Metal brackets under gunwale - Old Town Canoe

I’ve seen many canoes, but I haven’t seen this before.

I just got a used Old Town Penobscot, and right under the gunwales there are four brackets that I would call rectangular aluminum tubing, approximately 3/4" deep, and about 2.5" by 3/4" inside dimensions. They are spaced and placed in such a way I’m thinking there was a solo seat slotted into them. It doesn’t look like they were installed by the factory. The rivets go out the side of the gunwales, rather than on top. There doesn’t seem to be any hardware or holes to screw the seat in, so I’m thinking maybe the center yoke is removed, the hull is pressed out a bit, the seat is put in, and when the yoke is re-installed the seat stays put. If it was a seat, it seems like it would be a bit high (no drop from the gunwales).

Has anyone seen a seat put in this way? Maybe it was something else? Was this an Old Town invention, or somebody else’s idea? Thanks!

Maybe it was for a sailing rig?

That seems a reasonable possibility - maybe for lee-boards or outriggers.

I just took another look, and will add that two of the brackets are just beside the yoke, and I failed to mention that there are also a few snaps riveted to the top of the gunwale around that area.

Hard to picture your situation exactly, but I acquired an OT Camper a few years ago that was fitted for an OT rowing seat. There were some brackets added below the gunnels to work with the straps that held the seat in place.

That’s a neat bit of history! I don’t think any sort of strap would attach to what I have - it is really just a sort of rectangular metal pocket with no distinguishing features. I’m starting to think the sail rig suggestion is right, though probably not from Old Town (and I think there probably hundreds of sail rig/outrigger/lee-board designs over the years).
Thanks for the rowing rig picture!