https://www.shawandtenney.com/how-size-your-oars

I posted the URL above after first reading the OP’s query, soon after I’d gotten off work then home.

Then I remembered the sliding seat outrigger rowing device the AW was designed for, described in detail here. That same page refers to an oar length of 9’-6”, dispelling any need to do any sharp-pencil calculations... unless you want to confirm what the CLC folks have already proven works well.