I began by building a couple of 1:12 scale cardboard models. These turned out
pretty well and I figured that I had the basic shapes close to what I needed.
Then I went and raided the cardboard recycling bin behind a local appliance
store and brought home LOTS of big pieces of corrugated cardboard. I cut out
the pieces of cardboard to the shapes I had figured out with the models, only
this time in life size. I then taped the pieces together and made the life size
mock up.
The first problem that I encountered was the fact that the cardboard does not
bend with nice smooth curves. It bends in hard folds and does not act the way
plywood does at all. I managed to work with it though and after a morning in my
shop ended up with half of a cardboard canoe (I only built half at a time to
see if it would work). I was encouraged by the results but realized that I
needed to work with real wood before I would get a true pattern for the real
boat.
I then went to the lumberyard to see what they had in cheap plywood to
experiment with. I ended up buying the thinnest material they had in stock -
3mm mahogany door skin. It was the cheapest too at $8.00 per 4x8 sheet.
I immediately set out tracing the life size cardboard patterns onto the door
skin and cut them out. I drilled the holes for the wire stitches and started to
tie it up.
I didn't get far.
Within half an hour, I had already broken my first pattern piece. The 3mm door
skin is very brittle and broke/split along a cut seam near the bottom of the
hull. I cut out another one and tried again. I got farther this time but it
just broke in a different place.
Cut another and try again.
This time I got both sides stitched together and managed to get the spreaders
in place. I then began to try and figure out how to do the floor. When I built
the Pirogue, I put the sides together, spread them apart with short boards,
then laid the bottom on and traced around the bottom of the side to achieve the
exact shape needed. Unfortunately this would not work here (although I tried).
I cut out the floor shape and then began trying to stitch it into place. The
spot where the sides change into the front of the floor was very much a V
shape. This area needed to transition smoothly into to a flat floor in order to
get the lines I wanted. However 3mm door skin does not like to do that - at
all. As I tried various different ways to flatten this V shape I broke both of
the side hull pieces.
In total disgust, I went inside late for dinner vowing to never even think
about building another canoe.
A week went by and every time I went into the shop I saw the broken hull
sitting on the work table (I was so disgusted with the results that I didn't
even bother to clean up the shop). I began to see a different way that I could
shape the pieces to get the hull and the floor to come together smoothly. It
would require a completely new pattern and a slight v hull, but I thought it
just might work. I went back down to the lumber yard and got a couple more
sheets of the 3mm door skin. I cut out the new pattern, and began stitching it
together. It took a few tries to figure out which seams to stitch up first, but
I finally got it. In addition, I was so gun shy about breaking the plywood,
that I soaked the pieces in hot water before I started stitching and spreading.
This seems to work well because the hot water softens the glue in the plywood
as well as the wood.
After I had figured out the shapes and how it would go together, I disassembled
the half-built canoe and made two other sets of patterns. One set went into the
other half of the boat, one half was saved for patterns for the next boat. When
the patterns were done, I saturated the pieces in a thinned down mixture of
resin (to thin the polyester resin, I used approx. ½ tablespoon of acetone per
2oz. resin BEFORE adding the hardener).
When the resin was cured (it seems to take longer when thinned but it will
cure), I re-tied the pieces together with .20 gauge wire.
I built this boat in two separate sections. The front half and the back half. I
joined them in the very middle with a 6 inch butt block joint on the inside.
This hides the seam from the inside (I wanted a bright finish on the inside).
The outside of the boat was going to be painted so the seam could be filled,
covered with resin and fiberglass, sanded smooth and then hidden by the paint.
So far it seems to have worked well.
After I got the hull joined together, I began taping the seams. There are a
couple of things to consider. This hull design has joints that are both convex
and concave on both the interior and the exterior. Where the sides meet the
floor the tied ends of the wires should be on the outside of the boat and the
inside should be pushed down as far as possible into the corner. You then fill
this with the filler of your choice (I used lightweight automotive body
filler). Get this fillet rounded and as smooth as possible (I used pastry bags
made from old pillowcases and an old spoon) and then use the resin and tape
over the fillet. The seams where the front of the floor joins the sides should
be done at the same time, only the ends of the wires should be on the inside of
the hull. The outside of the hull should be filled and taped. The rest of the
seams (the ones that run down the center of the hull) The ends of the wires
should be outside and the fillet and tape on the inside. When this first
fiberglass stage is done and cured, remove all of the wires, and do the other
sides. Presto you have a boat hull!
The next thing to do is attach gunwales. There is not much in the way of a
selection of wood in long thin lengths in the town where I live. In order to
save weight and money I decided to only put outwales on this boat. With only
outwales, I needed to have one long piece of solid wood - for strength reasons
there could be no joints. I looked and looked but could not find anyone that
would sell me the boards I needed in any type of hardwood (for less than $3.00
per foot). I finally ended up buying a 16-foot long Spruce 1x4 and ripped it on
my table saw. A 1x4 is actually ¾ by 3 ½ inches so I made my gunwales ¾ x 9/16
x 16 ft. I was worried that they would split when I bent them to the shape of
the hull so I soaked them in water for an hour and then let them dry overnight
while bent into an exaggerated canoe shape. The next morning I took them out of
the bending jig and attached them to the hull with no problem.
I had decided early on that I would let the gunwale determine the shear line of
the side of the canoe. So I spent a little time with the clamps moving the
shear up and down on the side of the boat. Clamps are very important - The more
the better. I have 9 small C clamps and that was enough for only one side at a
time. Start at the center of the boat and work out to the ends. This will allow
the gunwale to form to the the shape of the hull most easily. I found the shear
line that I liked the most and attached it with 12 or 14 ½”, #6 pan head, brass
screws (1screw every 6 inches). I then removed the gunwale and re-attached it
this time using resin as glue. Due to the shape of the hull the gunwale has to
bend in two different directions and it is also twisted so it sits flat against
the side of the hull. This means that the screws may not have enough holding
power until the resin cures so the clamps must be used again to line up the
screw holes. I then repeated this sequence for the other side, measuring often
and being very careful that the shear line was exactly the same.
After installing the gunwales, I decided to strengthen the floor somewhat. The
3mm plywood is quite thin, and I was using very thin coats of resin and varnish
so to increase the durability of the floor I laminated several 1” strips of 3mm
plywood 1” apart directly to the floor just in front of where the seat will go.
I used some darker wood from one of the broken pieces from the first design to
give a slight contrast to the rest of the hull - strictly for esthetic reasons!
I built a simple seat frame using a very simple design. I used 1” x ¾” clear
spruce with the 1” dimension being on the vertical plane for strength. It will
have nylon webbing (the kind used for tie down ratchet straps) woven around the
frame.
Because the boat has no inwales, I had to find a different way of attaching it.
I decided to compound miter the ends of the frame to fit the hull sides
exactly, then I simply put one 11/2” brass pan head screw through the hull into
the center of the seat frame ends. It seems very strong, but of course only
time will tell. If it does not hold up in use, I will cut some hangers for the
seat ends from ¼” plywood and install them inside the hull. This will help to
distribute the paddler's weight more evenly.
Another consideration is where to place the seat in relation to the overall
length of the boat. Because the boat is intended to be a solo, the seat must be
placed in a location that will allow the boat to remain nicely trimmed in the
water with a paddler and their gear. After looking at (and measuring) several
boats at a local canoe store, I decided to wing it and I installed the seat 18
inches from the center of the boat (67 inches from the stern). At one point I
had thought of designing an adjustable seat, but all of the designs I came up
with would require too much material and would increase the weight of the boat
too much. To trim the boat, the paddler will simply adjust the position of the
gear that they are carrying with them.
After using the boat for a full season and breaking a couple of seats, I have
come to the realization that the best way to install a seat for a solo boat is
to put it 27 inches from center (about 76 inches from stern). It should also be
mounted on a hanger or bracket of some sort. The stress of the paddlers weight
on one screw per frame piece is just too much. The frame will either split or
the screw will pull out of the frame end.
I built breasthooks out of some 3/4" pine shelving that was left over from
another project. Lay some cardboard over the ends of the canoe making sure that
they are square. Make each one separately as each end may be slightly different
than the other.
Reaching under the cardboard from the inside of the canoe, trace around the
inside edge of the top of the hull. Transfer this pattern onto the wood of your
choice, trim and sand it so it fits perfectly and then install it by driving 2
or 3 screws on each side through the gunwale and hull directly into the breast
hook. Pre-drill the holes in the gunwale to prevent them from cracking.
I like to paint the outside of the hull with a good quality oil based enamel or
a plastic paint. While you could use a water based paint (better for the
environment and less smell). Oil based paints are the toughest, hardest drying
paints available. Sand, sand, sand, finishing with 100-grit sandpaper. Then use
a foam roller or spray to prevent brush marks or roller marks, and apply 2-3
coats of paint on the hull. You should be able to get 3 coats out of a quart of
paint depending on how thick you apply it. You might want to top coat it with
some sort of clear coat but every coat of paint or varnish will add to the
weight.
I tend to play rough with my boats, so I don't worry about a scratch here and
there. Besides, I have enough paint left over that I could do a touch up or two
if it ever becomes necessary.
If you'd like to build one of my ultra light canoes, please select one of the
options
below.
