I have a 1986 M 15 with the iron ballast. ?To prevent problems, I sealed the bottom of the keel where the center board slot is with epiglass and followed with water tight. ?I then put a barrier on the centerboard and keel and then coated them with VC performance epoxy. ?I dropped the board in order to do it. ?I did as much of the inside of the slot as possible. ?Be careful and make sure the board will still go into the slot. My previously owned M 15, a 1983, had a barrier coat without the board being removed. ?It spent a week or two in salt water and never had any problems. Bert M 15, Zephyr