Fiberglassing 101

I have had very limited fiberglass experience in my life.  I did build a stitch’n’glue kayak about 12 years ago.  This gave me my first and only experience with fiberglass.  I knew the rudder and centerboard would be a good reintroduction to this incredible material.  I also hoped to learn a few things with these foils that would serve me later as I glass the hull and plank joints. With that as a backdrop, I’ll try to explain what I have learned glassing the foils.   DSC00001This is the leading edge of the rudder.  Notice how the fiberglass doesn’t wrap around and lay flat against the opposite side of the foil.  I cut the glass too short, not allowing enough wrap around to secure the edge fibers from lifting up.  DSC00004 It would have been nice to have a little longer wrap here.DSC00003The trailing edge of the rudder, with its sharp radius was very difficult to wrap.  Try as I might, I was not successful in coaxing this edge to stay down.DSC00005 The good news is that with the Shinto rasp, these edges cleaned up very nicely.  I have bragged a lot about this little rasp, It continues to amaze me.  DSC00002 Leading edge after clean up.DSC00006 Even the flat sides have an almost imperceptibly smooth edge of glass.DSC00007DSC00008 On the second side, I cut the glass about 1.5″- 2″ longer than the edge.  This allowed enough wrap around material to secure the raw fiberglass edge.  I also made a few small cut around the tip to allow the glass to lay flat on the opposite side.  DSC00010 If you drape the glass over the foil and smooth it out with your hands, it seems to almost take the desired shape of the foil.  I also think it helps to let the draped glass stay in this shape for some time if possible.  DSC00009I again cut the glass around the sharp corners for a smooth underside wrap of the glass.DSC00011This second side went much better with regard to the fiberglass wrapping over the edge.  The longer edge proved very effective.  This will in effect give 3-4 layers of glass on all the lower edges.

Summary:

  1. Drape the glass early, smoothing it with your hands and let it sit if possible.
  2. Make the first epoxy coat very thin for good glass to wood adhesion.
  3. Fill the weave with additional epoxy coat within 8 hours for good adhesion to the glass (remember, you cannot sand the initial thin coat without cutting into the glass, therefor the second coat must be applied within the proper adhesion window of the first coat, approximately 8 hours).
  4. 2″ glass overlap allows for very effective wrapping of glass, even over tight radius edges.
  5. Take your time and enjoy this.  It is an amazing process to behold and experience.
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