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Double ended 11.5 ft canoe ultra-light design
notes.
One goal is to get the weight down between 20 and 30 lbs with
the smaller rails, keel and thinner sides.
The sides are of 1/8 ply "lap straked" with 1
overlap. The lap is glued with Tightbond II and Ό staples. Upper
strake is 5.5 lower is 6.5. This overlap is the equivalent of a
1/4" x 1" stringer running along the middle of each side and
will lend additional stiffness.
Glue the overlap on the bow/stern panels before cutting them apart, or the
slant for the stems will be misaligned.
An 8ft half round rub rail could be added along the
lap if necessary for more stiffness. I don't think it will be necessary.
The bottom can come from half a sheet of Ό ply,
using the rotating triangles approach. (see sketch)
Butt glue the triangles with thickened epoxy or
tightbond II with no battens at first. The keel will reinforce the
longitudinal joint, and a 4" wide 1/8" thick butt block can be
used for the athwartships joint.
The stems are 41 degrees. A wood stem could be made, but
it can also be stitch and glued
with the usual epoxy and glass, or with PL and glass.
(I'll be doing the glass and epoxy to see how easy it would be to do
"student canoes" in the evenings.)
The rails are of 5/8 x Ύ ripped from 1 by
stock. (see sketch)
I've used cypress a lot because it is available locally very clear. This
time I'm going to look for a pine board. It may be lighter, and what is
more available to others.
The canoe is symmetrical fore and aft and side to
side. This makes the frame placement easier.
The first and 3rd frames are identical,
38 from the ends... at least according to the computer. I'll see how
the materials want to behave.
The rails and chine logs (if used) are installed
"on
the flat" with Tightbond II, or PL or Epoxy. I'll be using Tightbond
II and ring nails on this one, to more closely mirror the way the kids
will build them.
The side assemblies are coated with thinned epoxy
while they are still flat. This will prevent any drips or runs.
The side panels are bent around the center form with
the help of rope windlasses, and the stems are stitched together.
The bottoms triangles are glued and the Ύ x 1
keel is glued and nailed to it.
The bottom panel is slipped under the sides which are
right side up on saw horses.
Gravity creates the curve of the bottom.
Bottom can be marked, removed cut and put back in
place
or
.
Here's an innovative approach a friend of mine is
finding workable on small boats.
After making sure the sides are not racked or bent,
run a bead of PL Premium around the inside side bottom joint. Smooth with
a spoon or gloved finger. When set, turn hull over, trim off bottom with
laminate trimmer.
Round corners and apply 2 fiberglass tape and
epoxy.
Or....
Another approach still in the testing stage would
work like this.
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Run a bead of PL adhesive inside and out. After it
cures, trim off the bottom with a saw or laminate trimmer. Round and
soften the slight overhanging lip with a sander, and seal it with
epoxy. I'm currently testing PL Premium masonry sealant which
doesn't bubble as it cures & ways of minimizing the bubbles in
PL construction adhesive. |
Could gallon plastic jugs be secured fore and
aft for floatation instead of water tight bulkheads?? If so.... maybe they
could be made to nest.
Spreaders can be 7/8 dowels with 5/8 tenons cut
on the ends.
Drill 5/8 hole with a forstner bit into inwales.
The boat sides need to be flexed open to install and remove spreaders. If
they can be removable, the boats can be nested.
Perhaps a single slightly off center spreader that
doubles as a pivoting seat back support, might work?
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