I'm a new owner of a Catalina Capri 16.5 with a centerboard. It's lighter than my last boat, which had a heavy keel. It sometimes feels like moving the tiller is just a suggestion. Has anyone else experienced difficulty steering the boat? How did you solve the problem?
This is probably easier to think about if you can give us more details.
Is the Centerboard down? Probably, since you know about boats you have checked this.
Your boat is a lot lighter than your last. Light boats slow down faster, so if this is happening at slow speeds, like coming out of a tack in chop or shifty light winds, then maybe the boat is moving too slowly to answer the helm. The solution is bear off and sheet out, build boat speed and the helm should return to normal. Boats with narrow blades (as viewed from the side) don't respond well unless they have some speed over the CB and rudder to generate some lift.
This stuff is just guessing, again, perhaps more details like point of sail, boat speed, or pictures of the boat so a C16.5 expert can tell if something is not right on the boat.
OC