carbon fiber cloth (instead of fiberglass cloth)?

Discussion in 'Materials' started by mikakun2012, Mar 25, 2012.

  1. mikakun2012
    Joined: Dec 2011
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    mikakun2012 Junior Member

    Hello,

    i'm 100%newbie planning to build a plywood/fiberglass/epoxy cat-organization/sourcing phase-building will start in 6 month or so.

    I have a question to the knowledgeable members of this thread :

    imagine you were given (for free) carbon fiber 170g to encapsulate your boat, would you use it without hesitation instead of the fiberglass 200g ? why ? why not? (easy/hard? great benefits for the hull/no significant benefits?)

    many thanks for sharing your knowledge & opinion
     
  2. Herman
    Joined: Oct 2004
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    Herman Senior Member

    I would say: no significient benefits. Harder to laminate, less abrasion resistance, lower elongation means it might fail before the plywood does, higher modulus means it has to bear the full load, which means you need a considerable amount of fiber.

    I would use it for specific parts though. Cosmetic or low load when used alone, or if you can combine with UD, on load bearing structures. (rudder, rudderpost, chainplates, tiller, etc etc)
     
  3. mikakun2012
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    mikakun2012 Junior Member

    thanks & forgive my french & newbieness :

    what counts as "low load" ?

    what is UD ?
     
  4. michael pierzga
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    michael pierzga Senior Member

    Uni directional UD when the fibers all go in the same direction as opposed to normal cloth with fibers running 90 x 0.

    You use uni fabric the same way you would use a piece of timber whose grain runs in one direction. Conventional cloth is more like a piece of plywood and has no specific grain, fiber axis ,


    What weave of carbon do you have ? Many times FREE STUFF ends up with more work needed to apply and finish than if you purchased the correct fabric, weave.

    Eglass is more expensive than FREE, but the variuos weights weaves are much much cheaper than carbon.

    Is the fabric covering only a sheathing ? or is it structural to the boat.
     
  5. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    For the application you're describing carbon fibre isn't a good match. It sounds like it will be applied as a sheathing. Carbon fibre sounds like a silver bullet but it's really anything but and is only useful in the most engineered of situations.

    High Modulus means amazing strength for its weight and in carbon fibre virtually no stretch to failure. So if you are matching it with a structure where the plywood is intended to carry the loads the carbon fibre will be too stiff to allow the plywood any loading. What ultimately this will lead to is failure of the carbon fibre skin and water getting to the plywood underneath.

    There is an argument that you could stack on more carbon fibre until it was strong enough to bear all the loads but that would mean an inefficient structure as the plywood would not be utilised for strength and then you would be better served by using a lightweight core to maximise the benefits of the carbon fibre in a sandwich style of construction.
     
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  6. mikakun2012
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    mikakun2012 Junior Member

    ok thanks Corley & Michael to make me less ignorant; i think i understand why the idea doesn't make sense (that's the problem in having many ideas without the knowledge) :

    too much stiffness & so it will take the load off the plywood, making the plywood pretty much useless... was seeing and addition rather than a subtraction.

    what about the vertical parts of the hulls ? is it the same effect ?

    Michael, by free I just meant regardless of cost consideration... not getting any for free unfortunately - however could get both type if i pay; price might be interesting; could get aramid as well also bi and uni, waiting for more info on an hybrid fabric that same company produce.

    i think for this boat i'm looking at it is only meant to encapsulate plywood against corrosion & for insulation... so sheathing i guess ? (forgive my french & ignorance) from my understanding the structure is the timber & plywood & screws & epoxy glue that seal the joints

    still regardless of price, do you know of any alternative to fibreglass for corrosion/insulation, whether hitech, whether natural (like coir but lighter?) with really added benefits (like better protection against corrosion, more waterproof, better thermal insulation...?)
     
  7. michael pierzga
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    michael pierzga Senior Member

    Then use eglass. Stitched 45 x 45 degree orientation eglass fabric compliments the strength of plywood , is easy to drape around corners and is perfect as a structural sheathing for many small ply boats. .
     

  8. tunnels

    tunnels Previous Member

    I would take the roll and sell it to the highest bidder and then when i got paid buy glass to skin my boat and even have change to do other work as well as have a beer of two !!. :D
     
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