The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

204 First Production Steps
To detect twist, hold the spirit level in a vertical position
in various locations on the station face. If you have
applied the legs precisely parallel to the centerline, you
can use the legs as the arbitrarily chosen points to be
made plumb. To eliminate twist, you usually need to
adjust the diagonal or to install a second, and sometimes
even a third, diagonal.
If the set-up is on a floor, you can use wooden wedges,
tapped under the legs with a mallet or manually, for
minute increments of vertical adjustment. If the set-up
is on a strongback, you can make these adjustments in
the clamping of the legs to the anchoring blocks. Vertical
adjustment usually necessitates adjustment of the
diagonal(s) to bring the station back to plumb and the
taking up or letting out of line to the plumb bob. Keep
working until the station position is accurate. One
adjustment may necessitate others.
If you are using the two-level method instead of a plumb
bob, you will need a second spirit level. Clamp this
horizontally along the spall. <strong>The</strong> straightness of the spall
edge is obviously very important. With the two-level
method, bringing the bubble of the second level into the
reticles takes the place of bringing the plumb line over
the station’s centerline. Bringing the straightedge to the
cable then performs the function of aligning the centerline
onto the cable. <strong>The</strong> other level is used as before.
Orient the level that is clamped to the spall in the same
direction on all the frames. In other words, if the frames
are being set up in a north-south direction athwartship,
mark one end of the level “N” or “S” and always
position it accordingly. In this way, any error in the
level will always be in the same direction and the result
will be that all of the station centerlines, though they
may not be perfectly vertical, will at least be in the
same plane, which is all that really matters.
Before applying any filleting, it is a good idea to go to
the lofting floor and measure and make notes on the
distances for each station of the cable to sheer and the
cable to the top of the mold frame. After a station is in
position, check the measurements in the set-up before
applying the filleting. <strong>The</strong> check is good for revealing
any gross errors in manufacturing or setting up the
frame. Such errors would reveal themselves rather soon
in any case, but it is better to discover them before it
becomes necessary to chisel away the filleting material
in order to correct them.
Figure 18-6 A frame set-up showing the straightedge, a
string on the reference waterline, and levels.
When you are sure that the station is in perfect alignment,
you can fillet the legs to the anchoring blocks
and the floor. Use a high-density filler/epoxy mixture
that is roughly the consistency of peanut butter. <strong>The</strong>
strength and holding power of this mixture is adequate
to support the legs throughout hull construction if you
make generous fillets along all the lines where the legs
and the block meet. <strong>The</strong>re is no need to put adhesive
between the surfaces or to otherwise support the legs if
the fillets are formed on clean, oil-free surfaces.
Nailing and Screwing Legs
If you have plenty of clamps, you can just fillet around
them and leave them in place until the filleting material
cures. This allows you to proceed immediately to the
next station. You can patch in the remainder of the fillet
later, after the clamps are removed.
If you don’t have enough clamps to go on to the next
station, you can use nails and/or screws driven through
the legs to the anchoring blocks to hold the frame in
position while the filleting cures. Drive the nails and