wood plank encapsulation materials and techniques

Discussion in 'Boatbuilding' started by shnarkle, Jan 30, 2019.

  1. shnarkle
    Joined: Jan 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Florida

    shnarkle New Member

    Hi, I just joined this forum and haven't figured out how to navigate my way around to finding the topic I'm interested in. I'm trying to find out information dealing with:

    1. applying polyuria paint to wood plank hulls
    2. applying "poor man's fiberglass" to wood plank hulls

    I know that these are not ideal applications, but I'm not an idealist. I've seen these techniques utilized, but don't know how well they work ten or fifteen years down the road.

    These techniques don't seem all that different from ferrocement or seaflexing a wood plank boat which seems to work out fairly well for getting a few more years out of an old wood plank boat.

    My primary interest isn't in applying these techniques to tired old rotten hulls, but to hulls that are still in fairly good condition; just looking to save some time and money.
     
  2. Blueknarr
    Joined: Aug 2017
    Posts: 371
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum.

    I hate delivering sad news. You won't find advice advocating "PMF" on this forum.

    Polyurea paint will not effectively encapsulate wood.

    Encapsulation can only be achieved if epoxy is applied to very surface of wood. Especially those surfaces inside joints. So isn't effective after hull is built.

    The lifespan of immersed PMF is about 15 HOURS!!!

    An epoxy glass cloth shell over an older hull will only extend its life 15 months.
     
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  3. shnarkle
    Joined: Jan 2019
    Posts: 2
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    Location: Florida

    shnarkle New Member

    Thanks for your reply, could you perhaps indulge me by pointing out how you know "PMF" would only last 15 hours?
    Thanks again.
     
  4. Blueknarr
    Joined: Aug 2017
    Posts: 371
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    Location: Colorado

    Blueknarr Senior Member

    Admittedly the 15 was prompted and copying your numbers. Bit isn't far off.

    I have twenty plus years applying architectural and industrial coatings and over a decade in boat construction and repair.

    PMF uses architectural coatings to do a marine resin's job. A building is said to be "water proof" when it actually only sheds water. A much lower bar than the maritime definition of immune to osmotic penetration. The products I have seen suggested for PMF will form osmotic blisters in less than a day of immersion. Some in as few as two hours. Immersion for more than 12 hours voids all architectural coatings manufacturer's warranties. Cotton cloth speeds water's entry into PMF.

    By the way, 15 years is an expected lifespan of a well made wooden vessel.
     
  5. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Blueknarr. Your estimates on the life of wooden vessels is way off. A well built and maintained wooden boat will last many decades, even in commercial use. I have fiberglassed many old commercial wooden boats and they got more than 10 years of extra hard work with poor maintenance.
    Shnarkle: Coating a wooden hull without understanding the structure may actually decrease its life and increase maintenance costs. For starters, what type of construction and wood species are you referring to?
     

  6. JamesG123
    Joined: Mar 2015
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    Location: Columbus, GA

    JamesG123 Senior Member

    To OP: Blue is right. If you were coming in saying you wanted to use polyurea and PMF on a stitch n' glue or composite core structure, that might fly, er... float. But its really not practical on a plank on frame construction. Especially not on an existing structure which will have who knows what contaminants that have soaked into the wood. Thus his realistic expectation of 15 hrs. before it starts to fail. Not even if you disassemble and encapsulate each board separately. Its just not the right technique for that build style.
     
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