Since I did not want to spend a lot of money on a carbon shaft on my first "test" SUP paddle, and did not have ready access where I currently live to thin foam sheets to make the blade from, I decided to just make it with a lightweight wood core. Plus I decided to just use scrap pieces of carbon, kevlar, and fiberglass cloth I have remaining from previous projects.
I knew the end result would be heavier than a foam core carbon blade and shaft paddle but I felt confident I could build one that would still be light enough to be good for paddling until I have time to build my next all carbon paddle.
To begin I made a template for the paddle blade based on the general shape and size of most commercially available paddles. I then transferred that to a piece of 4mm (3/16") thickness plywood.
Then I applied a single layer of 4 ounce bi-directional E glass to both sides of the blade and then began to work on the shaft. (No photos of this step.)
For the shaft I found a lightweight wood dowel about 6' long and about 1 1/8" diameter which seemed about right.
The photos now follow the process.
After making a plywood jig to allow me to cut the paddle shaft at the desired 12 degree angle, I used my favorite Japanese razor saw to cut the shaft following the angle on the jig.
Jury rigged jig to hold down the cut paddle shaft to allow epoxying to the paddle blade at the proper 12 degree angle. I used a mixture of epoxy and West Systems 406 Collodial Silica filler to make a very strong glue joint.
Epoxying on plywood shaft doubler behind the end point of the blade to allow extra strength once reinforced with carbon fiber and glass at the critical blade to shaft joint.
West Systems Microlight Filler # 410 used to fill in voids and depressions in the shaft to blade epoxy joint. Too be sanded smooth after hardening.
Uni-Directional Carbon Fiber cloth alongside shaft and paddle blade and ready for epoxying to the paddle. Uni-Directional cloth will give superior strength to paddle to resist excessive bending at the shaft to paddle joint as well as additional overall paddle strength.
Uni-directional carbon applied along mid- axis of paddle blade and shaft and then reinforced with pieces of 5.7 ounce/sq yard bi-directional carbon cloth. Also you can see the application of "peel ply" dacron cloth over the layup. This will peel right off when the expoxy has hardended leaving a much smoother surface, compression down smoothly the carbon cloth end fibers, and resulting in much less sanding and filling needed latter.
(Note: When I make the next all carbon paddle I will use a single ply of uni such as shown above and then additional plys of 5.7 bi-directional cloth to completely cover the top and bottom surfaces of the blade and extending up the paddle shaft a short distance to provide additional strength, torsion and bending resistance. I will not need to use 4 ounce E-glass on the paddle blade then since the carbon cloth will be plenty strong.)
The opposite side of the blade and shaft getting the uni-directional carbon and bi-directional reinforcement. Also, note the use of the "peel ply" again.
Too provide increased ding and damage resistance to the paddle blade edges I decided to add a layer or 2.5 ounce / sq. yard kevlar cloth. I cut it on the "Bias" (45 degrees to the fiber orientation) so that it would much more easily stretch tightly around the edge of the blade as well as follow the curve of the blade.
Kevlar cloth now applied to one side of the blade and ready to be wet out with resin on the edge and opposite side.
View of kevlar cloth edge strip now completely wet out on both sides of the paddle.
Now adding additional layer of 4 ounce glass over the paddle blade and kevlar cloth. Note: After doing this step it was apparent that the underlying kevlar cloth created a ridge depression in the overlaying fiberglass all around where the edge of the kevlar met the glass. This would require some filler later. Lesson learned: Add kevlar first to paddle shaft then add carbon cloth plys over it.
Side view of paddle shaft to blade joint after applicaton of carbon reinforcement and West System 410 Microlight Filler, and subsequent dry and wet sanding.
View of blade after filling with microlight filler and dry/wet sanding smooth.
T-Handle made out of piece of cut off shaft wood dowel and epoxied onto shaft with mixture of resin and Collodial Silica filler.
Another view of the paddle after application of microlight filler and dry/wet sanding.
View of completed paddle dry and wet sanded and ready for primer paint.
Note: I used a layer of 4 ounce bi-directional E-Glass in a single wrap around the entire length of the paddle shaft to give it additional strength and stiffness. The wood alone was too bendy and would be prone to breaking otherwise. Once I make the all carbon paddle with a carbon shaft, of course this step will be unnecessary.
Paddle blade and lower shaft with auto-primer paint to fill in small voids. Will be wet sanded with 220 grit wet paper after drying.
Note: Years of work and familiarity with composite hang glider and knowledge of composite construction of sailplanes makes me very hesitant to leave any epoxy and/or carbon surface unpainted. This is because UV and sunlight in general can weaken the epoxy composite matrix over time and if left in the sun cause enough heat build up to actually soften the resin matrix enough to cause warping.
Side view of paddle blade with addition of black plastic edge guard glued onto the paddle to further protect both paddle and board from dings.
Also note the use of SOLAS (Safety of Life At Sea) reflective tape. Could be used for helping to signal rescue craft in an emergency.
Next I will post some photos of the paddle getting its first real water tests.