Repairing Damaged Ply

Discussion in 'Wooden Boat Building and Restoration' started by MastMonkey, Apr 18, 2011.

  1. MastMonkey
    Joined: Oct 2009
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    Location: Cali

    MastMonkey Junior Member

    During our cold and rainy season here in California I left the boat project in the garage while I focused on other tasks. I didn't check back as often as I should have and after a particularly heavy rain found that the roof on the old garage had developed a large leak. Unfortunately this was right above a portion of the boat. Now the ply bottom on the exterior of the boat has gotten a bit of water on it, enough to discolor the wood. I immediately moved the boat and put a heater on it for several days to dry the wood out and haven't touched it in a weeks while I let it dry. The wood is 6mm Hydrotek Philippine Mahogany. Now I am worried about loss of strength in the hull bottom. And I am also worried about mold. Looking at the wood, it is now discolored with some black streaks from the water. This is probably related to the mineral content of the water, but there are separate black spots that look potentially to be mold.
    My current plan to repair it is to bleach the wood with Oxalic Acid prior to sealing the bottom with penetrating epoxy.

    But, I am wondering is the oxalic acid step necessary if I am going to paint the boat and the discoloration will not be visible. Could I hit the suspected mold spots simply with bleach? Or will using penetrating epoxy only prevent mold from damaging the wood in the future.

  2. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    If it were me, I'd just wipe it down with a 5-10% bleach solution and see if it cleans up. After making sure that the plywood is completely dry I'd think that the epoxy would bond just fine.

    I had a similar situation develop in the v-berth area of my boat while I was restoring that area (the deck above had been removed and over the winter some water found it's way onto the berth). I cleaned it up and dried it out as described above and have seen no issues with the epoxy bond over the past couple of years as I continue with my work.

    I'm sure othere will weigh in as well.

  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Discoloration is a cosmetic issue only. If there is no delamination or softening of the wood, you shouldn't worry. Bleach breaks down wood fibers and weakens them. If you are going to paint it will not give you any advantage.
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Hydrotek is a WBP, marine grade sheet, so you don't have any structural issues. You can use a scraper to remove much if not all of the discoloration. This is preferable to sanding. A beach wash will change the color of the mold spores, but they're still there. Oxalic acid is also an option, but attempting to restore the color to match neighboring pieces will be problematic at best.

    Personally, I scrape it clean if you're finishing bright. If not, then just sand, clean then encapsulate or paint.

  5. MastMonkey
    Joined: Oct 2009
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    Location: Cali

    MastMonkey Junior Member

    My original plan was to clear finish, but now it looks like it'll be paint. Thank you all for your help.
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