Itrec B.V.

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 power tong includes a lower tong and an upper tong, each with multiple grippers distributed around a tubular passage, for gripping a lower tubular and ripping an upper tubular respectively. A torque actuator includes a first hydraulic drive and a second hydraulic drive, for rotating the upper tong relative to the lower tong. The first hydraulic drive and the second hydraulic drive each have a drive shaft that supports a guide wheel for cooperating with a guide track, and a pinion for cooperating with a rack, which guide wheel and pinion are concentrically, mounted on the drive shaft of the hydraulic drive. The hydraulic drives are mounted with the drive shafts parallel to the main axis, and the upper tong or the lower tong comprises a guide track receiving the guide wheel and a rack cooperating with the pinion.

The invention relates to a crane for assembly and installation of offshore wind turbines on an offshore location, to a vessel for assembly and installation of offshore wind turbines on an offshore location, and to a method for assembly and installation of offshore wind turbines on an offshore location. According to the invention the crane is provided with a base section and a top section, wherein the top section is rotatable supported by a bearing, and can be rotated with the wind turbine hoisting device relative to the base section about a vertical axis, wherein a first trolley guide is mounted to a top section of the installation crane for giding a vertically mobile wind turbine supporting trolley. According to the invention the vessel is provided with one or more assembly stations on different sides of the installation crane.

In an installation of a wind turbine on a floating foundation in floating condition and subject to sea-state induced motions, e.g. at the site of an offshore windfarm, use is made of a vessel with a crane arranged on the hull and provided with a hoisting system adapted to support the weight of the wind turbine and suspend the wind turbine from the crane. A heave compensation device compensates for sea-state induced heave motion of the wind turbine mast relative to the mast mounting structure of the floating foundation. Use is made of a mast alignment system configured to engage on the suspended wind turbine, e.g. on the mast of the suspended wind turbine, and to bring and maintain the mast of the wind turbine in alignment with the mounting axis of the floating foundation in order to compensate for sea-state induced motions, at least including tilt motions in one or more vertical planes, of the wind turbine mast relative to the mounting axis of the floating foundation.

A semi-submersible crane vessel for use in assembling a wind turbine and for installation by means of a crane of the vessel of the assembled wind turbine on a foundation. At an assembly station, the hull of the vessel is provided with a mast-receiving well that is sunk into, or through, the hull, preferably a well that extends into, or through a support column of the hull, which well is configured to receive therein at least a portion of the mast of the wind turbine during an assembly step of the wind turbine. For example, the mast-receiving well has a depth of at least 15 meters, e.g. at least 30 meters, measured from the deck of the deckbox structure.

The first aspect of the present invention relates to an offshore drilling system and a method for performing subsea wellbore related activities involving a riser extending between the vessel and a subsea wellbore. The offshore drilling system comprising a drilling vessel with a floating hull, a drilling tower and a tubular string main hoisting device. A vertically mobile working deck with a rig floor slip device is positioned above the moonpool. A telescopic joint and a diverter are provided, wherein the inner barrel of the telescopic joint is secured to the diverter via a flexible joint. Furthermore an integrated heave compensation system is provided such that said travelling block and the mobile working deck move synchronously in heave compensation.

A tool and method for hoisting an longitudinal end of an offshore wind turbine component which is in a horizontal orientation. The tool is after being attached to a lifting block to be moved into a proximate position in which gripping members of the tool are longitudinally spaced from the longitudinal end but the radial contour of the tool at least overlaps with the radial contour of the longitudinal end. While the gripping members are in a retracted position guiding actuators can move the tool from the proximate position into a gripping position longitudinally aligned with the longitudinal end in which the gripping members are movable to engage said surface of the longitudinal end, thereby connecting the longitudinal end to the tool and suspending the longitudinal end from the lifting block so that the longitudinal end can consequently be hoisted.

A pile holding system is to be mounted on a deck of a vessel, e.g. for installation of a pile adapted to support an offshore wind turbine. The pile holding system is configured to support the pile in an upright position at a pile installation location next to the vessel. A vessel is provided with such a pile holder system. A method for installation of a pile and a pile holder are also disclosed.

A crane for use on an offshore vessel is provided with a boom restrainer, wherein the boom restrainer is a hydro-pneumatic boom restrainer, for reducing upward pivoting of the boom, when the boom is in the top zone, wherein the boom restrainer includes: multiple hydraulic cylinders, each having a hydraulic circuit and a cylinder rod with a cylinder head, wherein the cylinders are mounted on the crane structure with the cylinder heads directed towards the boom of the crane, preferably are mounted on a stay of the crane structure, a catcher for each hydraulic cylinder, wherein each catcher is mounted on the boom and is configured for receiving the cylinder head of the corresponding hydraulic cylinder, and to lock the cylinder head, preferably pivotable locks the cylinder head, relative to the boom, when the boom pivots upwards in the top zone; a gas buffer for each hydraulic cylinder, wherein each gas buffer is mounted to the corresponding hydraulic cylinder, and is connected to the hydraulic circuit of the corresponding hydraulic cylinder via a medium separator, wherein the gas buffer forces the hydraulic cylinder in an extended position, and wherein the volume ratio between the hydraulic cylinder and the gas buffer is such that the hydraulic cylinder acts as a progressive spring, e.g. the gas buffers each have a size in the range of 1000-1400 litre, for example 1200 litre and the hydraulic cylinders each have a size in the range of 800-1000 litre, for example 900 litre, and preferably the ratio between the volume of the gas buffer and the volume of the associated hydraulic cylinder is 4:3.

A crane with a pivotal boom. The crane has a first and a second main hoisting system, which main hoisting system are configured for independent operation. Each system comprises a hoisting cable, an upper sheave block, a hoisting block assembly suspended from the upper sheave block by the hoisting cable in a multiple fall configuration, and a hoisting winch. The upper sheave blocks of the first and second main hoisting systems are each independently pivotable about a common pivot axis relative to the boom. Each hoisting block assembly comprises a hoisting block body, multiple fixed sheaves that are fixed on the hoisting block body, and multiple disconnectable sheave members, each disconnectable sheave member comprising a frame and at least one sheave rotatably supported by the frame.