Tips on Dagger Board Trunk Construction?

Discussion in 'Boatbuilding' started by CatBuilder, Dec 21, 2011.

  1. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member holding true course

    Maybe you can use wax on daggerboard as a meltable medium once infusion is complete and cases hard. Some toilet seal rings are cheap and melt easy with a hair dryer. Put 1/8 inch coating on board, then your cardboard or whatever shim material for board clearance in finished case.
    To extract board, heat case with hair dryer/s and use come-along to drag board free. Then other material that remained in trunk could be peeled out.
  2. Yobarnacle
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    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    or a whole bunch of rolls of waxed paper wrapped round and round board.
  3. CatBuilder

    CatBuilder Previous Member

    Yeah, that would work. I think maybe I can't infuse it. I did see someone else online that built just the inner skins, a half of the clamshell at a time (then sanded) and attached them.

    (then he sanded)

    Then attached the core (then sanded) and then attached the outer laminates.

    I wonder if this is the only way to do it?

    It seems like infusing won't work because I can't get things to stay put and I also can't peel any of the infusion material from the inside of the case once complete.
  4. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member holding true course

    I'm the least expert fiberglasser you can meet. I know how to paint on the resin, lay on glass, wet out, lay on glass...ect to 3 layers. sand when dry, and add 3 more layers. sand, fill with resin thickened with cabosil, or chalkline powder. sand, paint with gelcoat sand, sand, sand, and wax.
    more than that, I'm igornant. :)
  5. CatBuilder

    CatBuilder Previous Member

    Thanks anyway. Valiant effort. :D

    I'm just hoping someone who has made a dagger board trunk can clue me on in the best way to lay the thing up. It's complex.

    Doesn't seem like I can infuse because I can't get the flow media off the inside when done.

    If I pre-make the flat panels, I don't think I can then hand laminate properly to do a taper where it goes from core to solid glass, since some of that taper is on the inside of the trunk.

    I am just hoping someone on this forum may have made dagger board cases before and can help me figure out how to get this stuff together.
  6. hoytedow
    Joined: Sep 2009
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    hoytedow Fly on the Wall - Miss ddt yet?

    I like the wax idea. I would merge the 2 ideas, wax and polyethylene rope, using the wax to smooth the surface of the rope. after the outer shell cures, just pull the end of the rope and it will extract the wax as it comes out a coil at a time.

    Attached Files:

  7. CatBuilder

    CatBuilder Previous Member

    I already have the molding of the board done. It's spaced out rope and bubble wrap. Works fine.

    I am too cheap to go buy 1152 feet of 1/2" rope for at tight wrap.

    I need help with the lamination. Is there a good way to do this as a hand layup? Anyone?
  8. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member holding true course

    As I posted much earlier, I used to make wooden trunks in two halves and bolt together. I imagine you could whip stich the 2 halves together like the build sewn seam frameless plywood boats. The stiching could be stainless wire or kevlar or something simularly strong. After mechanically fastening two halves together, could glass the forward and aft seam inside and out for water tightness. Good luck. Hope somebody can give you a better idea.
  9. CatBuilder

    CatBuilder Previous Member

    No no... I think that's it.

    I did see another guy who made the inner skins, then put the core on those, the keep building the thing up.

    It's a very long process with a lot of sanding, but maybe it's the only way to do it?
  10. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member holding true course

    As a captain, you are very familiar with "Ain't got time to do it right, but got the time to do it over again" excuse.
    With all the work you have put in and will yet put in, I bet the time on doing your cases right will be a small % of over all effort.
    Soldier on, Cap!
  11. Charly
    Joined: Dec 2009
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    Charly Senior Member

    Hey Cat, FWIW, here's how I did it with plywood:
    I laid up the fabric on the inside of the board trunk sides to plan specs.

    Cut a few two bys to the correct width of th trunk to use for spacers.

    I used two sections of pvc pipe for the leading edges of the trunK I had to screw on a shim on each side of the pipe to get it to the exact same width of the spacers.

    sealed the edges of the ply

    stacked the ply on a sawhorse with the spacers running lengthwise, and the pipe with spacers screwed to it, temporarily screwed to the edges of the ply, but also covered in 6 mil plastic.

    Layed up some biax over the pipes and lapping the outside of the trunk, to make the whole trunk into one unit

    reinforced the outside of the trunk with triax, biax, uni, etc, per plans

    removed the pvc pipes from the ends by unscrewing the temp screws and sliding them out of the trunk, along with the plastic sheet.

    made up structural bog and faired out the joint on the inside of the trunk where the ply sides met the rounded layup at the trunk leading and trailling edges YOu may have to get creative here- it was a long reach inside from each end. I made a special squeegee shaped to fit

    while still green, inserted some varying width 10oz tape on top of the bog and squeegeed it out. I put mine in dry. It was easier that way.

    Marked the keel for the cutout with the trunk in place using the trunk as template, after cutting out the bulkhead to the correct angle per plans

    removed trunk and cut hole with sawzall

    dropped trunk into hole after coating with resin, tweaked angles,etc, and bogged in place with trunk running wild out bottom and top (deck was not on yet)

    reinforced trunk at vulnerable impact areas, etc

    it worked out fine, except I made the trunk the wrong dimension. :)
  12. Silver Raven
    Joined: Oct 2011
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    Silver Raven Senior Member

    G'day C-B. WE here are 18 hrs in front of you - so it's 0858 hrs here in Far North Queensland Australia.

    Or am I - as they say - a day late & a dollar short - or might I be somewhat useful at this time. I've had well over 40 years experience in building fibreglass c/b & cases as a business. There needs to be much - very exact info - passed here - or it easily goes - 'pear-shape' - as you already know.

    Wish I was 'in-your-face' so I could help. If I'm not smart enough at least I could sweep the floor, eh? Ha, ha, ha.

    Get back to me if you wish. Ciao, james - - I'll keep my computer on & watching it - so should be able to get back to you quickly -0 if the network allows us to. jj

    You are getting lots of great info - so I may not be of much help. I do think you've missed a few matters though. jj
  13. CatBuilder

    CatBuilder Previous Member

    Silver Raven... here is the configuration of the case....

    There are some questions on that post, but they are not important at this time.

    The main issue here is I don't know how to go about building this out of glass and foam.

    Charly's post makes sense and is perfect if you have some plywood. I have floppy 1/2" foam (already feathered for the indicated tapers) and a pile of glass and epoxy. I have no idea how to put this stuff together correctly to form a high quality dagger board trunk that doesn't leak and doesn't have voids that will rupture some day.

    How would you go about the layup?

    Any insight?

  14. CatBuilder

    CatBuilder Previous Member

    Was that appropriate? Just a lap joint from the square edged plywood to the solid glass curved part of the trunk?

    If you cram the board, will that lap joint be a weak spot?

    Earlier in this thread, I was told it was very important (and told by Richard Woods as well) to taper my core down as I go to solid glass.

    Did you taper the ply? If so, how did you do the inside laminates so they staggered up the inside taper?

  15. CatBuilder

    CatBuilder Previous Member

    Right... I just don't like wasting time (10 hours now!) doing nothing. I should be building, not trying to figure these plans out. I'm on a build schedule. I'm not retired and this isn't a hobby. It's work.
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