The float over method (float over installation method) is an installation technology that uses a barge to carry the topside of the offshore operation platform. During the installation process, the topside is lifted and lowered by means of tide level, barge load adjustment and lifting mechanism. At the same time, special connecting parts are used to complete the butt joint between the topside and the lower jacket platform.

During the floating installation of offshore platform module, the module is loaded onto the barge (Figure 1.1) by dragging and shipping, and then transported to the sea area where the platform is located by the barge to enter the jacket notch (Figure 1.2) specially designed in advance and installed in place in advance, so as to ensure that the column of the platform module is directly above the corresponding jacket leg, and cut off the connection between the platform module and the barge, As the tide level decreases or/and the draft increases due to the ballast of the barge, the docking between the platform module and the jacket is realized, so as to achieve the purpose of safe installation of offshore platform module. According to its operation process, its docking principle can be summarized as obtaining clearance, positioning guidance, active addressing, docking closure, load transfer and safety separation. This technology can realize the integral installation of 10000 ton large module and super large module.

Compared with other installation methods, float over method has the technical advantages of "four integrity and one zero":

① Overall design - to realize the integrated optimization design of platform blocks and reduce the interface error;

② Overall construction - simplify the construction process, significantly shorten the construction period, and realize the sea land commissioning conversion;

③ Overall transportation - significantly improve towing safety and economy;

④ Overall installation - greatly shorten the offshore operation time and reduce the construction risk;

⑤ Zero commissioning - offshore "zero commissioning", realizing the rapid commissioning of offshore platforms.

The single vessel floating installation method refers to the installation connection between offshore platform module and jacket by using a barge, and the platform module is transferred from the single hull to the jacket by load adjustment or/and tide level reduction. For the module installed by the single ship floating installation method, the lower support structure needs to be specially designed according to the dimensions of the barge used for installation to facilitate the barge to enter the lower support structure;

However, the double ship floating installation method, in which two barges enter the platform from both sides of the platform, has low requirements for the design of the supporting structure of the platform jacket. Up to now, most modules are installed by single ship floating installation method. Compared with the single boat floating installation method, the double boat floating installation method has extremely strict requirements for environmental conditions and the level of on-site operators, which has greater technical risks and is rarely used by the industry. So far, there are only two engineering examples in the world, and they are all completed in the sea area with excellent environmental conditions.