RETROSPECT
in the presence of salt. You can safely predict the
ultimate strength of the resulting assembly, since
the lashings will bear the load equally, and there
are no hard stress points to form a weakest link or
to propagate cracks. When you sew a seam on a
thick nylon kayak skin with four 40 lb. test stitches
every centimeter, you can count on the seam taking
a load of 200 lbs. per inch without tearing apart.
Not only are lashed fastenings unusually robust
and structurally sound, they are pleasant to work
with, are forgiving of sloppy craftsmanship, and celebrate the abilities of human hands. If you complete
a seam or a lashing and decide it could have been
done better, you just undo it and try again. You can
stop work at a moment’s notice, and resume at any
time. You can strive for perfection, but a haphazard-looking lashing will be almost as strong.
Traveling through heavy seas in a loaded and
lashed-together kayak, there is a reassuring creak in
the vessel’s joints, similar to the old days of loosely
fastened wooden sailing ships, designed to work in
a seaway for months and years on end. In a modern
welded or composite vessel (or aircraft), any sounds
emanating from the structure are cause for alarm.
With a load-bearing structure that is sewn or
lashed together, what you see is what you get. Finite
element analysis (FEA) is now used, in association
with computer-assisted design, to predict stress,
requisite materials, and required fasteners in a
given structure under a given load. The empirical
design of lashed structures is the ancestor of FEA.
Lashings (and the elements they join together) are
finite elements, and can be used to handle stress
(and predict strength) in a directly analogous way.
If we examine how nature joins high-strength,
high-stress materials — mending a broken bone,
joining the plates in a baby’s skull, healing a cut in
an animal’s skin, or attaching a mussel to a rock
in the surf — we see lashings at work, on a microscopic scale. In designing and building our own
structures, we can do no better than to emulate
nature. We have, and we will again.
Approximately 35,000 years ago, a small band
of human beings launched into the open Pacific
Ocean from Malaysia in lashed-together vehicles.
The experiment was a success. Why stop?
George Dyson, a kayak designer and historian of technology,
is the author of Baidarka, Project Orion, and Darwin Among
the Machines.
188 Make: Volume 09
Baidarka (kayak) construction, circa 1986. The completed
5-meter ( 16.4-foot) skeleton, made of 5" aluminum
sheet and ½" o.d. 6061-T6 aluminum tubing (.049" wall)
weighs 18 lbs. The skin material shown here is a 26 oz.,
(per square yard) double-weave heat-shrinking nylon.
The twine is a phenolic-coated nylon obtained at very
low cost as remaindered tire cord.
Photography by Ann E. Yow
