Pneumatic load-transfer system and method for mating an integrated deck with a pre-installed platform substructure

A method for transferring a module having a plurality of downward extending legs during an offshore floatover installation using a load-transfer system, the load-transfer system having a transport vessel with a transport vessel deck, a support structure situated on the transport vessel deck, and a plurality of air bags horizontally placed inside a layer of housings located between the bottom of the module and the top of the support structure, the load of the module is transferred from the support structure to a plurality of main legs of a preinstalled jacket contacted at a plurality of mating surfaces through a plurality of mating apparatuses, the method comprising:

• transporting the module via the transport vessel to an offshore installation site with a pre-installed jacket having a plurality of upward extending legs;
• injecting air to the plurality of air bags to life up the module and form a flexible support to the module;
• aligning the mating surfaces;
• ballasting the transport vessel;
• properly reducing the internal air pressure of the plurality of air bags to make full contacts at the mating surfaces without any separation;
• further reducing the internal air pressure of the plurality of air bags to a minimal;
• and
• exiting the transporting vessel from the slot formed by the upward extending jacket legs without the module;
• wherein the load of the module is uniformly distributed among the plurality of air bags during installation;
• wherein the flexible support is equipped with telescopic structures against lateral loading and is able to provide adjustable spring rate during installation.