Fiberglassing overhead - How?

Discussion in 'Fiberglass and Composite Boat Building' started by jdory, Jun 11, 2018.

  1. rwatson
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    rwatson Senior Member

    I've never tried it myself but, if you apply a thickened layer, then apply 3 layers of glass, could two of the layers be "out in the cold" and tend to fall off or just hang loose and form bubbles ?

    Or, you could "squish them together", but do you then you run the risk of bits hardening before you can roll the clear resin on them to fill in the dryer bits ?

    Then of course, thickened epoxy doesn't have the same adhesive strength against the plywood, so are you introducing a problem layer ?

    So much thinking.
     
  2. jdory
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    jdory Junior Member

    Thanks for the thoughts on this guys. The biaxial is 17 oz., or I think that is getting close to 600 gsm. No mat. Hoping to get it all on and establish a vacuum bag before it sets too hard to eliminate any voids.
     
  3. jorgepease
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    jorgepease Senior Member

    Have your tape in place and one side of the bag taped and hanging down, use slow hardener. I bet you could do it without vacuum but with vacuum you are going to get a nice dense laminate. I also like the idea of wetting out the layers on the table all three with the peel ply and breather if you want, when you vacuum it the consolidated glass will require less resin so starving it is not going to be a problem.
     
  4. ondarvr
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    ondarvr Senior Member

    Epoxy tends to be strong enough that unless highly stressed even the thickened epoxy is more than adequate.

    When using thickened polyester the bond can (may) become an issue, in those situations I brush some plain resin on the surface and let it start to gel, then use the putty on that surface, the bond is improved dramatically doing it this way.

    In the recent test samples I made to compare polyester bonding putties and catalyst ratios, the putty and bond didn't fail, the substrate failed. The substrate was a standard ORTHO laminating resin, there were glass strands pulled apart in the laminate in every test piece. These putties are used to bond stringers and liners into the hulls, typically whatever polyester can do, epoxy does it better (physical properties that is)
     
  5. ondarvr
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    ondarvr Senior Member

    I'm thinking trying to handle that much wet glass, plus a bag, and then getting everything to hang nearly upside down is going to be a bit of a challenge at best. I've done a lot of upside down laminating, it can go well at times, but everything goes down hill (no pun intended) quickly when it starts to slip and sag, then fall on you or the floor.
     
  6. Yellowjacket
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    Yellowjacket Senior Member

    +1 on painting on a coat of resin and waiting for it to start to set up.

    The engineering definition of a fluid is a substance that continuously deforms under a shear stress, NO MATTER HOW SMALL!!! For that reason any fluid has a very hard time holding up even pretty light glass on an overhead surface... A more viscous fluid deforms more slowly, but it still keeps deforming (flowing) and it can eventually be a mess.

    I did the first coat and let it get tacky, and then put the cloth on and rolled it with a hard rubber roller.. Waited just a bit more and then wet it out using as little resin as I could and it worked pretty well. I was using 8 oz cloth and 17 0z is pretty heavy will tend to drop off as you try to wet it all out without doing something to get it to stick first. The rewetting will soften the stuff that is there, to some extent, so you still don't want to put on too much resin, but it will still be better than if you didn't let it start to cure first.

    Even if you're using a vacuum pump I'd still do the first coat and let it get tacky, it'll make the whole job a lot easier. To my mind the hard rubber roller was the trick, it pushed the glass hard down into the still soft epoxy and that seemed to get the cloth to stick a lot better than just trying to get the viscosity of the resin to hold it all up..
     
  7. fallguy
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    fallguy Senior Member

    Can I be the dumb guy here?

    Why didn't you glass that on the table and just join the finished part? Or is the pipe attached? No depth perception.

    I don't like moving biax. It is too snaky.

    Go buy 4 yards of 17 oz with mat I say.
     
  8. jdory
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    jdory Junior Member

    I had planned on using eye straps when the boat went together. Over time I realized I didn't have good access to putting the nuts on the eyestrap fasteners, and when inquiring on ways to do this, everyone suggested going with this method of glassing on pipe, which gives the benefit of no penetrations to worry about leaks. There never was a time that the part I was joining the pipe to was on a table.. it was built in place. That was fun too.. vacuum bagging two layers of 3mm luan plywood upside down.
     

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  9. jdory
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    jdory Junior Member

    Well, for better or worse I did the deed. I didn't use slow epoxy which was perhaps the first mistake, we'll see. I wanted the epoxy to get tacky like Yellowjacket and maybe others suggested, and my slow hardener seems to take forever at 60 deg. F. So by the time I got the bag on, it may have been setting up. I'll see if there are any voids when I remove the bag. Everything can be fixed, if necessary.

    So I coated the area to be glassed with epoxy, using a foam roller. Then I laid out the 12" layer of glass on a table and worked some epoxy in with a squeegee. I had set up a work platform near the area to be glassed for potential disasters. I rolled up the glass on a stick and then began unrolling onto the boat.. didn't go too bad. There's enough of a slope that the area above the pipe stuck pretty easy so I worked the length of that, then went back and got the part under the pipe that was more upside down.

    Then I wet out the second layer and began trying to apply that and it didn't go well at the start. Just didn't want to stick and fell off a few times onto that platform. But after awhile it stuck. The third layer went a lot better, being quite narrower.

    Then on went the peel ply, the release membrane, and some breather fabric I had (not enough) and got the bag going. The foam roller that I used at first was getting pretty hard, but the first layer of glass seemed good. (that's when I started wishing I went with the slow hardener).

    So we'll see. I didn't use any thickened epoxy. I'll post a followup post when I get the results. I sure appreciate all the advice - lots to consider.
     

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  10. ondarvr
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    ondarvr Senior Member

    I forgot to add the other part about letting it gel before laying the glass is to let it cure more after the glass is put in place, it doesn't long until it's cured enough that the old resin won't be softened by the new stuff used to wet out the glass. There isn't really a right or wrong way to do, just many options that all work in different situations.
     
  11. fallguy
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    fallguy Senior Member

    I'm so slow; I'd have had no choice but the slow hardener.

    I thought you were laminating over the pipe when you said 12" joins. I figured 8" tapes would be plenty, but I get the 12. I might have glassed the tube alone first on the bench, but maybe you decided it didn't need it.

    Is the plan to pierce the pipe with eye bolts? I am going to put the idea in my memory bank.

    I like the cat. Is it a remodel or new build? Hard to tell a bit. What cat?
     
  12. jdory
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    jdory Junior Member

    The cat was first built in 1993-94 and launched unfinished as a motorized version for the purposes of getting into a new commercial king crab fishery. Plan was to take it out and finish it as a sailboat, but it got smashed by a runaway barge before getting out of the water. Sat for 25 years in a shed, and now I'm finally doing the repair and finish work. It is a 30' KHSD cruising cat.

    A picture is worth a thousand words so here is a stolen pic of the net attachment on a trimaran. The pipe/fiberglass is notched. A fiberglass or stainless rod is inserted into the pipe, and tramp lashing is done around that rod, through the notches.

    I used 12" biax as the first layer because the substrate wasn't the best for resisting peel forces. I had primed the boat back in 1994, and didn't want to completely sand it off as I would be cutting into the structure fiberglass. Otherwise, perhaps 8" would be fine.
     

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    fallguy likes this.
  13. redreuben
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    redreuben redreuben

    Sounds good carry on
     
  14. TeddyDiver
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    TeddyDiver Gollywobbler

    010 On ply first a layer of pure epoxy, 020 second layer thickened after first one has started to settle. 030 A layer of glass and 040 wet more with unthickened untill totally wet out. Goto 020 until done all the layers
    BR Teddy
     

  15. rwatson
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    rwatson Senior Member

    THAT sounds a bit more like it.
     
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