A slew bearing includes a stationary bearing ring to be fixed to a base, and a moveable bearing ring to be fixed to a moveable object, wherein the stationary bearing ring and the moveable bearing ring are configured to enable rotation of the moveable bearing ring relative to the stationary bearing ring about a rotation axis. A main axial bearing and an auxiliary bearing are provided between the stationary bearing ring and the moveable bearing ring, wherein the moveable bearing ring includes one or more main portions and one or more auxiliary portions, which one or more main portions are moveable relative to the one or more auxiliary portions between an operational position, in which the main axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring, and a raised maintenance position, in which the auxiliary axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring and the main bearing is allowed to be inspected and/or maintained so that the slew bearing during inspection and/or maintenance is still operational.

A slew bearing includes a stationary bearing ring to be fixed to a base, and a moveable bearing ring to be fixed to a moveable object, wherein the stationary bearing ring and the moveable bearing ring are configured to enable rotation of the moveable bearing ring relative to the stationary bearing ring about a rotation axis. A main axial bearing and an auxiliary bearing are provided between the stationary bearing ring and the moveable bearing ring, wherein the moveable bearing ring includes one or more main portions and one or more auxiliary portions, which one or more main portions are moveable relative to the one or more auxiliary portions between an operational position, in which the main axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring, and a raised maintenance position, in which the auxiliary axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring and the main bearing is allowed to be inspected and/or maintained so that the slew bearing during inspection and/or maintenance is still operational.

A system for lifting loads from a mobile offshore platform includes a boom pivotally at one longitudinal end mounted to the platform. A boom extension line is coupled at one end to the boom to cause rotational movement thereof about the pivotally mounted end of the boom. Another end of the boom extension line is either (i) coupled to a movable subplatform on the platform or (ii) supported by a device coupled to the movable subplatform. Movement of the subplatform causes change in effective length of the boom extension line so as to move the boom between an extended position and a retracted position.

Disclosed is an active compensation system, intended to compensate at least partially for the effect of an undulating movement on a load, advantageously in a vertical direction, preferably for the active compensation of the swell. The active compensation system includes: — an electrical supply electrically connected to electrical storage unit; — electrical energy dissipating unit; and - a controller for discharging the electrical storage unit during a first phase of the undulating movement, to participate in the electrical supply of the electrical motor in addition to the power supply, and to recharge the electrical storage via the electrical supply during a second phase of the undulating movement.

Disclosed is an active compensation system, intended to compensate at least partially for the effect of an undulating movement on a load, advantageously in a vertical direction, preferably for the active compensation of the swell. The active compensation system includes: — an electrical supply electrically connected to electrical storage unit; — electrical energy dissipating unit; and - a controller for discharging the electrical storage unit during a first phase of the undulating movement, to participate in the electrical supply of the electrical motor in addition to the power supply, and to recharge the electrical storage via the electrical supply during a second phase of the undulating movement.

A pile upending and holding system includes a support assembly configured to be mounted on the vessel and to provide compensation for wave-induced motion of the vessel to maintain a predetermined X-Y location of the pile holder independent of said motion, and a pile holder mounted on the support assembly to be tillable about a substantially horizontal tilt axis. The pile holder includes a lower ring and an upper ring, and a pile holder frame supporting the lower ring and upper ring, the upper ring longitudinally spaced from the lower ring. Each of the rings include pile engaging devices distributed about the circumference thereof, each pile engaging device being adapted to engage an exterior of the pile extending through the lower and upper ring. Each of the lower ring and upper ring includes a ring base fixed to the pile holder frame and one or more movable jaws, movable between a closed position for holding and guiding the pile and an opened position for entry of the pile. The pile holder is provided, below the lower ring thereof, with a pile foot end support for engaging a longitudinal end of the pile to limit longitudinal movement thereof.

A method for handling of an offshore wind turbine component includes using a vessel having a hull on which a motion compensating crane is mounted. The crane includes a main boom; a main boom luffing assembly; a mobile hoist cable suspension member; and a hoist winch and a hoist cable driven by the hoist winch. An object suspension device is suspended from the hoist cable. The mobile hoist cable suspension member is supported by a motion compensating support device that is fitted to the tip end of the main boom, the motion compensating support device including one or more motor powered motion displacement actuator assemblies and a motion compensating support device controller. The method includes connecting the offshore wind turbine component to the object suspension device; and operating the motion compensating support device to provide motion compensation in at least one direction of the object suspension device and the connected offshore wind turbine component. The crane is provided with one or more nacelle position detectors that are configured and operated to sense at least one of actual position and actual motion of the nacelle or of one or more components in or on the nacelle, and the one or more nacelle position detectors are linked to the motion compensating support device controller.

A method for handling of an offshore wind turbine component includes using a vessel having a hull on which a motion compensating crane is mounted. The crane includes a main boom; a main boom luffing assembly; a mobile hoist cable suspension member; and a hoist winch and a hoist cable driven by the hoist winch. An object suspension device is suspended from the hoist cable. The mobile hoist cable suspension member is supported by a motion compensating support device that is fitted to the tip end of the main boom, the motion compensating support device including one or more motor powered motion displacement actuator assemblies and a motion compensating support device controller. The method includes connecting the offshore wind turbine component to the object suspension device; and operating the motion compensating support device to provide motion compensation in at least one direction of the object suspension device and the connected offshore wind turbine component. The crane is provided with one or more nacelle position detectors that are configured and operated to sense at least one of actual position and actual motion of the nacelle or of one or more components in or on the nacelle, and the one or more nacelle position detectors are linked to the motion compensating support device controller.

A catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames are spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. Each of the frames provides a space under the frame and in between the barges that enables a package to be lifted and/or a marine vessel to be positioned in between the barges and under the frames. In this fashion, an object that has been salvaged from the seabed can be placed upon the marine vessel that is positioned in between the barges and under the frames.

A catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames are spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. Each of the frames provides a space under the frame and in between the barges that enables a package to be lifted and/or a marine vessel to be positioned in between the barges and under the frames. In this fashion, an object that has been salvaged from the seabed can be placed upon the marine vessel that is positioned in between the barges and under the frames.