If you do locate a M-15 and the centerboard appears to not move, it may not be damage from swelling. Nobody mentioned this yet (but they did two years ago when I got my 15 and I had the same question) but because the clearance is so tight in the CB cavity, if by chance the rope gets down in there, it can jam between the wall and the CB. So don't automatically dismiss a CB not going up and down as swelling. You won't be sorry! Buy it anyway. Or post it here. Someone is always looking for an M boat. Kendall M-15 #164