The LOOSE GOOSE Custom Build

Discussion in 'Boatbuilding' started by NeverYachtz, Aug 3, 2013.

  1. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    Say I go with the 2 external layers of CF (200g./7oz.).

    Would 3.7 or 5.6 oz. S-glass be the best to fill in the rest of the hull?

    Also, anyone have any good recommendations on epoxy? I can get West Systems for cheap at work (West Marine).
     
  2. rwatson
    Joined: Aug 2007
    Posts: 5,869
    Likes: 301, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    I am not quite sure what you have in mind when you say 'external' layers.

    I think you were going to create a mold, and layup in the mold, which would mean that there is only one layer however thick, not an internal and an external layer.

    Are you planning on using some core material perhaps ?

    From my recent large model building experience, 1 layer of S glass may be sufficient in the much of the hull with such a curved shape. The only down side will be pulling such a thinly laid hull out of a mold.

    Lightness will be a prime consideration for this boat. I would try one layer at first, but get some 2 or 3 mm thick high density foam sheet, and cut ribs and re-inforcing pads out of it ( using vacuum for easiness of application ) for areas that dont seem stiff enough, or may encounter severe impact. Put a layer of 200g glass over the top of any foam you place. For hull locations that are just to hard to apply foam to, mix an epoxy and microballoon paste, and lay it in the crevices and other problem areas before glassing over. The narrow bow ( stem ) space is a prime example.

    If you do this before you de-mould, the hull will be plenty strong enough.

    West System epoxy will be fine. Its the glass cloth that will be the experimental thing.

    I found that 2 layers of 200gm, were still quite flexible, and comparatively heavy, which is not what you may want. With the foam in between the layers, the extra stiffness was amazing.

    Once you get it out of the mould, if you find that there are parts of the hull that seem to 'floppy', you can put the hull back in, and add section of re-inforcing as you like. The joining of the superstructure and the hull will add a great deal of rigidity to the whole boat.

    It would be well worth the bit of extra expense if you want to get an excellent result.
     

    Attached Files:

  3. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    I meant exterior layers of fabric, which are the first layers placed into the mold before bagging, resulting in the outer layers of the hull after being removed from the mold.

    I like those foam ribs.

    Another question relating to the plug:

    [​IMG]

    It's been re-coated a few times with the Styropoxy and sanded with 60 grit. I was going to sand it again with 400 and then a really high grit wet-sand. Then apply the wax mold release and bag it.

    However, could I paint it with some sort of epoxy or paint prior to bagging? This would result in a perfectly smooth glossy finish which the sanding might not accomplish. The styropoxy never lays out smoothly so I can't use that because the hull would be glossy but bumpy. Any ideas???
     
  4. rwatson
    Joined: Aug 2007
    Posts: 5,869
    Likes: 301, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    OK. I understand. Certainly, 2 layer of 200 gsm will be strong enough. I am only worried about the weight v stiffness result. If you can put a whole lot of lightweight stringers and frames and microballoon pockets between the layers, then the stiffness will be fine. The 2 layers alone will stand some pretty heavy impacts. Do make a couple of test bits at least 12" square to get the 'feel' of it. Put some 'stringers' in one bit to check out the stiffening effect.


    Hmmm. I am not sure what styropoxy is, but a coat or 2 of epoxy that you can sand very smooth would be a good way to go I reckon.

    Roll the layers on, then tip with a foam brush. An hour with sanding blocks and wet and dry sandpaper will cure all mistakes - that might even be the secret for the styropoxy. Sanding without a firm block behind it will always result in ripples.
     
  5. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 197, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    You should finish the plug to the finish you want on the boats. Somebody else can maybe tell you how to get a good finish on styrofoam, but I don't know how. Maybe some high build primer, work that down and then some sprayed paint.

    Wax and PVA.

    You want to build the mold like regular molds. There would be no harm in using polyester as then you could use tooling gelcoat on it. There's no sense in vacuum bagging the mold either. You don't need a lightweight, high glass to resin ratio plus vacuum/pressure increase the chances of the mold sticking to the plug. I also wonder about the styrofoam holding up to or distorting under a high vacuum.

    That sharp corner on the sheer on the bow area will take a little finesse to mold to, it's easy enough though. I'm wondering if you want it like that though anyways, it doesn't seem very aerodynamic for 60 mph.

    Uhm, you do know about having positive draft in the plug so the mold doesn't get locked on it or the parts don't get locked in the mold?

    Actually, disregard what I said about polyester and gelcoat, as the odds are the styrene will melt your styrofoam plug.
     
    Last edited: Sep 2, 2013
  6. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    That's why I was wondering about a glossy paint that the wax and pva will go on well with. I want the plug to be glossy and perfect. More so than I can accomplish with just wet sanding.

    The Styrofoam will be completely covered by the styropoxy (blue stuff). It's pretty hard so the vacuum shouldn't hurt it. I've been putting my body weight on it while sanding with no problems.

    The black line shown on the picture is where the foam will be cut. Then it will be glued to a backboard of MDF. This is just the deck btw, the hull plug is in previous photos. The vertical side portion of the final deck part will be cut off before the deck is attached to the hull.
     
  7. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    The styropoxy sands to a flat surface, but definitely requires a block and elbow grease.

    If I sanded the plug with say 1200 grit, would it result in a glossy finished mold and part? If so then I don't need to paint the plug to make it glossy.

    Sorry for the confusion, I've never made a plug/mold before so I'm unsure of the finishing that goes into it.
     
  8. rwatson
    Joined: Aug 2007
    Posts: 5,869
    Likes: 301, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Yes, you dont even have to go to 1200, anything over 500 will probably do the job.

    The good thing about having solid colour, is that you can see any bad bits.

    You can get colours to mix into epoxy, but they end up semi transparent. Thats why special mould gelcoat is handy.

    With your project, I would spraypaint the plug, so you can detect any flaws before you ,make the mould. Its true, paint isnt as tough as epoxy, but it will be plenty hard enough after you have waxed and pva'd the surface.

    I presume you are making a female mould first, before pulling a hull.
     
  9. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 197, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    If your last step is sanding, to get it gloss shiny you have to go to polishing and buffing compounds with polishing/buffing wheels. Go try 1200 grit on a glossy paint job, like your neighbors car, and you'll see what I mean.

    If you want to turn out glossy hulls, you have to have a glossy mold and that is easiest achieved by a glossy plug. Polishing a positive convex surface like a plug is much easier than polishing a concave surface like the inside of a female mold. The shinier everything is the less problems you have with part release.
     
  10. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 197, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    If your last step is sanding, to get it gloss shiny you have to go to polishing and buffing compounds with polishing/buffing wheels. Go try 1200 grit on a glossy paint job, like your neighbors car, and you'll see what I mean.

    If you want to turn out glossy hulls, you have to have a glossy mold and that is easiest achieved by a glossy plug. Polishing a positive convex surface like a plug is much easier than polishing a negative concave surface like the inside of a female mold. The shinier everything is the less problems you have with part release.

    As rwatson says, if you get the plug glossy, that's about the only and best way to see if you have the plug 'fair'. Reflections of lights, fluorescent lights etc will show any ripples or bumps, hollows etc. The darker the color the better to see imperfections.
     
  11. rwatson
    Joined: Aug 2007
    Posts: 5,869
    Likes: 301, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member


    yes, thats good. But no more than 500 grit on the epoxy, so the paint has something to grab on to.
     
  12. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    Haha yeah I get the idea, no need to mess up the neighbor's Mustang :D

    Would an easier alternative to polishing and buffing be using a glossy paint? I know Interlux Brightside (which I can get cheap at work) has a durable glossy finish. Then I put a lot of coats of wax mold release over that, pva, and call it good? I get what you're saying about the female mold. I don't want to touch that, so the plug has to be perfect... for a perfect mold... for a perfect part.

    Thanks for all the info! Now I just need some time to work on it. My last semester just started today though so it's going to be slow going.
     
  13. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 197, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Glossy paint works. I made a number of plugs using all auto products, bondo, high build primers, 1 part auto enamels, then wax and pva. Exactly the same as any body repair work. I usually lightly buffed the mold, as the hand applied PVA would leave an almost invisible impression.

    I made one mold very quickly of a hand hewn oak beam. I put some painters plastic overspray drop cloth over the beam, using the kind that is real thin like a dry cleaning bag, .2 mil or something. Saran wrap would have worked. I built a frame around the edge and then hooked up a vacuum pump to the plastic (an old refrigerator compressor) which pulled it tight to the beam. I mixed up some plaster of Paris and poured that in the frame. When that cooled down I separated it from the beam and sprayed it with some $1 a can spray enamel, waxed it up and laminated a fiberglass replica beam. Nothing stuck anywhere and all the detail was there, you could still see all the tiny nicks in the cutting edge of the adze, separate splinters, growth rings etc.
     
  14. NeverYachtz
    Joined: Aug 2013
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: United States

    NeverYachtz Junior Member

    The deck and hull plugs are almost ready to be mounted. I have mdf board from Home Depot that should provide strong and flat support for the foam.

    [​IMG]
     

  15. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 197, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Don't forget the draft. It looks to me like the bow has a negative draft that might lock the mold on the plug or the parts in the mold.

    It looks to be the same on those steps on the hull bottom.

    I can't tell about the transom.
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.