basics about ring frames

Discussion in 'Fiberglass and Composite Boat Building' started by robwilk37, Aug 27, 2012.

  1. robwilk37
    Joined: Nov 2010
    Posts: 120
    Likes: 3, Points: 18, Legacy Rep: 24
    Location: san diego

    robwilk37 Senior Member

    thinking ahead...

    im rebuilding a 40' heavy fiberglass (polyester) cruising sailboat. these boats were for the most kit built and the one ive got was put together by someone with shall we say limited skills. so after much demolition its time to start getting my head around tabbing in new bulkheads. i dont plan to change their location in any way just replacing with marine fir of greater thickness, tabbing with biax/epoxy, foam spacer at the hull etc. now ive always liked the forepeak layout of the gozzard 41 and will incorporate its design into my boat and this leads me to consider a ring frame to replace the main bulkhead and open things up. as my boat is deck-stepped with a compression post, im thinking 6/4 or thicker, ply laminated frame, lets say 8-10" web thickness across the coach roof then full depth from the side decks down to furniture hight and tied into the step and CP. of course ill have a NA draw it up b4 i jump in. im just thinking ahead about thinks like

    1... is there a benefit to having layers of fiberglass between the ply sheets ?
    2... better to lam up the ply then wrap with biax ala an encapsulated stringer ?
    3... since the CP bears the rig load, does the ring frame really need to be so much more substantial than the original ?

    gozzards video for anyone who wants to have a look :
    http://www.youtube.com/watch?v=SSDy7WiPkcI

    any comments are always appreciated.
     
  2. gonzo
    Joined: Aug 2002
    Posts: 14,586
    Likes: 701, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    That thickness is way too much. A heavy boat should have a rather thick laminate. If you need to spread the load, two frames of 1" separated 8" will be better. Also, creating hard spots or areas is a bad idea. They load the transition too much and create structural problems.
     
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