Composite foam board sandwich technique

Discussion in 'Boat Design' started by scottperkinsusa, May 23, 2004.

  1. scottperkinsusa
    Joined: May 2004
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Atlanta

    scottperkinsusa Junior Member

    I am thinking of building a very basic Prioque type
    flat bottom hull with foam board and covered with cloth
    and resin.

    Basically I think any design programs for plywood
    or steel or aluminum sheet should be able to work
    with foam board as long as the thickness can be dealt

    Maybe the Stitch and glue method would be appropriate.

    I have not been able to find any specific internet sites
    dealing with people builiding boats with this
    composite foam board technique
    but there must be many and I want to explore all the
    materials choices between the foams and resins
    and cloth etc to choose from.

    If anyoen knows of any pertinent links I sure would
    appreciate them sharing the info.
  2. Chris Krumm
    Joined: Aug 2003
    Posts: 92
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: St. Paul, MN

    Chris Krumm Junior Member

    If you're thinking of making a sandwich composite hull using low density (2#/cubic foot) extruded polystyrene or urethane, basically insulation board, think again. SHeer strength, friability, and compression strength are too low to bother with for a boat hull, deck , or cabin structure. Stick with stitch and glue plywood if you want a simple, epoxy boat and you're new to this.

    Foam cores such as Corecell as core materials are a different story - well worth looking at for lightweight sandwich composite hulls. But again, why bother for a pirogue?

    Chris Krumm
  3. scottperkinsusa
    Joined: May 2004
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Atlanta

    scottperkinsusa Junior Member

    foam composite sandwich components

    Thanks for the suggestions. I need other recommended
    components in addition to Corecell and links to others
    using composite to build their boat hulls.

    Are there any websites featuring composite boat construction
    where I can discuss resins and foam alternatives etc. ?

    By Piroque I meant hull of simple design. actually I need
    a higher bouyancy hull for my amphib airplane.
    see photo

    Is Corecell the undisputed leader in boat hull building?
    or are there other competitors ?



    Attached Files:

  4. sorenfdk
    Joined: Feb 2002
    Posts: 511
    Likes: 27, Points: 28, Legacy Rep: 394
    Location: Denmark

    sorenfdk Yacht Designer

    Hi Scott,

    As they would say in the UK: "Fancy meeting you here!"

    CoreCell is not the undisputed leader in boat hull building. Divinycell, made by DIAB, is up there too!

    Their websites are:


    On both sites you can download technical litterature that might be of interest.

    In another thread, you've asked about software. Here's another possibility: Hullform 9S. It's freeware and can be downloaded from the website of Blue Peter Marine Systems - I'm sorry, but I don't have the URL.

    Best regards,
    Søren Flening (another Profili-user!)
  5. JR-Shine
    Joined: May 2004
    Posts: 341
    Likes: 4, Points: 18, Legacy Rep: 54
    Location: Vero Beach, FL

    JR-Shine SHINE

  6. SeaDrive
    Joined: Feb 2004
    Posts: 223
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Connecticut

    SeaDrive Senior Member

    In your place, I would check out sources for making surfboards. That is the biggest use of foam core construction by amateurs, as best I know.
  7. Vanbokklen
    Joined: Jun 2004
    Posts: 15
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: California

    Vanbokklen Junior Member

    Are your prices $30++ a sheet more than a place like or am I just reading your pricing wrong?
  8. JR-Shine
    Joined: May 2004
    Posts: 341
    Likes: 4, Points: 18, Legacy Rep: 54
    Location: Vero Beach, FL

    JR-Shine SHINE

    I dont know what they have, but make sure you are comparing the same density, thickness, and plain sheet or grid scored. The grid scored sheets are much smaller. We are one of the only places I have found on the web that sells Divinycell per sheet. If you need a case or more, I can give better deals. We also will pre-cut the foam core so it can be shipped UPS.

    Hope that helps

  9. Ilan Voyager
    Joined: May 2004
    Posts: 1,222
    Likes: 143, Points: 63, Legacy Rep: 758
    Location: Cancun Mexico

    Ilan Voyager Senior Member

    my God it's an hydravion... my answer will be simple:
    1/ Pirogue shape is not suitable for a boat plane. The plane will never take off, and add some stability problems while taxiing. After 80 years of trials, a few thousands dead pilots and dozens of fired engineers, the answer is; stepped hull very carefully designed.

    Make a search in the Nasa internet site, they have good doc. Buy a scientific calculator and take some courses for Excel programming. You'll need it.

    2/ Stresses are very high on hydravion. Heavy PVC foam needed, at least 100 kg/m3 at the bottom. Imagine the stresses; you let fall down a hull in the water at 35 miles an hour... That's true engineering work for the scantlings.

    Think well over all that. You'll have probably problems of certification, surely resale value loss and an insurance mess: a problem with an insurance company and its lawyers is worst than death in the States.

    Better to contact the company which makes this ultralight kit, and discuss with them. Or hire a aeronautical engineer...

    And finally, you'll be the first actor and stunt in the movie "The man who died in the landing crash of his hydravion". A very bad movie...
  10. Karsten
    Joined: Jun 2004
    Posts: 184
    Likes: 8, Points: 0, Legacy Rep: 33
    Location: Sydney

    Karsten Senior Member

    Have a look at They make all sorts of panels with different cores and face materials for boats. For aircraft structures like floor boards, galleys and overhead bins they use "Fibrelam" which used to be made by ciba gigy? It's basically a honeycomb core with fibreglass or carbon skins. They are certified for aircraft structures.
    Checking with the designer before changing the material is always a good idea.

  11. gonzo
    Joined: Aug 2002
    Posts: 13,944
    Likes: 485, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    When we were teenagers and poor, we made surfboards of white styrofoam, polyester resin and mat. The trick to use polyester over styrofoam, is a layer of paper (newspaper) glued with white or yellow carpenter's glue. They took a lot of abuse and we could patch them fast enough not to loose to many waves.

  12. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I'm glad someone got around to the real message needed here, you're not going to design a successful hull on this thing without the engineering necessary to be successful (thanks Ilan)

    Step hulls are not easy to design, without a considerable data base and a good bit of experience. This hull form is the only one that will allow you to break the suction the hull will have with the water at flying speed. The step, it's placement, rise and details are the reason it works on floats and fuselages of water born aircraft. You'll notice that these hull forms, both boats and aircraft have very similar shaped forms. The step location and arrangement are all very similar and the reason is, it works. Other styles of form have been tried, but we keep coming back to the traditional shapes seen, because it is the most reliable, effective and buildable fashion conceived. There may be better ideas in the offing, but until someone can prove repeated takeoffs without a hitch and can qualify that with data and the appropriate math, we'll stick with what is known to work.
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.