Late '70's or early '80's, I think
I don't believe it was an option on the early boats. I think it was added sometime in the late '70's, like '78 or '79. I've seen several '75 and earlier boats (mine is a '73), and none had the centerboard. But it's an easy matter to ask the seller, whenever you see an O22 being offered. Or you could e-mail a selection of owners from the list on this site, picking an owner from each year. I'd be curious myself. Lots of other changes could be cataloged that way, if you made a list when you did it. For instance: The first year had no forward hatch, then they went to a forward hatch which was higher than the deck, then they made the "flush hatch", which was curved to the shape of the cabin top. The first year or two had a port dinette, but then they went to the table/post arrangement. And they changed from a 600 pound keel to a 700 pound. And at some point, from a fractional rig to the 3/4 rig. They added a self-draining gas tank compartment in the port cockpit seat around '80. Also, I noted that the mast step went from a tabernacle to the stainless steel "hinge" type mount in later years. And so on. Lots of changes made in the designs life.
