Adding stringers to reinforce mast step and trunk.

Discussion in 'Fiberglass and Composite Boat Building' started by Canracer, Dec 2, 2014.

  1. Canracer
    Joined: Aug 2009
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    Location: Florida

    Canracer Senior Member




    That fiberglass is heavy stuff. It's a mat and bi-axial combo (6" wide.) The weight is similar to AstroTurf. :)

    I wet out with a chip brush. The glass got plenty of mashing and brushing. Accessibility is close to nil. I'm happy to add a few pounds here, I can take weight off in other places.

    Today, I flipped the hull and started to add more glass from the improved angle. The bow in the truck.

    [​IMG]

    Sawhorses at the stern.
    [​IMG]
     
  2. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    This is a switch back to epoxy. I found a small crack at the forward end of the centerboard trunk.

    The area was ground into bare fiberglass. I added 5 layers of new glass (3 layers make the turn and continue into the slot) and a big blob of micro-spheres.

    [​IMG]
     
    Last edited: Jan 21, 2015
  3. Canracer
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    Canracer Senior Member

    Today I picked up a tube of Six10. I'll bet it works great for fillets, never tried it before.
    [​IMG]
     
  4. Canracer
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    Canracer Senior Member

    Max is worried about his boat. I'll get it back together little Buddy, promise.
    [​IMG]
     
  5. Canracer
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    Canracer Senior Member

    Six10 is interesting stuff to work with. I'm sure it's has great properties.

    Here's something surprising, I payed 24 bucks for this and all I got is what's between my thumb and finger. The plunger stops at that point and your done.

    [​IMG]
     
  6. JosephT
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    JosephT Senior Member

  7. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    It was a dusty weekend, but I'm happy with the results.

    The compression post was separated with a 6" cutting disk. This is the mast side of the post (boat is upside down,) those globs of adhesive are similar to concrete. I switched to a grinding disk and removed the concrete.

    [​IMG]

    The mast step in the cockpit attaches to this block of wood with four screws. All cleaned up and ready for a rebuild.
    [​IMG]


    The post was originally mounted onto a 1/4" plywood strip that ran from the centerboard trunk to the bow. It was soggy and moldy. Pro tip: seal wood properly (especially the end grain.) You can see where the strip starts just forward of the trunk corner (edge radius also visible.) It was covered with bad fiberglass, and I removed it all.
    [​IMG]


    This is where the post attached to the hull (remember, the boat is upside down.) The soggy plywood strip and the bad fiberglass are removed. I feel like I just reached a big milestone. This is becoming a much better boat.
    [​IMG]
     
    Last edited: Jan 26, 2015
  8. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    I sealed this mast step structure with straight epoxy and then faired it to the underside of the cockpit sole. The old polyester resin was sanded away to expose fresh plywood.
    [​IMG]

    I wet out the plywood with epoxy and added three layers of 6oz fiberglass cloth. Each piece of cloth was a little smaller; full thickness was kept at the mast step. The smallest piece of cloth takes up most of this picture.
    [​IMG]
     
  9. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    The stringer project is rolling along. Don't mind all the dust.

    Factory stringer reinforcement: This shows the polyester work. The top is mat and roving, the bottom is two layers of heavy biax over a fillet. The section aft is where I switched to epoxy. Those surfaces were wet out and long fillets of Six10 were added top and bottom. Total length is 43".

    [​IMG]

    The polyester ends and the epoxy begins.
    [​IMG]

    The forward end of the factory stringer (right) with new epoxied glass on the underside of cockpit (foreground.)
    [​IMG]

    Looking inboard everything is epoxy and glass. At left is the mast step, then the top corner of the trunk, solid clear epoxy, and then 23" of fillets with fiberglass. To my eye it all looks overbuilt, but this is were the forces from the mast, centerboard, and side stays come together.
    [​IMG]
     
  10. Canracer
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    Canracer Senior Member

    Somehow I have to install web frames back in those spaces. Any ideas?
     
  11. Canracer
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    Canracer Senior Member

    I put together a router table and milled a 3/8" grove into the frame rails.
    [​IMG]


    Unless I get a better idea, I'm planning to rip the rails down the middle and then reassemble everything using epoxy inside the boat. It might be a little complex and I'm not sure if it's necessary.
    [​IMG]
     
  12. Canracer
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    Canracer Senior Member

    I thought this would help give you an idea of how much space I have to work in.
    [​IMG]
     
  13. Canracer
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    Canracer Senior Member

    Reaching aft, far as I'm able with these arms. I added more reinforcement to the top edge of the centerboard trunk. It's 4 layers of glass set in epoxy on both sides. The top inside lip of the slot will have to be widened with a router in order to accept the new foil.
    [​IMG]
     
  14. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    I finally broke my dependence on retail epoxy. This is a three quart kit from U.S. Composites. I also bought 2 yards of 10oz E-glass (50 inches wide.)

    Great price and great service.

    [​IMG]
     

  15. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    I'm in the process of fitting the centerboard. This position is 3 degrees of aft rake (when measured to the hull.) Would anyone be willing to explain how small changes in rake affect the boats behavior? I think some class boats are set with 0 degrees rake and others are at 3.

    I also have a chance to move the whole board forward by 1/2 inch. How would that change things?

    [​IMG]
     
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