Abstract: A method and apparatus are disclosed for use in the installation of a platform structure upon the upper elements of a previously-installed substructure. The platform structure is mounted on a barge positionable between the upper elements of the previously-installed substructure. The barge can be flooded and lowered a sufficient distance to allow leg elements of the platform structure to contact and mate with leg support elements of the substructure.Impacts between the structures during the mating operation are absorbed by resilient neoprene pads carried by the leg supports. After the platform structure rests upon the leg supports, and the barge is removed, the platform structure can be lowered and leveled by draining a select volume of sand from the leg supports.