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You are ready to apply the fiberglass covering to the boat you are building. All of the screw holes and imperfections have been filled and sanded smooth. You even took great care to minimize sanding over the Douglas-fir plywood surface as you knew that would accentuate the grain and cause more work to finish; the filled areas were hand sanded. The area has been cleaned and you’re ready to fiberglass…or are you?


Are all corners radiused? Fiberglass will not easily form around sharp corners, so be sure they’re well rounded. And, if you have any interior corners (such as on a catamaran), radius the junction with thickened epoxy or possibly a wooden cant strip.


What about preparing for the appendages? The bow eye has a flat base as it contacts the bow and the stem is rounded. That area must be flattened before fiberglass is applied. Otherwise, you will need to cut into the fiberglass; drill the hole and fit the bow eye before fiberglassing.


Does the boat have an outer keel or skeg? If the bottom has a vee, the area will need to be flattened. Or maybe you will cut a vee in the underside of the member to match that of the boat. But the angle is ever-changing and mostly impractical to pre-cut. Or perhaps, the vee is so great that it can’t practically be leveled. In that case, as much of the area as practical is flattened.


Thickened epoxy is applied to the area and the skeg or keel, with contact surface covered with sheet plastic, is laid on the surface, forced down, and surplus resin faired from the keel or skeg to the planking. After cure, the skeg is removed. The area is NOW properly prepared BEFORE fiberglass is applied.


The same method is used for the skid fin (if used) or the strut on an inboard.


Think! Consider any hole or fittings that must be installed. Cutting into the finished fiberglass will require patching. And, if you have painted the surface before preparation for the fittings you have a mess (lotta work) on your hands.


The word “think” is a good word to keep in mind in any boatbuilding project. A little time spent in using the noodle instead of the hands will pay off. And, isn’t thinking about the project in advance and solving it in your mind part of the fascination of boatbuilding?

Your Thoughts?

One Response to Think Before You Fiberglass

  1. Glen Witt says:

    Would agree 100% if you never intend to remove the appendage. My reference at the time was for smaller fast boats. Having to remove a keel/skeg one time convinced me that bedding them in mastic is preferable.

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