On my first boat, a Chesapeake 17, smoothing out the laminated layers of plywood on coaming was FAR more labor-intensive that I expected. On my latest project, a North Bay, I carefully laminated the multiple rings and then used a router and a "pattern bit" (i.e., has a bearing on top of the blade rather than at the bottom). I ran the bearing along the uppermost coaming ring using it as the "pattern" and the rings below were quickly trimmed into submission (and looked quite nice).

I still have a bit of hand finishing to do, but it's probably 1/10 of the work that I did on my first boat where a surform and elbow grease were my primary tools.