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Thread: 3-D demon 44" mono hull build

  1. #1
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    May 2020
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    Default 3-D demon 44" mono hull build

    I received my 3-D demon hull a few weeks ago and I got around to doing some work on it today.

    20211117_164320.jpg

  2. #2
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    May 2020
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    NC
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    The hull is pretty thick and it seems quite strong but I decided to try my hand at some carbon fiber inlay for looks and to get experience for future projects. My shop had some leftover plain weave laying around which was pretty mangled from improper handling (there was lots of warping in the weave). I used the tape and cut method which helped keep it all together as I cut my sheets. I did a little test piece in the cowl and it turned out pretty good.

    20211121_143304.jpg

    So I moved over to the real thing. I laid one of my pieces down the middle between the wooden rails, tacking the tape down with some ca on the sides. This turned out to be a big problem as in some places I had not pushed the cloth down enough so it couldn't sit flush on the bottom of the hull. I realized this as I was already putting down epoxy so I had to cut the cloth down the middle so it would release tension and sit flush. This wasn't too big of a deal because I still had another sheet to lay on top and conceal that mess. My method for wetting out the cloth was to pour some epoxy over, use my mixing stick to spread it out across the cloth, press down everywhere with my foam brush, lay paper towls over to soak up excess epoxy, then brush everywhere with the foam brush to get a nice finish. I then hit it with the heat gun to try to release any remaining bubbles.

    20211121_151842.jpg

    Heres the finished product. Im honestly not super happy with it as there are a lot of lumps and the finish isn't super smooth. There are also a few epoxy puddles that I didn't remove all the way. Everything is still curing right now so Ill see what I think when its all dry.

  3. #3
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    Jun 2009
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    GA
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    There are two ways to do it.

    1) Use a spray adhesive like 3m77. There is debate in whether it interferes with the cure of the epoxy or the adhesion, but the fact that it's up for debate means it's so insignificant that it doesn't really matter for our purposes. You spray the cloth, give it a minute to tack, then work your way from the center outward.

    2) Roll the area with a thin layer of epoxy. Allow this to tack, then apply the cloth.

    Super glue of any kind is not the way to go as you can't assure the material is properly laid, and you impede adhesion (strength) by having a brittle material between your two surfaces of interest.

  4. #4
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    CO
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    "Look good doin' it"
    See the fleet

  5. #5
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    May 2020
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    NC
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    After the epoxy cured, I feel better about my work. The few bubbles where the cloth didnt adhere to the hull are up front far away from the motor mount. The unevenness in the surface is mostly because of the unevenness in the hull. I also brushed a thick layer of epoxy over the wood rails and wood deck supports to make sure they are fully waterproofed.

    The next step is painting. I am going to do the bottom white and the top metallic grey, split at the seam, as I have some left over paint in those colors from a previous project. I also have some nice automotive 2K clear to give a sealed high gloss finish. Sanding is going to be fun as always. Any suggestions on grits to use?
    I also have to do some repair work as well before painting. There are some chips in the gel coat that I will bondo and there is a crack in the nose that I have to patch up.

  6. #6
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    May 2020
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    NC
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    Started work to repaint the hull today. First I patched the chip on the nose of the boat and a small chip on the cowl.
    20211215_113512.jpg
    I sanded the nose chip flat and then started laying down little rectangles of fiberglass cloth prewetted with epoxy, probably about 7 layers.
    20211215_113526.jpg
    For the cowl I laid two pieces of cloth over this chip. I didn't have access to my west systems so I just used some jb clearweld 5 minute epoxy. It seemed to do the trick in a pinch so we'll see how it holds up.

    After everything cured I cut off the excess cloth from the cowl and sanded it flush and started shaping the nose with a dremel grinding wheel.
    20211216_112815.jpg
    20211216_113726.jpg
    20211216_113732.jpg
    Both patches came out really well and I was really happy with how the shape of the nose came out. Once its painted it should look like it was never chipped.

  7. #7
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    May 2020
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    NC
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    I spent today trying to fix some voids on the transom. There were two small bubbles and one large area where paint was chipping away. I used a razor blade to chip off all of the loose paint and I used a Dremel with a fine ball tip to bore out the bubbles a bit so they could accept epoxy.
    20211217_104423.jpg
    I then put tape along the transom to act as sort of a mold to hold the epoxy in for the bubbles and added in epoxy with a toothpick. At first I tried to use epoxy slightly thickened with chopped fiberglass but it was too thick to get all the way into the hole so I just used the epoxy without anything added.
    20211217_110012.jpg
    One of the bubbles didn't get filled in all the way and ended up having more void behind it than I thought so I bored it out all the way and added in more epoxy
    20211217_143458.jpg
    Finally, I laid some slightly thickened epoxy over the large paint chip area
    20211217_143508.jpg
    Next I'll be sanding everything flat and adding glazing putty to any areas with smaller chips or imperfections then I should be ready to prime and paint.

  8. #8
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    May 2020
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    NC
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    20211223_114140.jpg
    I primed the boat up a week ago but I'm back at school now and left the boat at home so I wont be working on it for a while. In the meantime I will be thinking of color schemes for the paintjob and starting to order some parts.
    I'm going to go with a speedmaster 3/16" stinger drive. Apparently back when these boats were made people were running them with submerged drives but I read on the international waters forum that a more modern surface drive would be better for this hull.

  9. #9
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    "Look good doin' it"
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  10. #10
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    NC
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    Its been a while but I got back from college and finished up painting the hull. I decided to do the top in metallic red and the bottom in some metallic grey that I had left over from another project. I'm really happy with how the colors came out and the metallic really pops in the sunlight. There is some orange peel but it was a rattle can job so you cant expect too much. I may add some vinyl decals to add some contrast on top but we'll see.
    20220511_100904.jpg
    20220511_100937.jpg
    20220511_101003.jpg
    20220511_101007.jpg

  11. #11
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    May 2020
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    NC
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    My images keep posting upside down :/

    Well I've ordered some hardware for the boat, speedmaster 3/16 stinger, dual inlet rudder, trim tabs, and carbon fiber turn fins.

    I am still wondering what motor, esc, prop, and cell count I should run, any advice would be great. I am thinking about running a tp 4050 1330kv on 6s. I'm still not sure what size esc is needed for that motor and prop choice for that motor.

  12. #12
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    Dec 2010
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    NY
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    Quote Originally Posted by lilbigmacky View Post
    My images keep posting upside down :/

    Well I've ordered some hardware for the boat, speedmaster 3/16 stinger, dual inlet rudder, trim tabs, and carbon fiber turn fins.

    I am still wondering what motor, esc, prop, and cell count I should run, any advice would be great. I am thinking about running a tp 4050 1330kv on 6s. I'm still not sure what size esc is needed for that motor and prop choice for that motor.
    don't waste to much money on that boat it don't turn worth a $hit but they are fast in the SAW

  13. #13
    Join Date
    Apr 2007
    Location
    AZ
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    Cool

    ?I am still wondering what motor, esc, prop, and cell count I should run, any advice would be great. I am thinking about running a tp 4050 1330kv on 6s. I'm still not sure what size esc is needed for that motor and prop choice for that motor.

    What are your goals for the hull? Speed, type of running, run times? At 44? long it will run best with a larger motor with a lower KV and a larger prop. The setup mentioned above is more suitable for a hull 10? shorter.







    .
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  14. #14
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    May 2020
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    NC
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    Quote Originally Posted by Fluid View Post

    What are your goals for the hull? Speed, type of running, run times? At 44? long it will run best with a larger motor with a lower KV and a larger prop. The setup mentioned above is more suitable for a hull 10? shorter.







    .
    I want to do top speed runs. Ideally I want to have enough run time to get in 5 or more passes. I wanted to do 6s because I have a bunch of 3s packs but I can go with a different cell count if its more ideal.
    Also I think I made a mistake when measuring because the hull is actually 38 inches long.
    Last edited by lilbigmacky; 05-14-2022 at 08:52 PM.

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