I recently had a stuck centerboard after beaching for a night. I assumed either damage from side waves or gravel or gunk. I tried to push a metal rod in a hole I had in cockpit (I had drilled and used before, as suggested in the ‘Centerboad problems’ post) No joy. Then I tried the side portholes in the trunk - same. When I pulled the boat out, I pulled it partway onto the trailer, but with centerboard slot exposed in the water. I dove under and tried to see the problem but was too muddy there and couldn’t feel anything.
So I took her home and thought. My trailer has a U channel to support the boat, but this means the centerboard slot is completely covered. So I thought a dry land version of my dock attempt might work. My bunks went back far enough that I measured that I could back the boat partway off the trailer to clear the centerboard slot and still be supported on the bunks. So I removed the rudder and hooked the boat/trailer to my car. I took some piano dollys and placed wood blocks across them to make the same height as the rear keel on the trailer. I then tied ropes to the base of the boom galley poles with other end to a tree. Then slowly moved the car and trailer forward a bit (with boat pulling off the back) until I could get the dollies under the keel. Then pulled boat forward until the keel slot was out of the U channel and exposed. I then added a fixed screw jack and chocked everything before I went under. See attached pic. Turns out there was caked (rammed in) red clay between the keel and trunk. After some scraping with a screw driver and washing out with a spray nozzle, the board came down. Hooray! I had other scenarios where trunk was damaged, but was not the case. While I had it exposed, I repainted some rubbed spots on keel and boat bottom.
Then I untied the back rope, removed the fixed screw jacks, and used the trailer winch to pull it back onto the trailer. I know other folk have the same U channel trailers, so thought I would post this easy solution.
Lesson learned: Don’t beach on a red clay beach. Look for sandy spots or anchor out a bit. I have have done both in the past - without problems.