An apparatus for stabilizing a watercraft for boarding or exiting comprising an elongated cradle arm support member for attaching vertically to a docking structure and a cradle arm for attaching to the cradle arm support member, in which the cradle arm has a generally V-shaped upper surface for cradling the under surface of a watercraft, restricting roll. The cradle arm is adjustably connecting the cradle arm support member, for selectively fixing the arm to the cradle arm support member in one of a range of vertical positions to accommodate changing water levels.