The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

72 Getting Started
unimproved lumber are quite low, so shipping costs
over long distances are fairly reasonable. Since they
serve large markets and specialize in specific types and
qualities of wood, the mail order houses are able to
offer quality materials at moderate prices. <strong>The</strong>re are,
however, problems with ordering by mail: you must
often buy wood sight unseen, with the reputation of
the company as your only assurance of quality, and
you may have to schedule around the lag time between
ordering and receiving your lumber.
It’s sometimes possible to acquire wood in other ways.
If you live where timber is harvested, you may be able
to purchase top quality boards directly from a small
sawmill. This lumber is usually green and rough sawn,
but its price is accordingly low. Other potential sources
are wholesale houses, which provide special woods to a
regional industrial market. <strong>The</strong>se firms like to deal with
large volume trade, but they often accept smaller orders
at a slight premium.
Choose the kind of wood you will use in your boat
before you order. You may need more than one species.
Check plans for specifications or select particular woods
for their physical properties. You will probably discover
that relatively few of the better boatbuilding varieties
are available at one time, and if you can’t find what you
want, you may be forced to make substitutions. In most
applications, several different species will work equally
well, so if you can’t find your first choice, another with
similar physical properties and density might stand in
its place. See Appendix B for the mechanical properties
of selected boatbuilding woods. Price may also be
a factor in your selection.
If at all possible, buy lumber that has been dried to
approximately 12% moisture content. Green wood is
heavier than dry wood and therefore costs more to ship.
If your lumber has not been seasoned, give it time to
reach equilibrium or dry it in a kiln. Although wood
may be damaged by very high temperatures, we’ve never
had any problems with the kiln-dried lumber we’ve
received. Before using any wood, follow the procedure
described in Chapter 3 to check its moisture level.
<strong>The</strong> amount of time it takes to air dry wood depends on
the moisture content of the wood, its ratio of exposed
surface area to volume, its density (softwoods tend to
dry more quickly than hardwoods), and the temperature
and humidity of the atmosphere in which it is seasoned.
<strong>The</strong>re is no magic formula for predicting how long you
will have to wait before you can use a board. Green
1 ⁄8" (3mm) cedar veneer might reach 8% to 12%
moisture content in weeks, while 2" (50mm) hardwood
will take much longer to dry.
When ordering lumber, specify dimensions in thickness,
width, and length. In the United States, thickness, the
most important of these measurements, is often given
in quarter inch fractions, although it is also sometimes
listed in inches. In the quarter system, 1" thick stock
may, for example, be referred to as 4 ⁄4, 11 ⁄2" as 6 ⁄4, 2"
stock as 8 ⁄4, and so on. Width is always measured
in inches and length in feet. A board foot of lumber
measures 12" � 12" � 1".
We prefer to buy thinner, rather than thicker, stock
because it dries faster and can be used sooner. We
do purchase thick lumber, however, when there is a
price advantage or when it is the least wasteful way
to develop the size we need. To expedite drying and
reduce stressing, we usually re-saw lumber that is
more than 1" (25mm) thick.
As you work out a lumber list, calculate the board sizes
that will result in the least waste. Unless we are buying
boards in specific sizes, we try to get the widest and
longest stock we can without paying a premium. As a
rule, lumber over 20' (6mm) long or over 8 or 10"
(200 or 250mm) wide is more expensive, and prices
are usually high enough to warrant scarfing shorter
pieces for length and laminating thinner pieces for
width.
Thickness and width dimensions stated in inches
measure the stock before surfacing or finishing: a
1" (25mm) board is 1" thick rough and 3 ⁄4" (18mm)
thick finished. Wood measured by the quarter, on the
other hand, is identified by its finished measurement. A
4 5 1
⁄4 board was ⁄4, or 1 ⁄4", thick before planing and is 1"
thick at the time of sale.
Boat lumber is usually available either rough sawn
or finished. Rough sawn boards are generally simply
called rough. If a board is marked S2S, two of its major
surfaces have been planed. <strong>The</strong> marking S4S means
that all four sides of a plank have been put through
a planer. We often purchase rough lumber because
with careful surfacing we can use more wood from the