The invention relates to the naval field and in particular to a method for launching a structure (1) intended to float in water (15). This method comprises loading the structure (1) onto a pontoon (10) floating in the water, the bearing placement below the water (15) of at least one prop (2) connected to the structure (1) while the structure (1) rests on the pontoon (10) floating in the water (15), lowering the pontoon (10), with disengagement of the pontoon (10) vertically from the structure (1) and its subsequent removal while the structure (1) is supported by the at least one prop (2) bearing below the water (15), and lowering the structure (1), which is still supported by the at least one prop (2), until the structure (1) floats in the water (15).

An apparatus for use in marine platform jacking is disclosed herein. In one aspect, a jetting valve includes a valve body with a piston assembly disposed therein. The piston assembly is selectively operated to open and close the valve. A biasing member is coupled to the piston assembly. The piston assembly includes a first piston and a second piston. The dual pistons, in cooperation with the biasing member, allow the valve to self-seal thereby preventing entry of a fluid which is external to the valve.

A jack-up platform is described having a horizontal working deck that may be jacked up out of the water by moving its legs to a position wherein they take support on an underwater bottom. The jack-up platform further comprises a mooring system for mooring a floating vessel at a mooring side of the jack-up platform. The mooring system comprises an elongated support means for supporting a hull part of the floating vessel, and guiding means connected to the hull of the jack-up platform at the mooring side. The guiding means are able to rigidly hold the elongated support means in a support position, in which the elongated support means is within reach of the hull part of the floating vessel to be supported when the hull is jacked out of the water and the jack-up platform rests on its legs. A method for mooring a floating vessel using the jack-up platform is also described.

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 first permissible operating range of the self-elevating vessel is determined based on a first structural analysis of the self-elevating vessel under a first set of conditions. A structural utilization ratio of the self-elevating vessel is determined based on a second structural analysis of the self-elevating vessel under first and second sets of conditions. Safety of lowering the self-elevating vessel from an elevated state to a first hull draft level is determined when the structural utilization ratio is less than a predetermined value. Safety of lowering the self-elevating vessel from the first hull draft level to a second hull draft level is indicated when positional displacement data obtained while the vessel is at the first hull draft level indicates that the positional displacement of the self-elevating vessel while at the first hull draft level is within the first permissible operating range.

Drilling installation comprising a cantilever with a drilling floor for performing drilling operations; further comprising an independent operations handling system arranged for handling equipment underneath the drilling floor independent of the drilling operations on the drilling floor, wherein the independent operations handling system comprises a handling element for cooperation with the equipment to be handled, wherein the handling element is extendible underneath the cantilever.

An offshore platform for use in combination with an offshore rig comprises an upper deck defining an upper deck aperture which is alignable with a rig aperture of the offshore rig, when said offshore rig extends over the upper deck, to permit objects to extend between the offshore rig and through the upper deck. The offshore platform further includes a sheath arrangement aligned with the upper deck aperture and extending upwardly relative to the upper deck to be alignable with the rig aperture, wherein the sheath arrangement defines a confinement zone for confining objects which pass downwardly from the offshore rig through the rig aperture.

An offshore wind turbine installation vessel includes a crane provided with a computerized crane control system. The computerized crane control system is linked to the slew drive, the luffing drive, and the hoisting winch of the crane, and is programmed to perform a foundation pile installation routine providing a coordinated pattern of slew motion of the superstructure and of luffing motion of the boom structure, as well as operation of the hoisting winch so that the load connector of the crane moves from a foundation pile pick up position thereof, where the load connector is connected to the top end of a horizontally oriented foundation pile stored on a storage deck, to a foundation pile overhoarding position thereof, wherein the foundation pile is in vertical suspended from the load connector, outside of the hull.

A floatable structure is described having a hull and a deck. The floatable structure further includes a mooring system for mooring a second floating structure at a mooring position relative to the floatable structure. The mooring system brings the second floating structure down in the water from an initial floating draft to a larger mooring draft to reduce motions of the second floating structure relative to the floatable structure. A method for mooring a second floating structure using the mooring system is also described.

The invention relates to a crane as a component of a wind farm installation vessel which consists of a vessel body and a plurality of jack-up legs arranged in vertically movable manner thereon, wherein the crane is arranged rotatably about one of the jack-up legs. According to the invention, the crane is rotatably mounted on an eccentric platform which itself is arranged rotatably about the jack-up leg.