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Building Kobuk
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As with
most any task that is undertaken alone, deciding to build the boat was
the
hardest part of the job. Once committed
to the project, each step towards its completion was a small nibble out
of a
big pie. I knew it would take years to
finish; I knew that no matter how generously I estimated the time it
would take
me, the actual project would take longer; I
knew that the cost would be more that I could afford.
All this I knew because it had been true when
25 years earlier I had built a small cruising sailboat in Hawaii. That earlier success, though, had given me
the greatest feeling of accomplishment in my life and remembrance of it
was a
constant source of encouragement as I started to construct Kobuk. |
Setting
up the Framing Box
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Making
Frames
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The
Frames on Their Stations
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The first
big problem was how to build a boat outside in a rigorous climate. My home was located in the mountains of Utah
at an elevation above 7,000’. Summers
there are dry and cool and ideal for outdoor work, but they are
short—very,
very short. Winters, on the other hand,
arrive early and leave late, and bring with them plenty of snow. Since there was not enough room in the house
to build the boat indoors, I had to create an outdoor area sufficiently
protected that at least in spring and fall I would be able to carry on
with the
project. In the fall of 1997, I constructed a deck on the downhill side
of the
house that had sufficient space beneath to accommodate a 21’ boat. The hull was to be constructed upside down on
a perfectly level platform, so under the deck I set two posts in
concrete and
used them to fabricate a long, narrow platform that was to be the base
for hull
construction. By the time that project
was finished, winter was upon us and I was driven indoors. |
Running
the Stringers
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Joinery
at the Bow
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Planking
the Hull
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It was
possible, though, to work in the garage during the winter months, and
so I set
about constructing the frames that in the spring would be set up on the
platform. Over the next two years, the
hull took shape—a structural ribcage of mahogany supporting a shell of
marine
plywood planking. When all was shaped
and fair, the entire external surface was sheathed in epoxy and
fiberglass
cloth. When at last the hull was ready,
the waterline was demarcated, a black bootstripe was painted on, four
coats of white
marine paint were applied to the sides of the hull, and two coats of
red antifouling
bottom paint were rolled onto the area below waterline.
On July 4th,
2000, friends were invited for an afternoon
barbeque and everyone helped to lift the hull off its platform, turn it
over,
and reset it on a rebuilt support structure. |
The
Bow Configuration
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Kobuk
Planked
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Spike
on Moving Day
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Traditional
methods of boatbuilding often require levels of skill and experience
possessed
by few, but the hard-chined configuration of the River Rat and its
simplified
methods of construction outlined in the directions provided by Glen-L
Marine made
this building job the sort of thing that can be accomplished by anyone
who is
patient, thoughtful, and thorough. Although
the building process constantly requires mating
wood surfaces
that are something other than perpendicular to the run of the wood, one
learns
to adjust to this complication and after having had to cope with it a
couple
dozen times, the procedures involved become
quite routine. The job was enormously
simplified by the fact that the construction plans for the boat
contained a 3’
x 8’ sheet of paper upon which every structural piece of wood in the
entire
hull is sketched. All that needed to be
done was transfer a pattern to an appropriate piece of wood and then
saw it to
shape. Hull
construction was neither simple nor quick, but anyone who can
competently
handle a tape measure, a hand saw, a screwdriver, and a plane can build
this
boat. It is not the skill that is in
question; it is the will. |
Rebuilding
the Rack
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Turning
the Hull
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Turning
the Hull
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For those
of a technical bent, there are two aspects of the River Rat hull that
might
offer a little intrigue. The first has
to do with the planking of the bow area where the shape consists of
more
complex curves—curves like the surface of a sphere rather than a simple
curve
such as would exist on the surface of a tube. Plywood
planking can generally be flexed to fit a simple
curve, as long
as the arc is not too tight, but once a simple curve is present the
plywood
sheet is very resistant to flexing along a different axis.
Of course, the thinner the plywood the more
likely it is that it can be gotten to cooperate. The
designer of the River Rat overcame the
problem of curves in the bow by specifying that it be planked with two
thin
sheets of plywood instead of one thicker one. This
made it possible to fit the complex curves, but it
had the
additional benefit that when the second sheet gets glued onto the first
it
creates a remarkably strong form of planking. If
the two sheets together could be removed from the boat
and inspected
as an isolated item, its curves remain in the wood and their existence
gives
much greater rigidity and strength to the sheet of plywood than if it
were
flat. This is especially valuable
because the bow area of a hull is where the most ferocious aquatic
forces are
brought to bear. |
Moving
Kobuk Back onto the Rack
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The
Turning Job Completed
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Framing
the Deck
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The second
aspect is similar in concept to the first. As
a hull is constructed, frames running from side to side
and located
at more or less equally spaced distances from each other give the hull
its
shape and insure that the sides and bottom do not flex inward to any
significant degree. The plywood skin for
the hull is not laid directly on the frames. Rather,
stringers are run the length of the boat and
perpendicular to
the frames. These stringers provide
longitudinal
rigidity and the plywood skin is attached directly to them. In the bow area, these stringers must curve
upward out of the water and to the deck level. Since
the bow is the area that needs the greatest
strength, the River
Rat designer specified that in this region some of the stringers should
be two
layers of long, somewhat narrow plywood that do not reach all the way
to deck
level and that get pulled back like the arm of a bow while the plywood
planking
is applied. After the plywood skin is in
place, glue is slathered onto those sprung tabs and they are released
to press
against the planking. When the glue
cures, these curved ply stringers give even more strength than usual to
the
forward area. It is all very
ingenious—lightweight and tough. |
Holes
Cut for the Jet Drive |
Preparing
the Bow area
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Framing
the Floor
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| There
is a
tendency to think that once the hull is built and painted, and turned
right
side up, the job is nearly done. Actually,
you’re not even half way. Most of the
woodworking has been finished, although
constructing the deck,
fitting the carlings, building the cabin, installing the floor,
fabricating the
steering console, making the driver’s seat, assembling the engine box,
and
doing various other small carpentry jobs consumes more time than one
might think. The day finally arrives,
however, when the
boat looks finished even though intimidating tasks remain.
In this case, they were to
install the jet drive, mount the engine, rig the steering and control
system, run the wiring, and outfit the final product with a staggering
array of storage places for particular items and pieces of equipment. |
The
Cabin Floor Layout
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Starting
the Cabin
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Framing
the Cabin
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Of all the post-hull tasks, the one most stressful
is that of cutting enormous holes in the bilge and the transom to
accomodate the Kodiak three-stage jet drive. I had gone out of my
way to insure that the hull would be waterproof and in fact avoided as
much as possible installing through-hull fittings (such as a
self-bailing drain or thru-hull depth sensor) because I wanted to avoid
potential leaks. Now, however, it was necessary to do on a grand
scale the very thing I had been trying not to do on a much smaller
scale. I must have measured the size and shape and positioning of
the jet unit apertures at least a dozen times before actually starting
to chop holes in Kobuk. The caution paid off: the fit was perfect
and after two years of operation Kobuk still still does not permit a
drop of water to enter through the bottomsides. |
The
Cabin Planked
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David
in the Cabin
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The
Engine
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From the beginning, there was the question of
what kind of engine to use to power the jet drive. In the
end--much to the disgust of my mechanic friend, Werner--I opted to
install a gasoline engine rather than a diesel. I became
fascinated by a 240 horsepower rotary engine that is prepared for
marine use by a company called Rotary Power Marine Corporation, located
on Long Island. The engine block is the standard 175 horsepower
Mazda engine used in their automobiles, but RPMC modifies it for marine
use and supercharges it. Rotary engines are reknown for long
life, low maintenance, and (less conclusively) fuel efficiency.
These were considerations, but the thing that sold the engine to me is
its extraordinarily light weight. At roughly half the weight of a
comparably sized standard block engine, it frees up over three hundred
pounds that could then be used to add all the things that would be
needed for long distance cruising--a cabin, a bunk in the bow, an
auxiliary outboard, a collapsible bicycle in a suitcase, an inflatable
kayak, extra anchors, food supplies, and much more. Even though
it was not the engine he would have chosen, Werner was gracious enough
to install it for me in his shop. It took Werner a day to get the
engine installed and attached to the jet drive--and this is the one
construction job that I did not do alone. |
Werner
Installing the Engine
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The
Steering Console
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Wiring
and Interior Work
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Building your own boat is not a rational thing to
do. The number of hours of labor required to complete the task
are extraordinarily great and no matter how modest the nature of your
regular employment you almost certainly would be better off
economically to work at it extra hours and use the excess earnings to
buy a boat. In the case of Kobuk, I kept a log of the time I
worked on construction and it tallied roughly 950 hours. In fact,
the time was much greater because I did not count such things as
shopping trips--of which there were many dozens, each involving a
50-mile round-trip journey to Salt Lake City. Neither did
it count the hours of time spent studying plans and contemplating how
an upcoming task might be done. This thinking time almost
certainly exceeded the time actually spent constructing. If you
were to spend this volume of time working on communicating with your
spouse or significant other, the odds are that your relationship would
be in really, really good shape. Since I live alone, Kobuk
absorbed virtually all of the thoughtfulness and intimacy that I might
otherwise have lavished on some (undeserving?) woman. |
Hinging
the Cabin Top
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The
Cabin Complete
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The
Finished Product
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As one gets older, it becomes ever harder to remember
things, and I found this to be rather shocking problem once Kobuk was
finished. Many of the small jobs that I did over the years are no
longer clear in my mind and when I look at various aspects of the hull
I wonder to myself how I managed to get them done. It is very
disturbing. If the steering fails, for example, I cannot remember
how I originally rigged it. If the instrument panel with all of
its wiring has to be removed in order to get at the bilge and repair a
hole in the bottom, I cannot remember how--and in what order--its many
wires and cables were attached. If a fuel tank under the floor
boards has to be worked on, I do not recall how I managed to run the
half dozen fuel lines and electrical wires that are connected to
it. I dearly hope that these sorts of problems do not afflict me
until enough of the voyage has been completed to compensate for the
burden of having to give myself a refresher course on how I lived my
life for five years.
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In
Kobuk's Cabin
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Kobuk
on the Jordanelle
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Kobuk
on Lake Powell
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