For canoes that were originally sold with oars and oar locks, is there any documentation describing the length of the oars that would have typically been sold with the canoe? In my case, I am specifically wondering about an 18-foot square-stern canoe with sponsons (http://wcha.org/forums/index.php?threads/old-town-with-sponsons-serial-number-7180-18.15860/) but I am also asking about documentation in general. I occasionally see sets of used Old Town or even Shaw and Tenney oars for sale on Craiglist. I'm sure that if I called Shaw and Tenney they could provide a recommendation, but I am wondering if there is any historical documentation. For those (few!) of you that don't hate sponsons and have rowed canoes that have them, what length oars have you found to be comfortable and effective? Thanks for any feedback you can provide!