The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

268 Hull Construction Methods
have to rely entirely on hand pressure to guide the
stock through the saw blade. For those who can justify
the cost, a stock feeder attachment for your table saw
can efficiently produce accurate strip planks. It not only
holds the plank against the rip fence during the cut but
also propels the plank through the cut, dramatically
reducing the physical effort required for the job.
You probably won’t be able to buy planks long enough
to cover your entire hull. Usually, you have to cut at
least one scarf and perhaps as many as four to make up
a plank to span all of the hull stations. It is much easier
to scarf strips before you apply them. It can be quite
difficult to scarf strip planking in place while bending it
over frames, especially in short, wide boats. Do all
scarfing carefully and accurately, following the instructions
in Chapter 12 so that there will be no dog legs,
kinks at the scarf, or overlaps to increase planking
thickness at the joints.
Spiling and Beveling Strip Planks
<strong>The</strong> concept of planking a hull is at least several
thousand years old. <strong>The</strong> traditional carvel-built hull has
planks lying edge-to-edge, and the techniques developed
for carvel planking are well known. Traditionally,
because boats are fatter in the middle and smaller out at
the bow and stern, planking has always been tapered at
its ends to adjust for this change in dimensions.
Because planks are joined one-by-one around a curved
surface, it’s also common to bevel their edges so that
they meet flush where they join. Both the spiling and
beveling operations are very tedious and timeconsuming,
and both require a good deal of skill.
With traditional procedures, two workers might be
lucky to apply five or six planks a day on a 40' (12m)
hull. To speed up the planking process and make this
construction method more practical, we have eliminated
spiling and beveling. When these two jobs are
unnecessary, two well-organized people can apply up to
25 planks in eight hours and even more if the planks
incorporate edges that self align. <strong>The</strong>se include bead
and cove or tongue and groove edges. Planks with these
features minimize the need for edge nails and dowels
except for the most stubborn areas.
Instead of spiling, we adjust for dimensional decreases
as planks approach the ends of the hull by allowing
them to run out at the keel and the sheer as they do
when we build a mold. Unless the hull is particularly
fat for its length, this technique presents no difficulties,
provided that the planking is thin enough to bend
easily edgewise as it arcs toward the sheer or keel. With
a thick WEST SYSTEM ® epoxy mixture, beveling is usually
unnecessary for structural reasons. Eliminating it saves
a great deal of time. When viewed from the interior, the
planking on most hulls always fits tight and looks the
same, whether it has been beveled or not.
Applying Strip Planking
As might be imagined, locating the first plank on the
set-up is of paramount importance because the location
of this master plank determines the direction and
amount of curve that all succeeding planking will
follow as it approaches either the keel or sheer.
Improper location of this first plank might cause the
planking approaching the sheer to become overly
curved to the point where it would be difficult to bend
the planks in place, while the planking on the other
side of the master plank that is approaching the keel
might hardly curve at all. <strong>The</strong> goal is to locate the
master plank about midpoint along the hull and in an
arc that will allow the planking installed on either side
of it to bend about the same amount as it approaches
the keel or sheer.
<strong>The</strong> simplest method of determining the location of the
master plank is to determine mid-frame locations at
various points along the hull. Establish these positions
by measuring along the perimeter of the frames
between the keel and the sheer, starting in the middle
of the hull and working out toward the ends.
Temporarily exclude the first few stations at the bow
and the transom because the shape of the boat is
changing abruptly at these points and will not give you
a true overall reading of what is happening with the
majority of the hull. When you have located a point on
the frame at each station that is equidistant from both
the keel and the sheer, position a batten along these
marks and temporarily nail it in position. Using your
eye as the guide, move the batten wherever needed to
achieve a fair curve that still intersects the mid-frame
marks as closely as possible. You can extend the batten