The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 20 – Building a Mold or Plug 227
saw them to shape. You might even prefinish them on
that part that would show on the interior of the completed
laminated hull, saving some time later on. It is
usual to scarf and join together the keel/stem complex
right in the mold and final fair them after they are
solidly secured in position. Hold them in this secure
position by installing screws from the interior of the
mold, usually through a cleat that is attached to the
mold frame. Locate these screws in an easy access area
so that you can back them off when the hull is complete
and ready for removal from the mold. Complete
the final shaping and fairing of the keel/stem complex
to the mold surface, using the techniques that we have
explained in Chapter 19.
With some types of laminated hulls, it is also possible
to include the permanent transom in the mold set-up.
You can only do this if the transom does not have any
reverse slope or if the hull does not have any reverse
slant. Either of these would prevent removal of the
laminated hull from the mold. It is rather easy to install
a permanent transom by temporarily attaching it to the
mold transom, to which the ribbands are already
attached. <strong>The</strong> transom might be prelaminated or might
simply be a sheet of plywood. You may have laminated
on some additional cleats to create more bonding area,
which should not cause any problems. Once you have
positioned the transom, fair it off flush with the general
mold surface, just as was done with the keel/stem
complex. When permanent transoms are not set in, it is
usual to extend the mold transoms an 1" or 2" (25mm
or 50mm) to allow a little extra length for trimming.
Prior to beginning any laminating over a mold, take
steps to ensure that you will be able to remove the
laminated hull from the mold when it is complete. To
prevent any bonding of the laminations to the mold, we
generally cover the entire mold surface with a layer of
polyethylene sheet, usually 4 to 6-mil thickness, using a
new sheet for each hull produced. For molds that do
not have any permanent keels, stems, or transoms
inserted, it is a simple matter to cover the entire mold
with plastic. For molds that do have these permanent
inserts, you must insert the plastic around these structural
members so that permanent bonding between the
laminations and the permanent members can take
place. Usually you can tuck the polyethylene sheet film
in between the slight gaps that will exist between the
permanent members and the mold itself. If this is
somewhat difficult, relax the screws holding these
permanent members in place just a bit so that you can
insert the plastic under or beside them. This will
provide the necessary barrier so that you do not bond
the lamination members to the wrong part. When you
have completed this step, you are ready to begin the
process of building the laminated hull with the mold
method.