differences between: Glass-Epoxy-Composite and Fiberglass hulls

Discussion in 'Boatbuilding' started by gp333, May 4, 2009.

  1. gp333
    Joined: Mar 2009
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    gp333 Junior Member

    what is differences between: Glass-Epoxy-Composite hulls and Fiberglass hulls

    can someone more experienced create simple vs. list good/bad by technical and prices list
     
  2. McFarlane
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    McFarlane Macka

    You will find that most production boats ( boats out of moulds ) are usually built from polyester resin as you dont have the waiting you do with epoxy for curing.( epoxy curing time is aruond 24 hours and polyester you can have it gel in minutes and cure within hours ). These production boats have a layer of gelcoat over the fibreglass, which protects the glass from water saturation, this doesnt always protect it though ( osmosis ).
    A lot of the time epoxy sheathing or glassing is put on timber hulled boats or plywood hulls or over one off boats ,as epoxy sticks to timber a lot better than polyester.but there are high performance racing yachts made out of epoxy in moulds Epoxy resins and fillers are better under water as well. Always remember "you cant put polyester over epoxy but you can put epoxy over polyester'', the poly will not adhere to the epoxy in most cases.
    Epoxy resins are a lot more expensive compared to polyester resins as epoxy is better under the waterline.
    With most repairs I do under the waterline on polyester glass boats, I will glass the repair with polyester resin then use epoxy filler to fair the repair, then apply epoxy primers and undercoats.
    My opinion Epoxy is better but takes to long to cure.
    Cheers
    Macka
     
  3. apex1

    apex1 Guest

    Sorry McFarlane, he asked for some experienced to answer, you are obviously not!

    Polyesther resins are not water resistant, epoxy resins are! Curing time is equal for both, depending on the formulation of the resin in use.
    Polyesther adheres to nothing than poly! And even that is sometimes tricky.
    But you´re right Epoxy costs much more than polyesther and cost is a factor in the maritime world. Moreover, a good poly resin has some advantage over several EP resins in strength.
    Epoxy coating has nothing to do with one off boats! I do all my production line in wood Epoxy, so every boat is EP sheathed.
    For amateur building there is no choice, you can use EP only, it is much easier to handle and as mentioned it is the perfect glue too! And if you like, you can have it cured in 30 minutes! But who does, and why?
    So, the answer is: mass production uses Poly / glass, one offs and high tech racers use EP / glass. The word "composite" is irritating `cos it is used for several, absolutely different techniques. Glass/foam/glass is named composite in either EP or Poly resin layup or infusion technique. Cold moulded wood / Ep is named composite and some say Epoxy/glass sheathed plywood is composite too.
    At the end, glass and resin already is a composite material.
    Regards
    Richard
     
  4. marshmat
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    marshmat Senior Member

    A composite is just a material comprised of two or more distinct components.
    Such as fibreglass set in polyester.
    Or carbon fibre set in epoxy.
    Or fibreglass set in epoxy on either side of wood.
    Or multiple layers of wood joined with epoxy.

    Standard production fibreglass hulls consist of an outer gelcoat skin, some combination of fibreglass chop-strand mat, cloth or roving set in polyester, and sometimes a foam or balsa core in between layers of fibreglass to make it thicker and stiffer.
    This can be an economical and durable system for mass production, if you have skilled lamination crews and good quality control. It's generally not economical on short-run or one-off projects. Polyester resin is really only suitable for conventional fibreglass lamination in a controlled factory environment; although it can be used to put fibreglass on wood, it's not particularly good for this. It doesn't make for particularly good repairs or secondary bonds, either, without very specific, tedious surface preparation methods.

    "Glass-epoxy-composite" hull could mean many things.
    At its simplest, this is the same as the "standard fibreglass" hull, with epoxy in place of polyester.
    It could also mean any number of other things. Is there a core? What's the core made of? A laminate needs to be evaluated on its mechanical properties and its durability under heat, water and stress. The name alone means little.
    Generally speaking, epoxy is more expensive than polyester, but tends to be easier and more reliable to work with, adheres better, can be made compatible with other materials (ie. wood), is usually more water-resistant, among other advantages. Hence why it's usually the resin of choice for one-off builds, for anyone working with wood-composite construction, and for hulls based on expensive high-tech fibres such as Kevlar or carbon.

    "Advanced composite"
    If they won't tell you what's in the "advanced composite" hull, what the core material is, what the structural fibres are and how much fibre is in there..... a lot of the time, "advanced composite" is marketing speak for "whatever cheap crap we can get away with".
     
  5. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Gp, Marsh and Apex are both right....
    But some thoughts...
    Not all epoxies are equal quality - resins either...
    A not so good epoxy is as good as a great resin...
    Resin will not bond to epoxy....
    For weight reductions you can use lite fillers in epoxies with care.
    For cost reduction use a sandwich of resin and glass covered with epoxy.
    I find glass stiffer, epoxy more flexible without fillers.
    So for one off, you can build stringers in glass and resin for stiffness, strength and cost then cover then in Epoxy.
    Composite means made from various materials... I have built boats plywood covered with resin, covered with epoxy. Or aluminum covered with epoxy. Or Fiberglass, vinlylester and foam board. Or Epoxy with fibers and aluminum oxide over cardboard. All are composites...
     
  6. Jimbo1490
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    Jimbo1490 Senior Member

    True. Concrete is a composite as it comprised of portland cement and aggregate; this is even before you consider the reinforcing steel.

    Jimbo
     
  7. McFarlane
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    McFarlane Macka

    Sorry apex your answer is exactly what i have said, maybe you should read it a bit closer, ive only been building and repairing boats for 25 years , maybe not enough experience yet, we dont use 5 minute epoxy to build boats in Australia, only 24 hr and pre-preg epoxy, yes you can set epoxy off quickly but the resin becomes brittle and the glass looses its strength. If you cant make poly stick to poly maybe you! are lacking in experience
     
  8. apex1

    apex1 Guest

    Dear fellow member, it was not only this post that lets me assume you are not (as claimed) a professional. And I still have the same opinion.
    If you have a 25 years experience in boat repairs, it is impressive (at least) that you made some of these statements.

    http://www.boatdesign.net/forums/newreply.php?do=newreply&p=272075

    and the last point:

    The glass (or wood, or every other matrix) does not know how fast the goo is curing, it does not loose its technical properties! That was again a statement that did not show "professional" knowledge!
    And, not to start a competition, I´m in this business for almost 40 years now, and I´m doing it on the uppermost price and quality level. After about 6.500 tonnes of boats and yachts built, I claim to have a clue what I´m talking about.
    Regards
    Richard
     
  9. mydauphin
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    mydauphin Senior Member

    On Epoxy, I have seen manufacture using infusion and vacuum bagging almost build a boat in a day. As far as professional, I cry every time I see a boat being repaired by "professionals" using bondo or resin with fiber and paste. Use epoxy to fix polyester resin. Simple... No if and or buts... use epoxy for repairs. Also I can't tell you how many boats over the years I see coming in with blister, get grinded off, then resin again... Cover outside of resin with at least epoxy paint to make fiberglass water tight...

    The only problem with epoxy is the skill and quality of workers and materials....
     
  10. apex1

    apex1 Guest

    Absolutely mate, there is no difference building a boat in glass epoxy or glass polyesther!
    And repairs can be made ONLY in one method: use Epoxy, nothing else has any reason or is sufficient at the end!

    Not my two cent, the knowledge of the boatbuilding world!
    Regards
    Richard
    and Mydauphin: you mean poly if you say resin, yes? `cos epoxy is a resin too.................
     
  11. Jimbo1490
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    Jimbo1490 Senior Member


    There are so many curing agents for epoxy, literally hundreds. And there are several different types of epoxy resin, each with its sub-types sorted according to molecular weight (EEW) that it's really not accurate to say that the faster curing systems (a system is a resin + a curing agent) are all too brittle. Then there are the reactive modifiers, many of which reduce brittleness and improve toughness and elongation.

    Do you think that West with fast hardener is brittle? That stuff ticks off in like 5 minutes in even a small mass, and I doubt that West is going to sell a sub-standard product. Over-priced, maybe. But not sub-standard.

    Jimbo
     
  12. apex1

    apex1 Guest

    There are a few manufacturers and many formulators of Epoxy resin out there, West is just one of the latter, that you can have nearly every formula you would like! If not, ask them, they make you a goo that calls your cellphone when cured.
    So, the statement was absolutely incorrect, one may say what he likes.
    Thanks Jimbo.
     
  13. mydauphin
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    mydauphin Senior Member

    Yeah they are all resins

    Yes, they are all resins made from that evil oil....
    I kind of call then all resins except epoxy and leave epoxy for the two part stuff.


    When someone make a mistake with poly, sometimes they had more Mek on the surface or heat... and hope it stiffens. You have potential future problem at least the resin is more brittle or not . On epoxy you have to sand it down and start all over...

    Quick comment on polyester, vinlyester and all those...
    Over the years they have gotten better, some products are almost as good as epoxy in some regards, but so are some of the prices as high. Epoxies are still king.
     
  14. McFarlane
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    McFarlane Macka

    Step into the real world apex, gone are the days of building timber boats although i did enjoy building them, its nearly 2010 fibreglass is the way to go, quick to build, easy to repair.:D
     

  15. mark775

    mark775 Guest

    Almost as bad as a few (anyone with "mas" in their name, some dude from the territory of Puerto Rico, and one from Florida) that segue every conceivable post into their personal anti-USA or anti-Western tirade, with sometimes subtle barbs and always unnecessary attacks, is the wont of Apex to not simply correct or disagree with another but discourage anyone from opening their mouth for fear of denigration.
    Are you Aryans still just better than everyone else, Apex? Should we all just step into the "shower" and let you run the place by yourself?
    Epoxy's cool, sure, but as fast as poly? A repair can be done in poly as long as it is sealed. I drive a poly COMPOSITE that is older than the Gougeons themselves. How do we know epoxy will stand that test of time? (That being said, my next boat is epoxy and all of my skiffs are put together with it)
     
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