The offshore jack-up has a hull and a plurality of moveable legs engageable with the seafloor. The offshore jack-up is arranged to move the legs with respect to the hull to position the hull out of the water. The method comprises moving at least a portion of a vessel underneath the hull of the offshore jack-up or within a cut-out of the hull when the hull is positioned out of the water and the legs engage the seafloor. A stabilizing mechanism mounted on the jack-up is engaged against the vessel. The stabilizing mechanism is pushed down on the vessel to increase the buoyant force acting on the vessel.

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.

The offshore jack-up has a hull and a plurality of moveable legs engageable with the seafloor. The offshore jack-up is arranged to move the legs with respect to the hull to position the hull out of the water. The method comprises moving at least a portion of a vessel underneath the hull of the offshore jack-up or within a cut-out of the hull when the hull is positioned out of the water and the legs engage the seafloor. A stabilizing mechanism mounted on the jack-up is engaged against the vessel. The stabilizing mechanism is pushed down on the vessel to increase the buoyant force acting on the vessel.

An offshore platform with at least one pile of a pile foundation with an outer wall having an external diameter and with a tube (8, 12) with an inner wall having an internal diameter which is greater than the external diameter, on the exterior of which attachments are arranged, and which is slid over the pile (2, 3) driven into the seabed (4), wherein at least one spacer (20) is provided between the outer wall of the pile (2, 3) and the inner wall of the tube (8, 12).

An offshore structure includes an adjustably buoyant hull including a plurality of vertical columns and a plurality of horizontal pontoons. Each pontoon extends between a pair of the columns. The adjustably buoyant hull is configured to receive a topside. Each column has a central axis, an upper end, and a lower end. Each pontoon has a longitudinal axis, a first end coupled to one of the columns, and a second end coupled to another one of the columns. The offshore structure also includes a foundation assembly attached to a lower end of the hull. The foundation assembly includes a column skirt extending downward from the lower end of each column and a pontoon skirt extending downward from a bottom surface of each pontoon.

A method of ballasting a vessel comprises positioning a vessel having a first draft adjacent to or underneath an offshore installation. The vessel has at least one ballasting tank and at least one port in fluid communication with the at least one ballasting tank. The at least one ballasting tank is arranged to selectively adjust the flow of ballast water in and out of the at least one ballasting tank. The method comprises pushing down from the offshore installation on the vessel to increase the draft of the vessel from the first draft to a second draft. The method further comprises opening the at least one port when the vessel is at the second draft and the at least one port is below a waterline. The method also comprises filling at least part of the at least one ballasting tank.

A support device configured to be positioned on a lifting vessel in order to support a topside of an offshore platform, the support device comprising: a main cylindrical casing having an upper opening, the main casing defining a main vertical axis, the main casing further defining an upper support rim, a reservoir located inside the main casing for holding a granular material or a fluid, the reservoir having a discharge opening for emptying the reservoir, a spring support slideably arranged within the main casing, the spring support resting on the granular material or the fluid and being movable from an upper position to a lower position in dependence on a filing degree of the reservoir, a spring device positioned on the spring support, a receptor support positioned on the spring device, the receptor support defining an upper surface, and a receptor device.

Process for installing an offshore tower, comprising: a) manufacturing a foundation comprising a block, manufacturing at least one superposition section of a shaft, and manufacturing a base section of a shaft; b) applying said base section to said foundation block (starting unit) to assume the relative position for the installed condition, applying said superposition sections to said starting unit in a multi-layered configuration, and applying lifting means to at least one of said foundation block and said base section; c) moving said starting unit up to the installation point; d) introducing ballast in said foundation block so that said starting unit sinks until resting on the bottom of the body of water; e) actuating said lifting means to expand said sections into the installed condition; f) between step a) and c), placing said foundation block or starting unit in the body of water of the installation point.

The present invention relates to a lifting device for lifting an upper part of a sea platform, the sea platform comprising a support structure and a top side, the lifting device being constructed to be positioned on a lifting vessel, the lifting device comprising: a base frame constructed to rest on the lifting vessel, at least one console frame connected to the base frame via a flexible connection system, a suspension system connected to the console frame and comprising a leg connector, wherein the suspension system is constructed to allow freedom of movement of the leg connector relative to the console frame, wherein the flexible connection system forms a flexible connection between the console frame and the base frame and allows a predetermined movement of the console frame.

A variable-draft barge configured to transfer loads in a body of water, and having a water line which is a function of the draft; the barge having: a hull; an underbody; at least one first chamber located in the hull and floodable selectively to alter the draft of the barge; at least one flood valve located below the water line to flood the first chamber; and a control device configured to selectively open the flood valve to flood the first chamber.