The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Synthetic Fibers and WEST SYSTEM ®
<strong>The</strong> term synthetic fiber includes fiberglass (glass fiber), carbon (graphite) fiber, aramids (Kevlar),
and low-modulus fibers like Dynel and polypropylene. <strong>The</strong>se fibers share similarities with wood, such
as being strong parallel to the fiber direction and weaker off-axis. In most cases, the density of synthetic
fibers is greater than that of wood.
When this book was written in 1979, the materials and techniques it described were the “cutting edge” of
boat construction. <strong>The</strong> use of wood was in serious decline, and many boats were being built with fiberglass
and polyester resins. Because a solid fiberglass laminate is several times heavier than an equal volume of
a wood laminate and not as stiff, <strong>Gougeon</strong> <strong>Brothers</strong> were not keen on using fiberglass. Indeed, our mindset
in the 1970s might be summed up by the sign on the wall in the boatshop: “If God had wanted us to use
fiberglass, He would have created fiberglass trees.”
Nonetheless, we at <strong>Gougeon</strong> <strong>Brothers</strong> did realize the value of synthetic fibers early on. At the time, carbon
fiber and Kevlar were primarily aerospace materials, but we experimented with their uses in boatbuilding,
mostly to reinforce wood locally in areas such as centerboards, rudders, and masts. We also recognized
the value of bonding a woven fabric, such as fiberglass, with epoxy to exterior surfaces of a boat to
increase durability and resist abrasion and impact loads. Not much was known then about how these
synthetic fibers would interact with wood. Time has proved their effectiveness.
<strong>The</strong> technology of manufacturing fiberglass, carbon fiber, Kevlar, and other synthetic fibers has advanced
rapidly. Fiber manufacturers have developed better sizings for their fibers as well as more sophisticated
weaving techniques. Since this book was last revised in 1985, <strong>Gougeon</strong> <strong>Brothers</strong>, Inc. has become a
leading proponent of the use of synthetic fibers. We have developed testing techniques, including the
Hydromat Test Method (ASTM D-6416), that characterize the strength and stiffness of low-density core
sandwich composites as well as solid synthetic fiber laminates. <strong>The</strong>se test data are used by naval architects,
laminate engineers, and composites scientists.
A large volume of data now exists on static and fatigue performance of solid fiberglass and carbon fiber
laminate and sandwich composites. Much of this information is in the public domain and can be found on
Internet sites such as www.sandia.gov and in NASA documents.
We have not tried to incorporate all the new information about synthetic fibers into the 5th edition
because, as explained in the Preface, this book represents a snapshot in time. So this chapter remains
largely unchanged from when it was written except to reflect the current WEST SYSTEM ® product line and
to discuss special application techniques for clear finishing. Nonetheless, it provides an excellent
overview of synthetic fibers and their use with WEST SYSTEM epoxy.
<strong>The</strong>re are many areas in wooden boat construction
where we and many others have successfully used
synthetic fibers to augment wood structures and increase
their overall capability. Synthetic fiber augmentation has
been particularly effective in areas where constrained
geometry is necessary. Centerboards, rudders, and
masts are all components where denser, high-strength
Epoxy
CHAPTER
13
fibers can be incorporated with wood to improve
performance.
For hulls, the fiberglass-covered, wood strip composite
process described in Chapter 23 has proved to be an
excellent mating of wood and synthetic fibers. In more
typical wood/WEST SYSTEM Brand epoxy construction,
synthetic fibers are regularly used to increase exterior