Sailboat Deck Replacement!

Discussion in 'Fiberglass and Composite Boat Building' started by Laoch, Oct 3, 2007.

  1. Laoch
    Joined: Jan 2005
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    Location: Miami

    Laoch New Member

    I am currently undergoing a deck replacement for a 30' long by 6' beam daysailor. Its original deck (rotting away) is teak groove with plastic toungue and mahogony trim along the sides and down the middle. The stringers are soft wood. Those I am also replacing. I used the old ones as a template to cut new wood that will be sealed up and painted. The deck itself I would like to sandwich and vacuum bag with composites, structural foam core, glass and CF; even If I have to bag it in sections (Bow deck, stern deck, and each side deck)

    The deck has a slight curve to it evident from my stringers. My question is how do I go about molding the composite "decks" to the curvature of the stringers?

    Would it be possible just to lay the decks inside the bag on top of the stringers and shaping via gravity and curetime?

    Thanks.
     
  2. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    What is your original construction, age of boat, and do you have pictures?

    Your biggest concern will be attachment of deck to the boat, and any method you use must anticipate that. Your idea of coring the deck may not be the best or most cost effective solution. Coring anticipates fewer framing members, so it is lighter, but your boat was designed with stringers under the deck. Aside from the actual layup, hardware attachment as well as the actual deck attachment are far simpler without a core to deal with. If you have stringers, coring may be superfluous.

    Alan
     
  3. Laoch
    Joined: Jan 2005
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    Laoch New Member

    Thanks Alan. I am still toying with the notion of doing MDF-I plywood layed up with some glass and CF. It's just so rigid to attach to the stringers.

    To clear some confusion, the stringers are attached via wood screws from underneath each stringer corner from bottom up into the aluminium corner rails. Then a top wood bolt/washer/nut assembly threw the mahogany inner side trim threw each top side corner of the stringers. All Teak originally was attached via teak nails (bottom-up fashion; traditional as well as rusted threw).

    The new stringers will be attached the same at the ends, then depending on the laminate; wood/composite, or foam/composite; regulates which deck fasteners will be used!

    Forget new teak! Way out of my price range, in addition to the South Florida sun and humidity!!!

    The boat is a '76 built Trias (German Lake racer almost identical to the U.S. Etchells 22 additionally with a bulb keel, "one design", blade rudder, running backs, etc.!

    I do wish I was able to save the decks; no longer possible! A family member neglected the poor girl in south FLA on a trailer!

    Thanks in advance (TIA)!

    Laoch
     
  4. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Laoch,

    You might consider strip-building the decks. While it's impossible to suggest details without a lot of pictures, I can tell you it will make a good deck that can be screwed and tabbed down, which will self-fair to a compound curve, and be light and tight. Also will curve to the side decks easily.
    I'd go with 1/2" cedar, and 10 oz glass/epoxy inside and out, maybe another 6 oz layer on top for a woven in non-skid.
    A.
     
  5. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    Laoch, If you want to do it simply and economically, just cut the traverse frames, lay stringers to suit and plywood cover it, use thin ply and double or triple if required, then just seal with Dynel and epoxy, followed by two pack polyurethane paint with non skid dust sprayed over it on the final coat.

    Easy do do, very strong, long lasting (if you Everdure the insides) and quick.
     
  6. Laoch
    Joined: Jan 2005
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    Location: Miami

    Laoch New Member

    Plywood requires soaking the crap out of it with epoxy before laying up to seal it!!! I was trying to avoid that process by going light and all composite! I appreciate the feedback! However, if I lay downn plywood and then ply on layers, I would want the bottom done as well before they are attached to the stringers. The MDF plywood needs to be 3/4" to 1" in order to reach the same flush level as the mahogany side trim. The underside of the deck is clearly visible from the cockpit and needs to be painted in addition. I store my boathooks, sails, have sheet hammocks under all the decking! No part of this boat is hidden, as in having closed off Lazerettes. Thanks.
     
  7. alan white
    Joined: Mar 2007
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    alan white Senior Member

    First, the plywood needs no sealing prior to layup with glass. It is good to control temperatures in order to prevent out-gassing, meaning application of the epoxy during a cooling period. Enough resin can be applied to saturate the glass and the wood at once.
    The height of the deck can easily be determined by gluing the right thickness of thin strips to all framing components.
    I don't know, but I assume you have compound curves in the deck. To what extent, only you know. 1/4" plywood in two to three layers could be tortured into moderate compound shapes, an ideal method if there's not too much compound curvature. If there's a bit more compound curvature, you are approaching cold-molding technique, which involves narrower strips of ply that are spiled somewhat.
    How exactly it would be done would depend on the extent of curvature. Such a deck would be moderate in weight but extremely tough and strong. It would be ready for fastening hardware anywhere on its surface. Only painting the holes with epoxy would be needed. Screwing the deck down would be easy and straightforward. Fastening layers together would be best done using temporary steel screws. The underside need only be sealed with epoxy and painted if desired.
     

  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    You'll likely use more resin to make a solid or sandwich laminate, then wetting out and sheathing plywood.

    With a solid or sandwich laminate deck you'll need a mold. This could be as simple as some closely spaced furring strips, maybe light ply over temporary station molds or possibly foam over temporary station molds.

    With a plywood deck (I'd highly recommend two layers of thin ply then one, difficult to bend full thickness panel) the mold framing could be much lighter and wider spaced (if at all necessary), because the ply is self supporting across unsupported areas. If the thin ply was placed on a bias to the centerline and ripped into reasonable widths, then you could mold compound shapes.

    3/4" to 1" of material is not necessary on your boat. If sandwich construction was used, this would be a handy dimension, but plywood, should probably be shimmed to the necessary height. A molded compound curve deck, made with two layers of 1/4" ply wouldn't need the stringers in all likelihood, to provide the strength necessary and would be surprisingly light. Maybe a layer of 1/8" ply over the stringers with 3/4" foam and another layer of 1/8" ply, all bonded and sheathed could be a way to go. You'd have a very light composite deck.
     
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