Coosa vs Nidacore

Discussion in 'Fiberglass and Composite Boat Building' started by rlilley, Jun 13, 2010.

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  1. rlilley
    Joined: Jun 2010
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    rlilley Junior Member

    I am refurbishing the interior of a 1975 Chris 33 Coho. The interior is gutted down to the hull. I am planning on replacing the plywood floor joist with fiberglass I beams on 24" centers. (to give me more headroom)

    What would the better product be for the decking? Coosa or Nidacore.
    My original thought was 3/4 or 1" Coosa. I talked to Coosa but have not talked to anyone at Nidacore

    Thank You
    Bob
     
  2. kach22i
    Joined: Feb 2005
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    kach22i Architect

    I think that Coosa is a substitute for plywood, no re-engineering of details or fasteners as it holds a screw. Half the weight, twice the strength of plywood, but depending on where you get it, also twice the price.

    Honeycomb material will have you re-examining every connection and fastener, not sure you want to get into that here. Some details of how it is being secured might help you make a sound decision.
     
  3. tunnels

    tunnels Previous Member

    The decking is the floor ??
    I would use Coosa ! end of story !!
    Have done quite a bit of work with nida and was not impressed with it at all . How do you intend to make the floor panel?? Glass both side ? but what glass are you going to use ??and how do you intend to make it :confused:
     
  4. rlilley
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    rlilley Junior Member

    Thank You very much

    I am just learning how to work with fiberglass, not sure of anything at the moment. Would greatly appriciate some direction.

    I plan to seal all edges of the coosa then paint the topside. Wasn't planning on glassing - is that required. I have not seen coosa board yet. On top of the board will be carpet

    4" Fiberglass I beam is replacing the 10" deck joist to give me more headroom, then the coosa will rest on the I beam

    Bob
     
  5. tunnels

    tunnels Previous Member

    Have you seen coosa board ? do you understand what it is ??HAVE YOU READ ANYTHING ABOUT IT ?? YOU HAD BETTER DO SOME HOME WORK REALLY QUICKLY !! :confused:
     
  6. rlilley
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    rlilley Junior Member

    I know it is closed cell foam, cross thread fiber and roving. Not UV protected. 3/4 bluewater 26 is what I was going to use instead of 3/4 plywood. All I know is to seal the cut edges. I intend to secure the flooring to the fiberglass I beam with 3m 5200. Am I on track?

    Thank You
    Bob
     
  7. tunnels

    tunnels Previous Member

    I know it is closed cell foam, cross thread fiber and roving. Not UV protected. 3/4 bluewater 26 is what I was going to use instead of 3/4 plywood.

    Oh dear me
    Its a sheet of glass reinforced Foam !!!!It needs to be glassed each side !!!:eek: :confused:
     
  8. apex1

    apex1 Guest

    To the original question:

    none of them! Both are insufficient without a strong panel backing both sides. This could be a GRP layup.

    But the cheaper way would be marine ply! When encapsulated in Epoxy and painted, it would give another 30 or so, years of service life. The argument that it can rot (when not proper executed) is as valid (it´s even worse) for any foam core.

    Regards
    Richard
     
  9. rlilley
    Joined: Jun 2010
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    rlilley Junior Member

    Please be patient - I am by no means a boat builder

    I am confused - Coosa has told me the 3/4 BW 26 could be used directly as decking (flooring).

    I want to get away from marine ply due to weight.

    TUNNELS
    you stated you were "going" to use coosa - does that mean you have changed your mind or it is what your are planning to use.

    Bob

    Are you saying coosa is not as strong as I have been told?
     
  10. apex1

    apex1 Guest

    From the structural strength yes, they are right. But the stuff is NOT impervious to water intrusion.
    Nida is just foam, too weak to be used unsupported by glass both sides (all sides to be correct).

    In both cases you MIGHT end up a tiny bit lighter than with ply, but at about twice the cost and a higher risk of failure over the years.

    Regards
    Richard
     
  11. LarryMcI
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    LarryMcI Junior Member

    I've used plywood, Nida-Core and balsa cored panels for flooring throughout my catamarans. Plywood is relatively inexpensive but it must be sealed against moisture. Nida-Core flexes more than balsa and large spans (18"-24") resonate annoyingly. Balsa is lightweight, stiff and attenuates sound well. It must be sealed to prevent moisture intrusion. I recommend 3/4" thickness for unsupported spans <18" and 1" thickness for 18-26" spans, regardless of material choice.
     
  12. apex1

    apex1 Guest

    That is valid for ALL core materials, more so for foam than for Balsa.

    Thanks for sharing your experience.

    Regards
    Richard
     
  13. rlilley
    Joined: Jun 2010
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    rlilley Junior Member

    thank you very much.
    I plan to reduce the joist span from 24" to 16" CL. 3/4 coosa BW 26 for the flooring.

    Bob
     
  14. apex1

    apex1 Guest

    Welcome Bob,

    and still you would have to encapsulate the coosa in EP!


    Again, ply would be cheaper, almost as rigid, and less trouble >>>when completely encapsulated in Epoxy<<<
    Leave the so named advanced materials! The profit on them is advanced. The homebuilder / restorer has not a big advantage (usually the opposite) using that stuff.

    Regards
    Richard
     

  15. LarryMcI
    Joined: Mar 2010
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    LarryMcI Junior Member

    I must agree that, unless you're building an ultra-light-weight vessel from-scratch, exotic materials (like Nida-Core, Baltek and Coosa) are expensive overkill. Just seal the marine plywood with resin and apply the savings to your beer-and-pizza fund.
     
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