4 Meter mono foiler project

Discussion in 'Sailboats' started by wind_apparent, Apr 27, 2008.

  1. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    I plan to cover all the flatter area's first, then steam the ply onto the easier curves, anything with a steeper curve than that I plan on using thin strips or 1/4'' bendy ply. I have some scraps of both 1/4'' ply and bendy ply around that I've been messing with a little today, seems like it should work well enough. I think that I would lean more towards the strip method because I'm not sure if the bendy will be able to take the stress loads of the vacpress without getting a bit tweaked. (if anyone out there has any experiance concerning this I'd love to hear more about it)
     
  2. Chris Ostlind

    Chris Ostlind Previous Member

    Strips. Cleanest build, easiest to fair.
     
  3. Paul B

    Paul B Previous Member

    Thanks. I couldn't wrap my head around 1/4" ply bending to that shape.
     
  4. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    Thanks Chris, that's what I've been leaning towards in my mind, I'm sure that's the road I'll take. On a related note, what is everyone's favorite "domestically" (USA) available fairing compound?
     
  5. kprice
    Joined: Oct 2006
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    kprice New Member

    Fairing compound

    Drywall compound, from Home Depot. $10 for 5 gallon pail. Not very durable, but easy to fair.
     
  6. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    I'm thinking epoxy thickened with westsystems microlight.
     
  7. Chris Ostlind

    Chris Ostlind Previous Member

    Epoxy thickened with microballoons will certainly provide the most durable fairing compound, but it will likely also be the most expensive.

    For fairing a tool, I'm thinking that you do not need to go the full tilt route for long term durability unless you are really sure that this particular hull iteration is going to be The One.

    Otherwise, you could use a mid point product, such as Bondo and see how the boat performs as formed-up and then, if you plan to pull more parts from the tool after testing, you can sand away the Bondo and re-fair with epoxy for a longer lasting tool. The part, itself, cares little about what kind of tool material was used, as long as the part can be pulled without messing things up and the surface is the of the quality you expected.

    This is your project and you should do it any way you want. The above are merely options on the table and in no way give meaning to your personal goals.

    Chris Ostlind
    www.lunadadesign.com
     
  8. Doug Lord

    Doug Lord Guest

    First sand* the wood/foam as much as practical. Then I'd suggest coating the wood/foam with poly/vinyl ester laminating resin and then using cabosil and resin as a rough fill-put it on smoothly with no edges.Use a fairing board(like a sanding board but with a sharp edge) to apply. Follow that with bondo(use the board to apply), then sand* with 36 grit and get it nearly perfect then glass with polyester/vinylester resin. Follow that with 20 mills of white(exterior-no wax) gel coat sprayed very fine. Wash with acetone.Then use Blue Dykum mixed 50/50 with acetone to coat the gelcoat(apply with an acetone proof rag). If done right you should be able to start with 80 grit dry paper then proceed to 220 wet sanding.The dykum gives you a sanding guide so you can see that you've sanded the whole part to the same level. Don't go beyond 220 since this is the inside of the hull. Then wax with partall #2 and spray 3 FINE coats of PVA on the part and layup.
    Epoxy will bond to polyester but the reverse is not true if the epoxy is fully cured.Bondo is polyester.You don't need the expense of epoxy on the plug. Fairing the hull is a whole different story. This method of plug construction is simple and relatively inexpensive and can produce a perfect surface.
    * Make sure to sand double diagonally-never just back and forth. Use the longest board you can from the initial sanding on.
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    If you have people who smoke around you when you work with acetone or polyester you will die. If you have machinery that is not ignition protected you will die. I can't stress enough how important it is to use these chemicals in a safe environment! You can use epoxy as the base resin but then you have a VERY time sensitive application regime to follow: if you allow a layer of epoxy to fully cure before applying a subsequent layer the next layer may not bond. This is even more true when using bondo over an epoxy substrate.
    Have you ever worked with epoxy? It doesn't smell like polyester does but epoxy sensitization is very nasty. Be sure to wear gloves and a respirator no matter which way you go.
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    In my experience(50 years of tooling): for a plug polyester is the way to go,for a mold epoxy is the way to go. For all practical purposes your tool is a "plug"-I'd do it with polyester/vinylester to do it at a reasonable cost.
    If you go with epoxy be aware of the critical timeline and look at "super fil" from Aircraft Spruce and Specialty...Also get the Freeman catalog-they have epoxy gel coat and fillers. Try to avoid bondo on an epoxy substrate.
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    If you have to fill the final gelcoat surface DO NOT use bondo- use gel coat plus cabosil.MOST IMPORTANT: Do not mix two different consistencies on a sanding surface-you will CREATE unfairness when you sand rather than eliminating it!. Do not mix your own batches of epox+ micro balloons unless you mix all you will need at the same time: mixing individual batches leads to different consistencies on the sanding surface which leads to unfairness. Try to only use pre mixed fillers. Anything mixed with micro ballons should wind up UNDER the glass to prevent surface problems with the microballoons gassing off.
     
  9. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    Thanks Chris, you win again..........I'll bondo the sucker, I'm pretty sure this is just the beginning as far as SR-71 tooling goes, I've never seen anything I've ever made or been a part of making go from prototype to production without some updating and changes. If I do the impossible and nail this first iteration perfect (ya right) I can always make a fiberglass and foam plug off of this mould the same way I would lay up another hull. If I ever was to make a real tooling set for this thing, I really would want to go full blown female in gelcoat.

    (I really like your open ended way of providing information, thanks again)
     
  10. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    Thanks for the input Doug, If in the future I make a nice female production mould, this info will come in very handy. (and yes I work with epoxy and solvents everyday, thank you for your concern) If you have anymore info on sanding boards and fairing techniques I would love to here about them. (I'm not really sure how I'm going to fair out the super steep inside curve where the hull meets the deck)
     
  11. Doug Lord

    Doug Lord Guest

    Sam, do not let microballoons or similar material wind up on the finished surface or it could lock the part even if you use pva. Make sure you DO use PVA: it will wash off the part leaving no wax residue on the inside.
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    And once again: make sure that - whatever your final surface material is- that is 100% consistent-fillers from the same batch etc. or else the finish will be compromised.
     
  12. Chris Ostlind

    Chris Ostlind Previous Member

    Microballoons can wind up on the surface of a faired tool, or part and it's really no problem as long as you fill the opened microballoon cavities with the chosen resin (epoxy?) and sand smooth. It makes for a perfectly fine tool surface.

    I use Chemlease 15 Sealer on all my tooling and have had wonderful results. This stuff really responds to a heat gun or placing the tool in a heated environment when applying the release agent. (I've even used the sun for smaller part production) evaporates quickly and allows repeated applications (3 coats are suggested from my experience) which insure good part removal success.

    You might also look at this product, Chemlease PMR-90, as it is especially formulated for deep draft part release applications.

    Call this guy:

    PAT MCGILL
    TMI
    6122 Stratler Street
    Salt Lake City, UT 84107

    Phone: 801-265-0111
    Cell: 801-652-2792

    Tell him that you are building a tricked-out foiling boat hull in carbon laminate and ask him if these suggestions will work for your needs. Pat has a terrific understanding of high tech composite part production, to include some of the most hairy carbon procedures for existing aircraft production. He's also a great guy who has a strong background in sailing and will steer you in the right direction.

    Chris
     
  13. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    will do Chris, thanks again..
     
  14. wind_apparent
    Joined: Apr 2008
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    wind_apparent wind driven speed addict

    so would this work for the bondo plug process? bondo the plyskinned moulds that I'm making, than fair them, seal them with the Chemlease 15, than release agent, than go nuts?
     

  15. wind_apparent
    Joined: Apr 2008
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    Location: boulder colorado

    wind_apparent wind driven speed addict

    Finally got to Kinko's today and got everything I needed for the rest of the boat project printed (except for the foredeck stanchions). So I'm cutting everything out. over the next couple days I hope to get the Bulkhead templates mounted and cut out, the Deck mould stanchions glued to MDF and jigsawed, build the Deck mould structural framework, and start skinning the hull mould. Its going to make for a very busy week, but it should make up for the work I didn't get to last week. Sometimes its good to just take a week to think about things and formulate a plan before jumping in to the next phase...........
     

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