The varnish they use is useless. I sanded mine bare and then applied
epoxy to them and then painted them white with WR155 epoxy primer. I
have found that this primer holds up very well.
I don't even know if this stuff is still available, but about 20 years
ago I painted a pair of 9ft spruce with Rustoleum Woodsaver (or
something like that - the can is still out in the shed) and they have
been outside for maybe a dozen season since and still look pretty good
fro work boat oars.
Matt
"Easy" is high gloss oil based enamel. Sand them bare, prime, and put
on several coats.
If you want to spend more time, money and energy on sinmething as
mundane as oars, you can always sand them bare, and then starting with
very thinned, slow cure epoxy, and then add a few layers of unthinned
epoxy followed by a topcoat of oil based enamel.
I'd take the first option. It will hold up a long time. For oil based
enamel, you can get Rustoleum, or similar in small quantities. It
holds up a lot better than water based enamel in this application.
I wouldn't use poly on oars. Subsequent coats don't really bond very
well and the finish will quickly degrade, especially where oar meets
oarlock.
I paint my oars white. Makes them a lot easier to find if you lose one
in the water, and it makes you more visible to speedboats.