Building materials - again

Discussion in 'Multihulls' started by aussiebushman, Jul 3, 2015.

  1. aussiebushman
    Joined: Oct 2009
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    Location: Taralga NSW

    aussiebushman Innovator

    The bridge-deck of the new (home-built) Cat is only about 2100 mm wide X 3200 long (including cockpit). I'm trying to keep the weight down, but also the cost, so I spoke with several suppliers. I learned a lot in the process:

    Foam/vinylester etc is just not feasible for me working in this location but I looked at other options: One was MAXI-T-BOARD and is though it is recommended for boat building and has the advantage of not needing to be epoxy coated, it is only available in minimum 10mm thick sheets and at 14.8 Kg and $180 per sheet is is just not viable, despite the labour savings.

    From a trusted supplier, Gaboon plywood is the best looking for a clear finish (not an issue for the deck) but is THREE TIMES the price of marine grade hardwood ply and actually not much lighter

    So-called PINK marine plywood is Meranti and a fair bit lighter at 10.4 Kg per sheet and frequently of dubious quality

    "Tropical hardwood" ply is only 9 Kg per sheet and guaranteed quality (from a trusted supplier) at only $53 per sheet Interestingly. any rejects go back to the importer and are (wait for it) resold to less fussy csutomers

    Hardwood ply it will be then and 6 mm thickness should be plenty on 300 X 300 mm framing

    Anyone strongly disagree?

    Alan
     
  2. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    How many layers ?

    I suspect its only 3. The trade name "Marine Tropical Hardware" is not encouraging.

    Does it have any certification at all ? (not by the manufacturer )


    It would be interesting to see the actual price difference for the whole bridge deck between using this, and the Gaboon Plywood.


    For such a strategic part of the structure, I would be inclined to go for the very best quality.
     
  3. aussiebushman
    Joined: Oct 2009
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    Location: Taralga NSW

    aussiebushman Innovator

    No. the hardwood version is 5 ply to BS 1088, the same rating as the Gaboon. Boatcraft Pacific and their resellers Drive Marine are very reputable suppliers who give their suppliers a hard time over quality

    The price difference for the entire bridge deck is precisely double. I appreciate the total is only a small component of the overall build cost but epoxy coated both sides, I fail to see the downside, especially when it is also epoxy bonded to a lattice of Paulownia stiffeners that are in turn bonded to the crossbeams.

    If you saw my previous topics, you will be aware that my 6.4 metre tri was stripped and torched and this cat is a low cost inshore craft made mostly from the bits I recovered from the burnt and sunk tri. Its objective is merely to get me back onto the water with reasonable sailing qualities and tight but comfortable accommodation.
     
  4. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Good reasonable strategy but what's the actual dollars value of 'double'. The actual weight difference would be interesting too.
     
  5. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    I guy up here built his entire 37ft cruising cat (easy 37) from BB grade face hoop pine plywood. Ive used a bit of it here and there and its good stuff. Uses the waterproof glue etc. Its about $40 per sheet and has very good faces with no voids. Have a look for it at your local timber suppliers...
     
  6. aussiebushman
    Joined: Oct 2009
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    Location: Taralga NSW

    aussiebushman Innovator

    Thanks Groper

    Hoop pine ply sure is excellent stuff. Any idea of which supplier? At arounf $40 it would be terrific value because the hardwood ply I mentioned is $60 a sheet and probably heavier
     

  7. aussiebushman
    Joined: Oct 2009
    Posts: 264
    Likes: 14, Points: 18, Legacy Rep: 132
    Location: Taralga NSW

    aussiebushman Innovator

    Just checked the Boatcraft website - they DO have marine grade hoop ply but at $155 a sheet!!
     
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