The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Wood as a Structural Material
CHAPTER
3
We have long been passionate about wood as an engineering material. This chapter highlights our convictions,
with supporting data, that wood has a rightful place among engineering materials.
References are included to the extensive testing programs we participated in from the late 1970s through the
mid-1990s. <strong>The</strong>se test programs characterized the mechanical behavior of Douglas fir veneer/WEST SYSTEM ®
laminate used in the fabrication of wind turbine blades. <strong>The</strong> testing, in its narrowest interpretation, provided
definitive design and fabrication guidelines for our blade manufacturing business. In its broadest interpretation,
the testing sensitized us to the incredible potential for wood as an engineering material.
As proponents of wood/epoxy technology, we believe this composite shares all the synergistic qualities of
any successful composite technology—the combination is superior to the individual elements. Wood, as
one of our oldest engineering materials, carries all the positive feelings that centuries of familiarity with its
strength, stiffness, and easy working properties provide, along with the misgivings, equally familiar, of its
natural weaknesses. Epoxy in combination with wood accentuates the positive properties and reduces the
weaknesses.
This book, as originally written, set out an emerging technology that shared many of the traditional uses and
choices of wood in boatbuilding. In some areas, we departed from these traditions—we suggest more use of
softwoods or less rot-resistant species, and we suggest construction techniques optimized for gluing rather
than fastening.
Much has changed in the world of wood over the twenty-five years since this book was originally published.
<strong>The</strong> population of the world has increased from 4.3 to 6.3 billion. That increased population has stressed the
traditional sources of supply and made environmental consciousness, once an individual choice, now influential
in broad areas of public policy around the world. Deforestation, reforestation, national forest products
policies, tree plantations, forest monocultures, and biodiversity are important issues that influence the choice,
availability, and price of many wood species.
At the same time, the general populace has become much less knowledgeable about wood. Boat manufacturers
advertise their products as “wood-free,” ignorant of how to use the material properties of wood to
their advantage.
This chapter provides a primer on how to consider the fundamental properties of wood as an engineering
material, irrespective of species. Wood/epoxy composite construction allows for broad substitution of wood
species based on balancing density, strength, and price. You can use less durable woods (if their other
mechanical properties are important to you) by addressing the durability issue in a different fashion. Consider
how broadly balsa is used in modern boatbuilding—unthinkable forty or fifty years ago. Encapsulated in a
properly fabricated plastic composite, balsa has advantageous properties.
If you find it difficult to obtain certain kinds of wood, be bold and substitute. But do your homework and make
test samples to prove to yourself the viability of these alternative species and how you may introduce them
into your project. Some quite extraordinary boats have been built out of non-traditional boatbuilding species.