coosa core in place of plywood

Discussion in 'Fiberglass and Composite Boat Building' started by adventuris, Jan 31, 2009.

  1. adventuris
    Joined: Dec 2006
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    adventuris Junior Member

    i am looking at building an arch davis 26' jack tar. the plans call for 1/2 ply ,i would like to use coosa core in place of the ply ,looking for thoughts on doing this .
     
  2. apex1

    apex1 Guest

    some links, pictures ?:rolleyes:
     
  3. adventuris
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    adventuris Junior Member

  4. PAR
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    PAR Yacht Designer/Builder

    This is certainly a possibility, but the scantlings and laminate schedule would have to be worked out by a designer, as the physical differences between Coosa and plywood are quite different. Also note that you'll be building essentially a plastic boat, which is very high in goo factor (my term for lots of epoxy use). This alone could jack the cost up over double what a plywood build would be.
     
  5. adventuris
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    adventuris Junior Member

    i know cost will be higher , but i will have a stronger boat with 20lb 1/2 coosa glassed both sides then just 1/2 ply with one layer glass on the outside .
     
  6. PAR
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    PAR Yacht Designer/Builder

    Your making an uninformed assumption Adventuris. With proper scantlings and laminate schedule, you might make the boat stronger, but it will likely also be heavier, unless you employ some pretty high tech techniques and fabrics (read even more expensive).

    I'm not trying to insult you, but you just can't substitute a 3/4" plywood panels for a 3/4" Coosa panel and come out okay. Composite construction is a highly engineered form of building, especially if you expect it to be fairly cost effective and keep the weight manageable. Sure you could just slap on enough fabric and make it "strong" enough, but it will cost a small fortune and weigh a lot more.

    If you're determined to have a composite build, you should strongly consider two options. The first is simply to select a design arranged for the build method you desire. Second is get this one converted to the desired build method.

    This isn't something a novice can reasonably be expected to accomplish. In fact, a conversion for this design would essentially be a completely different build in comparison to plywood.
     
  7. adventuris
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    adventuris Junior Member

    Par ,the coosa panels are 40 percent lighter then plywood so i would be saveing weight there so adding extra glass resin would not make it to much heavier at all. i have done alot of work with coosa for decks ,stringers ,bulkheads hardtops .i am very familar with it it is very strong stuff just have not used it for a hole boat . i am not a novice at this i have build over 25 downeast boats of different sizes this would just e my first not using a mold .
     

  8. gamecock413
    Joined: Jan 2009
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    gamecock413 Junior Member

    Do you know how to do the inertia and moment calculations to tell you what coosa core thickness would be comprable to the 3/4 plywood? And, you will need to know the specs on the particular wood called for to even start those types of calculations. It can be done, but it should be done with precision.
     
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