Fiberglassing plywood deck

Discussion in 'Fiberglass and Composite Boat Building' started by KMD, Feb 7, 2006.

  1. KMD
    Joined: Oct 2005
    Posts: 8
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    Location: Maryland

    KMD Junior Member

    I have a 37' chesapeake baybuilt. I am building a new deck for the boat. The boat is a wooden boat so I want to be able to pull the deck up so I can clean the bildge, and seal the inside every once in a while, and work in the bildge, this is not a self bailing deck. I am going to build the deck out of 3/4" marine plywood, and each panel will be screwed down, I will predrill the holes where the screws go and epoxy in the holes first trying to seal the wood, then will use a good maring caulk around each hole. I dont like the idea of having screws all over the deck but this is a workboat (not yacht quality) and I want to be able to pull the panels up to work in the hull. The deck will have 6 panels, total.

    I would like to fiberglasss each panel, and need advise, I dont know anything about fiberglass work. I am going to fiberglass each panel in my garage then install it when it is complete. I posted on the site a while back and was told MAS epoxy with medium hardner is a good choice, and the type of cloth to use I got several recomendations but Dynel seemed to be recoended the most. I have a couple questions:

    1. Do I need to lay cloth on both sides of the wood? What type of cloth should I use, how thick and what brand?
    2. How many layers of cloth should I put on? The boat is a workboat but is used as a pleasure boat.
    3. How many layers of epoxy do I apply after the last layer of cloth is applied?
    4. I would like the deck to have some grit to the surface, what should I use to do this?
    5. the deck is approximatly 192 sq ft, how much epoxy/hardner should I buy.
    6. If several layers of epoxy are applied do I need to sand between layers?
    7 How should I prepare the bare wood before I start?
    8. I will be doing this work in my garage, will the fumes overcome me if the doors are shut, does the garage need to be heated for it to cure, I live in Maryland and its been around 40F at night lately.
     
  2. wdnboatbuilder
    Joined: Nov 2005
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    Location: Cape Coral Fl

    wdnboatbuilder Senior Member

    Question1: no, could be just 7 oz.
    2: 1
    3: Atleast 3
    4: Medium and fine non skid mix them
    5:i would say 2 gallon kit should do you
    6:no, unless you allow to dry between coats
    7:sand with 36 grit, until you feel good
    8: no, of course the hotter it is then the faster the epoxy will cure


    May I ask why 3/4 ply for the deck? If you are not using for a work boat why add the extra weight.
    I would use just regular 7 oz glass cloth, no Dynel, now if you were glassing the bottom yes use dynel.
     
  3. KMD
    Joined: Oct 2005
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    Location: Maryland

    KMD Junior Member

    The deck was 3/4" originaly and I want to keep everything original. I already bought the wood and its already cut and ready to be glassed. You said I only need to epoxy the bottom of the boards, will one coat do on the bottom? You mentioned on the cloth side, I dont need to sand if I re-apply before it cures, how long does it take to cure, and how tacky should it be before I start to put another coat of epoxy on? What type of hardner should I use, this is being done in my garage so time is not a factor I want the one that is going to do the best job. Thanks for your advice.
     
  4. wdnboatbuilder
    Joined: Nov 2005
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    Location: Cape Coral Fl

    wdnboatbuilder Senior Member

    whatever epoxy you use, use their hardner. DO NOT MIX MANUFACTURE'S.

    3 coats every where, top, bottom, and sides.
    for re-appling, if you stick your finger in it and is still tacky but does not come off on your finger then you are ready.

    putting your glass on: cut your glass to fit( a little over) you can staple(Stainless) the glass on one edge, fold back, apply epoxy. fold glass on top of epoxy and squeegee out, apply coat of epoxy. 2nd and 3rd coat follow behind yourself with a dry roller( find that the west foam roller works best). this will catch and extra epoxy and redistribute excess. makes for esier fairing.

    In 40 degree weather whatever you use it will cure slow, hardener will depend on what epoxy you are using.

    normally I will epoxy the bottom of the deck before I put it on the boat. Then I prime the bottom, and set with 5200 to the deck beam's. I'm sure that comment will cause some contraversy. But it makes for easier fininsh work underneath.
     
  5. DP Carbon
    Joined: Feb 2006
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    Location: Sacramento

    DP Carbon Junior Member


  6. boatbuilder.org
    Joined: Jan 2005
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    Location: Olympia Washington

    boatbuilder.org Junior Member

    The bottoms will need two coats. If you use MAS slow hardener you can apply one day and the next day you can knock the raised grain/fuzz off with a piece of 80 grit by hand. You are not sanding, but just knocking the tops off. The epoxy will still be soft and there will be no need to wash of the blush or sand between coats.
    Glass the tops with with a layer of 6 cloth. Lay the glass over the plywood, pour on epoxy and work it around with an automotive bondo squeegee. You will need to let it fully cure so you can sand smooth, then add two seal coats over it. On the second seal coat you will not need to do any prep, just go straight over it. After it has fully cured paint the top and while it is still wet use a salt shaker form about 4 feet high to apply the course nonskid (you will need to play around to get the proper salt shaker or even drill the holes bigger. The paint should dry/cure and hold the nonskid in place then you can roll thin coats of paint over that.
    When you do the edges and holes, seal them every time you work the top and bottom surfaces so they get extra. To sand or not to sand: this is determined by the hardener used. 10 years ago you needed to wash and sand just about everything(for the most part). The curing process create a slime on the epoxied surfaces. The colder and damper it was, the more slime. It washes off easily with warm water but was a hassle. Epoxy manufacturers have created non-blushing hardeners, usually the slow hardener, so there is no blush to wash off, and as long as you can make a dent in the semi-cured epoxy with you thumbnail you can re-coat without sanding.
    There is a bit of info on glassing here http://www.boatbuilder.org/mudpeepshapingandglassing.htm and you can get the materials you need here http://www.devlinboat.com/mascart/index.htm .
    ---Joel---
     
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