The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

168 First Production Steps
Figure 16-3 Applying offset dimensions.
buttocks sections. A second set of offsets will be the half
breadth view measured from centerline, which will give
you the deck line and half breadth section views of the
waterlines. Another set of offsets will give you the
diagonal sections from the centerline. <strong>The</strong> diagonal
sections are viewed at right angles to the diagonal lines
on the body plan.
Materials for Lofting
<strong>The</strong> lofting floor: <strong>The</strong> first thing needed is a place to
loft the boat. Ideally, this space should be about 6' (2m)
longer than the overall length of the boat, and about 4'
or 5' (1.5m) wider than the widest or tallest point of the
boat, whichever is greater. For a multihull, these dimensions
usually apply to the biggest hull. Some multihulls,
however, have cabins and wing structures that must be
lofted, and these need half of the total beam plus some
working clearance. With the multihulls we have built
here, we have been able to loft the hulls separately and
then fade in the connecting structures where convenient
on the lofting board. This enabled us to use a much
smaller lofting board, which could be narrower than
half of the true overall beam of the craft.
For us, it has been easiest to loft on a wood floor. If you
have a plywood floor in good condition, you can loft
directly on it. If you want to save the lofting, or if the
floor is in slightly rough condition, lay down a cheap
grade of plywood of sufficient size to do the entire
lofting. Coat this plywood with two coats of white
semi-gloss paint and lightly sand it with 120-grit
sandpaper. You can draw on the surface with lead
pencils as well as ballpoint pens, and the white color
makes everything easy to see.
Steel tapes: It is ideal to have a steel tape which will
measure the full length of the boat and a shorter steel
tape, say 12' (2m) long, that can lock in position. <strong>The</strong>
shorter tape is handier for doing smaller layout projects.
Straightedge: You can purchase one or make it
yourself. It should be at least a few inches longer than
the distance from the baseline to the uppermost part of
the boat to be lofted. If you are constructing a straightedge,
clear pine is a good material. To check the
straightedge for accuracy, joint one edge straight and
check it by placing it down on the floor and drawing a
line along the straightedge. <strong>The</strong>n turn the straightedge
over and slide it up to the line. If there is no error, the
straightedge will just touch the line in both positions.
It is very important that this tool be as accurate as
possible.
Square: For a smaller boat, you can use a steel
carpenter’s or framing square. On larger projects, you
will have to construct a square to fit the job. Clear pine
works well. We usually make the square out of 1" � 4"
(19mm � 89mm) wood, with the longer arm the same
length as the straightedge and the shorter arm about
half that length. Check the two usable edges of the
square in the same way you did the straightedge to
make sure that they are perfectly straight. Put in a
diagonal brace to maintain a perfect 90° angle. It is a
good idea to glue the square together, making sure that
any gussets or fasteners used will allow you to lay the
square flat on the lofting board on either of its sides.
This will make the square more versatile.