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    Navy Dave Junior Member


    That's why I'm here, I'm not a boat designer...

    I just read your post a little closer, and think you have misunderstood what I meant by "patterned in part after the sleek offshore catamaran racers" I only intended the general asthetics. No, it will not have a canopy or other "race boat" features... The hull dimensions have been determined using the "Tunnel Boat Design Program". If the software is as good as they claim, The boat should work as intended.

    I do appreciate your opinion, good food for thought.

    So do you have any advice on lay-up schedules?


    Thanks,
    Dave
     
    Last edited: Sep 28, 2007
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