I did a 16 ft Owasco some years ago - it was ONS 62.
I talked to the/a Penn Yan rep about when it might have been made, he claimed that the 16 ft O was 1st offered in 1931, and that in the 1st half of a decade, they dropped the year digits from the S/N. He also said that in '33 they used basswood for ribs instead of cedar.
From that, he thought that mine was a 31 or 32.
With out seeing more of the catalogs this is just a guess but,
with (if it is) the 2 digit model code, ie OC, one might assume it's pre 31, as that's when the 16 ft was offered and maybe the 3 digit code started.
And if the 1st half of the decade was used in the 20's, that would put it in the early 20's.
Also, mine had maple decks, thwarts and seats.
Another clue, the early PY's had the black/yellow vertical decal, the later (40's) had the rectangular blue decal, mine had an odd large horizontal oval decal,
Dan