confused about fiberglass layup process

Discussion in 'Fiberglass and Composite Boat Building' started by therigwelder, Feb 13, 2012.

  1. therigwelder
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    therigwelder Junior Member

    okay you all got me straight on the glass schedule.but my confusion is the procedure with laying the glass in the boat then applying resin.each layer has to be applied immediately after one another no hardening time?that scenario makes it difficult to move inside the boat to apply the next layer.also by the time i cover the deck with the first layer,the start of the first layer will be hardening before i begin the second layer.I am obviously missing some important info on the layup procedure
     
  2. ondarvr
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    ondarvr Senior Member

    The layers go down one on top of the next, with little rolling other than wetting out the glass (this will remove much of the air), once all the layers are down you start to seriously roll out the air. To wet it out you don't dab it with a brush, you pour it on the surface and rapidly move it around with a fuzzy roller. If you use cloth or roving as the top layer you can use a squeegee to remove the air, it's an easier and quicker method.
     
  3. ondarvr
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    ondarvr Senior Member

    You have three threads going on the same topic, it's much easier to follow and answer what's going on if you keep all the questions about this boat in the same thread.
     
  4. ondarvr
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    ondarvr Senior Member

    Make that four threads.
     
  5. therigwelder
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    therigwelder Junior Member

    sorry about so many posts.
     
  6. FMS
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    FMS Senior Member

    Wet on wet chemical bond is strongest. In the old days of polyester resin, poly resin was air inhibited meaning the top layer would stay tacky where it was exposed to the air.
    Epoxy's mechanical bond strength is much stronger than polyester's.
     
  7. therigwelder
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    therigwelder Junior Member

    I understand epoxy is a superior product. However my boat is 38 years old constructed of plywood mat and polyester resin.this is the first time the de
    ck is being replaced.millions of boats have been constructed this way maybe polyester is not as bad as everyone makes it out to be?I would like to master this skill set before moving to epoxy but I hear so much negativity about poly that it makes me wonder
     
  8. PAR
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    PAR Yacht Designer/Builder

    The polyester built boats don't last long, as their plywood and solid timber support structures die fairly quickly. Faster then a whole wooden boat in most cases. The production built craft need only survive their warranty period. It's not uncommon to see boats less then 10 years old in need of major repairs. I put a new transom core in a 12 year old boat recently and repaired stringers and hatch surround on an 8 year old boat a few months ago.

    This is all because they don't prime the wooden elements very well, use too thin of sheathing over them, polyesters don't really stick to wood well, isn't especially water proof (take your pick) and generally don't care much about what happens after a dealer sells it.

    I have a few older wooden boats, none of which has had a pampered life, all with original wooden decks and all either pushing 50 or over 50 years old.

    You can use epoxy, which will seal the polyester, better then more polyester. You can use polyester if you like, but epoxy is a far easier product to work with. Polyester has earned every inch of it's reputation from many, like me, that have had to hack it out of boats and the obvious signs seen during repairs, upgrades and modifications.

    Some manufactures are switching to epoxy, while most others have moved up to vinylester. These changes have come hard for the industry as they're more costly. Most manufactures are also substituting wooden elements for man made. Again it's a costly decision on their part, as these materials generally cost a lot more then wood. Simply put they're using vinylester resin because their shop is step up for styrene and MEKP, which isn't necessary at all with epoxy shops. Sticking with a poly base permits these builders, to keep much of the resin and material handling equipment used on polyester. It's a pure economic decision and has little to do with resin preformance.

    In the end it's your call, but even the slow to change manufactures are getting away from it. Once you go to epoxy, see it's preformance and ease of use, you'll never look back.
     
  9. therigwelder
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    therigwelder Junior Member

    i am a welder fabricator and i have access to 48-60 oz fiberglass blanket that we use as fire blanket to protect objects from heat up to 2490 Fahrenheit. i know it sounds crazy but one layer of this material would make a pretty stout deck.the fireblanket we use is uncoated fiberglass, its the cheapest type of fire blanket
     
  10. ondarvr
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    ondarvr Senior Member

    That heavy fabric won’t work very well, stick with the right stuff. Even if it would work and you got it for free, it would use two to three times the resin ($$$) and be very heavy.

    I agree with most of what Parr says, only that the reason for the rotten wood in production boats has little to do with the choice of resin and more to do with poor workmanship and design. Even if they used epoxy it would be defeated by unsealed screws holes, lack of resin, unsealed plywood, etc, these are the great equalizers, because wet wood rots. The change to VE in some shops is an attempt to improve the quality and overcome some of the poor production methods, it helps a little, but the lack of skill trumps it. The other part is about the ease of use when comparing epoxy and polyester (VE too), switching to Epoxy would be costly and slow production significantly. These boats are built to a price point and polyester is much lower in cost and can be dialed in so you can build 20+ boats per day , five days per week by a less than highly skilled work force. This may not result in high quality long lasting boats, but it does lead to a boat that can be purchased by the average guy.

    During the high points in production of these boats there were many hundreds being built per day in North America, some good, some not, and it can take many years for the difference in quality to make itself known. So even if a small percentage of these boats had severe issues it would be enough to taint the entire market perception.

    Epoxy tends to be used by low volume, high quality, semi-custom builders with a skilled workforce, the quality is much easier to control and maintain in this kind of environment.

    So is epoxy a better product….in many (most) ways yes. Is it going to make a big difference in rebuilding a 38 year old polyester boat….probably not.
     
  11. PAR
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    PAR Yacht Designer/Builder

    It would be unlikely you'd be able to fully wetout the fire blanket, though with infusion or bagging, maybe, neither of which is commonly used by the back yard builder.
     
  12. SamSam
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    SamSam Senior Member

    If this is just a regular old 16' trihull that someone wants to put back on the water for as little money as possible, without concerns that it might not last for decades, this is what 90% of the work was at the repair shop 15 years ago. We didn't use epoxy, it wasn't available down the street and was way more expensive than polyester.

    My 16' tri-hull deck went bad, so I ripped it out and liquid nail glued blue styrofoam to itself to create thick chunks, and those chunks to the hull taking care to leave a 1" or so ventilation space between the top of it and the bottom of where the new deck was going to be, and to leave room for water drainage back to the well where the bilge pump was. The width of the deck was 4', the bilge divided by two stringers so it was less than 16" span. I used dry, pressure treated 1/2" ply for the deck. I first coated the underside with resin. Once that set up, I put a good bead of liquid nails on the stringers and then screwed the deck to the stringers. I then primed the top of the deck with resin. After that set up, I put two layers of 1 1/2 oz mat on it. All this was with unwaxed poly resin. After the deck set up, I scraped off the big lumps with a sharp paint scraper, since it doesn't work to sand unwaxed resin, and then rolled on a coat of grey,waxed gelcoat. I would have used latex porch and floor enamel, but the gelcoat was there, it was free, so I used it.

    The boat didn't sit in the water for extended lengths of time, it was a trailer boat, and when at the house it was kept covered with a tarp that was open at the ends to let in ventilation. The deck is still pretty much as good as when I finished it 15 years ago.
     
  13. therigwelder
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    therigwelder Junior Member

    I think i will be using 2 layer of six ounce cloth.I dont feel that the deck i am redoing has signifigant structural impact on the boat.The deck sits directly on stringers in the bottom of the boat.There will be no real weight in the boat other than foot traffic and fishing gear.I really feel i need a watertight surface rather than structural integrity.The area of cloth will be 4 yards,how much resin can i expect to use?i have 10 gallons on hand.when i prime the ply with resin do i allow this to dry before procceding to lay down cloth?i will be priming both sides of the ply but glassing only the topside.this boat was originally done in the same manner except the factory used 3/8 ply and a few layers of csm.I am using using 3/4 ply and 12 ounces of cloth.:)
    .
     
    Last edited: Feb 15, 2012
  14. sabahcat
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    sabahcat Senior Member

    Are you a designer?

    Obviously not, that's a sole or floor, not a deck.
    The deck is the one attached to the gunwale that the cabin usually sits on:p
     

  15. therigwelder
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    therigwelder Junior Member

    No not a designer I am a fabricator welder by trade.thanks for the correction on my terminology. Correct me if I am wrong when I replace the plywood sole the structure rural integrity is replaced.then it becomes the job of the fiberglass to take up any flex impact and elements
     
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