Farr 11.6 (Farr 38)
That sure looks like a rudder head to me. As Knuterikt righly points out, the bronze collar covers the thrust bearing (or may actually be the thrust bearing) which prevents your rudder from dropping out of the boat. It is important to make sure that the part that you see in the picture is keyed into the top of the rudder post so that it can't turn independent of the rudder post. I had a very unpleasant surprise when I had to rig my temporary steering a few years ago and discovered that the rudder head was swiviling independent of the rudder, and more disturbingly, unscrewing the nut which keeps the rudder from dropping out of the boat.