A method of upgrading a knuckle-boom crane to a heave-compensating crane includes: removing a knuckle-boom from a main boom; mounting a main boom extension to the main boom for increasing the length of the main boom; and mounting a heave-compensating boom at a far end of the main boom extension such that the heave-compensating boom extends in a downward vertical direction (Z) in operational use of the heave-compensating crane. The heave-compensating boom is configured to be pivotable with respect to the main boom extension in both horizontal directions (X, Y). A heave-compensation system is provided to the knuckle-boom crane, wherein the heave-compensation system compensates for horizontal variations by controlling the orientation of the heave-compensating boom relative to the main boom extension, and compensates for vertical variations by means of a further vertical heave-compensation system, such as a winch-based heave-compensation system.

The invention relates to a system (1) for use with a crane (4) on a surface vessel (3), comprising a crane tool (15) attached or attachable to a hoisting cable (5) of the crane (4) and one or more adaptors (16) attached or attachable to one or more tools (11-14, 25) for carrying out operations or to one or more components (2, 10), the crane tool (15) comprising a connector (17) and at least one of the adaptors (16) comprising a connector-counterpart (18).

A tower crane includes: a jib provided to extend or retract along the lengthwise direction; a cathead provided to extend or retract in the vertical direction; and a movable balance weight installed under a counter jib to be slidable in the horizontal direction, outwardly moved to be farther away from a mast when the jib is unfolded to have an increased length, and moved toward the mast when the jib retracts to have a decreased length, so that the center of gravity of the tower crane is adjusted according to the length of the jib and thus the balance is adjusted. Moreover, the tower crane comprises a movement guide part installed between the counter jib and the movable balance weight to guide the movement of the movable balance weight in the horizontal direction.

Disclosed is a system for the storage and traction of a cable, in particular a synthetic cable fitted to an offshore crane. The storage/traction system includes a frame that carries in particular a storage device including a support carrying a storage reel through an assembly defining an axis of rotation. Between the storage reel and the support, the assembly includes of a single slewing ring including two rings that are free to rotate with respect to each other: a fixed ring that is fastened to the support; and a moving ring that is, on the one hand, fastened to the storage reel and, on the other hand, rotated by a motorization.

Disclosed is a system for the storage and traction of a cable, in particular a synthetic cable fitted to an offshore crane. The storage/traction system includes a frame that carries in particular a storage device including a support carrying a storage reel through an assembly defining an axis of rotation. Between the storage reel and the support, the assembly includes of a single slewing ring including two rings that are free to rotate with respect to each other: a fixed ring that is fastened to the support; and a moving ring that is, on the one hand, fastened to the storage reel and, on the other hand, rotated by a motorization.

A davit crane that includes a base adapted to operably engage with a ground surface. The davit crane also includes a drive assembly operably engaged with the base. The davit crane also includes an actuation assembly operably engaged with the drive assembly, wherein the actuation assembly is configured to move between a lowered position and a raised position via the drive assembly. The davit crane also includes a boom assembly operably engaged with the actuation assembly. The actuation assembly of the davit crane is operable to pivotably adjust the boom assembly between the raised position and the lowered position.

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 securing the vessel with respect to the hull of the offshore jack-up when the hull is positioned out of the water and the legs engage the seafloor. A lifting mechanism mounted on the offshore jack-up engages with a cargo carrying platform positioned on the vessel. The platform is lifted with the lifting mechanism between a first position on the vessel and a second position clear of the vessel.

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 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.