I don't think what I see there necessarily would mean dropping the keel. And this would not be an automatic deal breaker for me. If the leak was to the inside of the boat, I would certainly consider it a problem--you might look in the bilge to see what it might look like and pay attention to bilge water in the sea trial if you get that far. As folks have mentioned, cracks and drips at the keel stub (and it looks like that is where this is) is common and not always a problem. As Christian suggests, I would probably get a couple of opinions. One of them would be from someone at the yard with lots of experience in repair--someone who has done the work--I am sort of underwhelmed with the expertise in the surveyor world these days---seems like SAMS and AMS have graduated some folks who have read the books and passed the tests, but just do not really have practical boat repair and building experience--I have had some miserable recent experiences with poor surveys--so I would not rely solely on a single surveyor's comment in your purchase survey. I am told by my diver that I have a new crack in my keel stub joint and, because there is no leak internally, I am going to ignore it until my next scheduled haul. I will probably just torque the keel bolts when the boat is blocked and put some glass in there after digging around to see what is in there. Keels have fallen off some of the around the world racers with exotic keel arrangements, but I have never heard of one dropping off a decent production boat. I disagree with others who have suggested that dropping the keel is part of predictable maintenance of older production fiberglass boats (old wooden boats are a different matter). Most of those keels were put on at the factory with the idea that they would never be removed--properly applied 5200 is largely impossible to remove without removing the substrate it is glued to.