The disclosure is related to a method for forming structures in a liquid, preferably underwater using a flowing, settable material, wherein the material used has a density which is substantially equal to the density of the liquid in which the structure is formed as well as a system for such method and structures formed.

A cofferdam is disclosed that includes an open frame structure having double walls defining a hollow space within each double wall, with each double wall having an open bottom end and a closed top end. Each of the double walls are configured to act as suction piles allowing liquid to be removed from the space within each double wall to thereby induce negative pressure when the cofferdam is installed in a sub-sea configuration. Each of the double walls may include a plurality of partitions respectively defining a plurality of suction piles, the suction piles fluidically coupled by a manifold that may allow liquid to be removed from the suction pile to thereby drive the cofferdam structure into the subsea surface due to the induced negative pressure. A further embodiment cofferdam structure includes an open frame structure and one or more suction piles attached to the open frame structure.

An assembly for installing an object under water at a desired location, including a vessel arranged to carry the object; a submersible frame; and a connection between the object and the submersible frame. In use the vessel is spatially separated from the submersible frame along the direction of the water surface. The object, the connection and the submersible frame are arranged such that, when releasing the object from the vessel, the object becomes submerged and carries out a pendulum motion until the object is suspended from the submersible frame.

A coating film capable of being peeled off in the shape of sheet to facilitate a coating film removal work, and is less likely to peel even after long periods of use on an underwater structure is provided. The coating film comprises an undercoat layer to be bonded to an underwater structure, and an antifouling layer bonded to the undercoat layer, wherein: a 100-gram underwater constant load peeling degree of the coating film is less than 5; a ratio of a tensile breaking strength of the coating film to an adhesive force of the coating film with respect to the underwater structure, as measured after immersing the coating film in pure water at 60° C. for 5 weeks is 1.5 or more; and a 1-mm square cross-cut stretching-caused peeling degree of the antifouling layer with respect to the undercoat layer is 0.05 or less.

A greenhouse for underwater cultivation of terrestrial plant species comprising a dome (2) suitable for being filled with air in an underwater environment, provided with an aperture (21) for lower access and made of a material that is impermeable to water and permeable to light, such dome comprising means for restraining to the sea floor, and means for adjusting the level of water/air in the dome itself which must ensure that plant species cultivated in the greenhouse always reside above such level. Inside such dome a system for the automatic irrigation of the cultivated plants is present comprising a tubular structure (3) on which a plurality of mutually spaced holes (31) is provided, inside which supports are placed for housing and cultivating plant species, irrigation water flowing inside such tubular structure and irrigating such supports in order to achieve a hydroponic culture.

A modular HVDC platform and a method for constructing the same are disclosed herein. The modular HVDC platform has a topside disposed on a structural jacket. The topside includes a first rectifier module, a second rectifier module, and a utility module. The first and second rectifier modules have equipment for converting AC power to DC power disposed therein. The utility module contains equipment for supporting the operations of the rectifier modules. Each of the rectifier modules and the utility modules can be fabricated and commissioned onshore prior to installation on the structural jacket at an offshore location.

A protective subsea housing for protecting an equipment space enclosed by the housing has an access opening in a wall of the housing for providing access to the equipment space by an unmanned underwater vehicle (UUV). The housing has a closure that is movable by translation, or by rotation relative to an axis transverse to or extending through the wall, to open and close the access opening, and an operating member, such as a rotary coupling, that is positioned outside the equipment space and is engageable and movable by the UUV to move the closure.

A method of installing an object under water at a desired location includes providing the object on a vessel, connecting the object to a submersible frame located below the water surface, wherein the vessel is spatially separated from the submersible frame along the direction of the water surface, releasing the object from the vessel such that the object becomes submerged and carries out a pendulum motion until the object is suspended from the submersible frame, and moving the object to the desired location.

A cofferdam is disclosed that includes an open frame structure having double walls defining a hollow space within each double wall, with each double wall having an open bottom end and a closed top end. Each of the double walls are configured to act as suction piles allowing liquid to be removed from the space within each double wall to thereby induce negative pressure when the cofferdam is installed in a sub-sea configuration. Each of the double walls may include a plurality of partitions respectively defining a plurality of suction piles, the suction piles fluidically coupled by a manifold that may allow liquid to be removed from the suction pile to thereby drive the cofferdam structure into the subsea surface due to the induced negative pressure. A further embodiment cofferdam structure includes an open frame structure and one or more suction piles attached to the open frame structure.

A cofferdam is disclosed that includes an open frame structure having double walls defining a hollow space within each double wall, with each double wall having an open bottom end and a closed top end. Each of the double walls are configured to act as suction piles allowing liquid to be removed from the space within each double wall to thereby induce negative pressure when the cofferdam is installed in a sub-sea configuration. Each of the double walls may include a plurality of partitions respectively defining a plurality of suction piles, the suction piles fluidically coupled by a manifold that may allow liquid to be removed from the suction pile to thereby drive the cofferdam structure into the subsea surface due to the induced negative pressure. A further embodiment cofferdam structure includes an open frame structure and one or more suction piles attached to the open frame structure.