On the centerboard topic. You should have a 2"x2" stainless steel plate over each side of the centerboard trunk. These plates are to give you access to the centerboard pivot pin. The plates have a red colored gasket behind them for a seal and are held on with small stainless steel screws, one on each corner of the plate. Check to make sure these plates are not leaking while underway. Use baby powder or tape paper towels around the plates to see if there is any sign of water coming around the plates. Water from other sources would run below the plates.
Rudder - You need to tighten the swing bolt on the rudder just tight enough that it doesn't swing while sailing, but loose enough to swing up if you ground. Do you have large thick doughnut washers on each side of the bolt? I'm suppose to, but mine are missing. I just use very large fender washers and i tighten mine as hard as i can with a 10" box wrench. It stays put while sailing, but swings up if I ground. If I ground and it swings up, I loosen the bolt and push the rudder down with my boat pole and re-tighten the bolt.
Hope this helps.
Rehoboth Bay/Indian River, DE
S/Y KJ, Helms 25