The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

290 Hull Construction Methods
Composite Chine Construction
Many smaller boats and some larger ones have been
built with no chine log at all. Instead, the plywood
panels are joined with a composite chine made of fiberglass
cloth or tape as shown in Figure 24-10. This is
also referred to as stitch-and-glue construction. It is
frequently used in kit boats, such as kayaks and small
craft. A variety of stitch-and-glue plans are also now
available for drift boats, car toppers, power, and
sailboats. Some are well over 20' (6m) in length. In
most cases, especially with thinner plywood, it’s easy to
manufacture a fiberglass joint between two plywood
panels that is stronger than the plywood.
Stitch-and-glue is a method where plywood panels are
cut into specific shapes that eventually get connected
together along the keel, chines, stems, and transom to
create specific hull forms. <strong>The</strong> panels are pulled into
shape with pieces of soft wire (or plastic wire ties) that
are fed through matching holes drilled along the edges
of the mating panels. Each twisted wire or plastic wire
tie forms another “stitch” along the joint. In simple
designs, the panels can be connected together without
elaborate mold frames or stringers. In larger designs,
permanent or temporary frames are required to help
define the shape. <strong>The</strong>se are typically few in number as
the panels end up being quite stiff when bent and
connected along the joints. Gaps of up to 1 ⁄4" (6mm) are
acceptable as the joint will be filled with a generous
fillet of thickened epoxy prior to being glassed over.
Electrical tie
2 layers
fiberglass tape
Epoxy/407 fillet
Round over edge
Fiberglass tape
Figure 24-10 A composite chine joint using fiberglass tape
over a low-density fillet. Finish the inside of the joint before
rounding over and finishing the outside.
Figure 24-11 A stitch-and-glue pram under construction.
Frames will hold the shape until stitching is complete. A
brace across the gunwales will hold the shape while the
hull is inverted and the interior joints are filleted and taped.
Eventually the outside of the joint is faired and glassed
over with as much glass as desired. A properly designed
composite joint should easily be stronger than the
panels connected to it. This is especially reassuring in
joints that will potentially take abuse like keels, stems,
and chines.
You can also construct a composite chine over conventional
framework. Sheet plywood can be used with a
permanent stringer-frame support system to produce
strong, seaworthy hulls, and the simplified chine
system makes them easy to build.
<strong>The</strong>re are endless variations for making up a properly
strong composite joint. We normally make up some
samples of the joint system that we plan to use and
Glass tape
over radius
Stringers form
a gutter
Glass tape or
tape and mat
Figure 24-12 A taped composite chine with conventional
stingers.