Systems and methods for a rack structure for a transport vessel adapted for use with an offshore self-elevating vessel

Abstract

A deployed L-shaped rack structure interengaged with a self-elevating vessel is used for supporting a feeder transport vessel, such as an ocean or sea barge, to eliminate relative motion or movement between the vessels. Some of the proposed rack structures are movable between a stowed position and a deployed position. The method of use for the movable rack structures includes the self-elevating vessel arriving at a predetermined location, elevating the hull of the self-elevating to a suitable height above the sea surface at a desired still water line (SWL) to create an air gap, and then deploying the rack structure. A feeder transport vessel, with its cargo and/or components, can then be floated over the deployed rack structure. The self-elevating vessel then uses its jacking system including a plurality of legs supported on the seabed to raise the feeder transport vessel and its cargo and/or components to a desired height above the SWL. From this position relative motion between the self-elevating vessel and transport vessel is eliminated so that the self-elevating vessel lifting device, such as a crane, can be more safely used to install energy components, such as wind turbine components. A bottom supported tower/column section could also be assembled and installed in seabed using the self-elevating vessel and rack structure along with the lifting device. A fixed rack structure system and its method can also be advantageously used with a self-elevating vessel. The systems and methods could be used in reversing the method or steps for deinstallation of the energy components installed in the sea.