An apparatus for supporting an additional structure near a surface of a body of water, and a system which includes the apparatus and further includes the structure attached to the apparatus. The apparatus and the system are each configured to assume a rest position and orientation when the apparatus or system is floating at the surface and when the body of water is substantially still, where the rest orientation defines a vertical direction extending from the surface to a keel at a lowermost position of the apparatus. The apparatus includes a support member, which, in use, is attached to the additional structure; and buoyant units. Each buoyant unit is attached to the support member at or near the keel and extends from the keel in a longitudinal direction of the buoyant unit, which longitudinal direction defines an angle of approximately 35-65 with respect to the vertical direction.

A mooring device for an offshore wind turbine includes: at least two mooring lines including a first end configured to be attached to a first attachment point of a floating offshore wind turbine platform, and at least three anchoring elements configured to anchor the floating offshore wind turbine to a seabed, each mooring line being flexibly retained through at least one anchoring element, a second end of the mooring lines being attached to an attachment point in order that a first mooring line length extending between the floating offshore wind turbine platform and the anchoring element can vary in function of the forces exerted on the floating offshore wind turbine platform.

An offshore structure is separated into an upper structure and a lower structure. Part or whole of the lower structure is kept in an upright standing state in water. The upper structure is moved to above the lower structure kept in the upright standing state. A uniting step includes one or both of raising the lower structure to arrange the lower structure on a lower side of the upper structure and lowering the upper structure to arrange the upper structure on an upper side of the lower structure by submerging part of a carrier vessel on which the upper structure is mounted while being held by a pair of arm-shaped structures of the carrier vessel and integrating the lower structure with the upper structure. In this way, an offshore structure is moored safely at an offshore installation site without using a crane vessel.

A system includes mooring lines arranged respectively in three to eight directions, and at least one of a plurality of offshore structures included in the offshore structure group is moored by locking the mooring lines in the respective directions with separate mooring bases, and at least one of the mooring bases locks the mooring lines which are connected respectively to three to eight of the offshore structures in the offshore structure group. With this configuration, even when part of the mooring lines mooring the offshore structures is broken or the mooring function of the mooring bases is lost, although the offshore structure moves, the offshore structure is kept being moored by the remaining mooring-line group, so that the offshore structure can be prevented from colliding with another offshore structure.

A hybrid winch system for use with an anchor handling vessel is disclosed that includes but is not limited to an electric winch mountable on the anchor handling vessel, an electric generator for providing generated power to the electric winch, a battery for providing stored power to the electric winch, an anchor cable wound around the electric winch and passing over a roller drum for guiding the anchor cable, an anchor attached to a distal end of the anchor cable and a winch controller for selectively applying the generated power and the stored power to the electric winch. The winch controller is configured to provide the stored power to the electric winch for controlled release of the anchor cable in the case of loss of the generated power.

An offshore electricity production assembly comprising a floating platform, a wind turbine fixed to the floating platform, and inclined mooring tendons, the floating platform comprising: a tubular central buoyant column extending along a longitudinal axis intended to be vertical, the column having an immersed portion defining a first average external diameter, and a plurality of tubular radial buoyant pontoons protruding from the column along radial axes spaced around the longitudinal axis, each of the pontoons defining a second average external diameter, the pontoons being immersed in a body of water.

The first average external diameter is larger than the second average external diameter.

Techniques are disclosed herein for minimizing movement of a fixed marine structure. Using the technologies described, a wind turbine may be mounted on a fixed marine platform (e.g., a fully restrained platform (FRP)) that is secured by mooring lines that may be maintained at a tension to restrain movement of the platform due to environmental loads (e.g., wind, waves, etc.). The mooring lines may be attached to the platform with assemblies that include a stopper attached to the mooring line and engaged with a mooring porch. The stopper may be positioned and/or repositioned to adjust the tension on the connected mooring line and secured in the adjusted position using the various systems and techniques described herein.

An apparatus for supporting an additional structure near a surface of a body of water, and a system which includes the apparatus and further includes the structure attached to the apparatus. The apparatus and the system are each configured to assume a rest position and orientation when the apparatus or system is floating at the surface and when the body of water is substantially still, where the rest orientation defines a vertical direction extending from the surface to a keel at a lowermost position of the apparatus. The apparatus includes a support member, which, in use, is attached to the additional structure; and buoyant units. Each buoyant unit is attached to the support member at or near the keel and extends from the keel in a longitudinal direction of the buoyant unit, which longitudinal direction defines an angle of approximately 35-65 with respect to the vertical direction.

The present invention relates a structure comprising rigid elements connected together by interconnecting elements in such a way to form a statically determined or statically over-determined structure, wherein said structure comprises at least one tension element comprising polymeric fibers having a stabilizing creep of at least 0.3% and at most 10% and a minimum creep rate lower than 110.sup.5% per second, said stabilizing creep and minimum creep being measured at a tension of 900 MPa and a temperature of 30 C. The present invention also relates to said structure being a framing structure, preferably a space frame; a suspended body; a platform, preferably a marine platform; or a wheel comprising spokes. Furthermore, the invention relates to the use of polymeric fibers having a stabilizing creep of at least 0.3% and at most 10% and a minimum creep rate lower than 110.sup.5% per second, said stabilizing creep and minimum creep being measured at a tension of 900 MPa and a temperature of 30 C. for a statically determined or statically over-determined structure, preferably for a framing structure, such as a space frame; for a suspended body; for a platform, preferably for a marine platform; or for a wheel comprising spokes.

The invention allows setting up floating platforms comprising an elongated central body (1) from the lower portion of which legs (2) come out intended to fix the platform to anchoring elements arranged in the sea bed (5). The vessel comprises: a) a longitudinal through groove (4) up to the vessel bottom, and leaving part of the vessel bow (5) open; and b) a plurality of slots (6, 7) placed at the bottom of the vessel, wherein the groove (4) and the slots (6, 7) are configured both in dimension and in shape in such a way that they fit in at least some of the legs (2), so that the legs (2) can be inserted, at least partially, in the slots (6, 7) to attach the platform to the vessel.