that's a good question. First I had the bottom inspected to make sure that it was just a smile. The smile is commonly caused due to the flex of the keel. I can fill it with epoxy and fair it but the smile will only return because of the flex. The simplest solution would be to sand and grind the area and fill with compound that will flex. I've been recommended 3M 5200 will do just fine. Then paint over it. That should allow the area to flex without causing the smile anymore. Other wise, if it's not leaking through, the smile is just a smile. I would fix it already but it's too cold to do work on the hull. So that part of the project is waiting for warmer weather.Seriously, not owning a Catalina 30, but considering one, how do you repair the smile? Jeff