A floating drive-on dry dock assembly (10) for a small craft (60) is assembled from two kinds of hollow flotation units, tall units (12) and short units (14). The units are interconnected so that their top surfaces are substantially coplanar. The units are arranged to form two arms (52, 54) which support the hull of the craft (60) on each side of the longitudinal center line of the craft (60). The entire length of each arm (52, 54) is made up of tall units (12) except the distal end portions of each arm (52, 54) which may be made up of short units (14).
