in need of a boat builders opinion

Discussion in 'Boatbuilding' started by fcreamer88, Sep 13, 2012.

  1. fcreamer88
    Joined: Sep 2012
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    fcreamer88 Junior Member

    Hi yall. Please excuse me as I'm not realy here to find out about boat building. Honestly, I'm building a tear drop camper and have some questions about fiberglass. I hear yall boat builders know a bit about the stuff. I have no idea and have never even used the stuff. the walls are built out of 3/4 plywood. I want to fiberglass the entire exterior of the trailer. Is this a good idea since the inside wont be sealed? What do I use? I want it painted also. Do I paint over the fiberglass or paint the wood before I fiberglass? Please dont reject me for not asking a question pertaining to boat builds. I just really need some advice on this and hear yall are experts in the stuff. :)
     
  2. alan white
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    alan white Senior Member

    3/4" plywood is twice as thick as you need but regarding fiberglassing, no, you don't have to seal the inside. Not on a "land structure". But frankly, I don't see why you even need to glass the whole exterior. Possibly because you used cheap fir plywood. Fir can be a problem after painting has been done, after a few humidity cycles. Fir "telegraphs" the wood grain through more than most species. Glassing can help in that regard, but bear in mind it's only cosmetic and only the joints/seams would benefit from glass in the form of tape.
    You paint last of all. Don't make work by glassing over paint. It wouldn't stick as well anyway.
    Plywood boats are generally taped-seam only except for some cases where the bottom is glassed to prevent shredding the plywood on beach stones.
    You will probably want to "fair" the surfaces as you might do taped seam drywall with gypsum in a house.
    So, summerizing, glassing the whole thing is a lot of bother and money for no real benefit except cosmetics to prevent grain showing later. Taping seams is a good idea (then you COULD use epoxy since you don't need so much resin for seams alone). Only boats need to be sealed inside as a best practice. Use polyester resin unless you have loads of money. Epoxy is not necessary and might cost a couple hundred bucks.
    Less than half if polyester.
     
  3. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    You might be building a very heavy object for no reason. Build it from 1/4" plywood, using some 1x2 for additional stiffing on inside so it wont warp until you build the whole. Then give it a three coats of fiberglass on outside, one coat on inside. The idea is to seal the wood. Alternatively you can use epoxy on inside. If you add some gel coat to the outside it will not need painting and it will look great. Don't paint wood if your going to fiberglass it. How big a trailer and what is your budget? I think this will determine the next questions and answers.
     
  4. mydauphin
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    mydauphin Senior Member

    If I was building it for me, and I am almost an expert... LOL. I would build an aluminium frame then cover it in a plastic ply that I use that is featherlight, then fiberglass the whole thing with three coats of Biaxial. Then give two coats of epoxy, that I sand smooth, and then paint. It would be super strong, light, pretty and last forever, or until someone rear ends it. The door would be built as a hatch and unit would be water tight to be used as an escape pod.

    Point is you can spend or do as much as you want. Fix a budget then lets talk.
     
  5. hoytedow
    Joined: Sep 2009
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    hoytedow I'm not a cat.

    You are building those walls awful heavy but I guess they would come in handy in bear country. I built mine with 1/4 inch walls and glassed it. If I were to do it again I would use epoxy instead of polyester resin. It is much better to work with. See http://www.tnttt.com/viewforum.php?f=21 for the teardrops forum which is loaded with trailer specific knowledge(I lurk there too).
     

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  6. fcreamer88
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    fcreamer88 Junior Member

    I'm going with 3/4" because the windows and door rings come in 3/4". I've reviewed a fw builds that used fiberglass. Maybe it's just for the edges. The inner side f the wall will be panelling glued to the plywood. If I just fiberglass the edges where's the roof meets the walls, will it be flat enough to not show? Then what should I coat the exterior with to seal it?
     
  7. fcreamer88
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    fcreamer88 Junior Member

    I'm an active member of tnttt.com. :D
     
  8. hoytedow
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    hoytedow I'm not a cat.

    Good to know.
    I used stringers in places where I needed the thicker wood. You need to rout the edges where the 2 surfaces meet for the fiberglass to bend around them, at least 1/4inch radius.
     
  9. Petros
    Joined: Oct 2007
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    Petros Senior Member

    Fiber glass is added to the outside of wood boats to make the surface more durable. If you already built it out of 3/4" plywood, it is plenty strong and durable, so all you need is to make it weather proof. Fiber glass and epoxy is very costly way to accomplish that, I would not do it, you still need to paint it to protect the epoxy from sunlight (which will break down in sun light). Paint can make it water proof, but as pointed out cracks will eventually show up from the wood drying out.

    You might try this: buy some light weight polyester fabric (weave, not a knit that stretches). First fill all dents and irregularities, round corners and edges, sand smooth; than glue the fabric over the outside with Tightbond 3 water proof glue and allow to dry, than put 5 to 7 coats of exterior grade high gloss paint. It will prevent the cracks from showing up, make it weather tight, and a durable surface. And it will cost far less than fiberglass and epoxy. You can even use cotton cloth but the polyester will not absorb moisture.

    This is also much lighter than fiberglass, this is how they finish off wood aircraft and should hold up fine on a trailer, just keep the paint in good condition.
     
  10. hoytedow
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    hoytedow I'm not a cat.

    The heat in South Texas, as in Florida, will make those cracks appear very quickly. What works in Washington State will not fare so well down south. I had to learn that the hard way. That is why I glassed it. You don't need heavy cloth. The lighter the better.
     
  11. fcreamer88
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    fcreamer88 Junior Member

    Thats a great idea! I should also add this is actually not so much a tear drop shape, but more of a grasshopper camper. Pointed front end, straight walls and roof. It's going to be an off road trailer as well, mainly for on the beach. Im not too sure the wood would dry out as its always humid down here. I'm just 10 minutes from the gulf.
     
  12. hoytedow
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    hoytedow I'm not a cat.

    Mine cracked and leaked where I didn't glass. I had to re-do it. It would have been easier to do it right the first time. :(

    Texas humidity is no greater than here.
     
  13. PAR
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    PAR Yacht Designer/Builder

    Truck bed liner will seal 'er up. I'd tape the seams just to be sure, fair and paint with truck bed liner. The coating will be bullet proof and you can paint over it if you want. If you have the truck liner sprayed on professionally, they can do it with a smooth coating. In other words, it doesn't have to look like a gator's ***.
     
  14. hoytedow
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    hoytedow I'm not a cat.

    This is a good idea. Probably the best so far.
     

  15. fcreamer88
    Joined: Sep 2012
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    fcreamer88 Junior Member

    That is a great idea too. Seems like it would be a little hot though.
     
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