Should I Fasten first layer of fiberglass in the layup process

Discussion in 'Boatbuilding' started by stranchy, Sep 15, 2009.

  1. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Do not thin your epoxy. If you want to increase the penetration ability (why?) of the resin, use temperature to control viscosity. This is covered in the "user's guides" of the major epoxy formulators. There should be no reason for you to even think about fooling with thinning resin on this project. If you do thin your resin, even just a small percentage, say 5% or less, you'll dramatically reduce all the physical attributes (like 40% reductions in strength, waterproofness, etc.) of the cured matrix, which is self defeating frankly. If someone specifically told you to thin your resin, stop paying attention to this person, as they haven't a clue and likely are full of other, not so wise advise, they'll happily share.
     
  2. stranchy
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    stranchy Junior Member

    Thanks for the advice Par, I thought that you needed to have thinner resin to pour into older wood to fill the pours. I will take your advice, thank you.
    I have read about sucking the resin in by warming either the resin or the wood.

    How many layers of glass do you recommend for the hull walls? I was planning on one since I was going to seal the hull walls with several coats of epoxy resin.
    Once the glass is on and tacky do I re apply resin until the surface is smooth?

    Thanks again, for everyone taking the time to post. All my wood has now been sanded and I'm am confident it has been breathing long enough in the 80 degree sun that I can start sealing this weekend. I will post updates with mistakes or triumphs. (I will wait until it cools to start sealing)
     
  3. PAR
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    PAR Yacht Designer/Builder

    The amount of fabric you employ is subject to it's location and what's it doing. Tabbing bulkheads back to the hull shell (for example) require much more then one layer of fabric. In short, each location where fabric will be applied will have a "schedule", that tells you precisely how much material is applied.

    Dry runs of the laminating process will determine just where materials go (you'll have to cut them to fit). It's best to be overly prepared for the "goo" work. This is two fold; one you don't want to be looking for tools or supplies with goo on your gloved hands and second an ideal laminate is one that is done at the same time, all within the "green" time window, so you get the best bond possible with the least amount of effort (you don't have to sand between layers, etc.).

    Again, go over the user's guides about wetting out fabrics and heating surfaces to draw in resin (only used on raw wood and probably not necessary for you). Maybe a small project first, to get your feet wet is a good idea, preferably one that can be ripped out if you screw up real bad or one that at least isn't a structural element. Much of this stuff is experience and there's really only one way to get this.
     
  4. stranchy
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    stranchy Junior Member

    Thanks Par, luckily I have some areas to practice on that will be covered by seats and storage areas, I know I can lay it so it will be structurally sound but the hidden areas will give me some time with the process to gain some skills.. I have worked with Glass and resin but not to this extent so the "get your stuff together before the goo" advice is well received.

    I hope to have a report after this weekend maybe sooner if I can seal this week.
    Is there any issue with mixing white pigment into the resin?
     
  5. naturewaterboy
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    naturewaterboy Steel Drum Tuner

    You got some good advice there about getting all of your tools out and handy before you start - do this before you start mixing epoxy, as the clock starts counting down as soon as you pour the two components together, and the clock ticks way, way faster if all of your epoxy is in the bucket.

    Par is right on about experience. Start with some little jobs, even try working with some scrap. Try to go thru a "dry run" with all the pieces. Think about what can go wrong - because it probably will. Don't try to tackle too big of an area at once, especially at first. Try to keep adding layers while the epoxy is tacky. Never add additional layers over non-tacky epoxy, you will NOT get a good bond, and it will delaminate, maybe at the worst possible time (remember you are taking your family out in your boat).

    Just my 2c worth.
     
  6. naturewaterboy
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    naturewaterboy Steel Drum Tuner

    I meant to say, don't add layers over non-tacky epoxy unless you sand them thoroughly with 80 grit or coarser (I like 40 or 24 grit on an electric sander).
     
  7. stranchy
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    stranchy Junior Member

    Thanks Naturewaterboy, advice received. Is there any issue with adding pigment to the epoxy, does it act as a thinner or is it fine and acceptable?

    Par mentioned a "Schedule for how much glass to apply to certain areas" where would I find that schedule.

    Any issues with adhereing glass and epoxy resin to older well adhered glass and polyester resin? From what I gather as long as I rough it up good I should be fine.

    Thanks for the feed back, this information is allowing me to feel much better about doing this project properly knowing that my family will be out there with me hopefully soon. I'd post pictures now but it's a horrible mess and I'd rather have some before and after stuff to post.
     
  8. PAR
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    PAR Yacht Designer/Builder

    A laminate schedule would mean the thickness of the tabbing for most of your efforts and the order in which it gets applied. In general it should be as thick as what was removed and have generous overlaps. Scuff up the old polyester with very course grit, like 40 or less. It should feel physically roughed up having visible and deep scratches.
     

  9. stranchy
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    stranchy Junior Member

    Thanks Par, should I ask the guy's I'm getting my glass from for the schedule for certain areas, I also have some pieces I pulled off to match the thickness.

    In the process of replacing the deck I will be replacing the Scuppers with some 2" self bailers. Once I cut the hole for them through the transom should I glass the hole in the transom or will sealing the holes with the proper # of coats of resin be sufficient?

    Pigment, and issues with using it?

    I also have a couple questions on how to join electrical wires together for marine applications, should I post a new thread for that?

    Thanks to all, I had no Idea that my lttle 20 minute fix the cracks project would lead to this depth of work (wood rot will do that I guess). But in for a Penny....
     
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