The factory kick-up rudder has a little stainless steel spring tang that prevents it from coming off the boat, however, over time, and misunderstanding what these things are, they get bent and non-functional. Hopefully your rudder will be in the mud behind the boat. Maybe your boat insurance can help? As already mentioned, if you intend to race in a sanctioned C-22 race, only factory rudders are allowed IAW our C-22 racing rules. I've raced PHRF, and declared my Rudder-Craft rudder, and they didn't care. HUGE improvement in the boat handling with a Rudder-Craft style. "If" you have to get a new rudder, this would be a good time to also upgrade your rudder hardware to the 1/2" pintles and gudgeons,(1983 is probably still 3/8").
Hopefully the rudder is sitting under your boat waiting to be recovered, good luck and keep us informed.
Don