Discussion in 'Multihulls' started by redreuben, Feb 11, 2016.

  1. redreuben
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    redreuben redreuben

    I've noticed the brokers here in Australia have caught the overseas habit of calling plywood boats "composite" presumably because epoxy resin magically turns wood boats into "composite".
    To my mind composite means at least a foam cored boat, polyester is fibreglass, foam and other lightweight cores and fabrics other than glass are composite.
    Am I being pedantic ?
    I mean I looked at an Arbor 30 which was advertised as composite, but on viewing the photos its 100% plywood, I think it's dishonest.
  2. Corley
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    Corley epoxy coated

    I think it's a loose term and doesn't necessarily infer a foam core. For example one of Kurt's boats if you take a cylinder molded plywood shell and vac bag a core onto it for panel stiffness (foam or end grain balsa) is it wood or composite? Is durakore composite or wood? Is duflex composite or wood? They are all boatbuilding materials that combine different materials. I agree though that it's a bit of a stretch to claim a plywood boat with stringers is composite.
  3. waikikin
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    waikikin Senior Member

    Might as well add ferro cement & ferrolite as well... could be timber over iron/steel too..
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Every second boat ad I see is full of lies. Probably the pirate gene.
  5. daiquiri
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    daiquiri Engineering and Design

    Technically, a composite is any material consisting of several different materials bonded together, one of which carries loads (reinforcing elements - fibers or other kind of solid shapes) and the other is a matrix which keeps the load-carrying elements together.
    Even wood is a composite material in a technical sense, because it has a matrix (lignin) and reinforcing cellulose fibers. A composite made of other composites is also a composite.

    So plywood is technically a composite (made of layers of wood - a natural composite), likely the first one created by the mankind (back in ancient Mesopotamia).

    I suspect that their lawyer has checked these technical definitions before giving the green light to the marketing dept to use the term "composite" in their sales brochures. :)
  6. upchurchmr
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    upchurchmr Senior Member

    +1 what Daiquiri said.
    Yes you are being pedantic and creating a new meaning.
    Welcome to the club, I have a coworker who does this all the time - I call him Dr. Know it all. But he is obnoxiously excessive.
    You just got carried a way a little. :p
  7. PAR
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    PAR Yacht Designer/Builder

    This is normal and done all the time. Epoxy is a key word, so any product that has portions of the epoxy molecule in it, be it real epoxy or not, will have epoxy on the label, as a major marketing point. These sort of marketing ploys are pretty common. For example have you ever seen a new housing development getting built with a name of what it actual is? Of course not, as it's always called "Glen", "Woods", "Brook", "Heights" etc., not the swamp it was built on or the landfill it was constructed over or the imminent domain convolution employed to capture the land it actually was. "Heather Tar Pits" just doesn't have quite the ring as "Heather Brook", so . . .

    The same is true with products, with the possible exception of WD-40, which is innocuous enough, most butter up or massage the name so it hits the most "likes" in a focus group, before it's released. In a lot of instances you can look up the former suggested names of some products, with many of them being obvious why they weren't selected.

    Composite is just as the word sounds. Two ply toilet paper could be consider the new and improved "Composite Paper". I've seen advertisements for Mobile Homes with composite construction. They're the same 2x4 and particle board pieces of crap they always were, but now are selling better, from the new marketing approuch. Hey, I've got some composite sheet goods I like to sell you. Comes in Douglas fir, meranti and Okoume and can be faced with hardwoods of your choice is so desired.
  8. Tom.151
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    Tom.151 Best boat so far? Crowther Twiggy (32')

    Here in Northeast USA the term composite became more popular because of the difficulty/cost of getting "wooden" boats insured. Some insurers would require a full survey before considering coverage for a wooden boat. But the "epoxy composite" didn't trigger the need for survey and higher premiums.
  9. rxcomposite
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    rxcomposite Senior Member

    Well, according to my composite training material, it was the Egyptians who first discovered "composite" by reinforcing clay with reeds.

    Concrete reinforced with steel bars is also composite. Luckily, those guys who combine wood and other materials do not call it composites. They call it "engineered lumber".

    Then there is Marine Composites, Advance Composites, and Aerospace Composites.
  10. daiquiri
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    daiquiri Engineering and Design

    This could indeed be the most comprehensive explanation. ;)
  11. DCockey
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    DCockey Senior Member

    A century ago "composite construction" of a boat or ship usually meant metal frames with wood planking.
  12. DGreenwood
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    DGreenwood Senior Member

    My personal ethics previously have prevented me from using the word "composite" in referring to a plywood cored boat. When it finally occurred to me that you can use the least rot resistant plant material on the planet and call it "composite", (namely balsa), I started thinking of plywood/epoxy as cellulose cored composite.
  13. catsketcher
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    catsketcher Senior Member

    I like what DCockey says with composite - the Cutty Sark was composite with her metal framing, hardwood hull and Muntz metal sheathing.

    In reality a modren plywood catamaran is much different from a carvel Tahiti ketch and shares much more with its foam sandwich sisters - similar weight, strength, stiffness. Carvel and clinker produce heavy, often leaky boats. Modern plywood construction, including epoxy glass coating, epoxy coring of holes for fittings, glass chainplates, wonderful things called COVES, all help make modern plywood a vast leap different from early Pivers et al.

    I know some people don't like ply but for me it is one of the best ways to build a modern, successful boat with lots of epoxy, glass, microfibres, microballoons and embedded plastics. So composite describes my cats well - even though they do use ply in there somewhere.


  14. gonzo
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    gonzo Senior Member

    By the definition of composite, FRP falls within the category. It has glass fibers in a polymer matrix.

  15. upchurchmr
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    upchurchmr Senior Member

    In a aerospace context (at least at my company) composite means graphite / epoxy, and recently includes graphite / BMI (higher temperature). Glass/ epoxy has fallen out of the "composite" usage range, probably mostly because of the minimal use of glass.
    But metallic composites were discussed for a while, but aren't mentioned because of lack of use (aluminum/ particulate ceramic).

    Almost like a "fashion" statement.
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