Offhand, I can't think of any manufacturer that put keelsons in standard canvas canoes. Some of the kit boats may have had them (it looks like one is shown in a 1912 Brooks Boats catalog, e.g.). Plans in magazines like Popular Mechanics often included a keelson.
Some of the larger canvas canoes and boats had keelsons. For example, Old Town used them in their Square End Paddling Canoe and War Canoe.
All-wood canoes such as Lakefield, Brown and Peterborough had keelsons. Many were later canvased. Is it possible this is what has happened to your canoe?
Red House Canoes in Fenwick, Ontario used a keelson on their wood/canvas canoes. The keelson was about 3/8" thick, tapered and about 2" wide at its widest point.
I saw an Old Town in an antique mall that had a keelson. Looked like original equipment to the casual observer. but to us scrutineers it was nothing more than an add on by a pretty good carpenteer.
I just got off the phone with Brian Baker. You may notice he has some cedar and ash for sale in classifieds. He is giving it up after only fifty years of canoe building and restoring.
Anyway, he was talking about construction methods and told me how his father Jay Baker used to make canoes. Brian could tell if he had a picture. But--
1) does your canoe have any inlays? Baker canoes often did on thwarts/decks.
2) Does your canoe have close spaced narrow ribs?
3) Does you canoe have copper cut tacks?
4) All Baker canoes were made by first laying the keelson.
Its a canoe at a boy scout camp. I have not personally seen it, but know it has a keelson of some sort. I'm waiting for pictures. Thanks to everyone for the response and I'll keep you posted.
I have a friend who is an exec with BSA and I have been asking him for years to bolo for an old wood canoe at one of the camps. He claimed there were none. Apparently just to shut me up. Let me know what you find.
Regards, Dave.