Wood sealing questions?

Discussion in 'Wooden Boat Building and Restoration' started by scott_n06, Jul 9, 2010.

  1. scott_n06
    Joined: Jul 2010
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    Location: Northwest MO

    scott_n06 Junior Member

    Hello all,

    I am thinking of building a mouse boat. I want something small and cheap that I can carry into smal ponds and lakes so it seems like a pretty good boat for a first timer. Anyway my question is, I work at an auto parts store so I can get a pretty good price on paint and other supplies. Would it work to coat the inside and outside of the plywood with fiberglass resin then paint over it with an acrylic enamel spray paint?

    Thanks,
    Scott
     
  2. apex1

    apex1 Guest

    Assuming the boat will not sit in the water for more than a couple of hrs before it is hauled again, right?

    In that case skimp on the resin (which most probably is just polyester anyway), and apply a few more layers of paint.

    Touch up the paint when the surface got scratched and enjoy your time.

    Regards
    Richard
     
  3. alan white
    Joined: Mar 2007
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    alan white Senior Member

    The kind of resins typically available in auto supplies are polyester and at least for your type of construction, aren't of much value in terms of waterproofing.
    You can tape the seams with either polyester or epoxy but as apex says, paint alone is completely adaquate and even desirable for entire panels of a boat that lives mostly out of the water. You save money, weight, and time using just paint.
    Well painted boat hulls, if maintained by immediate touch-ups and (for instance) every-other-year recoatings will last almost indefinitely.
    Nor should you be sold on the idea of Imron or Awlgrip, no matter what the discount. Get a gallon of one-part polyurethane and brush it on. Properly applied it will look like a spray job and will be quite hard.
    Two-part paints are not really ideal for softer surfaces anyway. You need a paint that can flex enough to stay unbroken if banged. Hard paints are best for hard materials such as fiberglass. Hard paints fracture if stressed.
    If you can find or tint a gallon of porch and deck enamal that gives you the right color, they can be very durable paints for boats, generally requiring no primer and costing a third of the cost of marine paint.
    Porch and deck paints are reinforced with polyurethane so they are hard and retain gloss well just like marine paints.
     
  4. scott_n06
    Joined: Jul 2010
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    Location: Northwest MO

    scott_n06 Junior Member

    Thanks for in info. Are all porch paints the same or are some made of different bases. Such as water vs. oil based?

    Im thinking of painting it white so porch paint will work pretty good Im sure they sell it in white.

    Also, I was wondering if when doing stitch and glue construction all the directions say to use epoxy to bond the seams. What do they mean by "epoxy"?
     
  5. apex1

    apex1 Guest

    They mean Epoxy!

    That is a completely different animal than polyester resin. It is watertight (poly is not), much easier to apply, and it sticks perfect on wood (poly does not).

    Raka for example is one brand, West another.

    For stitch and glue you MUST use Epoxy there is no other (sensible) way.

    Cannot cmment on the paint stuff, I don´t know whats on the market in the US.

    Regards
    Richard
     
  6. scott_n06
    Joined: Jul 2010
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    scott_n06 Junior Member

    I understand I MUST use epoxy Im not trying to go with something else, I guess I should have been more specific on my question. What Im asking is the epoxy they are talking about something specific to this type of construction and marine use? Im just trying to narrow my search.
     
  7. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    There are numerous brands of general purpose epoxy resins suitable for boat buillding, take a look at the following and you will understand the various uses and advantages of epoxy resins. Be warned though, once you start using epoxy and become comfortable with it's application you will be using it for all kinds of repairs and improvements.......properly used it's a safe and very useful product.

    http://www.systemthree.com/reslibrary/literature/The_Epoxy_Book.pdf

    MIA
     
  8. apex1

    apex1 Guest

    No Scott, there is nothing special. You can well stay away from everything with a "marine" label on it. That would just triple the price. In fact the cheapest stuff you can find will be more than sufficient.

    But what you need is a 100% solid Epoxy resin and a matching hardener. !!!

    Lookup "Raka" epoxy and you will find products in a fair priced range which are quality wise top level. Use the cheapest they offer and just choose a hardener which fits your needs. (usually a slow hardener is more convenient for a novice than a fast one. It gives you more time to get your layup done, and allows you to do layer on layer in one go without letting the former layup cure completely)

    Take care, there are some products called "Glassfiber resin" or even "glassfiber Epoxy" which are both not Epoxy, but polyester resins!

    Make sure you paint all the epoxy layups properly to prevent UV degradation.

    Regards
    Richard
     
  9. alan white
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    alan white Senior Member

    I would only use an epoxy formulation specifically recommended for marine use. If the company doesn't say "for marine use" or something similar, don't use it on a boat.
    It's that simple.
     
  10. apex1

    apex1 Guest

    We are talking a simple S&G skiff here Alan. And then just the seams. You´ll have it hard to find any Epoxy resin (for laminating) which will not do that job perfect.
    In fact I have never seen a single example insufficient for that purpose.

    The recommended Raka btw. is for marine use.

    Regards
    Richard
     
  11. scott_n06
    Joined: Jul 2010
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    scott_n06 Junior Member

    Ok thanks alot guys Ill look into all the info.

    Thanks again,

    Scott
     
  12. apex1

    apex1 Guest

  13. scott_n06
    Joined: Jul 2010
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    scott_n06 Junior Member

  14. apex1

    apex1 Guest

    There should be a BOM to be found either on that website or in the plans. If not, ask here again, some have built similar designs. (sorry I have no clue how much that can come down, the smallest craft I ever built was about 20- 40 times the displacement you are building)

    Regards
    richard
     

  15. scott_n06
    Joined: Jul 2010
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    Location: Northwest MO

    scott_n06 Junior Member

    I really figured the BOM would tell the ammount as well Apex, but all it says is
    "5) Glue; tube of polyurethane construction adhesive (PL premium), plastic resin glue (Weldwood) or epoxy"
    From looking at the plans I will have approx. 20ft of seams to seal.
     
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