Composite (glass/foam/glass) For Beginners?

Discussion in 'Fiberglass and Composite Boat Building' started by CatBuilder, Oct 15, 2010.

  1. CatBuilder

    CatBuilder Previous Member

    My wood/epoxy build was a failure due to many issues.

    As one possibility, I am exploring building the same 45 Kurt Hughes design out of glass/foam/glass. He has plans available for those more standard materials.

    Now, I have several questions:

    1) Do I have to build a mold for this type of construction, or can it be done somehow without a mold or plug?

    2) If I have to use a mold or plug, can I just do one sandwich at a time, all by myself or with a helper, using peel ply between layers? Is this the best way to do it?

    3) Is there a FAQ or a website you could recommend where I can see a glass/foam/glass boat being built and that might discuss various ways of building them?

    Thank you. If this is not possible for me (due to skills and labor), I am just buying a boat, but I wanted to give this one last look.
  2. srimes
    Joined: Sep 2008
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    Location: Oregon

    srimes Senior Member

    Can't answer your questions, but it seems to me that if you can't afford to continue on the other then you can't afford to build the same boat this way.

    Or to turn it around, if you can afford to start over then you should be able to continue the project.
  3. CatBuilder

    CatBuilder Previous Member

    Thanks, Srimes.

    I wasn't talking about money above, though...? I was talking about what it's like to build in glass/foam/glass. I'm not sure how the process goes.
  4. apex1

    apex1 Guest

  5. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    You can strip plank the foam over frames. This is a relatively simple way of construction.

    If you can, cut the planks of foam into strips of the desired width, and create a bead and cove on them. (this is relatively simple with a router mounted in a table)

    Start at the deckline (assuming the boat is up-side down) with the first plank. If you wish, you can first screw a wooden batten on the frames, to rest the foam on. Make sure the bead is pointing upwards. Do not bother to make preassembled long strips from the planks. But make sure your joints never align.

    Now apply glue in the bead, and install the next layer. You can temporarily screw the strips in the (tape covered) frames, screw hinges from the rear into the foam and frame, or use a tool to hold the strip: A short piece of tube, fitting in the bead, and with a piece of wood screwed onto it so it forms a T-shaped structure, with the top part of the T being the metal tube. This T can be used to press the foam down, and then screw the T to the frame.

    I recommend using polyester glue, a very lightweight version (for instance ATC Polybond B-33). This cures rapidly (retarders for polyesters can be used if you need more working time). These glues are more easy to sand than epoxy based glue. Afterwards this will not cause any problem with epoxy used for the laminate.

    In certain areas you might end up running strips vertical instead of horizontal. This is no problem. The goal is to close the structure, nothing more.

    After this excercise you need to sand things fair. Use a very coarse sandpaper, grit 36 or 40, on a plank. this prevents you from sanding hollows. Do not overdo this step. It is also not neccesary to sand with finer sandpaper.

    Now you can start laying up your glass. I recommend starting in the rear, laying up all layers, vertically, at once, working your way to the front. When it is time to call it a day, cover the edge that needs a secondary bond with peelply, so the next day you can start without much work. With a bit pf planning you can do this job alone, and with little extra work due to spreading work over multiple days. If possible, order your glass cut in half-width rolls. this saves you a lot of back-breaking lifting. Planning takes care of the overlaps. (spread them around as much as possible)

    After the laminating, you can fair and paint the hull up to the primer. Then build a cradle (on top of the boat), turn things around, and do the inside. This is similar to the outside.

    Oh, if you can trace Andre Bilodeau, he wrote a nice book on strip planking with foam.
  6. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Epoxy/fiberglass over wood is the easiest way to build. If you are having problems with that, a small project to learn boatbuilding is your best bet. Maybe start by building the tender and get the hang of it.
  7. CatBuilder

    CatBuilder Previous Member

    Thanks, guys. I'm reading the Bateau site after I finish this post. Herman, that was a really great overall summary of the process. Thank you. It helps me to understand.

    Gonzo: My problem was the cylinder mold method, not wood/epoxy. The method is the same one seen in the following thread:

    There were many problems for me:

    1) The method develops 15m x 2.5m sections that you must move over a dozen times. These sections cannot be moved without a team of men.
    2) The sections above cannot be built without a team.
    3) The bulkheads and stringers can't be put in without a team.
    4) The hull panels were cracking and splitting (see the thread link above)
    5) I'd rather have a glass/foam/glass boat anyway.

    So, it wasn't so much a problem with the construction. I created 3 good panels of this size (each panel is half a hull). I just can't manage them and they are not of the quality I would have liked to see.

    Vacuum bagging the panels was fun and and easy, for the most part... except when my team tore the bag and destroyed a panel. That wasn't fun. I do not want to build a boat where I need a team of people to help me (and make mistakes). If something goes wrong, I want to be responsible.

    I don't mind a team to turn hulls or do other things, but I'd like to build the boat myself.
  8. Milan
    Joined: Apr 2005
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    Milan Senior Member

    Yes, very good advice, it is easiest and cheapest. And you will need a tender later anyway, so you are not loosing any time.

    I think main problems that you had were difficulties with a vacuum process and handling big, vobley panels?

    Maybe one of the conventional building techniques, (ply and/or strip planking) would work better for you? A bit more time consuming, but a lot less to go wrong, more control of the shape and no big panels to handle.

    Have a look at this for an example – Gerard Dansone’s, (Outremer), 13 meter design for amateurs in ply. Very simple building process and still nice, rounded shapes. Hull cross-section has a simple dory form with a solid foam rounded bottom.

    For strip planking, catmando2 described how it can be done pritty quickly.

    Attached Files:

    1 person likes this.
  9. CatBuilder

    CatBuilder Previous Member

    Ok, I have read and understood foam "strip planking" with help from Richard and Herman's posts.

    The process seems much more manageable to me than the cylinder mold process I was doing. You build in a standard way with a strong back and either male or female mold stations.

    What I like about that technique is that I can handle the sheets of foam myself and glass as Herman mentions. This will produce very exact hulls (dimensionally) and result in hulls I just have to turn over from time to time. Looks like I can do most everything myself this way. Excellent!

    Here is a link to a PDF my designer has created describing this process to beginners like myself:

    Seems a lot easier than wrestling with hull-size pieces of plywood. Not only this, but the resale value should be much better someday with a foam cored boat as compared to a wood/epoxy boat. This is a significant improvement.


    1) The PDF says you can either vacuum bag the parts on the table, or you can resin infuse them. For a one off boat, which do you think is the right way to go? I have never done infusion, but I have bagged panels. Mistakes are very discouraging to me. ha ha ha

    2) I can no longer use the Shop Vac for a pump now, since I'm bagging (or infusing) foam. I have a Robin Air vacuum pump sitting around that I have used for HVAC work on marine refrigerators. Will this pump work for vacuum bagging on the table?


    3) I think I also need proper vacuum bagging material, right? Any suggestions on what I should use? The longest piece to bag will be as long as my hulls (14 meters or 45 feet).

    The boat building project is back on, in foam/glass. Thanks for the help. This is very encouraging!
  10. War Whoop
    Joined: Jun 2003
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    War Whoop Senior Member

    Bead and cove is a quick system, I use Corecell A-600 1" and a simple frame setup you could go 30" on center.
  11. War Whoop
    Joined: Jun 2003
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    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    Forget that toy pump! it will only get you in trouble, the bag size is no problem as the film can be had in most any width and a tacky tape joint will allow complete freedom in that regard.

    Foam ,glass is the best bang for the buck and the right foam is nearly indestructible,I setup the running surfaces of my race cats for @ 65 Psi.

    Here is some Video the desirable core is readily evident. Solid glass and Ply rot core are not shown for the simple reason they fail instantly.

    I use the R63.80 in the past with great results but now the Corecell A-600 is my core of choice for bottoms and the A-500-550 else where
  12. srimes
    Joined: Sep 2008
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    Location: Oregon

    srimes Senior Member

    I don't want to be obtuse, but doesn't that method involve moving hull-length pieces as well? Looks like "shiny side in" has you lining up halves just like CM. With "shiny side out" you're only lining up the topsides, so that would be a little lighter, but they're still hull length.
  13. CatBuilder

    CatBuilder Previous Member

    I was thinking the same thing when I saw that PDF.

    The large panels look annoying, just like in CM.

    There is one very big difference, though:

    I think, from what I can tell... using the shiny side in method these hull panels will only be moved once into place, then joined in place without movement. This becomes your actual hull, so you don't have anywhere near the wrestling you would have with CM.

    I'm thinking if I do the "shiny side in" method, I could create a panel on the table (by myself), then move it into place (with a couple helpers). I would repeat that again for the other half of the hull. Next, I'd joint the "top" (bilge radius) and I'm done. That's it. That's a hull.

    What do you think?
  14. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    I might have said this before but why you wouldn't take a look into strip planked wood/epoxy/biax.. much easier, less sanding, cheaper.. IMO

  15. CatBuilder

    CatBuilder Previous Member

    Well, I'm not sure. That's why I'm here - to learn.

    My boat comes only with plans for cylinder mold (thin plywood formed on a mold, then stitch and glued together) or foam/glass. I was under the assumption that I'd have to pay for a re-design to choose any other material since this is a very light, highly engineered boat.

    Also, aren't foam/glass boats more valuable? They are in the states... is that true everywhere?
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