Advise of corecell foam cored deck

Discussion in 'Fiberglass and Composite Boat Building' started by GringoJohn, Apr 21, 2012.

  1. GringoJohn
    Joined: Nov 2010
    Posts: 12
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    I want to build a foam cored deck. I want it to be super light and I am looking at the 16mm corecell foam. It is for a 32 sportfisher single screw. i want to do it vacuum infused on a table in sections (4 by 8 foot) and then stick it together. I was thinking Kevlar and no glass. Is there a reason to put glass? I was also thinking vinylester not epoxy, because we have to repaint it often, Gelcoat here is cheap, and it's a charter boat running 300 trips a year and get's lots of paint. I just bought a 7cfm pump by JB industries, and I have watched every video on Youtube 20 times :). The current floor is plywood sandwiched and all hand laid. It's heavy and has absorbed some water as well. I'm looking for something lighter that is impervious to water, hence the corecell. Ok, now on to the questions.

    1. How many layers of kevlar / glass should I put over and under the foam core.

    2. What is the process to vacuum infuse this? I was thinking do the top layer with a peel ply, peel it and then do a second infusion with the corecell and bottom layer. Any thoughts?

    3. Do I need one of those layers inside that helps the resin infuse?

    4. Is there much advantage to doing the bottom layer with epoxy? Top layer has to be Vinylester because i have to be able to put Gelcoat on it every year (we sand off the old stuff so as not to increase weight.)

    Here's a picture of the boat:
    [​IMG]
     
  2. Herman
    Joined: Oct 2004
    Posts: 1,618
    Likes: 89, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    1. How long is a piece of string? Or in other words: without knowing loads, support structure and mode of support, no-one can help you.

    2. How about infusing it all together?

    3. Depends. You will need some trick to get the resin flowing decently under the foam. You can use a Soric or a unifilo against the core, or press chicken wire into the foam. Also use fabrics or multiaxials that are suitable for infusion. especially woven aramides can be horribly closed and impermeable. On top you can use an infusion mesh. Make sure you perforate the foam every 2" or so, with 1/8" holes, or use so callled "double cut" foam.

    4. No, not really.

    5. I would opt for a 50/50 mixture of glass and aramide, if you insist on using aramides. They are more for shock protection than anything else, and I guess I would just do it in glass.

    6. Make a test panel first.

    7. Think about the seams in your panels before doing anything, You might want to make recesses which you can use to laminate things together.
     
  3. GringoJohn
    Joined: Nov 2010
    Posts: 12
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    Very good question, I guess that is important. I guess the longest unsupported run would be 3 feet between supports. Mostly around 2 feet. I was looking and there is a drastic difference in weight between the kevlar and the glass, but I didn't know it was harder to vacuum infuse. Should I just go with the lightweight glass? Which one in particular (like with vendor)? I am just trying to make up for higher gas prices, so any weight could save a couple of gallons over the course of the year. The foam, I want for insulation to keep deck noise from reaching the fish, and it doesn't seem too heavy :)

    I was planning on doing prefitted pieces (like measure the boat and do pieces that are exact fit as to not have any foam exposed), and I was thinking about putting a 2 inch piece (s) of peel ply on the bottom around the edges to have a ready to stick to recessed place to make the joints. Does that work?

    This all started from a friend who took me out on a foam cored invincible, stupid boat ran 70 knots and when you dropped something on the floor it sounds dead, no resonance. We won the tournament as well, I think all that was related....
     
  4. Herman
    Joined: Oct 2004
    Posts: 1,618
    Likes: 89, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    Ah, fish tournaments. Over here we have the same, but they look like this:

    [​IMG]

    Pretty exciting, huh?

    On the 3A Composites (Core materials) website there is a calculation module in excel that helps you with the amount of laminate needed for a certain thickness and properties of foam.

    I cannot help you with vendors, as I am on the other side of the pond.

    Your peelply trick should work.
     

  5. GringoJohn
    Joined: Nov 2010
    Posts: 12
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Quepos Costa Rica

    GringoJohn Fish Slayer

    Ha, that's great. I'd say that does look a little different! Thanks a ton for the info and all your help. To bad you aren't in the USA or I could buy the materials from you.

    If anybody states side wants to chime in, it could end up in a sale?

    Thanks a ton!
     
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