Two 3/4" pieces of Sitka spruce laminated
with epoxy for an
unfeathered one-piece paddle.
For the wood shaft,
Sitka spruce is best. It is light and strong, but it is also expensive
and hard to find. Look for knot free wood with vertical
grain. Also check that the
grain
runs
fairly
straight
the
length of
the board.
Position the vertical grain perpendicular to the paddle blades for
strength.
I squarely plane my shafts down to 1 3/8" wide
(front to back) and 1 3/16" thick
(top to bottom).
Carving the Shaft
Laminating a piece of wood to the shaft in the
blade area while
it is still square allows for a deep curve where the
blade is
epoxied on.
Blade curve and blade templates made of thin plywood.
Note the guidelines.
I like my blade to curve to a depth 1/4" short of reaching the
opposite side of the shaft to eliminate flutter and coming back 1/8" short
of reaching the center of the shaft at the tip to provide more power
at
the beginning of the forward stroke. To keep the blade area of the
shaft strong but still light, I keep it 1/2" thick at the deepest
part of the curve,
which
is halfway down the length of the blade.
The curved section cut out of the shaft where the blade will
be
epoxied on.
Use a bandsaw or jigsaw to cut out the blade curve. For final trimming
down to the lines, I like to use a rasp and then scrape with
a drawknife. Try to keep the blade curve square to the shaft.
The shaft marked for planning to round it.
For sort of an egg shape shaft that provides good indexing
and is comfortable to push and pull, I mark the rounding lines 1/4" from
the edges on the pushing side, 5/16" on the top and bottom of
the pushing side, 7/16" on the top and bottom of the pulling side,
and 3/8" on
the pulling side
The four corners planed down.
After the four corners are planed down, plane down
the newly formed eight corners evenly by carefully eyeballing it.
The shaft is rounded and sanded smooth.
The rounding of the shaft is continued with 60 grit sandpaper
on a 12" long
block of wood. Fine tuning of the rounding is done with 100 grit
sandpaper folded and held
in a curved position in the hand.
Hardening the shaft with the side of a screw driver
to make it
more resistant to denting.
Wet the shaft to raise the grain, and after it dries, sand the raised grain
smooth with 220 grit
sandpaper. Harden the shaft to make it more dent resistant by rubbing it hard
with the side of a screw driver. The hardening will cause some small pieces
of grain to peel off. Rub them off with your hands, very lightly sand them
off with 220 grit, and rub them off with your hands some more.
Seal the shaft
with epoxy before attaching the blades. Apply one coat of epoxy,
let it cure for at least 24 hours, lightly sand with
220
grit, and apply a second coat. Sealing the blade section of the shaft
isn't necessary because it will be covered with carbon fiber.
Squaring the blade curve with levels.
Slide
a level along the length of the blade curve to make a final
check that it is square with the shaft. I like to scrape with a
drawknife
to make corrections.
Building and Attaching the Blades
The blade lay-up is wetted out with epoxy resin.
Wet out the lay-up for the
blades with epoxy on wax paper on a flat piece of plywood. The
lay-up at
this
point in the building process is two layers of 6-ounce carbon
fiber.
Remove
the excess
epoxy
with a squeegee. After the epoxy has cured eight
hours, place the blade template over each lay-up, and trace around
the
template with a nail to scratch a mark.
Then cut the lay-up with
scissors
about
1/4"
outside of
the
mark. Also, using a pen to mark the centerline
on the smooth side of the blades helps with lining them up on the shaft.
Attaching the blade to the shaft.
While the blades are still flexible
(before the epoxy has cured more than 12 hours), attach them rough
side down to the shaft with
thickened
epoxy.
Some weights or clamps are necessary to bend the blades to match
the curved sections of the shaft. Make sure the blades are lined
up square and even with the shaft.
Using a level helps.
The back side of a blade after being epoxied to the shaft.
A
fillet of thickened epoxy is added along the edge between the
blade and shaft so the next lay-up layers will turn smoothly from
the shaft to the blade.
The back of the blade after the tip reinforcement and a layer of
carbon
fiber have been added.
On the back side of the blades, reinforce the
tips with a three-inch-wide carbon fiber strip. Then wet out
another layer of carbon fiber over the entire back side
of the blades.
Use a squeegee
to remove
the
excess epoxy. Add two coats of epoxy to the back of the blades to fill
the weave and sand them smooth.
Use
60 grit sand
paper
to trim
down
the edge
of
the blades to the mark scratched with the nail.
The wide blade is my Redondo Ridgeback Inshore design and
the narrow
blade is my Redondo Ridgeback Offshore design.
You can paint or varnish the blades and shaft, but I leave them
unfinished. Either way, the wood shaft should be sealed with two
coats of epoxy. For a perfect grip, lightly wet sand the shaft with
400
grit
sandpaper,
followed up with wet 00 synthetic steel wool.
As I final touch, I cover the transition between the blades and
shaft (where the carbon fiber meets wood) with a coat of slightly
thickened epoxy colored black with graphite
powder. Warning: I've heard that a finish should not be applied
over graphite powder.
Using the above methods, my paddles weigh around 32 ounces and
are very strong.
