Collars for wooden oars and a drop-in rowing unit

Hello Lads,

Can anyone tell me if the drop-in unit requires a specific oar collar?  I'll be using 9ft wooden oars.  

If your drop-in-unit has oarlocks that are round or U shaped, not really.  If one side of each oarlock is flat, yes, the collars will need to be D shaped (the oar shafts fit through the center of the Ds) and small enough to rotate inside the oarlocks.  Talk to the drop-in-unit vendor.