I rescued this O'Day 17' sailer a couple weeks ago. I did some fiberglass repair to a couple cracks in the hull. After about a 2 hour sail I returned the boat to the trailer and pull out the plug in the attached picture. (there was no plug in there initially but I assumed one was needed) Water came out like from a hose for about 15 minutes. Just glad it didn't sink! I could not identify any leaks coming from the hull. I'm wondering what the solution is? I've read that leaks are coming up in the centerboard area where it's difficult to repair. Just looking for solutions. Is a bilge pump necessary? Many thanks. Johnny.