A Personal Worst!

Discussion in 'Boatbuilding' started by CatBuilder, Dec 1, 2011.

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  1. CatBuilder

    CatBuilder Previous Member

    Has anyone here ever infused a core they just put together, but only infused a single side at a time?

    I am trying to do just that and I came up with a personal worst: 5in Mercury vacuum. Horrible. Just horrible.

    I plugged any leaks I could find on the underside (I'm infusing the top).

    I plugged any leaks I could find on the bag and sealant tape.

    I got all the big ones (apparently), but I'm still only at 5in Mercury. Complete garbage.

    Any hints at all from someone who has done this before?
  2. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    All I did for my coachhouse roof was hand-layup - each half separately - on one side then the other... Then the halves were joined, along the boat centreline, and ribs added to the outside which also take the PV panels... and the box girder made in situ for the 6 tonne load for the mast-step (radar only sits there at the moment)...

    Attached Files:

  3. CatBuilder

    CatBuilder Previous Member

    Cool pictures.

    Yup, hand layup is a piece of cake, except the amount of epoxy I usually get stuck in like a fly on fly paper. :)

    I am trying to see if anyone has tips about infusing a skin to a core on one side only. I'm leaking like crazy. This is an entire hull (well half of it) in one shot, inside skin only, on a new core.

    The core against the mold/form is not glassed. It's Core Cell with a balsa deck and it's leaking badly!

    The balsa is very well sealed with 2 thin coats of bog on the inside of the hull (where the infusion is taking place). Also, the edges are nearly all bogged all the way around, to give something to stick the bag tape to. Sometimes, it's stuck to plain Core Cell, but not always.

    Attached Files:

  4. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    Looks like the same sort of foam I used... - Hand layup is the only way I could see - hence cutting the job in halves to get the access as needed... The foam sucks air through it even though the cells are supposed to be closed (which they aint - it seems)...

    Rolled West epoxy on foam, placed pre-wet sheets of glass quickly smoothed then covered with 'Polyester taffeta' (peel-ply), then rolled using those steel rollers that look like a series of washers... Applying a fair level of pressure to get a fair and effective bubble free smooth and even surface... Then move to the next sheet to layup... You can tell by the runs of red polyester taffeta in my images...

    I would have done the shape with the frame on the inside then working on the outside doing half the hull (port first?) then the stbd half - a doubling overlap on the keel line... (when it has cured, lift it from the frame to prepare that frame to do the other hull...) The hull will need some support to hold it square and true to finidh the inside part... - Then do the insides from the keel line down, roll the other way and do the other inside... Then insert the major bulkheads whilst the cure is still green and glass them in place to hold the shape... A little preparation on the original frame then repeat for the other hull... - That part should be worked to just above the waterline, as the inside (45 degree) chamfers to join to the horizontal part of the bridgedeck will be on opposite sides of each hull...

    I am going through the methodology I used for the coach-house roof as I did the hulls in sheets of pre glassed balsa duflex and chine construction. as you appear to be doing the build... Sorry I cannot help beyond that as our build methods appear somewhat different...

    Attached Files:

  5. CatBuilder

    CatBuilder Previous Member

    Aw, MAN! Every time I see one of these Duflex builds I get a little jealous! :)

    I looked hard at them, but the cost of importing Duflex kits and finding a Z press thing in the States was just out of this world.

    It's a fine process you had there. A fine process indeed, though the fairing work looks a lot more involved than mine.
  6. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    catbuilder, ive been racking my brains for ages trying to figure out the most painless way of building my next cat... the process ive decided on so far, is a combination of many systems... i could have gone the duflex route, but have finally decided against it...

    the method im looking at using mostly for the hulls, is to infuse 1 side of the laminate on a flat melamine table and them bend it into place over a frame forma, similar to the way in which youd build with duflex and make your own panels similar to KSS. Using epoxy, simply apply a light layer of woven glass onto the table, wet it out and sqeegy it off making sure you have zero of those tiny air bubbles that can get trapped against the surface of the table- this first step is kinda like the gelcoat step if using vinylester... Once its green, go ahead and layup the main schedule and bag it down using a grooved core material- the air bubbles get sucked out to the edges of the panel along with the excess resin- and bubble wrap or shade cloth etc to allow the vacuum pressure to spread over the top of the core. For larger panels youd have to apply peel ply to the aesthetic first layer and let it cure, then infuse the main shedule as there wouldnt be enough time to wet it all out and bag it using epoxy...
    Once cured, you have a perfect finish on one side and nothing on the other yet... Transfer these panels to a female forma frame and bend them into shape holding them from the outside with screws. Once in place, glass the inside by hand or infuse it, the core should be perfectly sealed now... then add bulkheads etc, hulls finished...

    make the decks and cabins in the same fashion, off the table then using female forma frames etc, and once finished simply join the hull to the decks/cabin around the sheer line. Most of the outer surfaces should only need screw holes filled, then a light sand and ready for paint...

    Where there is little curvature or a minimal need for torturing the panel, you can laminate both sides of the panel leaving peelply finish to the inside of the hull ready for bulkhead taping... simple curves can be kerf cut one side then taped over etc...

    The main drawback is having a full size melamine table and difficulties with tight compound curvature... These areas will simply be hand laminated or infused rather than dealing with dart cuts and will happen over vertical foam strip planking in the same female forma frame thats holding everything in shape, the edges recessed 2mm to allow a fairing channel where the hand laminating overlaps/joins...

    Doesnt really help you with your hulls right now, but it might help you later with your deck or cabin etc... id also consider using vinyl ester instead of epoxy, the infusion vinyls are almost as good as infusion epoxy anyway, plus you can control the gel times almost infinately by adding inhibitor... last i played with it, i had a 6hr gel time which allowed me plenty of time and not have to rush things... i also had a nifty way of thinning and spraying waxed polyester resin straight onto the cured vinylester peelply surface for a perfect finish on that side too, although you must have zero pinholes for it to be blemish free... i was doing a clear carbon fnished part in this instance, one side finished off the table, the topside only needing the peelply removed, edges trimmed up, then spray on the finish coat of PE resin for a tough UV protection... i havnt tried spraying an infusion epoxy which should be thin enough to lay flat like a 2pk PU paint also... its on my 'need to try this' list... have i got you thinking yet? :)

    Only suggestion i can offer for your infusion leaks, is to go ahead and apply a skim coat of epoxy bog to the entire perimeter for the bag to seal to, i wouldnt trust a tacky tape seal directly onto foam... then id take a V shaped router bit to all the foam joins and rebog all these in the fashion that henny from FRAM yachting does it (the youtube vids of the Farrier F39 build)... these are the only places it could possibly leak from IMHO, assuming the rest of the bag is sound...
  7. CatBuilder

    CatBuilder Previous Member

    Hmmm. Did that already. I routed out the smaller cracks and re filled with more bog. I have epoxy on any rough edges.

    The tape sticks to corecell just fine. Did the last hull exterior by sticking to foam and no leaks.

    I'm pretty sure my core and those router cut, bog filled gaps are leaking. You can even see where the bag is loose over several areas.
  8. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Nice pix.
    People will be jealous of your hulls too.
  9. CatBuilder

    CatBuilder Previous Member

    The update is, I'm tearing the bag off and hand laminating the inside, saving the already cut infusion materials for the outside of the same hull section. The core leaks horribly and i can't get it to stop.

  10. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    Sounds like a smart move . Rick
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