My last pair of oars were made of British Columbia cedar, while sailing offshore in the Pacific. Those oars worked well, but one had a troublesome knot in the shaft, which caused it to break.
In Chile, I bought some manio--a good boatbuilding wood, and made a new pair of oars while in port. I took the basic pattern from one of the existing oars
With a hand saw (first picture), I cut out the basic shape, then used a sanding disc on an angle grinder to finish it.
The finished oars, in the centerboard trunk, waiting for the paint to dry (they are not as long as they appear in the picture). I paint the oars white so if they slip out of the oarlocks at night, they don't disappear.in the darkness.