Abstract: A method of installing an integrated deck onto an offshore platform substructure. The integrated deck is held by a support structure on a barge and transported to a preinstalled offshore platform substructure which is adapted to receive the barge and allow aligning of the integrated deck with the substructure for mating operations. Once the barge is positioned within the substructure, tethers are connected between the barge and anchoring foundation elements to moor the barge. Then the tethers are tensioned to minimize both vertical movement and lateral movement caused by wave action. Mating of the integrated deck and the substructure proceeds while tension loads in the tethers are maintained.