Bump for more comments.
The reason I'm asking is that I had kind of decided on 7 foot oars for my small raft for multi-day trips on quiet rivers, but my local shop only has 6.5 foot oars right now and I'm planning a trip for early July. I will likely never more than wider class II rivers with gear, possibly an un-loaded attempt at class III in the future. The frame is 42" wide, oarlock seperation is 48". A quick calculation of oar length based on a 4" handle seperation and the 1/3, 2/3 rule suggests 5.5 feet but this seems way too short to me. And the NRS website suggests a minimum 7 foot oars for a 48" frame. Maybe this is the frame width, not the oarlock seperation (so I should have shorter oars)?
7 foot oars on this setup would result in about 1/4 to 3/4 ratio, but Chips thread about rope-wrapping an oar-lock has a pic that looks like his oars are set at about that ratio... hopefully he can chime in here. I'm going with wooden oars with blades that are about 24" x 5", and I think I read somewhere on here that you can/should go with a little longer oar if you have narrow blades.
So should I hold out for 7 footers or get 6.5 footers? I know... only 6 inches difference, but again, I'm trying to get it right the first time in the interests of funds.