Laminate schedule verification

Discussion in 'Materials' started by Drewdriver, Jul 10, 2014.

  1. Drewdriver
    Joined: Jul 2014
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    Drewdriver Junior Member

    Hey guys, I have a question about general fiberglass work, not specific to boat building. What I'm making is more of an anti-boat, in that it is supposed to keep water in haha. There seem to be no forums for general fiberglass fabrication, and given that what I'm building needs to have structural strength, I chose you guys over some of the auto fiberglass forums. Feel free to tell me to get the hell out, but if you're willing to help, I would love some verification from someone with experience. I plan on building a fiberglass canoe at one point, so I'm sure I'll be back.

    Down to business, I'm designing a complete automated and optimized aquaponics system, and I would like to fabricate my own grow beds and fish tank. Fiberglass is the perfect material for this. I've done some fiberglass work in the past, but nothing that needed actual strength. I have several questions, if you would hear them, but I will start with the laminate schedule.

    I've never worked with a core material before, but I've done some research on it, and it seems to be the way to go. Here is my proposed schedule, working from the outside of the container, in:

    Gelcoat, 1.5oz cloth, 2oz mat, 18oz woven roving, core material, 2oz mat, 1.5 oz cloth, and gelcoat.

    My line of reasoning is that the core material and cloth will provide the strength and rigidity, the mat will help prevent delamination, and the woven roving placed on the outer side of the core will help with rigidity and to keep tension opposite of the outward force of the water, and the gelcoat obviously to resist the UV rays in the greenhouse and keep the water in.

    Once I get my schedule down, I plan to make a plug for a female mold, to be able to reproduce it.

    Please tell me if I have something misunderstood, if it's too weak, if I could do it a cheaper way, ect. Thank you, and sorry for the book you had to read to get to this point.
     

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  2. rxcomposite
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    rxcomposite Senior Member

    Innermost lining (the one in contact with water) should be a resin rich layer. Gelcoat or resin, veil cloth, CSM at least 2 layers, then whatever other layer you fancy.

    The plug (male) should be the mold to keep inner surface smooth and shiny.
     
  3. Drewdriver
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    Drewdriver Junior Member

    Is it important to use a male mold if the inside is just going to be filled up with growing media anyway?
    I've heard about veil cloth, was curious if I should use that. I'll throw that into the schedule.

    Do you have any suggestions on core material? Or should I just use layers of cloth, roving, and CSM? The fish tank is a tapered out 4' cube, will hold about 500 gallons, then the grow beds are 3' x 11' x 1' and will be filled with expanded clay beads and water.

    Also, what resin would be appropriate? Would a general purpose polyester work, or something more like this?
    http://www.fibreglast.com/product/Isophthalic_Polyester_Resin_just_resin_90/Polyester_Resins
     
  4. ondarvr
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    ondarvr Senior Member

    Actual cloth is a waste of time and money on this type of laminate, if you want low cost stick with mat and roving, you could use 1708 instead of roving if you wanted to.

    The larger the holding tank the thicker the core should be, it's best to keep the laminate the same on both sides of the core.

    The gel coat and resin used will need to be formulated for continuous immersion, many aren't.
     
  5. ondarvr
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    ondarvr Senior Member

    you made your second post while I was typing.

    Foam core would be the best, but balsa or plywood could be used. A rib (or two) around the tank will help keep the sides straight.

    VE resin at least for the skin would work well, but there are good ISO resins that would work.
     
  6. rxcomposite
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    rxcomposite Senior Member

    Drewdriver. You said fish tanks. the inner lining should be smooth so it is easy to clean and most important, will not bruise the fish when it swims. For growing plants, the inside can be rough but the outside is smooth and easily cleaned.

    For the materials, if it is indoor, ortho or DCPD resin can be used. If outdoors, ISO is a must as it is more UV resistant. If you want it to last for 20 years or so, use Vynil Ester as Ondarvr suggested.

    Veil is sometimes called surfacing mat. Holds a lot of resin and is standard liner for water tank. You dont need a core as this is not a sophisticated structure. You can easily build up the inner bulk by using heavy Chopped Strand Mat or Coremat or "Felt" materials. Cloth is used outside for a relatively smooth finish but woven rovings can be used as well.

    Panel design (thickness) is dependent upon the length and width of the unsupported panel. Remember, water is heavy at around 1 ton/cu meter. Base lamination is usually heavier, top most edge is usually reinforced or formed with a lip to prevent the tank from "bowing out".

    If the panel size is large, it can be broken down into smaller sizes. Add more stiffeners which can be 3-4" dia. cardboard tubes slit in half and laminated over, 3/4" x 2" plywood strips spaced every 18", or low density foam core "tophat" shape.
     
  7. ondarvr
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    ondarvr Senior Member

    Since he plans to have gel coat on both sides the determining factor on the resin won't relate to UV. Ortho DCPDs tend to not be the best products for long term immersion behind gel coat, they work OK short term, but for an application like this I would stick with an ISO or better. The issue you run into on resin choice is that not all ISO's are great long term under water, if you have a history on a particular resin you may know it holds up well, but most are sold based on lowest price, which doesn't always get you the best product. So to be sure it will would hold up I typically recommend going up in resin quality, which would mean at least a VE skin.

    This is all based on wanting to build a good product, frequently fabricators start off with good stuff but end up going cheaper over time, sometimes it works, sometimes it doesn't.
     
  8. Drewdriver
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    Drewdriver Junior Member

    Ok, so definitely will upgrade to the vinyl ester resin, I am wanting this to last many years.

    Rxcomposite, so for the fish tank I should use a male mold, and the grow beds can be made with a female mold, got it. I didn't think about the surface being rough on the fish, good save.
    You also recommended I forgo the foam core in favor of heavier CSM and more bulking... what would you recommend the thickness be built to if I did that with the roving thrown in?
    Would I only use the veil on the interior then, since that is the water contact side?
    Also, I'm attaching a better picture of the profile of the tank. Is that enough of a lip to keep from bowing out, or should I continue it down more?

    Ondarvr, you suggested a foam core with CSM outside, what would you recommend as the thickness of the core? Also, what density?

    Just trying to get multiple options. I'm absolutely willing to spend every dollar I need to to make it a strong, long lasting product, but I also don't want to just throw money at it that I don't need to.
    Again, thank you both for the detail of your answers, this is almost more information than I got from the days of research I've done.
     

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  9. rxcomposite
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    rxcomposite Senior Member

    Post dimensions of the tanks. It is easier to visualize the lam sched. Is it going to be modular construction? With steel frames to hold several tanks?
     
  10. Drewdriver
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    Drewdriver Junior Member

    The dimensions ended up kind of strange thanks to the curves and tapering, it started out as 4ft cubed.
    The dimension of the lip doesn't show up well, but it's 1/2 in.
     

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  11. Drewdriver
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    Drewdriver Junior Member

    And yes, due to the nature of the fish growth and nitrogen cycle, I'll have 3 separate grow beds. The first two will be planted at project start, and as the system expands, the 3rd will be planted. Possibly adding a 4th later on. They will be on pressure treated wood stands. I've never worked with metal, I do a lot of woodworking though.
     
  12. rxcomposite
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    rxcomposite Senior Member

    Will work on these later and see if I can find my old notes. We made a lot of these before for "Tilapa culture" it is in the net with a similar title. There is even a requirement for ozone generator. Lots of piping. Water filling, drain, air/oxygen enrichment.
     
  13. rxcomposite
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    rxcomposite Senior Member

    Just made a quick search in the net. It is there. Just have to find my hard copy as it is more complete.

    I remember now how complicated the pipings with all the filters and drain and air. That is why the cage was made of steel. It is very hard to move a tank filled with water so the system was it was a steel cage that can hold several tanks, empty or filled.
     
  14. Drewdriver
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    Drewdriver Junior Member

    Haha wow, looks like I came to exactly the right place. Who would have thought. How big were those tanks?
     

  15. Drewdriver
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    Drewdriver Junior Member

    Ahh I see. Well luckily the grow beds act as a biofilter, you just can't have near as many fish as a dedicated aquaculture system (unless you want kilometers of grow beds), so I'll only need a fill pipe and a drain pipe, not too complicated. That's why I put the stands on decking, so I can just run the pipes underneath and out of the way. I'm also going to run the PEX tubing under there for radiant heating in the colder months.
     
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