With the increase of offshore platform weight, the float-over method has been adopted for offshore installation. A major installation challenge is moving the large-scale topside of the platform safely onto a barge. Taking a deepwater semisubmersible production platform as an example, the wharf load-out and dock load-out methods were analyzed respectively. With regard to wharf load-out method, three transportation methods on land were discussed with emphasis on self-propelled modular transporters, sliding rail and track. The finite element method was used to analyze the stress and deformation results of the topside and stress state of bridges in three methods. It can be concluded that the track method was comparatively reasonable. The barge stowage plan during the load-out operation was studied as well. A hydraulic lifting platform was used in the dock load-out method. The barge was dragged into the dock, moored on the platform, and then the topside was skidded onto the barge through the track. In the end, a comparison was carried out between the wharf load-out and dock load-out method from the tooling design, environmental impact and safety point of view. This paper provides meaningful guidance for semisubmersible offshore installation.

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