The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 25 – Compounded Plywood Construction 309
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Figure 25-30 Developing hull rocker in a plywood panel layout.
of rocker, a double-ended hull will have more keel
rocker than a hull with a fuller afterbody, so on doubleenders
you can usually cut more keel rocker to achieve
the desired amount of rocker in the completed hull.
(See Figure 25-30.) Bow and transom profiles are pretty
straightforward because the flat cut shape is very close
to the compounded profile, except that the very tip of
the bow will move aft slightly when the hull sheers are
Figure 25-31 Developing the sheer in a plywood panel layout.
Flat panel for hull with transom and straight sheer
At section 3 the hull with fuller after body will have a
greater girth measurement than the hull with slack bilges.
<strong>The</strong> greater girth “F” will require a flat panel with more rocker
along the keel profile than will girth “S”.
Straighter sheer would increase measurement
around girth and should be added to panel.
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Panel layout for straighter sheer
spread apart. You may have to work with the model a
little and compensate for this to end up with the bow
or transom you want.
<strong>The</strong> sheer line can be more difficult to determine than
the keel line. <strong>The</strong> profile of a sheer line scribed on a flat
sheet of plywood may be considerably different from the
sheer line on a folded hull. <strong>The</strong> sheer on the completed
hull is affected by many variables, including hull width,
Flat panel with station lines
and reference lines.
Curved sheer