Note that the centerboard is only about 17" wide and does not take up the entire centerboard area.
This is so you can place the centerboard either toward the front or back for different
handling depending on if you use a jib or not. The centerboard is made of aluminum, about 3/16" thick. The white knob at the top of the picture extends 1" on each
side so that the centerboard doesn't slip down into the centerboard slot. The other knob extends about 1/4" on each side and slips down into the notches in the centerboard slot.