The present invention relates to a method for installing a wind turbine or other tall structure at a target location at sea, the method comprising: —providing an installation vessel comprising at least one crane, wherein the crane comprises a lower boom part, a right boom part, and a left boom part, wherein the right boom part and the left boom part are connected to an upper portion of the lower boom part and extend from said upper portion, wherein a space is present between the right and left boom part, —lifting a tall structure part, in particular the nacelle assembly, with the crane, wherein in top view the tall structure part is supported at least partially between the right and left boom part by one or more hoist lines extending from the right and left boom part to the tall structure part.

The present invention relates to a crane (1) comprising a mast (2), an elongated boom (3) connected to the mast having a front portion (6) extending on one side of the mast and a rear portion (8) extending on the opposite side of the mast, and the boom (3) is linearly movable relative to the mast such that the length of the front portion and the length of the rear portion is adjustable by moving the boom relative to mast, and a counterweight (12) movably connected to the boom (3). The boom (3) and the counterweight (12) are arranged so that they can be moved independent of each other, and the counterweight and the boom are arranged so that the counterweight can pass the mast and be moved between the front portion (6) and the rear portion (8) independent of the position of the boom (3) with respect to the mast (2).

The present invention relates to a blade positioning system configured for positioning wind turbine blades at a hub of a nacelle of a wind turbine from an installation vessel at an offshore location, the blade positioning system comprising: the installation vessel comprising: — at least one lifting device configured for lifting wind turbine components, and — an auxiliary support tower extending upwardly from the installation vessel, the auxiliary support tower comprising: o a nacelle support for supporting the nacelle, o a root end moving assembly defining a guide path which extends over a vertical distance, the root end moving assembly comprising a movable root end support base and a root end support configured for supporting and guiding the root end of the blade, the root end support being connected to the movable root end support base, the root end support being movable along the guide path, the root end moving assembly being configured for moving the root end of the blade along the guide path from the engagement position to an installation position, the at least one lifting device being configured for lifting the nacelle onto the auxiliary support tower, wherein the at least one lifting device and the root end moving assembly are configured to jointly support and jointly move the blade upwards towards the hub, wherein during the movement the root end is supported by the root end support and the lifting device carries a majority of the vertical loads on the blade.

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.

Method of lifting a wind turbine part (58) at a wind turbine site (1, 2), the method includes: providing a lifting apparatus (60) and a wind turbine part (58) to be lifted; providing a shield (40); providing manipulation equipment (45) associated with said shield (40); and suspending said part (58) from said lifting apparatus (60); moving said part (58) by means of said lifting apparatus (68); the method further including holding said shield (40) proximate and upwind of said part (58) being lifted by means of said manipulation equipment (45). The shield (40) may be held proximate the part (58) being lifted such that it acts to reduce the ambient wind force incident on the part (58). Preferably the method may be implemented such that wind speed conditions (w) at the part (58) being lifted are lower than ambient wind conditions (W) at said site (1, 2). A kite-flying apparatus includes a power kite (40) and associated manipulation equipment (45), including cables (42, 44) at least one steering winch (28, 29), the winch being received in a winching module (26) including a ballast receiving fitment and a winch control system.

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 of transporting a first vessel having wind turbine components to an offshore installation vessel. The method includes (i) securing the first vessel to a second vessel using a first tow line attached to a front end (or bow) of the first vessel, and (ii) securing the first vessel to a third vessel using a second tow line attached to a back end (or stern) of the first vessel. The method further includes transporting the first vessel to the offshore installation vessel using the second vessel and the third vessel secured to the first vessel via the first and second tow lines, respectively. The method also includes securing the first vessel to the offshore installation vessel. The first vessel can include one or more fender walls. The first vessel can be secured to the offshore installation vessel using one or more mooring lines.

A method for mounting or dismounting components of a wind turbine is provided. The mounting or dismounting is accomplished by fastening at least one retaining rope or guide rope to a component to be mounted by fastening the retaining rope or the guide rope to a rope winch unit and by raising or lowering the component to be mounted or to be dismounted by means of a crane. The component to be mounted or to be dismounted is held or guided by means of the retaining rope or guide rope. The rope winch unit comprises a base, a pivot arm and a retaining unit. The pivot arm is pivot-ably coupled to the base at its first end. A rope winch for receiving the retaining rope or guide rope is provided at its second free end. The retaining unit is pivotably coupled to the pivot arm. The base comprises a plurality of latching units for receiving a first end of the retaining unit.

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 hoisting crane or multi configurations crane system for use on an offshore vessel, such a vessel and methods for operating are disclosed. The hoisting crane comprises a boom having a proximal portion, an intermediate portion and a distal portion. An extension mechanism is provided that is configured to allow the distal portion to he slid relative to the intermediate portion from a retracted configuration to an extended configuration. In the retracted configuration, the intermediate portion is arranged substantially within the distal portion.