Question, NACA Foil in CNC flexible foam

Discussion in 'Boat Design' started by fluknick, Dec 23, 2025.

  1. fluknick
    Joined: Dec 2017
    Posts: 2
    Likes: 0, Points: 1
    Location: Cocoa, Fl

    fluknick Junior Member

    Hey all,
    I haved burned some time on the search feature without success, so now I ask...

    There was a previous thread where an individual used a foam NACA foil surface with a keel core ( I believe, my memory ). The foam was made out of a flexible material- the intent was encapsulating the whole thing in carbon fiber and epoxy.

    My questions:
    If anyone has this thread, could you provide a link ?
    Is anyone aware of what company does CNC foil surfaces ( USA, preferred ) ?
    What flexible foam material would this have been ?

    Thank you in advance.
    Nick
     
  2. Tops
    Joined: Aug 2021
    Posts: 473
    Likes: 139, Points: 43
    Location: Minnesota

    Tops Senior Member

    Welcome to the forum Nick.
    Assuming you meant 'steel core' instead of 'keel core'.

    If the rudder is to have a skeleton and be laminated in carbon and epoxy, I don't know why the foam would need to be flexible.

    Here is how Foss Foam in FL makes them:
    Rudder Construction https://www.newrudders.com/rudder-construction/

    Here is a one-off carbon fiber with CNC cut molds, etc.:
    https://explorecomposites.com/example-projects/building-yacht-rudders/

    Do you have any ins with foam suppliers and machine shops suited for your project?
     
  3. fluknick
    Joined: Dec 2017
    Posts: 2
    Likes: 0, Points: 1
    Location: Cocoa, Fl

    fluknick Junior Member

    I did mean "keel" as it was a lifting keel and I'm not certain the actual material- i only remember the highlights and what bewildered me; mainly the flexible cnc naca foam.
    I wish I could find the thread, but I appreciate the info, definitely.

    Thank you !
    Merry Christmas :)
     
  4. Tops
    Joined: Aug 2021
    Posts: 473
    Likes: 139, Points: 43
    Location: Minnesota

    Tops Senior Member

    Likewise!
    My bad, my brain jumped to rudder instead of keel.
     
  5. BlueBell
    Joined: May 2017
    Posts: 3,413
    Likes: 1,299, Points: 113
    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    @fluknick,

    I don't know the thread but I have done this on a 7 1/2' retractable, swing centre-board.
    I had an XPS foam board CNC'ed to a NACA foil. Epoxy glassed it, hand lay-up.
    Other than some strategic webbing inserts, it was very straight forward.
     

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