The invention relates to a compensating device (200) for maintaining specifiable target positions of a load (206) which can be handled using a cable hoist (202) and which is attached to a cable (216) of the cable hoist, the respective specifiable target position of the load changing unintentionally to an actual position deviating from the target position. The compensating device consists of at least one sensor device (240, 242) for detecting the respective actual position of the load (206); a rotational drive (226, 228, 230) for specifying a cable length of the cable hoist (202); and at least one controller (244) which changes the cable length after the respective actual position has been detected until the load (206) re-assumes its target position. The respective drive (226, 228, 230) can be controlled at least partly by at least one hydraulic motor (226, 228, 230) with opposite rotational directions, said motor being connected to an actuating device (246) which has at least two separate pressure chambers (250, 252) with pressure levels that differ during operation, thereby forming a drive section (248) for the respective hydraulic motor (226, 228, 230), and which can be actuated by the controller (244).

A knuckle boom crane at least comprising: a pedestal; a tower 2 arranged on top of the pedestal; an operator cabin 4 fixed to the tower 2; a machine house 3; a winch 5 with a wire 6 positioned at an upper end of the tower 2 so that the upper rim of the reel of the winch 5 protrudes above the top of the tower 2; or an alternative wire routing with a winch with a wire arranged external to the crane where the wire is fed to a first sheave arranged at an upper end of the tower 2 so that the upper rim of the sheave protrudes above the top of the tower 2; a main boom 14 which is at its first end is pivotally connected to the tower 2 at its second end the main boom 14 is pivotally connected with a first end of a knuckle boom 12, the second end of the knuckle boom is provided with at least one second sheave 10, where the main boom 14 is provided with an aperture 7 proximate to its first end.

The method of providing depth compensated motion compensation proximate a subsea landing package to isolate heaving motion of the supporting vessel from the supported subsea landing package, comprising a supporting cylinder for connecting to the subsea landing package having a first cross sectional area exposed to environmental pressure with a resulting first force, a second and opposing cross section area exposed to environmental pressure providing a second and opposing balancing force, a piston within the cylinder with compressed gas in a first chamber on a first side of the piston and a low pressure gas or a vacuum is in a second chamber on the opposite side of the piston, and adjusting the gas pressure in the first chamber acting on the piston such that the force acting on the piston is approximately the in water buoyed weight of the subsea landing package.

The method of providing depth compensated motion compensation proximate a subsea landing package to isolate heaving motion of the supporting vessel from the supported subsea landing package, comprising a supporting cylinder for connecting to the subsea landing package having a first cross sectional area exposed to environmental pressure with a resulting first force, a second and opposing cross section area exposed to environmental pressure providing a second and opposing balancing force, a piston within the cylinder with compressed gas in a first chamber on a first side of the piston and a low pressure gas or a vacuum is in a second chamber on the opposite side of the piston, and adjusting the gas pressure in the first chamber acting on the piston such that the force acting on the piston is approximately the in water buoyed weight of the subsea landing package.

A compact and simplified heave compensation system for reducing the effect of waves or wavelike movements on a lifting device. The system can have active and passive heave compensation components. An overload protection to protect lifting equipment can also be implemented. The system enables accurate load and displacement calculations, as well as simplifying the control schemes utilized for lifting devices.

A compact and simplified heave compensation system for reducing the effect of waves or wavelike movements on a lifting device. The system can have active and passive heave compensation components. An overload protection to protect lifting equipment can also be implemented. The system enables accurate load and displacement calculations, as well as simplifying the control schemes utilized for lifting devices.

The present invention relates to a motion compensation system for an element hanging from a mobile unit, the system comprising two blocks, at least two articulated arms, a compensation cylinder and a cable. According to the invention, at least one characteristic length of the articulated system (for example: the length of a link or the distance between two sheaves of two articulated arms) is adjusted according to the motion to be compensated for.

The present invention relates to a motion compensation system for an element hanging from a mobile unit, the system comprising two blocks, at least two articulated arms, a compensation cylinder and a cable. According to the invention, at least one characteristic length of the articulated system (for example: the length of a link or the distance between two sheaves of two articulated arms) is adjusted according to the motion to be compensated for.

Described herein are systems, methods, and structures for transferring an object between a ship and an offshore structure, comprising a hoisting mechanism arranged on the offshore structure and adapted to attach to the object, at least one range sensing device adapted to provide data relating to a detected distance from a reference point on the offshore structure to the ship, where the system is adapted to receive the data from the at least one range sensing device and to move the hoisting cable in response to the detected distance, and a motion reference unit adapted to provide data relating to a detected motion of the ship independently of the at least one range sensing device, and wherein the system is adapted to move the hoisting cable in response to the detected motion of the ship.

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.