The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

100 Core Boatbuilding Techniques
of wood near the edge of a bench, roughly 10" apart,
and support one test sample on them. Using a clamp in
the middle of your sample, slowly deflect
the wood toward the bench until it breaks. Study the
relationships between the various components to determine
where the sample failed and how. Take your
second sample, put it in a vise, and hit it with a large
hammer. This will give you some idea of how well
your sample will withstand shock loads.
Forming and Clamping Cored Laminates
Cored laminates are easy to make if their surfaces are
flat, a bit more difficult if slightly curved, and very
difficult if curved in more than one plane.
To manufacture flat parts such as bulkheads, partitions,
doors, counter tops, bunk bottoms, and floors, look for
a flat area which is at least as large as the part to be
laminated. This can be the floor or a bench. If you are
planning many flat laminates, it is worth building a
special form. Your work area must be perfectly even
with no twists or warps.
Figure 11-14 A cored deck constructed using lightweight
beams and resin-coated paper honeycomb core material. See
Chapter 27 for a full description of this deck construction.
Assemble components, usually two outer skins and
a core, on your surface, apply adhesive, and then use
weights for pressure over the surface area of your
assembly. Almost anything that is easy to handle and
weighs from 3 to 10 pounds (1.4 to 4.5kg) can be used
as a weight. Many common items, including bricks and
small pieces of scrap steel, work well. In our shop, we
often use double-wrapped sandbags.
<strong>The</strong> amount of weight you need depends on your particular
lamination. In all cases, pressure should be sufficient
for complete contact between the layers. If the outer
skins are thin plywood, very little weight is necessary
unless the panels are badly warped. Distribute pressure
over the entire surface of the skin using leftover stringer
stock, scrap lumber of equal thickness, or thicker pieces
of plywood or particleboard to spread the load.
You can apply some clamping pressure to the lamination
with staples. Usually, cored laminations have an
outer perimeter that is made up of a solid wood material,
which we refer to as core framing. This material is
prepared beforehand from stock the exact thickness of
the core material and can be used wherever desired in
conjunction with the core material within the laminate.
Some cored laminates may be designed to have a great
deal of core framing within the laminate so that only
staple pressure is needed for assembly. However, staple
assembly is usually successful only with thicker plywood
skins because of their increased panel stiffness. In most
cases, even with the use of staples, weighting will still
be needed to ensure a good bond between the laminate
components.
We usually plan our cored laminate layout right on
the plywood panel from which we will cut one of the
exterior skins. Once the perimeter of the laminate is
determined, you can lay out the exact positions and
dimensions of the core framing right on the panel.
Cut the laminate skin slightly larger than size (to facilitate
final fitting) and make a duplicate that will become
the second skin on the opposite side of the core material.
Saw the prepared core framing to length and position
it around the perimeter of the laminate and wherever
else desired within the interior of the laminate. When
the core framing is fitted, bond it into position on the
marked skin surface using either temporary or permanent
staples to hold the pieces in place until the adhesive