Restoring a small 15' boat. I need your advice!!!

Discussion in 'Boatbuilding' started by akick, Feb 24, 2014.

  1. akick
    Joined: Feb 2014
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    Location: augusta

    akick New Member

    I am currently in the process of restoring a 15 'x 4' fiberglass boat. When I bought it the floor and stringers were rotten and had to be removed. I would like your opinion on what fiberglassing materials any of you would recommend. My plans are to use 3/4" plywood to lay my stringer down the center. I will also use it in the two shorter ribs on the sides of the center. My plan is to use a 6 oz woven cloth with the US Composite 635 thin epoxy with medium hardener to glass in the stringers and to use on the floor. I was thinking a 1/2 sheet of plywood for the floor I am new to the fiberglassing world. I am wondering if I am going a little overkill on this size of a boat? Would 4 oz be better? I would also like recommendations of what grade plywood to use, do I need marine grade or some other kind? Any information will be helpful. boat.jpg
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    She has a limited amount of capacity, given her relatively narrow and shallow hull, so weight will be a constant issue, on a build like this. You want to keep it light, so plywood wouldn't be the first choice I'd make for structural elements. You also don't want to over build, thinking it'll be stronger, because of weight and because of increased point loading.

    You might want to consider foam or maybe solid wood for the stringers, as you'll get more bank for the buck in terms of weight/strength trade offs.

    A single layer of 6 ounce cloth will not be sufficient for the tabbing. In fact, cloth isn't the best choice either, so consider biax fabric instead. The tabbing thickness (weight) will be determined by how big your structural elements are (stringers, bulkheads, frames, etc.) and by how much power you'll toss at this puppy.

    Plywood will be the cheapest for these pieces. If you do elect to use 3/4" plywood, you should use a minimum of 3 layers of 12 ounce biax as tabbing to the hull shell. Personally, I don't think you need anything near this thickness, but I don't know what your intent is for this boat. How much power and target top speed will she need to tolerate? How big a load will she have to carry?
  3. djaus
    Joined: Jun 2013
    Posts: 163
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    Location: AU

    djaus Salted Nut!

    Agreed PAR, I would recommend a lightweight hardwood for new stringers.
    I'm no builder but going on past experience I'd use hardwood for stringers & ply for bulkheads & floor. I did a little work with plywood on my Hartley (the Hartley project here on BD.Net) & I found exterior ply to be sufficient for my needs. The glue is water resistant but the layers may have voids. Marine ply has no voids.

    I saturated a sample piece in a bucket of water & when it dried out there was no signs of delamination.

    As PAR said though ply is heavy. If it were me I'd keep all ply at or below the water line thus keeping the centre of gravity low.
    Looks like she'd be easily rolled too with a narrow beam so use some foam on the sheer to keep it upright & afloat should the proverbial hit the fan.

    Most importantly eliminate ALL air bubbles from woven cloth when applying resin. Use a small paint roller where possible.

  4. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    It's a low key project. Use 'regular' plywood. buy 1.5 gal kit of marine epoxy and a roll of 3 or 4 wide fiberglass tape (50 yard roll about $50) - repair and seal everything with epoxy and the fiberglass cloth - then prime and paint.

    Paul Oman - MS. MBA
    A.K.A. “Professor E. Poxy” - “Old Goat” - “Epoxy Guru”

    epoxies since 1994
    Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)
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