stats - boat - budget
- explanation - bio
||5.6 m (18' 8") (w/o rudder)
||5.3 m (17' 8")
||Beam (Main Hull)
||1 m (3' 4")
||2.40 m (8')
||3 m (10')
|Draft (leeboards/rudder up)
||15 cm (6")
|Draft (leeboards down)
||53 cm (1 ' 9")
||Freeboard (fully loaded)
||30 cm (1')
||Total sail area
|| 7.2 m2 (80 square feet)
|| 5.6 m2 (61 sq. ft)
||2.6 m2 (29 sq.ft.)
||2 HP air cooled outboard
Studying the report of Keith
Drury, and considering the tight financial and
temporal frame, it becomes clear that the voyage asks for flexibility.
You'll probably need to make progress in any conditions in order
to make it within the 90 days, in bad weather, in rapids and
lakes with big waves and wind. There my be unforeseen events
like boat repair, lack of fuel or engine problems etc.
My answer to this is a small
and lightweight canoe with two floats linked to the main hull
by means of platforms. This gives the canoe the needed stability
and safety, plus enough living space.
The boat is flexible in terms
of propulsion - it can be paddled, sailed or driven by the outboard.
The long narrow hull has minimal water resistance, and the floats
are mounted a bit higher, so that they barely touch the water
in upright position. The floats can be made from glassed styrofoam
or plywood. The main hull is glassed on the outside - two layers
of 3 ounces/m2 fabric on the bilge panels and bottom.
The boat has two short masts
with Gunther batwing sails and sprit booms. The total sail area
is about 7 square meters and each of the floats provides 130
kg lift - together with the beam of 2,4 m (8'), this means that
the boat can sail unreefed up to about 4 Bft. It has two leeboards
that are mounted to a shaft that hangs under the platforms,
just as in my folding tri (see Duckworks article). The leeboards
can be built massively with sink weights or hollow with a combination
of rubber and rigid lines holding them in place.
The rudder is built as kick-up
rudder with sink weight, as usually in Michalak designs (not
visible in the 3D model). It is operated by means of lines that
are linked to two pedals.
The outboard is mounted offset
in front of the rear seat for a better weight trim (note that
the outboard mount does not need to be as massive inside the
hull as shown in the pictures - the model is a 3D equivalent
of a sketch and therefore not to be mistaken as detailed design).
It is fixed as the boat is steered only by means of the rudder.
Keith Drury writes that the silt
in the Missouri will sooner or later destroy the water pump.
Therefore I would buy the air-cooled Honda BF2D 4-stroke engine
with 2hp. It has a very low fuel consumption, I read about 0.85
l/hour. Using it during the whole voyage, and making an average
4 knots (70% of the hull speed), you have about 660 operating
hours and thus need 560 l (160 gallons) of fuel. I think the
engine will burn more fuel in bad conditions, but probably a
big part of the journey is made by paddle and/or sail, simply
because that's how you will enjoy the trip much more. By the
way, in calm conditions one horsepower should push the boat
(920 lbs total, 17 feet waterline) at a speed of 4.7 knots according
to a diagram in an old Michalak article about electric boating.
(A rough estimation, of course, but the pointed canoe hull with
a length-beam ratio of 5.6 is particularly efficient).
Flexibility is also provided
in terms of accomodation. In nice weather, you may want to sit
in the open air, then the open middle section is the "saloon",
with the platforms serving as seat benches and a cockpit table
mounted to the main mast.
To travel in bad weather, you
mount the deck tent over a tube between the masts so that it
lies flat on the platforms and raises just enough to provide
sitting headroom in the middle section. So the helmsman can
still look over the tent and the other one can sleep or read
or just relax in the protected 200 x 100 cm space (6' 8"
x 3' 4").
A second "tent" can
be mounted over the raised mizzen sprit boom to protect the
helmsman - the main sprit boom is then mounted to the transom
If things are really bad and
you want to decrease air resistance to a minimum, you can lower
the tent to the platform level and still have very basic shelter
for a couple.
When you've anchored or pulled
the boat ashore, you can mount the deck tent at full height
and thus get a spacious cabin with standing headroom in the
middle and two 200 x 70 cm berths with sitting headroom on the
platforms (6' 8" x 2' 4"). On windy days, the foretent
mounted between the deck tent and the bow makes the front more
aerodynamic. It is open at the lower side, which gives dry access
to the river. However, the main tent can be completely closed
to keep the mosquitoes outside.
To make these many configurations
possible, several strips of hook and loop tape are sewn on the
tent and glued to the corresponding areas of the hull/platforms.
The tent is made from heavy polytarp and the sews are sealed
with adhesive tape.
Transport and Portages
The boat can be disassembled
for transport - the crossbeams are pushed through openings in
the main hull and bolted to the bulkheads. The platforms with
the glued-on floats are screwed to the crossbeams and the main
hull with drywall screws. After assembly some (removable) sealant
should be passed over any gaps and the screws.
At the dams I would try to get
a ride, as Keith Drury recommends. But to be on the safe side,
build a primitive boat cart consisting of a (wooden) double-T
profile with 20" wheels at both sides. The "board"
is simply strapped under the main hull a bit aft of the middle.
If necessary, boat and
gear will be transported separately. The boat can even be disassembled
until only the main hull with about 80 kg is left.
|plywood 10 sheets à 50$
|Epoxy, glass, styrofoam
|polytarp for sail and tents
|other building materials
|Wheels for boat cart
|foam for platform/berth matresses
|Outboard Honda BF2D or BF2.3
|600 l fuel (170 gallons)
|3 fuel tanks (3 gallons each)
|2 water tanks, 5 gallons each
|anchor, 10 m chain and 20 m rope
|2 life jackets
|top lantern, 12V battery
|solar panel for charging battery
|anchor & chain
|clothes, other equipment
The boat is built in stitch and
glue from a light 5 or 6 mm plywood - preferrably pine. The
total net area of plywood needed is 21.5 square meters, that
is 10 sheets are needed. Pine or fir lumber is used for framing
and the cross beams. The lumber budget also includes smaller
pieces of a heavy 16 mm plywood for the rudder, motor mount
and cockpit table. (assuming the leeboards are profiled hollow
construction from two 5 mm layers).
25 square meters of glass are
needed for the bottom and the floats - about 100$ here in Europe.
You'll need about 10 litres of Epoxy and hardener, that is another
100$. Then you need some styrofoam and blue foam for the floats
and the inner parts of the platform sandwiches - another 100$
will do easily.
The paint is exterior latex -
the bottom is glassed anyway. For Tents and sails you buy 40
square metres of polytarp for about 120$ and double sided adhesive
tape and hook and loop tape for 80$.
"Other building materials"
means glue, bolts, drywall screws, cable tiers, brushes, rubber
The boat cart wheels probably
will come from a junkyard. The foam for the berths can also
come from some unconventional source - or you buy two air matresses
and repair kits.
The outboard should definitively
be purchased new for the sake of reliability, fuel economy and
low noise. Probably you won't need as much fuel as listed. I
don't know the US fuel prices, but I assume it's about 1.75
$ a gallon. If it's more expansive you'll need to paddle a bit
more. The fuel and water tanks are plastic, light and cheap.
The GPS and maps are important
as you can't afford getting lost on the lakes. I think a used
GPS should be available for 100$ or less.
The 4kg anchor has a chain forerunner
of 10 meters. Maybe that is exaggerated for a river trip, but
on a windy day it can save your boat. As for rope, I would try
to get at least 20 m of 10 mm rope and about the same length
of 6 mm line.
The watertight bags/containers
play an important role as they provide additional lift if the
boat should get swamped or leak, if tied firmly to the hull.
A top lantern is probably necessary
in the parts of the river where you encounter substantial commercial
traffic. Therefore, you also need a battery and a small solar
panel to charge it. However I don't expect the lantern is used
frequently - at night you'll probably look for a secure place
in shallow water.
All this leaves 1500 dollars
for food and other travel supplies.
The total weight of the boat
should not exceed 460 kg. By the way, all heavy items like anchor,
battery, water and fuel are stored in front of the middle section
to ensure a proper trim.
I'm a mechanical engineer and have been reading about boat design as a hobby since 1998. I've built a 4.70 m folding tri of my own design in stitch and glue (and written a Duckworks article about it) and participated in two earlier Duckworks design contests. I use a self-written design system ("Ligo") for modeling and calculations. Today I work as a software developer.