Choosing wood for a wood/glass Chris Craft Coho

Discussion in 'Wooden Boat Building and Restoration' started by F14CRAZY, Nov 27, 2011.

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

    PAR Yacht Designer/Builder

    They had several wooden crews needing to stay busy. Skilled workers are hard to find and keep. A 'glass hull shell and molded deck cap, as is typical of modern craft requires less skilled workers, after the molds are made, so you'd lose this expertise if you went all 'glass. Many ended up in the finish carpentry department, but most just got laid off.

    Your deck was likely covered with canvas and painted originally. This often gets pulled up and just painted, which quickly kills the deck. Once you start digging into the deck, you'll find good spots, but a lot more bad spots then you can see now. It's usually easier just to rip it all off and lay a new plywood deck over freshened beams and carlins.
     
  2. seven up
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    seven up Junior Member

    Ok to put on some tunes first?


    [www.youtube.com/watch?v=ft82a4qZZ9E]


    MDO plywood is my new favorite. A couple of sheets were used to protect a plywood shipment. Alot less fairing before finish coat. And razor sharp edges.

    For framing an aft well and a couple other spots we layered 1/4" Okume with epoxy and staples. For a 2x2 frame it would be 8 layers of 1/4". A 4x8 sheet would yield 3 2x2 8 footers.
    This one is 1 1/4" thick, 2" wide, 98 1/2" long.
    DSCN1266.jpg

    I've been thinking to use a fir plywood cores and mahogany outer layers for brightwork.

    So F14, Surely I'm NOT telling you to do it this way. Just some other options to look at. The boat that is being finished up, here, in the next couple of years, I knew when I started that no one would want it when finished so it didn't bother me to change things around to my liking without sacrificing safety.

    It was pretty overwhelming at first.
     
  3. F14CRAZY
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    F14CRAZY Junior Member

    Am I correct that "MOD" plywood is equivalent to "exterior grade" plywood?
     
  4. seven up
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    seven up Junior Member

    The long name is Medium Density Overlay. MDO. The type used for outdoor signage. There may be an interior version although I haven't come across any.
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    If you mean MDO then no, MDO is the APA1-95 grade (marine), which is better then the three construction grades, typically used in land based housing. MDO (again) has fallen dramatically in quality in the last decade and I can't recommend it for planking any more. It's fine for lightly loaded stuff, bulkheads and furniture though. It's rosin coated paper makes painting very nice too. If looking to use a cheap construction grade, see if your local lumber supplier can order some T 1-11 for you. This is typically grooved, but can be had without them. One side will be rough, the other typically a C or D surface, but it's got a good core and is a WBP adhesive. It still has a low veneer count and voids, but it's a better sheet then the typical "X" grades. Of course it'll need more effort to finish, but with a Xynole, Dynel or combi-mat sheathing, it'll do fine.

    There is no interior version of MDO. It's all APA 1-95 grade and available in limited thicknesses.
     
  6. F14CRAZY
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    F14CRAZY Junior Member

    Thanks for the better explanation. I googled it quick at work so I didn't get a good idea of what it was
     
  7. seven up
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    seven up Junior Member

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

    PAR Yacht Designer/Builder

  9. seven up
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    seven up Junior Member

    The APA1-95 specification was revised to voluntary standard ps1-07 and later to ps1-09(in 2010).

    Otherwise, the panel listed above in the website link was the panel I've used. And was impressed by its' stand alone characteristics(1/2" 2-sided brown)

    And may or may not be useful for satisfying F14's original query ...help choosing wood:

    flybridge deck

    windshield framing

    saloon corners

    side deck cores

    base of interior side windows

    cockpit deck supports

    saloon sole



    Any progress or pictures to update us F14 ?
     
  10. F14CRAZY
    Joined: Jul 2011
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    F14CRAZY Junior Member

    Thanks for the discussion...choices are a good thing :D And yeah, all those areas listed are in need of attention, pretty much. Not much new progress aside from slowly getting the cabinets out of the salon. This is in a newer thread I made because I actually noticed how the cabinets were sloping outward (towards the sides of the hull) with how bad the sole has become. Leaking windows, leaking flybridge deck, leaking side deck to window base joint...its seen a lot of neglect but I'll turn things around. There's some pix in that thread if you're curious
     
  11. seven up
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    seven up Junior Member

    Where you been F14 ?
    The removal of decayed structure for replacement can take months(recall spending an entire fall season removing bronze screws lol).

    Are you still at it or is she in the water ?
     
  12. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    My guess is that he gave up. He probably found that the whole boat needed replacement (save the hull itself) after he got into it. I'd estimate at least $30,000.00 in materials to go through everything. Plus the thousands of hours of labor.

    I never saw the original thread but would have told him that PAR was spot on in his advise.

    MIA
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    As I suspected and as his last post revealed, the hull is probably showing some signs of distortion (sagging bilges), which requires long hard work to put back. Maybe he has, maybe life has gotten in the way, as it often seems to do, but lets hope he'll keep banging away and get back to us.
     
  14. seven up
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    seven up Junior Member

    Yes, but can an undertaking such as this be done in a piece-work manner ? And where do you start ? The underlying support deep in the bilge ? Patching the saloon roof ?

    I just could not say.

    Few threads capture my interest and there is a difficulty expressing in typed messages. And you get tired of writing "great job" after a while.

    We did follow the F14 "bayliner" thread and were impressed by F's speed, dedication to the project and choice of epoxy at a time when polyester was "good enough" as well as the "youngling" factor.

    As I look into my crystal ball...A HA ! I think they're out water skiing again.

    Enjoy
     

  15. F14CRAZY
    Joined: Jul 2011
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    F14CRAZY Junior Member

    Questions keep coming to my head so I searched the board...come on guys, I'm not the average one thread poster...

    I've been kicking butt (slowly) on the project. I've taken lots of pix and have a thread that I keep pretty current on the Commander board

    http://www.network54.com/Forum/424840/thread/1319687094/Introducing+my+33%27+Coho+project+and+I

    I'm planning on replacing pretty much all the wood. Cabin is pretty much gutted aside from structural members and the sole. Those filled over silicon bronze screws take forever to remove and CC didn't skimp on the amount of fasteners.

    Flybridge should be removed by the marina at this moment in preparation for moving INSIDE over the winter, which is where the real teardown will begin. I'll be making a purchase of marine plywood too.

    Sorry for not keeping you guys updated here but the project is alive and I'm as enthused as ever actually. I'll keep posting back here too.

    I came here to ask how you guys cover countersunk screws in plywood above the waterline. Still a lot of time before I'm ready for that but when I'm not working on the boat I'm brainstorming everything, from glassing the flybridge to interior wood colors to A/C to the stale gas in the tanks.

    This is from pretty recently. This thing had carpet, a couch, a head, a galley...it looked like a boat inside, albeit a soft, wet, rotting boat.

    [​IMG]

    Inside, I'll be able to tear out everything, use the old pieces as patterns for cutting the new stuff, and put it back together. Thank goodness for a fiberglass hull and stringers, but I expect most everything to need replacement if I haven't determined that already. Flybridge deck, the wood around the windows, the beams for the flybridge deck, cockpit supports, interior bulkheads, the side deck supporting wood...it's basically all bad but I'll get through it. At this point I'm focusing on just getting the structural stuff done and postponing things like cabinets, the head, appliances, etc. I hope to have it floating and operating by spring even if it's more or less an empty shell.
     
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