Joining a wooden deck to a fibreglass hull

Discussion in 'Fiberglass and Composite Boat Building' started by Sulian, Jul 13, 2009.

  1. Sulian
    Joined: Jun 2009
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    Location: Bath, UK

    Sulian Junior Member


    I am building a new cold molded ply deck and coachworks for my Marcon Trident 24, the deck will be glassed over when in place.

    The deck will be supported by bearers that I will glass onto the inside of the fibreglass hull along with 3 bulkheads and the there is also lip that runs around the top inner edge of the hull, approx 3 inches down and 4 inches deep, that can be used to support the edge of the deck and form the basis of a seal.

    My question is, what would you use to make the join/seal?

    It would appear that epoxy is probably the best solution, my only concern is that any flexing of the deck plus the differing expansion rates of the wooden deck and fibreglass hull may, over time, cause the seal to fail.

    Any thoughts, suggestions?

    Thanks in advance.
  2. elskimo
    Joined: Jul 2009
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    Location: Raleigh, NC

    elskimo Junior Member

    I am about to do the same. I am replacing old wood deck with new to fiberglass hull. I was instructed to use epoxy resin and 4 in fiberglass tape.
    I have been experimenting for years with the west system epoxy and it is really strong. If you forsee lots of heavy pounding while at sea, doublt triple, quadruple layer it from top and (if you can) bottom of the floor.

    Also .. if the seal leaks, I guess this is why God made pumps.
    Austin Reynolds likes this.
  3. keith66
    Joined: Sep 2007
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    Location: Essex UK

    keith66 Senior Member

    I have built a few composite boats with grp hulls & wooden decks, normally one would fix a conventional beamshelf bonded directly to the inside top edge of the hull, epoxy would be good or if you were worried about expansion you could use sikaflex or similar.
    laminated beams can then be let into the shelf & ply or cold molded deck put on top. Whatever you do the deck should be sheathed in glass cloth & epoxy.
    I would run the cloth run over the rounded edge of the deck so the Rubbing band covers the join in some way.
    The Trident 24 is an old design so i assume you are on a budget, Marcon boats were good quality mouldings but were somewhat thrown together at times!
    I am currently doing a total refit on a Sabre 27 also built by marcon.

  4. Sulian
    Joined: Jun 2009
    Posts: 10
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    Location: Bath, UK

    Sulian Junior Member

    Thanks for the info. elskimo I was probably going to use West products as there is a fairly good supplier that I was put onto from another member here.

    Keith66, having read your post a small lightbulb flicked on, as there is a lip premolded into the top edge of the hull it would probably be prudent to bond/screw a beamshelf to this and then bond in the deck bearers and finally bond the ply deck to the bearers and the seal between the ply beamshelf and ply deck edge should then be a solid and long lasting afair. Does this seem reasonable?

    Although I am on a tight(ish) £2K budget, I was given the boat aka project as a present from my girlfriend and I've since become quite fond of the way she'll will look once the deck and coachworks are redone to somewhere near original spec. My specimen was one of the very early versions that was fitted with wooden uppers before Marcon changed to GRP.

    Thanks for the advice and good luck with your project.
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