90 Ozark Deck Boat rebuild

Discussion in 'Boatbuilding' started by phil32, Jul 23, 2012.

  1. phil32
    Joined: Jun 2011
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    Location: Indiana

    phil32 Junior Member

    PAR,
    Finally ready for paint. After 4 barrier coats of epoxy is 80 grit to much tooth for some hi-build primer. It is a 2 part but doesnt say what grit to use.
    I know you always say give it a good tooth.
    Buy the way after all the filling and sanding, I chickened out and ordered Pettis Easypoxy (1 part) paint.
    Hope this finds you well.
    Best regards,
    Phil
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yeah, 80 is a bit rough on your lady's butt don't your think? 100 is better for the preliminary, knock down portion, but switch to 120 pretty quickly, as 100 can remove material almost as fast as 80. How ever many coats of primer you lay down, you'll probably cut them in half during the smoothing process, so take this into account before final top coats. In short, you want a minimum of 2 full coats of primer under the top coat. If you apply 2 and sand, you only have one left, so apply an extra coat, lightly kiss it (for tooth) with 180 or 220 then top coat. Can't wait to see her Phil.
     
  3. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    PAR,
    I got 2 heavy coats of primer on her today, had to stop an take a picture of the repair.
    I just wanted to say Thank you again for your guidence. Adding a layer of cloth to tie everything together sure made a difference in filling and faring. I was even able to keep the line straight. Again thanks.
    Best regards
    Phil
     

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  4. PAR
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    PAR Yacht Designer/Builder

    No sweat . . . now go get it wet . . .
     
  5. phil32
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    phil32 Junior Member

    PAR
    Better Pictures. Im pretty proud of that repair. Again thanks for your guidence
    Phil
     

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

    Stop on down here, I'll put you to work right away. You should be proud.
     
  7. phil32
    Joined: Jun 2011
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    Location: Indiana

    phil32 Junior Member

    PAR,
    Thanks I just might show up one day.
    This is my latest challenge I was able to get most of it out intact It was not attached very well. The piece I removed measures 1 1/4" but as you can see the slot is 1 3/4".
    The corners are broken and cracked and had 2 metal pieces holding them together
    Would you kindly suggest the proper wood and cloth to use for this repair to the motor transom.
    Best regards,
    Phil
     

    Attached Files:

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

    That type of transom relies heavily on laminate for stiffness. The transom core should be a minimum of 1.5". The usual course is 2 layers of 3/4" plywood. 3 layers of 1/2" is stronger if the layers are canted a bit (12 degrees to each layer). Lots of tabbing, after grinding back to good, unbroken laminate.
     
  9. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    PAR,
    Thank you for replying, but as usual you are a few canted degrees over my head. I have lots of tools, a 12 degree canter is not one of them.
    Yes, I know it is an angle and I know what 12 degrees means but I cant get my head around how that relates to basically 3 almost square 1/2" pieces.
    Im going to use 2-3/4 pieces but I had to ask. Would you kindly explain.
    I not only appreciate and value your help, you also cause us DIYers to study.
    In addition should I continue to lay this up with biax cloth?
    Again thank you.
    Best regards,
    Phil
     
  10. PAR
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    PAR Yacht Designer/Builder

    The grain of the outer face on each sheet is canted 12 degrees. On a 3 sheet laminate, the outer sheet has it's grain canted 12 degrees down, the center is horizontal, while the inner piece has the grain canted up. With two sheets, just cant one up or down 12 degrees.

    Biax is much stronger (with epoxy) than cloth, so if interested in strength and stiffness, with less fabric, then biax is the ticket.

    Shown is a typical transom with the plywood oriented so the grain will be canted. Because plywood is a 0/90 laminate, canting the grain improves both longitudinal and cross grain stiffness in the resulting homogeneous transom.
     

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  11. phil32
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    phil32 Junior Member

    PAR
    Ok I got it. I see how that is stronger, I have some 1/2 and we will do it that way.
    My Daughter who just turned 16, we work on the boat together said she has figured you out.
    She said Mr. Riccell tells us how to fix our problems, he also gives us homework. I thought that was pretty cute and true. We have learned a lot from you.
    Best regards
    Phil
     
  12. swade
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    swade Senior Member

    Dumb question time. See this tape measure pic is what I don't get when I did mine.

    When i was doing mine, I always read people using 2x3/4 online, i figured everyone else had a 1.5in gap! Duh!

    But you have a 2" gap there (which like mine i see now is probably normal), that means you've got a 1/2 inch gap to fill. I renforced the inner wall which added on a bit then used 3x1/2 + 11/32. And aside from a hangup on one corner (my dumb fault) i had a bit of a gap still that seemed ideal for a layer of epoxy between the outer skin and core.

    I know it's gap filling but i'm just curious if there's a difference in strength if you have less ooze + more wood. I guess with more ooze its more foolproof for not getting a bad lamination in there (though would seem with more ooze it would need to be thicker).

    Maybe i screwed mine up adding more core and thinner epoxy joints? From examing cuts in my core, i'd say the epoxy layer was about the same thickness as the ply glue. For all i know mine may sink =) i haven't got it in the water yet.
     
  13. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    Swade,
    Thanks for your reply. Hopefully PAR will respond to your post, but if there is anything I have learned from him Tabbing Tabbing and more Tabbing solves a lot of problems. He preaches light but strong.
    The core I removed was 1 1/4", being undersize and not set in with any thickened resin there was just not a solid bond between the wood core and the layup which is probably why it split in the corners. But im no authority.
    Regards,
    Phil
     
  14. PAR
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    PAR Yacht Designer/Builder

    Build to your core thickness. The core is sized for the maximum size engine that can be mounted. If you have 2" inside the core, then two 3/4's and a 1/2" or four 1/2" sheets. Of course the more sheets the stronger (more veneers), bit don't get anal about it.

    Generally, you want some ooze out around all edges and seams. This insures good contact, but you don't need excessive ooze out (God I love that word). If you do have excess ooze out, you can use this to begin the fillet process and it only beams you used a little too much, that's all.
     

  15. swade
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    swade Senior Member

    good to know. I'll only sink then probably from one of my other 10 mistakes =)

    Phil great job on that fairing repair, i'll be happy if mine looks 1/2 that good!

    yeah on the ooze out i looked for just enough clamping pressure to get a little even ooze out on all the edges. On the laminate bonding sides i thickened up a bit more to make up for more irregulaties in the face surfaces and since pressure wasn't as controlled as when I bonded the ply cores together outside the boat.
     
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