After the module is loaded on board, the floating installation vessel will transport the topside to the designated sea area, and install the topside on the fixed structure or floating structure by adjusting the ballast system. There are many factors that affect the selection of marine transportation ships. Considering the draft limit, width limit, load limit, barge stability in platform transportation, the weight and center of gravity position of the upper large module and other factors, how to select a safe and economical installation ship is the key to the successful implementation of the floating method.

The deck support unit (DSU), also known as the module support device, is located between the module and the skid shoe, and has two main functions: to support the weight of the module during the onshore prefabrication and shipping transportation of the module; During the floating installation, buffer the impact of the separation of the barge and the module. The DSU shall be designed according to the actual installation conditions.

The leg mating unit (LMU), also known as the leg docking device, is a docking device between the module column and the jacket steel pile. Its bottom is connected with the jacket leg, and its upper part is connected with the module column. It is a key component for floating installation. LMU is a very critical buffer device in the float over installation. When the float over installation is completed, LMU becomes a part of the jacket leg and plays a role in supporting the weight of the module. LMU plays a very important role in floating installation, mainly in the following aspects:

(1) It plays a buffering role in the process of transferring the weight of the module from the DSU to the LMU, which is completed by the internal device of the LMU sleeve;

(2) The automatic alignment of the module column and the LMU is realized through the disc receiver of the LMU.

Fenders of float over method is composed of surge fender subsystem and surge fender subsystem. The sway fender system is mainly used to limit the lateral movement between the installation vessel and the jacket during the process of moving in and out of the vessel, so as to prevent the installation vessel from excessive collision with the inner side of the jacket pile leg during the installation operation, so as to avoid damage and deformation of the pile leg. The surge fender mainly plays two roles in the installation process: one is to limit and stop the barge when the installation barge enters the jacket notch; The second is to prevent damage to the LMU caused by excessive surge during installation.

The floating method uses the draft or tidal range of the installation vessel to carry out the wharf loading and on-site installation of the topside. Rapid ballast system shall be used for loading or installation in the sea area with small tidal range or where tidal range cannot be used. By quickly adjusting the ballast system of the barge, the external water pump or sea water valve box is used to discharge/inject water into the ballast tank of the barge to make the barge heave, so that the weight of the topside can be safely transferred from the wharf to the transport barge or from the transport barge to the foundation structure (jacket).

Mooring systems (mooring winches, etc.) on the barge deck and auxiliary tugs, etc., are required for installation operations in shallow water. These auxiliary systems play a very important role in the installation process of the barge, such as slow approaching, initial entry, berthing and evacuation. When floating installation is carried out in deep water, only tug system and soft line positioning winch system are used. The main function of the cord positioning winch is to limit the offset of surge and sway. If the dynamic positioning barge is used in the float over installation, the positioning winch can not be used. In addition, a positioning monitoring system must be installed on the barge to monitor the relative movement of the barge and the lower foundation during the installation and evacuation of the float over.