The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

54 Getting Started
between layers of laminated hulls and in joints and
fillets. See Chapters 11 through 15 for detailed discussion
of application techniques.
To estimate costs for WEST SYSTEM resin and hardener,
use your study of the hull framework and interior to
figure out the total interior surface area. Remember
to include frames, stringers, bulkheads, and cabinets.
Make educated guesses about the quantity of epoxy
you will need for joints. Refer to the hull surface area
to estimate your requirements for exterior laminating
applications.
WEST SYSTEM epoxy application rates vary according
to the kind of job and work habits. For estimating
purposes, see Figure 7-3. Plan on coating an average
of 35 square feet with one mixed pound of resin and
hardener (7.1m2 /kg) or 40 square feet per pound
(8.2m2 /kg) for secondary coats. Rates for interlaminate
glue joints on hulls can be harder to predict because
they depend a great deal on the quality of the fit, the
quantities of filler, and the amount of clamping pressure
used. A good figure to use for hand lay-ups, with clamps
rather than vacuum pressure, is 13 square feet per
pound (2.7m2 /kg) per glue line. If you have many small
jobs or if you will be working at cool temperatures,
coverage rates may be lower. On the other hand,
careful fitting of joints and good planning will improve
your application rate. Always add a 20% waste
allowance to your total estimate.
When you have established interior area, divide the
figure by 35 to find how many pounds of epoxy you’ll
need for the initial coat (divide by 40 for secondary
coats). Add the initial and buildup applications together,
and add a reasonable amount to cover your interior
joints and fillets.
Before estimating the hull’s exterior epoxy requirements,
count the saturation, buildup, and interlaminate glue
joints you will apply. When you have a firm idea of the
number of exterior coats, divide your entire hull surface
area by 35 for the initial coat and 40 for the buildup
coats. Add the pounds for all the coats to determine
total pounds of mixed epoxy needed. A laminated hull
requires at least one adhesive coating between each
layer of plywood or veneer in addition to its minimum
three exterior coatings. To find out how many pounds
you will need for these applications, divide the surface
area by 13 and multiply by number of interlaminate
glue lines.
Add interior and exterior estimates and a waste factor
for a total epoxy estimate. Look over your plans and
consider your construction technique to determine
required quantities of WEST SYSTEM additives and fillers.
<strong>The</strong> current product guide and WEST SYSTEM website
provide estimating guidelines for each of these
materials.
<strong>The</strong>re are two things to consider as you price out WEST
SYSTEM epoxy. First, you have only estimated the
number of pounds of mixed resin and hardener you
will use. Be sure to include resin and hardener totals
so that you won’t make the very common mistake of
over-ordering. Second, consider ordering epoxy more
than once, especially if you are working on a big boat,
depending on your storage facilities, your financial
situation, and your experience. We recommend that
you buy in volume to take advantage of price breaks,
but you may want to order a little less than you think
you’ll need rather than the full quantity. This way, when
it comes time to reorder, you are much more experienced
and better able to correctly estimate what’s
required to finish the project.
To complete the hull estimate, think through your
boatbuilding project. Add up the cost of plywood for
lofting and molds and the cost of staples and screws
for molds and hull laminations. If you plan to use glass
cloth or graphite fibers on your hull, rudder, or centerboard,
price out the quantities you’ll need. Work out
the cost of paint or varnish. Estimate and include the
prices of core materials. Don’t forget disposable tools
and equipment such as sandpaper, rollers, and brushes.
Add the five portions of the bare hull estimate, making
sure to include a waste allowance in all areas. Raw
materials can represent as little as 10% of the cost of a
finished boat, so it makes sense to overestimate, particularly
in questionable situations. If you order a little
more plywood or lumber than you anticipate needing,
you may be able to avoid the expense and frustration
of running short late in the project.
Detailed Estimates—Hardware Costs
<strong>The</strong> second major part of the detailed estimate, hardware
costs, begins with an item-by-item inventory of your