Question about sealing plywood boat for a boat virgin

Discussion in 'Boatbuilding' started by Leftover40oz, Aug 11, 2016.

  1. Leftover40oz
    Joined: Aug 2016
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    Location: Ny

    Leftover40oz New Member

    Hi guys I've been googling how to seal plywood boats and I'm very confused about what I'm reading....I have no boating background and know nothing about boats.

    I see people talking about epoxy sealers and poly sealers but I need idiot-proof direction before I invest a couple hundred into making a simple plywood boat.

    I can do simple woodworking and plan on making a very simple small plywood boat.

    Very simple design and keeping costs to a minimum.

    So can you guys name efficient products that would be optimal for me to seal a simple plywood boat.

    I've never made a boat before so I'm guessing here....do I need to seal the entire outside to protect the plywood? Or am I just sealing the edges where the bottom plywood meets the sidewalls?

    Really need idiot proof directions here haha

    Btw I plan on keeping the plywood cheap and buying whatever wood lowes has in stock...I heard marine plywood a very expensive and I just really wanna get started in the boating world....thanks in advance!
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It depends on what you want. As a first time builder, you should not be too worried about having a great finish or creating a masterpiece. For example, I needed a dinghy in a hurry and built it with 1/2" pine plank sides and 3/16 underlayment from Menards. It has a coat of fence stain inside and a coat of some kind of oil base paint that was laying in my basement. I put a 1" fiberglass tape with epoxy on the seams. It stays at the mooring for 2-3 days at a time and is holding OK after 1 1/2 years. It is always outside on a rack, so it does not get treated delicately. It has a little delamination in one spot about 1"x 1/4" that I will patch eventually.
     
  3. Leftover40oz
    Joined: Aug 2016
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    Location: Ny

    Leftover40oz New Member

    Thanks for the fast reply gonzo! Yea I don't plan on a masterpiece at all.

    So I should be looking for fiberglass tape to seal each edge and just be generous with the epoxy?

    And should I just be getting a general latex paint for the overall outside of the boat? Not asking for looks, I'm just envisioning multiple layers of paint to make a "rubbery" layer on the whole outside.


    And I see you're a veteran around here so might as well ask....standard 3/4 plywood ok to get me started? This boat definitely won't be heavy use but I would like to put a cheap weak outboard motor on it
     
  4. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Perhaps you ought to let us know what boat you have picked.
    I'd follow the directions in the plans.
    3/4 is pretty heavy, but might be right for the transom - mounting the motor.

    Cheap quick generally means fiberglass / epoxy taped seams and paint for the rest of the boat. 3 coats should be good enough, but you just have to see how it looks.

    Occassionally check the boat for scrapes and spot paint.
    If you can keep it covered it will last a lot longer.

    Have fun.
     
  5. Leftover40oz
    Joined: Aug 2016
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    Leftover40oz New Member

    Looks simple, quick, and spacious.

    Would like to ask you guys more about outboard motors though

    Like how do I go about finding a very cheap and weak one.....I really have no interest in going fast....I just wanna go haha

    10 mph would be cool

    [​IMG]

    If u can't see pic http://woodenboatmaking.woodworkingplansfor.com/images/plywood-boat-2.jpg

    Would like to make the front of the boat a little pointier just so it looks more appealing than just a floating rectangle
     
  6. Rurudyne
    Joined: Mar 2014
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    Location: North Texas

    Rurudyne Senior Member

    Leftover ...

    If you do decide to use fiberglass over the whole hull, maybe even if just the edges, there is a technique that you may be interested in.

    IIRC, Mylar film does not stick to curing epoxy and this is the key to the idea. Essentially you lay down Mylar film over your fiberglass and then thoroughly squeegee and roller out all the air bubbles. Then once the epoxy has cured the Mylar is peeled away.

    What this does is compress the fiberglass producing a much smoother surface and greatly reduces the time spent sanding. You also don't end up sanding away so much of your material.

    You may need to confirm that it is Mylar rather than trust my memory ... I called my brother by my name today....
     
  7. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Mylar is stiff, no stretch, and will separate, but it will not smoothly bend across the joints in a stitch and glue boat.

    You would have to use multiple cut pieces, one for each side and one for the bottom (for example).
    Last I looked it was somewhat expensive.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Mylar has is places and on a plywood hull works fine, because of the developed surfaces. Rip stop nylon or PeelPly are better choices on compound surfaces and around chines, stems, etc.

    The best thing LeftOver can do is, download the free "User's Guides" and "Epoxy Book" from westsystem.com and systemthree.com. These will offer the information, techniques and product application stuff he needs to learn.
     

  9. Leftover40oz
    Joined: Aug 2016
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    Location: Ny

    Leftover40oz New Member

    Thank you par

    I'll be looking into all that throughout the workday today.....appreciate it
     
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