Comfortable and functional oar length depends mostly on distance between the oarlocks, but also the length of the boat. There are some different formulas out there, such as the following: Wooden Rowing Oars - Shaw & Tenney
, Information on oars
, Frequently Answered Questions - skiffs
. As I recall Bill McGinnis recommends that roughly 1/3 of the oar length should be inboard to obtain the right amount of leverage. I leave 4" between the handles, but use open oarlocks so I can draw them in and row overhand (Outward Bound style) in high wind situations. On 14' boats (raft and dory) 9.5 seemed to be just right, but if your 14' cat is "wide" between the locks, 10's may work. I only use Smoker solid ash, not counterbalanced, but keeps my shoulders and arms in shape. To me a wood oar is the best feeling and most reliable. They either break, or remain straight and true (if good quality). Current pair is 16 years old. Not too many composite or high-tech oars can match that. Like everything, more moving parts, fastners, etc., means more things to break or wear out.