The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 25 – Compounded Plywood Construction 305
Figure 25-22 A variety of framing, bulkheads, and interior
joinery is employed in supporting the plywood skin in this 35’
trimaran.
Install the bulkheads by using a simple fillet on each
side of the plywood to join it with the hull sides.
Usually, we add low-density filler to the epoxy to make
a lightweight fillet that provides a large bonding surface
area between bulkhead and hull skin. You can further
support the skin by laminating in place ribs manufactured
of thin strips of wood, which will bend easily
around the hull. Stack laminate the wood strips on top
of one another, using alloy staples that can be left in the
laminate.
Another method for skin support is to cut and fit
plywood web frames and fillet them in place, using the
same technique used to install bulkheads and plywood
frames. (See Figure 25-17.) In some situations, stringers
might be needed to give further longitudinal support.
We install stringers by holding them temporarily in
place with staples and cross-braces until the adhesive
cures. When stapling through the skin from the outside
to the stringer, we drill small holes to transfer the inside
stringer location as a guide to stapling. It is also possible
to install stringers on the undeveloped plywood panels
before they are folded up. We do not recommend that
stringers over 1 ⁄2" (12mm) wide be installed on the
unfolded panels because wider stringers will tend to
cause hard spots and overly stress the plywood in that
area during the bending process.
Depending upon the hull being built, you may have
many other interior items to install. <strong>The</strong>se might
include centerboard or daggerboard cases, special
Figure 25-23 A bunk bottom and laminated frames are used
to support this hull skin.
Figure 25-24 Deck beams being installed in a Tornado hull.
Note the notches for a stringer along the centerline.
compartments, and, in larger hulls, interior accommodations.
You can install some interior items after the
hull has been removed from the deck jig; however, you
must install large items now because the deck beams
that are needed to hold the sheer in final position will
be in the way later.
<strong>The</strong> deck beams are always the last items that you
install in the hull before removing the deck jig. Deck
beams serve an important function at this stage by
supporting the upper hull area so that it will not change
shape when you remove the deck jig. <strong>The</strong>re are various
combinations we have used to make successful deck
beams. Generally, we use small leftover pieces of proper
width plywood to construct them. <strong>The</strong> I-beam deck
section (as shown in Figure 25-26) is very easy to