Rebuild stringers, transom and deck without wood

Discussion in 'Boat Design' started by Resurrection, Apr 17, 2017.

  1. Resurrection
    Joined: Apr 2017
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    Location: Rhode Island

    Resurrection Junior Member

    Gentlemen,
    Hoping to get some info and ideas about how to aproach what is almost an entire rebuild of the stringers, transom and deck of my Dad's old 1978 19' Cape Codder without using any wood (at least under the deck).
    I cut out the floor, removed all of the waterlogged foam underneath and all other soaked wood, then cut out the inner skin of the transom and all of it's old rotted wood, and pried the wood out of all 5 full length longitudinal stringers after having cut off the top edges ( the glassed-over 2" plank had mostly seperated from the fiberglass).
    So I'm left with a clean inner hull with the skins of the old stringers remaining.
    My thought is because the stringer skins themselves still appear to be well bonded to the hull, having been laid out solidly when originally built, that I could still use them structurally, so long as they can be reinforced with an inner Fiberglass lattice which I would hand-lay, or filled with a structural element of some kind.
    I'm also trying to think of a way to use 4" or 7" thick DOW extruded polystyrene under the deck as lateral structural members as well as safety floatation.
    However I know there's a problem with trying to fiberglass over this material, but I like it for safety floatation because it won't absorb water unlike the blown-in foam that was used before.

    Any thoughts ?

    Joe
     
  2. Resurrection
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    Resurrection Junior Member

    I'll try to get some pics posted soon
     
  3. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    There's no problem rebuilding using zero wood, just get out the credit card.

    What's your budget?
     
  4. Resurrection
    Joined: Apr 2017
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    Resurrection Junior Member

    Aye, there's the rub !
    Trying to do a lot with a little.
    My little sister actually owns the boat now that my Dad has passed.
    We're gonna get our heads together soon to try to nail an approximate figure down but I'm thinkin no more than $2000 maximum
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    My first concern isn't budget, but how well the boat is currently supported, particularly now that the bulk of the structural elements have been removed. Distortions in the hull shell are pretty common and can occur for several reasons, even on a sound hull. Post a photo of the boat in profile, especially the bottom will help.

    Wood is used because it's the cheapest structural material going. It's easy to machine, mill and shape, holds fasteners well and also is easy to bond into place. You can use other materials, but the costs do go up (quickly). The wood previously used, offered 40 years of service, so how much more service do you think you can afford?
     
  6. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The wood and foam were waterlogged because the cavity wasn't well sealed. Usually is a combination of the way it was built and holes that were made through the years. If you build with the original materials, and seal everything carefully, it will last more than the 40 years it did now.
     
  7. Resurrection
    Joined: Apr 2017
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    Resurrection Junior Member

    Gonzo
    It was actually partially rebuilt once back around the mid 90's.
    A new plywood floor was put in and glassed over, albeit without proper attention to detail.
    As a work boat it was kept mostly in the water, not trailered so there was constant exposure to moisture.
    It's future use will see extended time docked in the water.
    My concern is that no matter how careful the repair/ rebuild will be, water will eventually find it's way under the deck, soaking any wood that is used.
    While wood rot would take time, weight gain wouldn't.
    I want to prevent that from ever being a possibility.
     
  8. Sparky568
    Joined: Jan 2017
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    Sparky568 Junior Member

    I don't see any reason why wood can't be used if properly sealed. That was most likely the case when originally built. It was the deck that sealed its fate. Past budget how long do you expect to keep it? There comes a time in all material things where it just doesn't make sense financially wise.
     
  9. Resurrection
    Joined: Apr 2017
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    Resurrection Junior Member

    These are some photos from last year's destruction phase.
    there was some cleanup after, but this gives an idea of what I'm left with.
    I also did what I would call a basic leak test by plugging the holes in the transom with silicone and filling the hull with water just about up to the scuppers.
    The hull is still solid with no leaks appearing anywhere except through a couple of the many holes in the transom where the silicone was hastily stuffed in for the test.
    Water stayed in for a few hours. Not sure if this was an entirely adequate test but it seemed to tell me what I wanted to know.

    IMG_0774.JPG

    IMG_0778.JPG

    IMG_0784.JPG

    IMG_0798.JPG
     
  10. Resurrection
    Joined: Apr 2017
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    Resurrection Junior Member

    Sparky 568,
    This boat has quite a lot of sentimental value so we're trying to save it and keep it in the family.
    Of course, we also have to try to think practically but we're still going forward with it.
     
  11. Resurrection
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    Resurrection Junior Member

    Par,
    Right now it's sitting on a roller type trailer
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Exterior profile shots are what's necessary.
     
  13. Resurrection
    Joined: Apr 2017
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    Resurrection Junior Member

    PAR,
    I'll try to get some profile photos ASAP but last I checked it's still tucked away in it's Winter hibernation spot.
    In the mean time, any info on the use of DOW blue dock foam as forms for structural members in this application ?
     
  14. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    The blue foam is not very structural.
    It doesn't have much strength.
    It will float just fine.
     

  15. Resurrection
    Joined: Apr 2017
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    Location: Rhode Island

    Resurrection Junior Member

    upchurchmr,
    Thanks for the interest.
    I'm really only considering using the foam as forms to fiberglass over. The foam itself wouldn't actually be designed to bear any stress, just the glass that is over it.
    I just trying to find a technique by which the foam could be used for this purpose.
     
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