Sorry to hear that. I had the same thing, that the P/O covered with paint. Took a few years to wear the bottom paint thin enough to see the problem. I almost sank at a gathering about 40 miles from home but only about a mile from the ramp. We all had our boats beached and I saw the transom getting lower in the water. The boat ('71) didn't have a bilge pump and I barely got the boat back to the ramp, boat had what seemed to be a couple hundred gals in the bilge, boat was sitting real low in the water on the way back in. Barely got it on the trailer at the ramp and drained water out for quite a while. This is how I tackled the inspection:
Get under the keel and make sure that section is not on a roller. Using an awl, I'd probe inside the crack/scrape/gouge and see if you feel "soft" (like foam) or feel the awl going through the gelcoat and fiberglass hull. Mine was like that.
Let me know what you find. If it is bad I can walk you through repairing it.
Here is what mine looked like from below the boat.
After a little sanding you can see that the crack was full of paint only.
