Custom Extended Swim Platform

Discussion in 'Boatbuilding' started by tpenfield, Jan 8, 2019.

  1. tpenfield
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    tpenfield Senior Member

    Yes, good observation. :cool:

    As I was cutting the foam strips I was thinking to myself . . . "how am I going to weave glass cloth between these things without causing a train wreck :eek: " .

    I decided to cut the glass cloth into strips and lay the cloth down every other strip as pictured below. That way each piece of glass cloth can 'self adjust' to the shape it needs without bunching up or causing wrinkles.

    Navtruss1.png

    In the picture above, the CSM and 1708 will be infused first. Then a thin coat of VE resin will be laid down. While the resin is still liquid, the foam strips and cloth strips will be laid down. Then it will be vacuum bagged while it cures, keeping everything nice & tight.

    In my VE resin tests the MCP hardner had a pot life of about 90 minutes. I figure that I will have at least that amount of time to get things laid out and the vacuum bag in place. . . . probably will be more like 60 minutes.

    Then the final laminates will be put over the navtruss core and infused.
     
  2. fallguy
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    fallguy Senior Member

    I still don't understand the reason for using strips and glass. At first, I thought you were going to infuse and so needed the glass for resin channels. My opinion is that it will be rather difficult to get the glass strips and foam strips to end up void free... there will simply be some place where the glass either wants to overlap or kinks or leaves a ledge. Unfortunately, I don't have enough experience in mould design to really critique it well, just some experience wet bagging where I would worry about it working well under vac. The strips will have a tendency to have variances in the spaces between in the final product just as they appear in the picture. I would have preferred a single piece of foam. The requirement for the way you are doing it is a lot of resin, imo. Anytime I try to get too fancy in wet bagging; it is trouble. If you are indeed wet bagging, then you'd need to have like 2-3 minutes per piece of glass unless you have staff wetting out and you are just laying.. Anyhow, work through it first a bit to see if you think it doable. I have realized a few times my plan can't work the way I wanted and fortunately, it has usually been before the attempt.
     
  3. fallguy
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    fallguy Senior Member

    If you used a single piece of foam, you could easily infill any edge issues with thixo prior to your last layer..you don't want foam edges per se.

    If you are still infusing that section, disregard my comments.

    You aren't going to get much strength from 7.5 oz glass on 45s if that is the idea..flexural rigidity comes from verticals (90s)

    Frankly, I would think a vertical glue joint would be stronger than the glass on 45s

    test it> the valid test would be the 7.5 ounce glass weaved over a couple of strips cut as you did versus the 7.5 ounce glass over a couple of strips glassed to each other on verticals...maybe you already found some test data....I just have some doubt

    all the best and hope for your success, despite my pushbacks
     
  4. tpenfield
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    tpenfield Senior Member

    Yes, a single piece of core material is no longer in the cards. :)

    I decided not to do a single infusion because of a lack of experience with more complex infusions. I think I have a better chance at success doing an initial infusion of the outer layers of glass, then lay down the core, vacuum bag it, and then do a second infusion of the final layers of glass. During the initial infusion, I'll have a better idea if there are any dry spots and can take some corrective action.

    In laying down the core pieces, I have them all numbered as to where they go, so it should go fast. I'm not planning on wetting out the cloth pieces - they will just soak up the resin that I lay down before the core pieces are placed. Then they will get additional resin from the top side during the final infusion.

    Overall, trying to match the approach to what I think I can achieve.
     
    Last edited: Apr 10, 2019
  5. tpenfield
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    tpenfield Senior Member

    Using my previous artwork, here are a couple of images depicting the lamination plan and the infusions.

    Navtruss2.png

    Navtruss3.png

    Not sure which structure is stronger - an "I" Core (90˚ angles) or a "Navtruss" (45˚ angles) . . . It doesn't really matter . . .they are both stronger than a solid core. My thoughts were that the 45˚ bevels would be easier for the glass weave and would tend to have fewer voids under the vacuum pressure.
     
  6. fallguy
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    fallguy Senior Member

    It is going to be tricky to get that all in the bag before gel. You have to wetout the core pieces and the glass and lay it and bag it.

    Just work out how long things take and be ready for the real job. You might need a helper to either wetout glass or wetout core pieces.
     
  7. tpenfield
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    tpenfield Senior Member

    Game plan for the upcoming weekend is to make the 2 hatches from their respective molds and prep the main platform mold, then get the gelcoat in the mold.

    Not sure I'll have time for much else. :rolleyes:

    Time has been flying by on this project, but my hopes are now that the molds are made, I can move things along. :)
     
  8. tpenfield
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    tpenfield Senior Member

    Starting on the actual parts . . .

    Here are the ladder hatch molds with gelcoat applied.

    IMG_2379B.jpg

    I plan of doing the glass/resin and vacuum bagging tomorrow.
     
  9. tpenfield
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    tpenfield Senior Member

    PVA is on the platform mold.

    IMG_2384.JPG

    I'll be gelcoating it tomorrow. :)
     
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  10. tpenfield
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    tpenfield Senior Member

    Hatches are made . . . not sure how well they will come out.

    I laid out the glass in the molds . . .
    IMG_2386.JPG

    then poured in the resin and vacuum bagged the mold.

    I was having trouble with a leak and could not hold much vacuum. The first mold was a tough go, the second one was a bit better.
    IMG_2392.JPG

    Of course with resin infusion, you can work out any vacuum issues prior to committing to the resin. With vacuum bagging you are committed from the get-go.

    Hopefully these 2 hatches will come out OK. They will sit in the molds for a few days.
     
    Last edited: Apr 14, 2019
  11. fallguy
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    fallguy Senior Member

    I would use release film and breather.

    Did you make a bag first?

    Resin gets ona bag and sealing is impossible.
     
  12. tpenfield
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    tpenfield Senior Member

    Hopefully, I won't have to re-do the hatches, but I'll know more in a few days. Resin came through & around the release film and made a mess. Sort of a learning moment for me :rolleyes:

    There was 1 layer of CSM, followed by 2 layers of DBM1708 in the hatch mold vacuum bagging. It seemed like the DBM1708 was a bit tough for the resin to penetrate. :eek: I thought CSM and Woven Roving were tougher for resin flow. :confused:

    Pretty much the same glass layup is planned for the first infusion of the platform, which will be infused, rather than merely vacuum bagged. I am wondering if I should re-think the layup? :( :oops:
     
  13. ondarvr
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    ondarvr Senior Member

    Did you find VE infusion resin, or laminating resin?

    VE tends to be a thicker and stickier resin, so working with the laminating version can be tougher.
     
  14. tpenfield
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    tpenfield Senior Member

    It was laminating resin, so that may have been the issue. I have been using the MCP catalyst which really helps with the working time and allows for a longer saturation time. I'll see what I can do for platform . . . it seems like I bought the wrong kind of resin, not thinking of the details of infusion.

    Based on your comments @ondarvr , I may infuse just a single layer of 1708 (along with the CSM base) then do more hand layup on the additional laminations. Thanks, very helpful.
     

  15. fallguy
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    fallguy Senior Member

    Normally, I put half the resin under. Then work it a bit with a bubble buster then pour the rest atop, but not sure about that and gelcoat.

    Sadly, I can't help with infusion flow. I am eager to learn about it. It is my crude understanding that csm inhibits flow and it makes sense as the csm is sort of haphazard in direction. For good flow; channels in the fabric would seem best.
     
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