The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 24 – Hard Chine Plywood Construction 285
Chine Frame
Figure 24-5 Notching the chine at the frame.
Notches sawn along
projection of mold
Gusset
To make a typical triangular chine log as shown in
Figure 24-4, begin by rough-shaping the chine stock as
close as possible to finished dimensions. Scarf the piece
to the proper length and attach it to the frames in the
set-up. Notch each frame to allow the chine log to sit in
position for final fairing. To speed up the notching
process, make a small marking guide from a piece of
sawn-off chine stock. As you lay out the notches, be
careful to adjust for any twist in the chine as it extends
from the bow to the midsection and back to the
transom. <strong>The</strong> angle of each frame at the chine will be
different, and you will have to shift the angle of the
chine log to compensate. Divide the angle change at
each frame so that you won’t increase bonding area on
one side at the expense of the other. You can get good
indications of the angle change and notching depth
from the body plan on the lofting board.
When you have completed the notching and fitting of
the chine, bond it to the frames, using clamps for
temporary pressure until the adhesive cures. Steel wood
screws that are later removed are a good alternative if
clamps are impractical. Staples are rarely used because
they will interfere with the heavy fairing that follows
after the chine is permanently bonded in position.
Because the chine in many boats is considered a major
structural element, it is usually fitted well to the stem
and transom. This is usually accomplished in the stem
by notching, but it can also be butted, provided that
there is sufficient bonding area. Chines are always
notched into the transom. Use either a triangular notch
or a full notch, but the chine should not pass through
the transom, exposing end grain. Bevel the chines using
the same techniques used to bevel the keel, as explained
in Chapter 19. At each station where the chine intersects
the frame, make saw cuts in the chine that represent
extensions of the frame on either side of the chine.
Notch the chines down to their true shape at each
frame station, as illustrated in Figure 24-5.
With most hulls, it is then relatively easy to achieve a
rough bevel on the chine using the notched-in bevel at
each station frame as a guide. Assuming that the chine
itself is bent around the frames in a fair curve, you can
use the edge of the chine like a batten to determine
whether your bevel is continuing fair from frame to
frame. To assist your eye in determining this fairness
between frames, you can lay a fairing batten directly on
the chine and hold it temporarily with clamps to detect
any high or low spots and mark them for further fairing.
If there are unusually large spacings between frames, it
can be very helpful at this point to install any longitudinal
stringers that are planned. Once the stringers are
installed, you can use them as helpful guides to assist
with the development of the chine bevel. Two or more
stringers notched into the flat area of the frames
between, say, the chine and the keel will act as excellent
guides to help develop the true surface over which the
exterior plywood panels will lie. You can use a straightedge
to make a fair extension of the stringers down to
the chine, indicating both the position and exact angle
of the bevel on the chine at any point between frames.
You can use the same technique, of course, to achieve
proper bevels on both keel and sheer clamps.
Typically, the stringers are positioned across the frames
parallel to the sheer and keel at the desired intervals so
that they run out at the chine, intersecting with the
chine itself. This is not always necessary, and with
certain types of chine systems, it is better to run the
stringers parallel with the chines, allowing them to run
out at the sheer and/or keel. As with rounded hulls, you
can also position the stringers so that they taper toward
each other as they enter the bow and transom area.
When the framework is finished, use a straightedge to
final fair the flat surfaces between the chine and keel
and the chine and sheer (and the chine and chine on a
multiple chine hull). At no point should any of the