DIY

MOTHER’s Dinghy: How to Build a Homemade Boat

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Allow it to perform well with a simple homemade sail rig.
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The clean lines of MOTHER's little dinghy.
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Here are the various prototypes built while perfecting the design.
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Diagram of boat building instructions.
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Our row-and-sail boat also accommodates a 1.5HP Cruise Air from Air Drive Systems of Tavernier, Florida (We'll have more on the power plant in a future issue.)

How to build a homemade boat. Buy two 4 by 8 sheets of 1/4 inch plywood, and you can start this rewarding winter workship project. (See the boat building diagram and boat photos in the image gallery.)

There aren’t too many homesites in North America that
aren’t within easy driving distance of a good-sized body of
water, So it’s a safe bet that those of you who don’t own a
boat had, over the past summer, occasion to wish you did.
And there are several reasons why right now would
be a good time to begin a boat-building project. Here’s how to build a homemade boat.

For one, the winter months ahead will provide some freedom
form the constant demands of yard and garden work ( and
from the tempetation to simply be outdoor in fine weather)
and thus should allow plenty of time for the
slow-and-steady woodworkers among us to have our hand-built
watercraft ready for launch next spring. In addition, if
you decide to buckle down and get right to this project,
you’ll be able to have a special Christmas gift ready to
give a watersmitten youngster . . . or a fine little
fowling boat for your own winter duck hunts.

You shouldn’t find MOTHER’s dinghy too difficult to
construct. Research staffers Dennis Burkholder and Clarence
Goosen built the brightly painted beauty shown here in just
four days . . . and most of that time was spent waiting for
glue to dry!

Your first task will be to collect two 4 feet by
8 feet sheets of
1/4 inch marine plywood (we used a less expensive plywood when
building the two prototypes used to refine our design, and
those boats have held up well so far, but we can’t make any
estimate of their long-term reliability), about 160 feet of
3/4 inch by
1-1/8 inch flexible, clear-grained hardwood (we
recommend oak, and ripped our strips from ten-foot 3/4 inch by
8 inch boards), a foot or so of 3/4 inch by
8 inch hardwood for the
motor-mount brace (you’ll measure it for exact fit later),
about 500 No. 6 by 3/4 inch brass wood screws, two dozen No. 8 by
1-1/2 inch brass wood screws (nickle-plated fasteners can also
be used), and a supply of plastic resin glue.

To begin, scribe a centerline down each sheet of plywood
(it’ll serve as a reference point for several of the
measurements to come). Then go on to mark the cutting lines
for one of the boat’s sides. To do so, select a long,
straight-grained strip of 1-1/8 inch by 3/4 inch hardwood to use as
a straightedge. (Keep this strip separate, because the same
one should be used to draw the curves for the boat’s bottom
later.) Clamp its center to one of your plywood sheets,
placing the clamp about 1/8 inch in from the edge at a point 3 feet
6-1/2 inch from one end (that end will be the boat’s stern).
Then, with a friend’s help, bend the hardwood into a bow,
clamping it so that its outer edges intersect the edges of
the plywood 3 inch from the corner in the stern and 5-1/8 inch from
the corner in the bow. With that done, scribe a line along
the outer surface of the hardwood strip.

Next, you’ll want to draw the upper edge of the boat’s
side. To do so, mark the clamp positions as in the
accompanying illustration, then–using a bar clamp
positioned 3 feet 6-1/2 inch from the stern end–secure the
hardwood strip with its outer edge 1 foot 3-1/4 inches from the edge
of the plywood, clamp the ends of the strip as marked, and
trace the line. Now mark the angles of the bow and stern as
shown, cut out the side, and flop it over to use as a
pattern for the boat’s other side. (It’s best to draw in
the patterns for the bow and stern transoms, allowing room
for the four corner pieces, before doing any more cutting,
to make sure all of the components will fit on the one
plywood sheet.)

Now, going to the other plywood sheet, use your
hardwood strip inch ruler inch to draw the boat’s bottom, employing
the same bend-and trace technique used when drawing the
sides. Then cut the bottom out, leaving a surplus of 1-1/2 inch
to 2 inch around the pattern on the sides and at the bow (it’ll
be trimmed away later).

With that done, you can cut out the second side and the
transoms and also draw and cut out the central support
frame. Then glue and screw the hardwood support strips, and
the cut-to-fit motor-mount brace, to the front and rear
transoms and the central support, using No. 6 by
3/4 inch wood
screws set at 3 inch intervals. (The upper support strips for
the front and rear transoms will have to be trimmed to
match the angles of the bow and stern. To do so, simply use
a sliding bevel to measure the appropriate angle on the
bottom panel–use the pattern lines, not the
inch hem inch –then set your saw’s miter gauge to that angle
and trim away.)

In the next step, use glue and 3 inch -spaced No. 6 by
3/4 inch wood
screws to secure the two sides to the central support
frame, which should be positioned 3 feet 6-1/2 inches from the boat’s
stern. Then swing in the sides and, starting with the stern
transom (you might want to loop a rope around the two sides
at a point near the front to keep them from spreading too
much while you do this), glue and screw the sides to the
stern transom support frame–again setting the screws
at 3 inch intervals. Now go on to secure the sides to the bow
transom in the same manner, and let the glue dry for its
full recommended period of time.

At this point, we come to the only really awkward part of
the construction process. After the glue has dried, you’ll
have to beg, borrow, or buy at least 20 clamps to secure
the hardwood support strips to the bottom edges of the two
sides. Cut the strips to length, leaving a 6 inch overhang on
each end, and then start each one–at the
stern–by running a No. 8 by
1-1/2 inch wood screw through
it and into the transom support frame. Then–working
with a helper and using glue and 3/4 inch wood screws set at 3 inch
intervals–bend, fasten, and clamp both strips in
place a bit at a time. (A brace and bit, and predrilled
pilot holes, will make this task go quickly.) Secure the
far ends of each strip with 1-1/2 inch screws, and when the
adhesive has thoroughly dried, trim the ends of the strips
and plane them flush with the bottom of the plywood.

When the next step’s completed, your boat will begin to
look like a water-worthy craft. Now’s the time to invert
the sides-and-transoms assembly and to glue and screw the
bottom in place. Once that’s done, you can go on to install
the bottom support strips, using the overlapping bottom
inch hem inch to clamp them in place as you glue and screw them
down (these 3/4 inch screws are inserted from the
inside of the boat).

Later, after waiting for the previously added pieces to dry
in place, you can trim off the excess plywood on the
bottom, flip the boat over, and attach the gunwales (top
support strips) to the upper edge of each side, employing
the multiple clamps to attach the two gunwales
simultaneously as you did when installing the lower side
support strips.

And, finally, it’s time for the finishing touches. Take
your scrap of plywood, and using the sliding bevel to get
the angles right, draw and cut out the four corner braces.
Secure strips of hardwood brace to these at the points at
which they’ll be fastened to the boat. Bring the sliding
bevel into play again, this time to measure the slope of
the boat’s sides and transoms at the appropriate points,
then set your miter gauge to the indicated angle and rip
the support strips before gluing and screwing them into
place.

You’ll have to use the sliding bevel once more to fit the
bow seat support in place; then run a strip of hardwood
from it, allowing the strip to rest on the central support
brace, to mark the correct height for the stern seat
support. With that done, go on to assemble the
hardwood-strip seat as shown in the detail drawing, leaving
off one of the side braces so you’ll be able to paint the
interior of the boat and slip some polystyrene flotation
blocks beneath the seat. (Simply attach the remaining side
brace to hold the foam in position,)

We used three coats of urethane floor enamel (about one
gallon total) to paint our skiff: However, a primer coat of
Thompson’s Water Seal (or a similar product) would
certainly be a worthwhile investment, especially if you
elect to experiment with a less expensive grade of plywood.

Once the paint has dried and you’ve positioned your
oarlocks (we’ve found them to work best when the holes are
centered 7-1/4 inches behind the center support brace), grab a
pair of oars and a life preserver, head for the nearest
lake, pond, bay, or slow-moving river, and discover, as
Water Rat noted in The Wind in the Willows, that
“there is nothing–absolutely
nothing–half so much worth doing as simply messing
about in boats.”


If you’d like a bit more help with your boatbuilding
project than we’ve been able to present in these three
pages, you’ll be pleased to know that we’re preparing a set
of detailed plans for both the boat and the sail unit that
will be featured in our next issue. You can order a set,
for $10.00 plus $1.00 shipping and handling, by writing to
Boat Plans, THE MOTHER EARTH NEWS PLANS, Hendersonville, NC.


COMING UP:
MOTHER’s researchers are fine- tuning the simple clamp-on
sail rig shown in the accompanying photos. This little
breeze-fueled power plant–which can be used with any
small, square-sterned craft, and which shouldn’t cost more
than $45 to assemble–will be described in detail in
MOTHER EARTH NEWS NO. 96.

Need Help? Call 1-800-234-3368