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.

The invention relates to a method for building concrete foundations for lattice-type offshore structures and to foundations built using this method, which has the main aim of replacing the piles used to anchor lattice structures to the seabed (7) with blocks of on-site reinforced concrete (1) which grant the necessary stability to the lattice structure (2), doing away with all pile-driving works but without performing any structural modification of said structure. Said elements (1) are positioned using templates (12). The advantages of this novel invention lie in the possibility of installation on any type of terrain, providing a perfect connection between the seabed and the foundations thanks to on-site concreting, as well as its ease of construction, reduction of noise emissions and of auxiliary means.

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.

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.

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.

A pile anchor reinforcing system includes a pile anchor having an end penetrating a seafloor, and a mudmat positionable on the seafloor and defining a reinforcing pile aperture or a surface area to receive a gravity anchor or both, and a pile anchor aperture sized to receive the pile anchor. A reinforcing pile is extendable through the reinforcing aperture and penetrates the seafloor. The mudmat and the reinforcing pile and/or the gravity anchor cooperatively reinforce the pile anchor against lateral and vertical loading.

The present disclosure discloses a combined offshore wind power foundation with duct piles and a bucket, which comprises duct piles and a bucket foundation; the bucket foundation includes a steel bucket skirt, a bucket top cover, main beams, ring beam and a transition section. A top of the steel bucket skirt and the bucket top cover are integrally formed into a semi-closed structure. The bucket top cover is provided thereon with main beams uniformly arranged in a circumferential direction. The ring beam are arranged at an edge of the bucket top cover. Each duct pile includes a duct, a steel pile, duct supports and high-strength mortar, each main beam is provided at its outer side end with one of corresponding. The duct support is connected with the main beam and the ring beam, and integrated with the bucket top cover, the main beams and the ring beam.