Inexpensive hull construction materials

Discussion in 'Boat Design' started by fpjeepy05, Dec 9, 2019.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I was thinking more of a politician who when petitioned by constituents about various issues, would always tell them he was "looking into it". I think the press gallery nick-named him the "Mirror Man" :p
     
  2. ondarvr
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    ondarvr Senior Member

    Yes it can be done, and has been.

    The problem is collecting it in sufficient quantities, transporting it to the processing plant, grinding it up (it’s extremely abrasive), packaging, then transporting it to the boat builder. Now it needs to blended into the resin and applied some how.


    You need huge quantities of scrap fiberglass, trim edges and stuff, to make enough to use as a filler in resin. Not many composite builders, very few actually, generate enough scrap to do much with, so you need to be very close to several very large factory’s that mass produce composites and have usable scrap.

    And once added to the resin it needs to be used quickly, the ground up particles start to react with the liquid resin and the cross linking begins.

    The first company doing it that I was aware of was in the 1970s I think. It worked, but the costs were far to high to make it profitable.

    There are companies that do it now, but they’re running into the same problems.

    Shops that generate huge amounts of grinding dust sometimes try to reuse it, but most of the time they generate far too little to have any affect on the cost of disposal, or as an additive in their production.
     
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  3. ondarvr
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    ondarvr Senior Member

    Now you get to PET foam.

    Again, the processing portion of a recycled scrap that is to be used again in production is the problem, the cost is too high for to it be a cheap core.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    What is the cost of PET foam compared to PVC ?
     
  5. fpjeepy05
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    fpjeepy05 Senior Member

    You are correct. Polyester does not bond well to PET PP and PE. Polyester resin doesn't bond well to glass either. That's why fiberglass comes with a coating called "sizing" No one seems to care about that. There are primers that will increase adhesion which I'm sure you are aware of. Or you could splurge $0.50/lb for recycled ABS plastic to get better adhesion, but you don't need to because it doesn't matter. Its a filler. The loads are carried by the skins. The core has to resist small amounts of compression and shear. 5lb density PVC foam is strong enough.

    This construction is heavy. The discussion prompt said nothing about reducing weight. This is a different discussion. CSM and polyester is also heavy and that is a large portion of the market.
    The structure is not weak. Failure mode for panels of a boat hull is in bending, so what matters most is stiffness. And in the 2-liter example, I showed you that it was stiffer than the product without.

    I guess we can agree to disagree. Not every method for using every recycled material has been proven to be "not effective" in every application.
     
  6. BlueBell
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    BlueBell Ahhhhh...

    Fpjeepy05,

    Interesting thread title.
    The most inexpensive hull construction material is pallet-wrap on skin-on-frame.
    I built an entire 3-man boat for under $100 (including Paddles) in three hours with no power tools.
    The boat then finished in front of 17 other boats in a race.

    But economising on hull construction material is one of the silliest things I've ever heard.
    It can be one of the lowest costs of an entire boat.
    Cheaping out on the hull could be the most costly mistakes you make.

    After 5 pages, I hope somebody has figured that out.
    Best of luck, carry-on.
     
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  7. Rumars
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    Rumars Senior Member

    If the grinding dust contains glass fibers please don't. Alkali–silica reaction - Wikipedia https://en.m.wikipedia.org/wiki/Alkali–silica_reaction
    Fiberglass used with cement is of a different variety from E and S called AR from alkali resistant.
    Using ground FRP as aggregate can be safely done with bitumen based compounds and thermoplastics.
     
  8. fallguy
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    fallguy Senior Member

    I was referring to the prior post; not yours.

    I rather like the idea of plastic bubbles.
     
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  9. ondarvr
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    ondarvr Senior Member

    This is exactly what I’m talking about, more processing required with escalating expense to create a workable product.

    Even when the base material is theoretically free, the cost, hassle and comprises to make it work make it more expensive to use.

    That’s why wood has been popular for so long, I’m not big a fan of wood, but when used correctly it can be a very easy to buy, easy to use, strong, and long lasting material.
     
  10. ondarvr
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    ondarvr Senior Member


    Yes, saving a very small percentage of just the hull materials by using a questionable (cheap) core rarely pays off.
     
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  11. fpjeepy05
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    fpjeepy05 Senior Member

    I can't stand this viewpoint. The principle is if you are spending a lot of money you can afford to waste a little extra. I'm sorry but no. You have shown no evidence that economizing on hull construction will degrade the quality of the product. And if it does that is not what I am talking about.

    Maybe I value my money more than you do. For every $200 I save that's another vacation day I get to spend fishing with my family and friends and not have to go to work. Or I can donate it to a charity that will change someones life.

    [​IMG]
    The photo on the left is of a woman whose name was Secoh's which means cursed. She lived 64 years as an outcast in her community because of her cleft lip. After receiving life-changing surgery to repair her face, Secoh's name was changed to Grace. How is your money better spent; putting fancy foam in your boat so you can brag to your buddies at the bar over a Mich Ultra? Or changing Secoh's life?

    But I'm the "silliest"? GTFO
     
  12. fpjeepy05
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    fpjeepy05 Senior Member

    No processing, no hassle, no compromise. Do I have to make a block of 50/50 recycle plastic / polyester resin to show you that it is stronger than 5lb density pvc foam? Have you ever held a piece of 5lb density pvc foam?
     
  13. ondarvr
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    ondarvr Senior Member

    Again, this is on you to bring new ideas, so far the ones you’ve presented have been around for decades and haven’t been used due to the high cost (in many different ways) in using them.

    I’m all for new ideas, products, methods, etc to lower the cost and make an equivalent, or even better product.

    But it’s getting harder and more expensive to do that all the time.
     
  14. ondarvr
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    ondarvr Senior Member

    The recycling industry in the US is being kept alive by government subsidies and regulation, not cost effectiveness.

    It’s not common for these recycled materials to be reintroduced in the manufacturing process and also reduce cost.

    I’m sure there’s a few items out there, but the examples are few.
     

  15. Rumars
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    Rumars Senior Member

    Yes make it, then test it to find out it's relevant properties, then make a sandwich panel with it of equivalent properties to solid CSM/poly. After this make a cost analysis of the two panels and tell us the result.

    Have you even looked at the link I provided to the FlipFlopi boat?
     
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