The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 14 – Hardware Bonding 147
When you have drilled all of the holes, position the
keel bolt pattern on both the inside and outside of the
hull over the drilled holes to check them for accuracy.
<strong>The</strong> holes will usually line up very accurately from the
side that you started drilling from, but the opposite
side of the hull may show some inaccuracy caused by
improper lineup or wandering of the drill bit. Carefully
mark these errors and then use a round wood rasp to
move the dimension of the hole toward the direction
needed to straighten it out with the pattern. Usually,
this situation causes no harm, only a slightly enlarged
hole which has the positive effect of increasing surface
area. <strong>The</strong> only disadvantage is the possible weakening
of the laminated floor itself. However, this should be a
minor problem in most situations. Make a final, careful
check with the keel bolt pattern to assure yourself that
the drilled holes in the hull will indeed receive the bolts
protruding from the ballast keel with no interference
from the wood itself. <strong>The</strong>n you can begin final preparations
for a ballast keel/hull union.
Usually, this is the last major job on a boat, and you can
do it just before launching. Up to the time you install
the keel, you will probably want the hull close to the
floor for easy access. To install the keel, however, you
will have to jack the hull up high enough to have room
to roll the keel and its bolts into position. When the
keel is in rough position, move it as necessary until you
can lower the hull onto it.
When you have lined up the keel bolts with the bolt
holes, you can set the hull down over the top of the
Figure 14-23 A keel set up in a specially-built handling fixture
so it can be final faired and moved around.
bolts, leaving a gap of about 2" or 3" (50 or 75mm)
between hull and keel. At this point, you can take final
measurements to note any possible discrepancies
between the mating surfaces of the keel and hull.
Check the keel bolts visually to make sure that there
are no hang-ups that could prevent the hull from seating
flush with the keel’s mating surface.
Coat areas of the mating surface on the bottom of the
hull from the foremost keel bolt forward and from the
aftermost keel bolt aft with a parting agent to prevent
epoxy from bonding in these areas. <strong>The</strong> reason for this
is that the ballast keel is a rigid, non-flexing mass, while
the wood hull structure is not. Invariably, over a period
of time, movement will take place between parts of the
keel and hull. It will occur just beyond the outermost
keel bolts, both fore and aft, creating small, hairline
cracks. If you bond the keel with epoxy to the hull,
these cracks will occur within the wood structure itself,
providing points of moisture entry into the wood fiber.
<strong>The</strong> parting agent causes the cracks to occur between
Figure 14-24 Rolling a 10,000-pound keel into position on a
handling fixture. <strong>The</strong> keel can be shifted slightly from side to
side and fore and aft.