Disclosed are tower erection systems and tower climbing systems and associated methods of operation. A tower erection system, in accordance with various embodiments, includes a ground-installed lifting structure, and a lifting frame configured to latch onto individual tower sections and traveling vertically inside the ground-installed lifting structure, lifted by a winch-and-cable or other lifting mechanism. Using this system, a tower may be assembled from multiple sections from the top down. A tower climbing system, in accordance with various embodiments, includes upper and lower climbers that can latch onto the lateral surface of a tower and a lifting mechanism that can move the climbers vertically relative to each other. The system can be used to carry a crane or other heavy equipment up and down along the tower. A climbing crane may be used, for example, during tower construction, or to reach the top of the tower for maintenance or repair.

In a vessel for installing a structure onto or into a seabed, multiple actuators comprised by a dynamic positioning system and a structure positioning system may be used for controlling a position and/or orientation of the structure. When two actuators are actuated simultaneously or in rapid succession, instabilities may occur. Furthermore, two actuators may be working in opposite directions or with opposite control goals. To increase stability and/or workability of the vessel's actuators, a supervisory control arrangement is provided to interconnect control systems of different actuators of the vessel, for example the dynamic positioning system and the structure positioning system. Where previously the dynamic positioning system and the structure position system were individually operating system, with the supervisory control arrangement one system can take into account an input and/or output of the other system.

The invention provides a lifting assembly comprising a support structure (4) arranged to support a load (2) suspended from the support structure, a guide line (501) arranged to extend from a first location, to a second location, a wheel assembly (601) with one or more wheels (621, 622, 623) arranged to engage, and roll along, the guide line (501), and a control line assembly (701) arranged to extend from the wheel assembly (601) to the load (2), wherein the lifting assembly comprises a retainer (801) arranged to connect, between the first and second locations, the guide line (501) to the support structure (4).

Provided is a method for installing or uninstalling a component of a wind turbine, which component is moved with a lifting device at which the component is fixed with cables, whereby two ropes are fixed to the component, with each rope running to a winch attached at a previously installed component of the wind turbine, with the ropes crossing each other and being moved around the winches for tensioning the rope while the component is lowered to its installation position or is lifted from its installation position.

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.

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 for use on an offshore vessel, such a vessel and a method for hoisting an offshore wind turbine component wherein use is made of such a crane and/or vessel. The hoisting crane includes a base structure, a superstructure, a boom having a longitudinal axis and a length of 80-200 meters. The boom includes a proximal portion connected to the boom connection member, formed integral via a joint structure with a single distal leg, wherein the length of the distal leg between the joint and the boom head structure exceeds 30 meters.

Provided is a lifting arrangement configured to facilitate alignment of a load with a wind turbine assembly. The lifting arrangement includes a crane arrangement for hoisting the load to the wind turbine assembly, a tagline arrangement for stabilizing the load during a lifting manoeuvre, a sensor arrangement configured to detect a motion of the wind turbine assembly relative to the load during the lifting manoeuvre, an actuator arrangement for adjusting the position of the load relative to the wind turbine assembly, and a control arrangement for controlling actuators of the actuator arrangement to reduce the detected relative motion. Also provided is a method of aligning a load with a wind turbine assembly.

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.

This invention relates to a large crane with an at least two-part main boom, wherein a lower and an upper part of the main boom are pivotally coupled to each other an articulation point. The invention furthermore is directed to a method for erecting or depositing a corresponding large crane.