The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 23 – Strip Plank Laminated Veneer and Strip Composite Construction 271
tub, such as the WEST SYSTEM 805 Mixing Pot, making
up only enough at one time to fill one third of the tub’s
volume. We apply it along the edge of the plank with
the stick, applying a controlled amount of epoxy to the
surface. If the epoxy is so thin that it runs easily off the
stick, and perhaps off the edge of the plank, thicken it
with more filler.
After you have applied the thickened epoxy to one edge
of a plank, wet out the edge of the strip that has already
been installed with a thin coat of unthickened epoxy.
You can do this quickly with a foam roller cut to a good
working width. Use the surmark you made earlier to
line up the center of the new plank and the middle
station. If the hull is very large, it’s difficult for one
person to install a plank without getting messy. Ideally,
two or three people can work together, but if you are
shorthanded, make some adjustable stands to hold the
edges of the plank at the right height while you fasten
its middle to the frames. As fastening progresses out
towards the ends of the hull, move the stands inward
and then remove them.
Think of the plank that is being installed as the glue
plank and the plank that has already been installed as
the permanent plank. Begin by fastening the glue plank
tight against the permanent plank about midway along
the hull. Insert a screw through the glue plank into the
mold frame. <strong>The</strong>n skip one or two stations, depending
on the size and curvature of the hull, and insert another
screw into a mold frame. Hold the glue plank tight
against the permanent plank so there is the best
possible fit between them as you insert the screw. After
you have fastened it at several mold frames on either
side of the mid-hull frame, the glue plank will be under
reasonable control and you can fasten it easily to each
frame in the set-up. If you have applied sufficient epoxy
to the new plank, some should squeeze out. Most of
this will be on the exterior of the hull because of the
tapered gap between the planks, but some will invariably
end up on the interior. Remove excess adhesive
from both surfaces before it cures.
Edge Fastening
It is common to have some misalignment between
planks in the areas between the mold frames. To keep
this misalignment to a minimum, you should allow
Planks laid
tight on
inside
Planks
1 ⁄8" birch dowels
Outside faired for
diagonal planking.
Epoxy with low-density fillers used
between planks. This thickened
mixture exceeds the grain strength
of cedar and relieves the need to
bevel and fit strips.
Staggered pattern fore
and aft for birch dowels.
This “fastening” system is
employed only in areas of
severe bend such as the
bilge. Some well-placed
staples will suffice in most
flat areas.
Figure 23-6 Doweling to prevent plank misalignment.
each plank to take a natural curve as you bend it
around the hull. You can correct plank misalignment
easily by edge nailing with the use of 1 ⁄8" (3mm)
diameter wooden dowels. While you could use nails
instead of wooden dowels, dowels are preferable for
several reasons. Because the hull will be laminated over
anyway, the extra cross-grain strength that nails might
provide isn’t needed. (Wooden dowels could also
provide excellent cross-grain strength if they were
bonded in place.) Of the hundreds of nails that might
be used in a hull, a small percentage will inadvertently
break through the sides of a plank. This is a particular
problem on the interior of the hull because the nails are
not only unsightly but will impede sanding and are
difficult to remove. If a wooden dowel happens to run
out in the planking, it is easily sanded smooth and is
not particularly unattractive.
To align the planking between frames, hold the glue
plank and permanent plank between your thumb and
forefinger so that they are in exact alignment. <strong>The</strong>n drill
a 1 ⁄8" (3mm) diameter hole through the edge of one
plank into the next, moving down the plank between
each station until you have drilled all of the holes while
holding the planking in perfect alignment. <strong>The</strong> hole