had some 6 1/2-foot oars that were terrible. They weren't tapered much. The blades were 1 1/2" thick at center and the edges 3/4"--planed some, but not beveled. No spring. Heavy. It was like rowing with baseball bats.
It's pretty easy to improve such oars. I lef the fat upper portion as they were. From the oarlock location down I tapered the loom with a drawknife until it looked right. I then planed a bevel on the blades. Planning didn;t work well. I used the drawknife. It didn;t work well. I got out my 4-inch monster belt sander, put on a 60-grit belt, and just brutalized the pine until the shop was kneedeep in sawdust. I continued up the looms with the belt sander, grinding away everything that didn't look like a decent oar.
The inboard part of the stock oars were still so fat that when I put leathers on, the ring oarlocks wouldn't fit. So I chistled down 1/8 inch to the leather lies flat. Then five-coats varnish. No epoxy because they don't stay in the water long.
Now the stock oars look good, have pleasing spring, are much, much lighter and better balanced, and look hand made. For a one-weekend project using no subtle skills at all, a very positive result (but a big job afterwards for broom and shop-vac).