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Re: Bad fiber butt joint

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  • porneaux
    (Damn I had that formatted nice before responding via email) Probably depends on how close the white areas are to the seam between the panels; the closer to
    Message 1 of 6 , Mar 5, 2013
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      (Damn I had that formatted nice before responding via email)

      Probably depends on how close the "white" areas are to the seam between the panels; the closer to the seam the more stress the joint will receive. I have found this procedure to be very effective for glassing a butt joint in plywood panels:

      Do a dry run of the procedure before mixing the epoxy. I hate finding problems after the wood is wet.
      Glue one side at a time!

      Use a flat surface big enough to work around both panels (concrete garage floor in my case)

      Align the panels on the floor with a heavy sheet of poly under the seam to prevent gluing the panels to the floor.

      Imobilize the panels so they won't move during the glueing operation. I use bags of rock salt and have even parked a garden tractor on a panel.

      Measure and cut your fiberglass strips for the joint.
      Mix your epoxy.

      Apply epoxy to the area of the panels that where the glass will lay.

      Make sure you get the edges where the panels actually touch - don't trap any air in there.

      Lay up the glass tape over the seam per typical fiberglass butt-joint instructions - parallel to the seam and stagger the layers.

      Saturate the glass tape with epoxy. Work it in with a brush and don't worry about excess - we'll flatten it good and remove any excess before it sets.

      Place another sheet of poly over the joint.

      Put something flat and heavy on top of the poly-protected joint, making sure it's protected by the poly and doesn't get glued to the panels. I use deep cycle batteries.

      The weight(s) on top will have a tendancy to "float" a bit as they squeeze the joint and push excess epoxy away from the seam. Readjust as necessary for the first few minutes.

      When the weights have settled you will notice excess epoxy around the edges of the weights (hopefully protected by the poly).

      Use a squeegee or wide plastic putty knife to pull the excess out from under the poly and off your panels.

      Let the epoxy cure completely.

      Remove the weights and poly and flip the panels to do the other side.Be very very very careful when flipping. A one-sided fiberglass butt joint is very weak against "folding" forces.

      Before doing the other side, sand the panels to remove any cured expoxy that may have oozed down through the seam.

      Repeat procedure for the other side.

      When boths sides are cured hard I use a sabre saw to remove the ragged glass edges that extend beyond the panels and sand everything smooth.

      You will now have a strong, flat joint.
    • prairiedog2332
      Happens to me all the time with yahoo posts! Seems you have add more returns between paragraphs than you generally have to. ... That is a great post regarding
      Message 2 of 6 , Mar 5, 2013
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        Happens to me all the time with yahoo posts! Seems you have add more
        returns between paragraphs than you generally have to.
        --- In Michalak@yahoogroups.com, owwin@... wrote:
        >
        >
        >
        > (Damn I had that formatted nice before responding via email)

        That is a great post regarding a glassed butt joint. Andre might be
        able to test his by placing some blocking under the joint as see how
        evenly it bends? If it appears weak he might install a backing plate on
        the inside or even another layer of glass? And test again.

        My plan it to do it with a solid lumber butt block for the inner side
        and only glassing the outside of the joint. Jim uses 1x4s (3/4x3/1/4")
        and explains how he does it on page 39 of his book. He installs the
        bottom joint sections right on the bottom one piece at a time. Some
        people suggest chamfering the edges of the blocks to about a 45 degree
        angle or filling the edges with an epoxy fillet so as to not be dirt
        catchers or a tripping hazard. Then glass the entire bottom before
        flipping the boat upright. Butt blocks can also serve as supports if you
        want to add removable floor boards. Have seen that on a cockpit and Rene
        Vidner has them in his AF4 Breve.

        Nels






        [Non-text portions of this message have been removed]
      • Andre Basso
        Thank you Brian. Nice procedure. I m following Payson s method and did fine for all but this one. My fault as I didn t wet the fiberglass properly and should
        Message 3 of 6 , Mar 6, 2013
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          Thank you Brian. Nice procedure.

          I'm following Payson's method and did fine for all but this one. My
          fault as I didn't wet the fiberglass properly and should have chosen a
          heavier weight.

          I decided to sand it off and redo one side of the joint. Better to step
          backwards now instead of discovering a failure in the future.

          Blog updated: http://umveleirosimples.blogspot.com.br

          Regards,

          Andre.

          On 05-03-2013 14:02, owwin@... wrote:
          >
          >
          >
          > (Damn I had that formatted nice before responding via email)
          >
          > Probably depends on how close the "white" areas are to the seam
          > between the panels; the closer to the seam the more stress the joint
          > will receive. I have found this procedure to be very effective for
          > glassing a butt joint in plywood panels:
          >
          > Do a dry run of the procedure before mixing the epoxy. I hate finding
          > problems after the wood is wet.
          > Glue one side at a time!
          >
          > Use a flat surface big enough to work around both panels (concrete
          > garage floor in my case)
          >
          > Align the panels on the floor with a heavy sheet of poly under the
          > seam to prevent gluing the panels to the floor.
          >
          > Imobilize the panels so they won't move during the glueing operation.
          > I use bags of rock salt and have even parked a garden tractor on a panel.
          >
          > Measure and cut your fiberglass strips for the joint.
          > Mix your epoxy.
          >
          > Apply epoxy to the area of the panels that where the glass will lay.
          >
          > Make sure you get the edges where the panels actually touch - don't
          > trap any air in there.
          >
          > Lay up the glass tape over the seam per typical fiberglass butt-joint
          > instructions - parallel to the seam and stagger the layers.
          >
          > Saturate the glass tape with epoxy. Work it in with a brush and don't
          > worry about excess - we'll flatten it good and remove any excess
          > before it sets.
          >
          > Place another sheet of poly over the joint.
          >
          > Put something flat and heavy on top of the poly-protected joint,
          > making sure it's protected by the poly and doesn't get glued to the
          > panels. I use deep cycle batteries.
          >
          > The weight(s) on top will have a tendancy to "float" a bit as they
          > squeeze the joint and push excess epoxy away from the seam. Readjust
          > as necessary for the first few minutes.
          >
          > When the weights have settled you will notice excess epoxy around the
          > edges of the weights (hopefully protected by the poly).
          >
          > Use a squeegee or wide plastic putty knife to pull the excess out from
          > under the poly and off your panels.
          >
          > Let the epoxy cure completely.
          >
          > Remove the weights and poly and flip the panels to do the other
          > side.Be very very very careful when flipping. A one-sided fiberglass
          > butt joint is very weak against "folding" forces.
          >
          > Before doing the other side, sand the panels to remove any cured
          > expoxy that may have oozed down through the seam.
          >
          > Repeat procedure for the other side.
          >
          > When boths sides are cured hard I use a sabre saw to remove the ragged
          > glass edges that extend beyond the panels and sand everything smooth.
          >
          > You will now have a strong, flat joint.
          >
          >



          [Non-text portions of this message have been removed]
        • Mike
          Andre, I had a few of those but not on the actual joint itself. I sanded down and redid the expoxy in those areas and then feathered it out. After that I used
          Message 4 of 6 , Mar 7, 2013
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            Andre,
            I had a few of those but not on the actual joint itself. I sanded down and redid the expoxy in those areas and then feathered it out. After that I used a thin plastic spreader to flatten out expoxy when I put it on so that it would release any airbubbles that were trapped. I notice some people use a ribbed roller to minimize air bubbles in the expoy but I haven't tried it myself.

            Regards,
            Mike

            --- In Michalak@yahoogroups.com, Andre <basso.asb@...> wrote:
            >
            > Yesterday I inspected the fiberglass butt joint I made to join bottom panels together. Noticed white areas where the fiber clearly wasnt epoxy filled. I would guess 15% or less.
            > What to do? just fill it with another epoxy coat?
            > Andre
            >
            > prairiedog2332 <nelsarv@...> escreveu:
            >
            > >I have Trilars plans.
            > >Twister meets my criteria regarding size and weight (16x16 350 lbs.)
            > >simplicity to build and trailerabilty. Can sleep two under cover
            > >snuggled up if built with the extended bridge deck which one has been
            > >built. The pram bow and flat bottom aft gives more interior space than a
            > >multi-chine with pointy bow the same length. Yet the warped V entry
            > >makes for less pounding in a chop over a flat bottomed pram. Flat
            > >bottom in the aft section "might" get some semi-planing flotation going
            > >over a multi-chine hull? My thinking is a bit straighter run in the aft
            > >section might just give more semi-planing ability than the aft rocker
            > >shown on the plans. At the cost of some sailing efficiency if the stern
            > >drags at the corners when heeled under sail.
            > >
            > >I also want the ability to venture into backwaters and creeks for
            > >shelter overnight as well as trying a yuloh and even poling to do that.
            > >But mainly my post was to share what other folks may be looking at as a
            > >versatile design. Sort of a hybrid design option over just a sail boat?
            > >
            > >Nels
            > >
            > >
            > >--- In Michalak@yahoogroups.com, tom s <tdsoren@> wrote:
            > >>
            > >> you might want to consider researching some kind of catamaran or
            > >outrigger. much higher displacement speed, less heeling under sail.
            > >Malcolm Tennant has some great articles regarding this.
            > >>
            > >> Sent from my iPad
            > >>
            > >
            > >
            > >
            > >
            > >[Non-text portions of this message have been removed]
            > >
            >
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