The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 23 – Strip Plank Laminated Veneer and Strip Composite Construction 267
or cross the sheer at an angle. Without hand spiling, it’s
very difficult to finish planking with strips running
exactly parallel to the sheer line. We usually install
permanent sheer clamps, although doing this means
that we often have to saw temporary frames in order to
remove them. This is only a problem if we want to use
the frames for another boat.
Precoat and sand exposed interior areas of the permanent
sheer clamp, keel, stem, transom, bulkheads, and
other permanent interior items before installing them in
the set-up. Protect all prefinished permanent members
by covering them with duct tape or other heavy-duty
tape, which will prevent damage from both dripping
epoxy and sanding.
When you have installed all of the permanent members
in the set-up and completed final fairing of both temporary
frames and permanent members, the set-up is
ready for strip planking. During this procedure, you
should attach the planking permanently to all permanent
members but avoid any possibility of accidentally
bonding the planking to the temporary mold frames.
Cover the edges of all temporary frames carefully with
strips of 4-mil or 6-mil polyethylene sheet, stapling the
plastic several inches back from the edges on both sides
of the frame. When you have completed this, you are
ready to begin strip planking.
Stock for Strip Planking
Choose the most practical planking size for your
project. Most boats will require strip planks between 1 ⁄2"
and 1" (12mm and 25mm) thick. Determine the
planking size for your hull after considering the
following:
1. <strong>The</strong> size and width of the boat.
2. <strong>The</strong> spacing between permanent or temporary frames
in the set-up.
3. Whether the chosen thickness of planking can bend
around the most severe curves in the hull.
4. <strong>The</strong> most efficient use of available dimensional
lumber.
Planking width is governed by two factors. First is the
need to attach one plank to the next with dowels or
nails in the process of edge nailing. This is somewhat
Figure 23-1 Four common strip edge profiles: (1) square
edged (2) bead and cove, (3) tongue and groove and
(4) ship lap.
impractical with anything wider than 11 ⁄2" (38mm)
strips: the widest we’ve ever used was 11 ⁄4" (31mm). <strong>The</strong>
flexibility of the planking in the edgewise direction is
the second factor and is an important consideration for
rapid application of strip planking.
More recently, strips have been machined on the edges
with a matching bead and cove feature. Strips machined
this way act like splines that align planks, eliminating
the need for most dowels and edge nails. If you can
select the base stock from which to saw strips, we
suggest that you choose slab-sawn planks which, when
ripped, will show edge grain on interior and exterior
surfaces. Edge-grain planks are usually more attractive
for naturally finished interiors. <strong>The</strong>re are two better
reasons for using them, however: edge-grain planks are
more stable than other planks, and they sand and
machine more consistently than flat grain. Fairing up
surfaces for final finishing and laminating therefore goes
a bit more quickly.
Dimensional accuracy is important when you are
sawing and milling the stock for planking. Accuracy is
particularly important in the thickness dimension. A
plank that is even 1 ⁄32" (.8mm) smaller than its neighbors
will create a depression along its entire length that you
will need to fill prior to further laminating. Sawing
enough planking for an entire hull is a large undertaking.
We always take the time to set up a proper
sawing operation by making sure that we have a good
feed ramp for easily moving the stock into the saw and
a good exit ramp for the stock to lie on as it is exiting
from the back of the saw. Whenever possible, we set up
spring tensioning to hold the stock down on the saw
table and up against the saw guide so that we don’t