Pontoon for transporting and placing a marine wind turbine on the seabed

A method for transporting, positioning an placing and decommissioning a one-piece marine wind turbine which comprises a base caisson (116) that can be fitted inside the open space of a U-shaped pontoon (111), characterised in that the method comprises the successive steps of:

• Partial ballasting of a first watertight compartments of the U-shaped pontoon, such that the pontoon develops a vertical movement until an upper side seats of one side of the U-shaped pontoons reaches a height above the water level that is lower than the height of the lower surface of an upper side wings of the base caisson,
• Horizontal displacing the U-shaped pontoon until the base caisson is fitted inside the U-shaped open space,
• Partial unballasting of the first watertight compartments of the U-shaped pontoon, such that the pontoon develops a vertical upward movement until the upper side seats of the side pontoons come into physical contact with the upper side wings of the base caisson,
• Synchronised partial unballasting of the first watertight compartments of the U-shaped pontoon and of a second watertight compartments of the base caisson of the wind turbine until the base caisson assembly fitted inside the U shape of the pontoon achieves a situation of buoyancy, Transporting by sea and positioning at sea of the base caisson assembly fitted inside the U shape of the pontoon in the positioning area,
• Synchronised ballasting of the first watertight compartments of the U-shaped pontoon and of the second watertight compartments of the base caisson of the wind turbine until the base caisson is arranged on the seabed,
• Complete ballasting of the first watertight compartments of the U-shaped pontoon, such that the pontoon develops a vertical movement towards the seabed until the upper side seats of the side pontoons lose physical contact with the lower surface of the upper side wings of the base caisson arranged on the seabed,
• Horizontal displacing the U-shaped pontoon until the base caisson is released or disengaged from the U-shaped open space, and
• Partial unballasting of the first watertight compartments of the U-shaped pontoon, such that the pontoon develops a vertical upward movement until an upper deck of the U-shaped pontoon is above the level of the water surface.