Don't know if this will help but check out their site:

http://www.rutabaga.com/subcategory.asp ... =3&scid=37

I recently added a center web seat and used the Sawyer seat hanger hardware. Had to drill through the tops of the gunwales but no big deal. One thing is that because of my size, a big guy, I am going to add a keel brace for the seat.

Shoot the folks at Rutabaga an email. I will bet they can help you.