Boat Buzz

Found this in the bottom of a 1953 18' Riviera I am restoring. The original rudder log was intact in the boat and the original rudder was lying inside the boat - although quite bent.

Lying next to it was this rudder, with log and all. Stripped it of layers of bottom paint to see if there were any identifying marks and found none. There are however a series of what appear to be slotted screws heads around the perimeter that you can just make out in the picture below.

Any ideas?

The rudder is for a Century.

Thank you. Greatly appreciated.