hull paint, gel coat, epoxy, vinyl ester, polyester compatibility question.

Discussion in 'Fiberglass and Composite Boat Building' started by Mark C. Schreiter, Nov 25, 2020.

  1. Mark C. Schreiter
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    Mark C. Schreiter Junior Member

    Hypothetical.

    I don't have to much experience with boat paint but I do with gel coat. I have equipment for spraying gel coat but (automotive) paint gun is much to finicky as well as the temps and humidity here in florida. I have painted a few things and failed miserably but have gel coated with much greater success.

    im looking at a foam core boat build that is to be done in epoxy and marine paint as a finish. now I know that polyester resin over epoxy is a not so great idea epoxy over poly is fine and also vinyl ester resin is compatible in either combination with both epoxy and poly.

    the hull is 2 layers of glass, foam and 2 more layers of glass. for the final layer of glass could I use vinyl ester resin and then gel coat over that. I know, hypothetically yes but have people done this or is it a legitimate thing?

    There are a few issues Im trying to avoid with this build and painting in my garage in florida is definitely one of those. yes I could just roll it on but id still need to block sand it as I would with gel coat.

    just curious.
     
  2. fallguy
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    fallguy Senior Member

    Final layer VE over VE? Explain the entire stack.
     
  3. ondarvr
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    ondarvr Senior Member

    You could do it that way, but you're just complicating the build to avoid your perceived lack of confidence in applying the final cosmetic coating.


    It also depends on how much time the boat will be in the water. If it's going to be tied to the dock year round you go a different direction than if it's out of the water except when in use.

    I could type out both scenarios, but its easier if say how you plan to use it and we go from there.
     
  4. Mark C. Schreiter
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    Mark C. Schreiter Junior Member


    How I plan to use it, quit my job, launch it every morning and head out to catch some bait fish, dock at the local bar and grill in the bay for a beer and lunch, fish the rest of the afternoon, head back to the boat ramp, load up, head home, clean the catch and have a fresh dinner.

    How I'll actually use it. build it in the garage while my wife develops a great disdain for a project that receives more money and time from me than I give her. once a month on a saturday when i've upset the entire family enough to be forced out of the house, i use that time to launch it and take it for a spin to the sandbar, drop anchor and sit for an hour or two then head home.

    basically it will be in dry storage and used a couple times per month in salt water.

    it's not necessarily lack of confidence in spraying paint as much as it is minimizing the investments. I would probably need a new primer spray gun and a finishing gun as well. plus an air dryer for my air compressor. these are things that would probably only be used this one time and then take space. I think im done selling stuff online, people are ridiculous and have ruined it for me.
     
  5. Mark C. Schreiter
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    Mark C. Schreiter Junior Member


    1 layer of 1208 and epoxy, 1 more layer of 1208 and epoxy, 5lbs foam, 1 layer of 1208 and epoxy, 1 layer of 1208 and vinyl ester, polyester gel coat.
     
  6. fallguy
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    fallguy Senior Member

    613806CD-274E-4EC2-B2D0-9AB16FF4CF1E.jpeg Two part lpu

    I did my boat in it. Looks nice. A flaw here n there. Prep is the same ftmp.

    I recommend Interux. I used a different brand.
     
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  7. ondarvr
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    ondarvr Senior Member

    Make the entire build out of epoxy, no polyester or VE involved.

    Use the Duratec VE primer over the epoxy, from there you can use just about any paint or gel coat you desire.

    One word of caution. Epoxy used as a fairing compound with micro balloons added can be difficult to bond to for several reasons. If you do this a layer of neat epoxy, or other epoxy products need to be used over it before switching to VE.
     
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  8. Mark C. Schreiter
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    Mark C. Schreiter Junior Member


    Did you spray it on?
     
  9. fallguy
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    fallguy Senior Member

    1208 and epoxy are sort of silly, imo

    it'd be lighter and stronger with 3xdb 1200
     
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  10. fallguy
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    fallguy Senior Member

    No. Rolled on no tipping. First hull was tipped. Second has very light orange peel. Looks great.

    Boat can be sprayed on a redo.
     
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  11. Mark C. Schreiter
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    Mark C. Schreiter Junior Member

    3 layers in total? I struggle to find that style of glass online, where do you get it from?
     
  12. DogCavalry
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    DogCavalry I aim to misbehave.

    Noah's Marine
     
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  13. Mark C. Schreiter
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    Mark C. Schreiter Junior Member


    Im curious why you think the 1208 is silly?
     
  14. DogCavalry
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    DogCavalry I aim to misbehave.

    A lot of extra weight, epoxy and cost in the mat, but no extra strength. Mat compensates for the weaknesses of a polyester resin layup. Epoxy doesn't have those weaknesses, so mat is not wanted.
     

  15. Mark C. Schreiter
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    Mark C. Schreiter Junior Member

    So a correction to the lamination schedule as I was mistaken. Per the plans the schedule for the hull is:

    • 1 layer 12 oz. biaxial 45/45 with 8 oz. mat (1208)
    • 1 layer 12 oz. biaxial 0-90 no mat
    • foam Divinycell H-80 12 mm (1/2”)
    • 1 layer 12 oz. biaxial 0-90 no mat
    • 1 layer 12 oz. biaxial 45/45 with 8 oz. mat (1208)

    in certain areas they also call for a 9oz "woven" fabric. Im not sure if they are talking about a woven roven (which I cannot find in 9oz) or just a plain weave fabric.

    I mean no disrespect to the designer of the plans but a few additional words here and there would really help clarify some details.

    -mark,
     
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