Traditional Build with Corecell

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Apr 7, 2017.

  1. fallguy
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    fallguy Senior Member

    I am going to build a Woods cat using traditional stringer on hull skeleton with Corecell M and Silvertip Epoxy. Hull is hard chine, developable, not round bilge.

    RW is suggesting 900g quad for inside and I'm planning on forming up the entire hull; then removing it and glassing the inside/save the seams; putting it back on the stations/molds; creating a tapejoint/s.

    I will use some ply and screws for the initial attachment, then glass the insides and replace on the mold. I will probably use some epoxy and balloons 4:1 with cabosil at the seams after all the pieces are back on and attached. Then I might use some raptor staples or nails before glassing the outside. It has a reverse chine, so removal of the jig once flipped in sections, tapes and bulkheads as I remove.

    Any thoughts or concerns with the general plan?

    Obviously I will bag and number the skeleton for a 2nd use.

    Thanks for any replies.
     
  2. Beamreach
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    Beamreach Junior Member

  3. Mr Efficiency
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    Mr Efficiency Senior Member

    I don't follow the detail of how this is supposed to proceed. I have visions of things going badly out of shape once removed from the former. Unless you can better explain it step-by-step.
     
  4. jorgepease
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    jorgepease Senior Member

    that's going to be tough. Better get it on the jig, glass the entire inside or outside and then flip the hull and do the other side
     
  5. fallguy
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    fallguy Senior Member

    Woods Cat

    It is the demountable version of the design.

    Mr. E,

    Let me be a little clearer.

    1. I will make a station mold (upside down) with stations 900mm apart and 1x2 stringers between on 6" centers or so.. There is a reverse chine, so I need to build the molds in 2 pieces for removal of the lower section of the mold.

    2. I will use corecell M and apply the corecell to a bagged mold. I expect to apply the corecell and then do some work inside putting 3/4 x 3/4" strips on each side of each station to avoid ripples and to meet Bilodeau's wishes for angles in the forms.

    3. I will use boards and screws to deal with any movement.

    4. After all the planking is applied, I will remove each section (there are like 4 flat sections on each side of each hull) and I will glass them on the inside only with 900 quad (or 2 400s 45/45 0/90). Handlay with silvertip and peelply-all precut glass to fit the sections.

    5. After each section is completed on the inside. I will replace onto the jig.

    6. Once the planks are all applied with glass on the inside, I will probably use some raptor staples to hold them tight at the joints. I will electric plane taper joints and then glue them together a bit with 3m balloons and cabosil 4:1 in epoxy. I will then apply 100-150mm of tape over each joint and fair each joint prior to glassing.

    7. After all the joints are mated, taped, and faired, I will glass the outside of the hull per the lamination schedule and use peelply, probably trying to complete the bottom and the transom one day and the sides another day. This detail I need to work out a bit more as the transom has 4 layers and the bottom 2 and the sides 1, but it is basically a massive canoe hull. (times 2)

    8. After the boat is glassed, I would fair all but the reverse chine.

    9. I would flip the boat and develop the bulkheads and the deck on the table. The deck is complex with beam sockets and openings for cockpit and each hull has a hatch, fuel tanks, lockers, livewells, etc.

    10. The original plans call for infusion on female mold, but my wife was a little blown away by the prices I got from the infusion guys for products that are not as good (vinylester, other core, etc) And I don't want gelcoat. RW has agreed to redo a plan for traditional core on jig planking.

    If you want more specificity; please refer to where in my list of 9 to make it a little easier.

    Thanks.
     
    Last edited: Apr 7, 2017
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    That has enough problems, too, jorgepease. You need a good cradle to keep it conforming to shape after being pulled off the former. Perhaps he meant he is using full length panels already glassed on one side before attached to the former, it would still be problematical though.
     
  7. fallguy
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    fallguy Senior Member

    Removal from the jig

    When I remove the boat from the jig, I expect to do it in pieces; the stringers will be somewhat sacrificial (big deal). That way, I can do the inside tape joints and bulkheads as I go.

    Build is in MN in controlled environment (a/c and heat). The space is 36' long, so a little short, but I can open the door in good weather.

    I only have room for one hull at a time.

    Plan to post cure prior to painting (method tbd).

    Start is hopefully July, plans are still on the table, though.

    Any help/advice would be GREATLY appreciated.
     
  8. jorgepease
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    jorgepease Senior Member

    the way most stitch and glue guys do it is they build the cradle on top of the upside down boat already leveled and flip it with the jig. Then remove the jig and take steps to get it back aligned. I hate this technique but doing it in pieces is asking for a tremendous headache.
     
  9. fallguy
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    fallguy Senior Member

    The lamination is 600g sewn biax x 2 on the bottom. 600 bi on the sides with 50mm minimum tapes each side at the joints (exterior).
    4 layers of 600 on the transom or tbd
    inside is like I said 900 quad or more likely 400 45/45 and 45 0/90 and double over the seams same minimum.

    In a hurry. Let me know what you guys think.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    I have no idea what the OP is planning, I have built boats on the male mould sandwich principle, but how you do it in pieces is too clever for me.
     
  11. fallguy
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    fallguy Senior Member

    1. Build pressboard station molds.
    2. Attach stringers with screws.
    3. From the inside, attach 3/4" square cleats to each station mold and each stringer.
    4. Remove screw from station mold.

    To remove mold unscew all cleats.

    You can do a few at a time to allow for inside seaming and bulkheads. It could be done before flipping if you guys think it best.

    So sorry Mr E. Hope this helps.
     
  12. jorgepease
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    jorgepease Senior Member

    I think the stringers are battens, just part of the mold.

    And the idea is to load the jig with corecell that is already glassed on one side so after glassing the outside he can crawl up in the upside down boat and tape the inside seams ... but you want to flip in sections because ... ?? You don't think you can flip whole boat as a single hull?

    That is going to be a real pain, if you flip as a single piece it may deform as you spin it but then you can install frames to get it back to shape. If you try to do it many pieces it's going to be really tough to keep aligned.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    If you are going to use panels pre-glassed on one side, it might be better to use a strongback that is going to be largely part of the finished product, as in bulkheads and any stringers.
     
  14. fallguy
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    fallguy Senior Member

    There is no flipping in sections. The entire outside of the hull and the inside of the pieces save the inside joins will be fully glassed prior to any flip.

    The only thing that won't be inside before the flip was the bulkheads.

    So, I could do a half flip in a cradle and take only a small section of the jig out at a time and replace with bulkheads and finish the inside seams as I go, but gravity might be a little against me that way.

    How much movement am I going to get from removing say the first two sections 1800mm with all the outside glass done and all but the inside seams done? Seems like I could run tapes on the seams and put BH one in pretty easily without too much trouble.

    If I build with the bulkheads in the original build, I can't use a full skeleton.
     

  15. fallguy
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    fallguy Senior Member

    Yes, I am improperly referring to the mold battens as stringers... aka stringer mold I've heard it called a couple of times..
     
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