core for cockpit floor ??

Discussion in 'Fiberglass and Composite Boat Building' started by marlin974, Nov 23, 2013.

  1. marlin974
    Joined: May 2013
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    marlin974 Junior Member

    hello,
    I'd like to get opinions,
    I'm looking for an alternative to the use of balsa,
    for the cockpit floor,
    I would rather use foam, but which one?
    and what density to withstand trampling, pressures,punching

    I'm not talking about scantling rules, but concretely what is usually used by builders \ architects

    project:
    6m fishing motor boat with center console
    materials: infusion polyester \ vinylester glass, sandwich and monolithic

    thanks
    see you later :)
     
  2. garrybull
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    garrybull Senior Member

  3. Vulkyn
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    Vulkyn Senior Member

  4. upchurchmr
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    upchurchmr Senior Member

    For years commercial aircraft used balsa core in the floors, because it took the impact, abuse, and punch loads (high heels) best.
    I don't know what is current, but Balsa has a proven record. It also has to be sealed very well - epoxy comes to mind.
    If you make the floor removable you can check to see that it is still dry by weighing it occasionally. Balsa most often fails by getting wet and rotting.
    If you go foam, make it a heavy density. Sorry I don't have a real density number to recommend.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    There are a number of materials you can utilize, including the honeycomb stuff linked above. Ideally, you take anticipated loads and design a schedule that can tolerate it, plus a safety margin. What kind of load you might ask, well how about starting with the contents of the cockpit being flooded with water. Will your sandwich structure tolerate this, as you bail frantically to keep from sinking, or will it collapse. How much longitudinal and athwart stiffness does the sole impart to the hull shell. Is the sole floating (hanging or part of a liner) or tabbed in? Simply put, there's a real need to figure out what you need. Then again you could just over kill it with the weight and stiffness of 3/4" plywood, which is why many do.

    I'd look at foams, instead of honeycomb, though both work. Coosa is an option, but bring your purse. You'll find similar pricing for other materials, which is another reason plywood is employed frequently. Nidacore is fairly inexpensive as is Plascore, unless prefinished ('glassed both sides)..
     
  6. marlin974
    Joined: May 2013
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    marlin974 Junior Member

    hi ,
    thank you for your opinions :)

    the best for the floor would be: marine plywood,
    but it is too heavy for the boat (6m), I try to lighten up, gain pounds as I can,

    The deck is built in polyester infusion,

    Nidaplast is a good solution, it is strong and lightweight
    but it is difficult to implement with infusion, and I don't know if it adheres properly with polyester resins,
    and on the absorption of moisture, but I think the new models are plastic,
    but it is a good idea,

    balsa is good too, although I take any precautions to encapsulate the core correctly, it is not immune to a microcrack on the bridge, through which water could seep.
    this is a good material that I prefer to use for interior floors etc..

    especially if it is not me who will use the boat, an unsuspecting customer will not see cracks or infiltrations, when it goes out it will be too late (this is my opinion)

    To my mind a balsa deck is not used to its maximum,
    it really is very resistant to compression,

    I already do the infusion of a boat hull with foam 80kg \ m3 (airex C70)
    it's solid, once infused with multiaxial skin
    I have not tried with a chisel and or a hammer lol :rolleyes:
    but jumping on a plate (1.5 m high) placed on the ground, this had no impact or crushing, however I have not tried the foam alone (without skin)

    I will not take this type of foam,
    but a better compressive strength foam,
    density around 150 to 200 kg/m3,

    no one has already tried a foam on a deck floor ??
     
  7. marlin974
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    marlin974 Junior Member

    some information:

    the deck is supported on partitions / stiffeners,
    creating panels around 0.35 m X 0.950 m for the deck

    max flood volume ( cockpit volume): 2m3

    .....

    some situations,
    two people entering the boat leaving the dock brutally and jumps on the floor of the bridge, on the same panel,

    or fishing material of 5kilos falls from around 1m


    it's a little pictorially, but this kind of load, I want to take into consideration


    usually what coeficient of security you use for the deck
    or for marine boat of this kind?
     
  8. OFFSHORE GINGER
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    OFFSHORE GINGER Junior Member

  9. upchurchmr
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    upchurchmr Senior Member

    Coosa's blue water weighs as much as solid cedar. Have you looked at comparible properties? How about cost? I could not get the website to open up on the products.

    Doesn't do much good to give a density without the strength and the thickness.

    Do you have any idea if other polyurethane foams with glass coatings are any different in strength, stiffness, and cost?
     
  10. OFFSHORE GINGER
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    OFFSHORE GINGER Junior Member

    First of once again maybe you just might want to review there web site or both because weight ,Density , strength , and the thickness is all there or would you like me to do all the work for you , and not to mention that http://spaceagesynthetics.com is Coosa's biggest competitor that often offers seconds ( scratch & dent ) at a fraction of the price , and let's not forget Marlins , first # 1 post asking for an alternative product with no mention of price .
     
  11. FMS
    Joined: Jul 2011
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    FMS Senior Member

    ATL composites has the data sheets on their website. http://www.atlcomposites.com.au/atl_composites2/products/cores/coosa_pu_foam

    COOSA PROPERTIES -
    Bluewater 26 - 19mm / 3/4"
    Compressive Strength 6.4 MPa
    Compressive Modulus 137.3 MPa
    Shear Strength 4.0 MPa
    Shear Modulus 32.6 MPa
    Flexural Strength 29.8 MPa
    Flexural Modulus 1931MPa
    Fastener Pull Test (ASTM 1761) 61.23 kg

    WEIGHT COMPARISONS 1200x2400mm sheet
    Thickness
    19 mm
    Bluewater 26
    24.04 kg
    Bluewater 20
    17.85
    Plywood
    31.8 kg

    Bluewater 20 - 1/2"
    Compressive Strength 834 psi / 5.75 MPa
    Compressive Modulus 7,050 psi / 48.60 MPa
    Shear Strength 463 psi / 3.192 MPa
    Shear Modulus 8,432 psi / 58.14 MPa
    Flexural Strength 3,693 psi / 25.46 MPa
    Flexural Modulus 115,000 psi / 792.92 MPa
     
  12. marlin974
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    marlin974 Junior Member

    does anyone has an idea of the price ?
    Is there EU distributors ?
     
  13. marlin974
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    marlin974 Junior Member

    divinycell H200 mechanical proprieties :
    density 200,
    Compressive Strength 5,4MPa
    Compressive Modulus 310 MPa
    Shear Strength 45 MPa
    Shear Modulus 3,5 MPa

    it's better than coosa \density


    in my opinion this kind of product (coosa) is best suited for bulkheads/partition
    that as a sandwich core, no ?
     
  14. boatbuilder41
    Joined: Feb 2013
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    boatbuilder41 Senior Member

    Why use. Core???. I use fibergass panels for it all
     

    Attached Files:


  15. marlin974
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    marlin974 Junior Member

    we don't talk about stiffeners/partition/bulkhead,
    but bottom of cockpit/the zone where you can walk on deck:)
    we are talking about Sandwich core
     
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