I too had a 28'Oday with a centerboard.It's really pretty simple. Remove the plastic cover on the cabin roof, drop the board down far enough to allow you access to the shackle/carter pin that conects the centerboard line to the board. remove the small carterpin, freeing the line. go back to the cabin roof, tie a messenger line to the end of the centerboard line, secure it. Go back to the board, simply pull the centerboard line thru. Use the messenger line to pull up the new centerboard line from bottom to top. If the messenger line comes loose and falls thru, simply go back to the roof, tie a small diameter nut to the end of the messenger line, feed it thru again....ensure that the top end is secure. The 28' is a great boat, we owned ours for 10 years and sailed her thru the ICW/Florida and back to MA.