The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

270 Hull Construction Methods
not insurmountable, but the double run planking
system takes a good deal of extra time in comparison to
the run out method where you have to do little or no
fitting at all.
Applying Epoxy
Assume that you are going to run bottom planking
parallel to the keel and topsides planking parallel to the
sheer in a double run planking system and that you
have accurately marked the set-up to receive the master
plank. Install this plank, using screws that are about
twice as long as the thickness of the planking to hold it
temporarily to the mold frames. We used to use
inexpensive roundhead sheet metal screws with large
washers. <strong>The</strong>se made it possible to apply more pressure
without damage to the wood fiber. Now drywall screws
would be used with washers instead. Chipboard frames
require longer screws than wood frames because
chipboard’s holding power is not as good as that of
wood. In areas where you need extra holding power,
screw or staple and bond a piece of wood to the side of
a chipboard frame and screw the planking into this.
Step drill bits, which can cut a pilot hole in the temporary
frame and a shank-sized hole in the plank in one
operation, save the added step of switching between
two different drills or changing bits.
Use alloy screws and epoxy thickened with highdensity
filler to attach planking to all permanent parts
of the boat. <strong>The</strong>se screws will be left in the hull.
Countersink them enough so they won’t interfere with
fairing. You will be using two different types and
perhaps sizes of screws: one to attach planking to
temporary frames and the other to attach it to permanent
members. Two drill motors set up with two
different size bits will save time. If you are using
drywall screws for temporary fasteners, you can get by
with a single conventional drill bit because the drywall
screw’s shank is smaller in diameter than the threads.
When you have installed the master plank, set up a
procedure to easily and efficiently apply the rest of the
planking to the frames. Mark the planks with surmarks
that line up with a station in the middle of the hull so
that you can accurately position them without having
to guess if they are centered.
Protect the
stand with
polyethylene
sheeting
Thickened epoxy fills
the gap between the
top of the strips and
the top of the stand
sides
Figure 23-5 An optional fixture for edge gluing multiple
planks. Adjust the width and depth of the fixture for the plank
width and number of planks you want to coat at one time.
If you are using a softwood such as cedar, use a lowdensity
filler with epoxy to make a thick syrup. This
combination will exceed the grain strength of most
softwoods. If you are working with high-density woods
with higher grain strength, like mahogany, use a highdensity
filler for a stronger epoxy mixture.
Support jigs will hold planking upright for convenient
epoxy application. We make them of 1 ⁄2" (12mm)
plywood, with slots in the tops just large enough for
the plank to sit in. We nail these to saw horses and
set up as many as are needed to support the plank.
About 3' (1m) off the floor seems to be a comfortable
working height.
Applying epoxy to the edges of several hundred planks
is a significant part of the work of strip planking a hull.
You need a quick, efficient, and clean method for
mixing and applying the adhesive to plank edges. In
the long run, we’ve found it best to spread the epoxy
mixture with an inch-wide stick. We mix epoxy in a