Uses and limitations of fiberglass mesh tape?

Discussion in 'Fiberglass and Composite Boat Building' started by farmerben, Dec 8, 2020.

  1. farmerben
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    farmerben New Member

    I'm totally new at boat-building. I was actually working on concrete hyperbolic parabaloid roofs, inspired by George Nez designs.

    I got a 500' roll of adhesive fiberglass tape for less than $10 reccomended for drywall joints and was messing about with dowel rod frames. I love the way this tape rolls around a round frame and sticks to itself. Weaving up many layers of mesh tape is easy. It is possible to get compound curves very tight.

    I also started looking into skin on frame boat building. George Dyson has a number of what appear to be steel electrical metal conduit frames with skin. Most of the skin builders sew up a single sheet around the boat then heat shrink then epoxy it.

    I like the way tape works in some ways better than a giant sheet. It is very easy to get tight everywhere. 4 layers of tape creates a decent cloth that acyrlic paint can fully coat and seal pretty well.

    I haven't bought any epoxy yet. I was wondering if it is even worthwhile fooling with polyester epoxy, like bondo? Or should I order an epoxy that costs triple online?

    I've seen tons of videos of people epoxying up strips of fiberglass cloth with ragged edges. Why are people not using fiberglass mesh tape?
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    I'd be surprised if drywall tape was ideal for much other than drywall, it is very "open", is it not, even if it was suitable in other ways, resin would run straight through it, and even if it did not, the glass content would be very low.
     
  3. farmerben
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    farmerben New Member

    This "drywall" tape seems more promising than fiberglass insect screens. I'm also tempted to get a 8" wide roll of roving cloth from amazon, that product has no adhesive.

    Has anybody tried the mummy method for wrapping a boat?

    I am confident that with overlapping tape and acyrlic or polyurethane I can create something like a rubber shingle. Not quite boat material yet.

    Also it occurred to me that I could reverse the glass on foam process by making space out of fiberglass tape on a frame and filling if with great stuff.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    At the end of the day, "cheap" materials can end up being expensive, inasmuch as they are not entirely fit for purpose, and can end up producing an end product similarly not "fit for purpose". You are better to stick to what is engineered for the specific end purpose. As for shaping a boat this way, I really can't see how you can avoid the greyhound dog look, with ribs poking through.
     
  5. Rumars
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    Rumars Senior Member

    You are confusing SoF construction with GRP. SoF boats don't use fiberglass or epoxy, they use nylon or polyester with urethane coatings.
    People don't use drywall tape with polyester or epoxy because it's useless, too light, too open, wrong kind of glass and sizing.
    When you see ragged edges the tape was cut from wider cloth, you can also buy selvage tape.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    SoF construction should be restricted to kangaroo hides, God that stuff is tough.
     
  7. KD8NPB
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    KD8NPB Senior Member

    Glass is cheap, it’s resin that’s expensive.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    He might take a look at C-Flex, it is more likely to meet requirements.
     
  9. farmerben
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    farmerben New Member

    I'm looking at rolls of roving cloth. The 2 oz/sq yd cloth has a pretty open pore structure. 6 oz/sq yd cloth not so much.

    Suppose I were to wrap a boat with 3 layers of 2 oz cloth, would this give similar results to a single layer of 6 oz/cloth? Could I weave multiple layers of fiberglass tape in a dry state and then wet through all of it at once?
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    You should read the C-Flex manual, which outlines the pitfalls of building with glass draped over a frame. I notice they recommend polyester casting resin, it is the type of project you need to be fully understanding of the limitations of.
     

  11. cracked_ribs
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    cracked_ribs Junior Member

    The only guy I ever knew who built a c-flex boat (a Sintes design, of course) described the process as exceptionally nasty.

    Of course that would apply to any build in which you slop esters on to a whole boat worth of fabric, of any sort.

    I have never heard of anyone using fibreglass drywall tape for anything but drywall but I think if I was going to goof around with it I'd start with cheap poly resin and do some testing.

    But even if it works... that's going to be a nasty build, I think.

    Which is not to say you shouldn't do it, I'd just start with the cheapest possible materials because I think there's a good chance that halfway through, you'll be about done with the whole experience.
     
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