Discussion in 'Boat Design' started by Alex34, Aug 21, 2014.

  1. Alex34
    Joined: Aug 2014
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: TN

    Alex34 New Member

    I'm building an 11' x 4' flatbottom plywood boat with an 8' floor and 3' bow and 1' sides. I'm building it out of plywood and I need some advice on water proofing and joining the boards .
  2. messabout
    Joined: Jan 2006
    Posts: 3,272
    Likes: 413, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Use your search resource to find......stitch and glue method, look at West System, also look for information at Wooden Boat Magazine web site. The West system site is helpful in describing the things you want to know about the epoxy adhesives and coatings that is so often used in boat building.

    You will almost surely want to make the sides of your boat higher than 12 inches. Fifteen inches is more realistic and more than that is specified on a lot of small boats.
  3. Petros
    Joined: Oct 2007
    Posts: 2,936
    Likes: 148, Points: 63, Legacy Rep: 1593
    Location: Arlington, WA-USA

    Petros Senior Member

    if you are doing a low cost build with lumber yard materials, than use the construction grade polyurethane adhesive/sealant at all the joints and just screw it together. This is the stuff that comes in Caulk tubes and you use a gun to apply it, kind of peanut butter colored. It is very tough and waterproof, and not too costly. The plated or coated exterior decks screws work well for a low cost built. You use a light frame of sawn lumber at each joint, a chine log, gunwale, etc.

    than paint it with six or seven layers of high gloss Latex paint, inside and out. If you store it out of the weather it should last for a number of years and will serve you well.

    I would advise against using CDX plywood, AC or AA plywood (with exterior grade glue) is the best a lumber yard usually has. Or of course marine grade plywood if you want the spend the extra money to built a top quality boat that should last for many years.

    Using fiberglass and epoxy over the outside, as suggested above, adds a lot of cost but will make the boat more durable. If you are going to spend that much on your boat than it would be best to use marine grade plywood. It still needs to be painted because the epoxy breaks down in the sun unless it has some UV protection.

    good luck.
  4. Dave Gentry
    Joined: May 2010
    Posts: 33
    Likes: 4, Points: 8, Legacy Rep: 50
    Location: Charlottesville, Virginia

    Dave Gentry Junior Member

    Your best bet would be to do a little reading before spending any of your money, time and effort.
    There are a number of books dedicated to building simple boats of plywood -
    I recommend Build the New Instant Boats (or any of the "Instant Boat " series) by Harold "Dynamite" Payson, or Jim Michalaks' Boat Building for Beginners and Beyond. All of these will have the information you seek, plus some plans for a few simple boats. You can get them online, or through your local library (though you might have to use interlibrary loan).

    Good luck!
  5. timj68
    Joined: Sep 2014
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Southbend, IN

    timj68 New Member

    Sounds like too big of a project.

  6. upchurchmr
    Joined: Feb 2011
    Posts: 3,287
    Likes: 258, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Everyone is trying to make it simple, not as complicated as it could be.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.