Reinforcing my deck

Discussion in 'Materials' started by windigo, Apr 8, 2007.

  1. windigo
    Joined: Apr 2007
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    Location: Richmond

    windigo New Member

    I have noticed that when I grab my pedistal or binnacle the deck floor flexes. I have good access to the underside and would like to add some stiffining to the area. I have never done this, and don't know how I would get wetted fiberglass to stay on the underside without gravity pulling it off. What materials would be best to use also. It is a sailboat about 28 years old, and I can envision the treated area being about 8 square feet.

    Thanks
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    You can add stiffness (and weight) to this area, but you likely have issues causing this flexing and adding a few extra beams or other reinforcement will not address an ongoing problem.

    I don't know much about your boat, so I'm guessing, but you probably have a cored deck and it's taking on moisture, which has delaminated or softened the core, maybe sheered the skins, etc.

    You'll need to fix these problems or you'll just be adding reinforcement to things that need much more.

    Have a skilled boat carpenter or surveyor come out and look her over. They'll spot the issues and offer suggestions on how to proceed with repairs.

    More information about your boat and photos of the suspect areas will be really helpful in future discussions about how to go about get things fixed up.
     
  3. windigo
    Joined: Apr 2007
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    windigo New Member

    This is the floor of the cockpit and it's all glass with gelcoat finish. There is to coreing to delaminate. And it might not be a problem at all. I've just noticed that when we're in rough weather and in moving around, you grab the binnacle and it has a tendancy to cause the floor to visibly flex. I accept that I bought a production boat and it's probably not as strong in places as it could be, but I'm always doing projects to try and make it better, and this is something that I thought I could do and make it a more stout vessel.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Glue a piece of plywood to the underside of the cockpit sole, using thickened epoxy. Brace it into position until the goo cures. You'll want to remove and reattach the binnacle and any other equipment that has through bolts or fasteners, to get these fasteners through or into the stiffer sole. Try to bridge the full width of the cockpit sole, length too, if possible, so the loads are transferred to the cockpit sides. A 1/2" piece of ply will likely make it considerably stiffer and not add too much weight.
     
  5. windigo
    Joined: Apr 2007
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    windigo New Member

    So is the role of the plywood just to hold the epoxy in place? I thought I would have to use fiberglass mat, and I didn't know how I would keep it from falling down, being upside down and all. Your plan sounds much easier and definately is something I can do. I'll get in there and make a cardboard template so I can make the plywood conform to the shape of the floor. Are you suggesting I make the epoxy similar to a soft peanut butter consistency, and how thick should I aim to make the epoxy after it has hardened?

    Thanks again.
     

  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The plywood will provide the vast majority of the strength in my suggested upgrade. The epoxy is the glue.

    Here's how I'd do it. I'd make a piece of ply fit to the outside dimensions of the cockpit sole. This will leave a small outside corner that needs to be filled, where the cockpit sides roll (molded) into the sole of the cockpit. Then grind down the rough underside of the cockpit with 36 grit on a buffing/polishing pad. This will provide the "tooth" necessary to get a good bond with the polyester cockpit. Do the same with the bonding surface of the ply. Next cut some pieces of 2 by stock to use as legs, braces and wedges to hold the plywood up against the sole.

    Do a dry run with the plywood and braces to insure you can press it against the sole bottom. Coat the ply and the sole bottom with unthickened epoxy. Be liberal on the plywood, you don't want dry spots. Take the plywood below decks and get it close to where you'll need it, then mix up some thickened epoxy, enough to fill gaps and bond the panel to the sole. Coat the plywood with the goo. It only needs to be about like heavy cream, if the boat is reasonably level, thicker if you suspect it could run out of the joint by gravity. Wedge it into place, starting in the center of the panel and progressively placing braces outward toward the edges. You'll have good contact if you can see goo oozing out all around the edges. You don't need lots of pressure, just good contact. I'd then mix up more thickened epoxy, to a peanut butter consistency and pack it into the radiuses along the edge of the cockpit sole to side transition. I'd also apply cloth tape around this corner so the ply was also bonded to the sides of the cockpit. Lastly I'd heavily coat the bottom of the plywood with unthickened epoxy and then paint it. A rounded over edge on the lower outer edge of the plywood will make "tabbing" the ply to the cockpit sides much easier.

    Any fasteners that need to be put into or through the sole should have their holes at least wetted out with epoxy (bonding is preferred), before the fastener goes in. This will seal the ply and help hold the fastener. The resulting sole will feel much more solid, dampen sound and vibration a bit, plus provide a more substantial base to attach things to. Good Luck . . .
     
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