A tension device for securing a floating structure to a fixed point includes an elastic member and an inelastic member. The elastic member has a length between a first end and a second end thereof. The length is elastically variable under tension. The inelastic member limits elongation of the length of the elastic member. The tension device has a first length when the elastic member is not under tension and a longer length when the elastic member is elastically stretched by a tension force. The inelastic member limits elastic elongation of the elastic member to a second length.

A vortex-induced vibration (VIV) suppression device including a body portion dimensioned to encircle an underlying tubular and a tail portion extending laterally outward from the body portion, the tail portion having a top end and a bottom end. The device further including an engaging member positioned at least at the top end or the bottom end of the body portion or the tail portion. The engaging member may be dimensioned to engage with an adjacent VIV suppression device.

A foundation for a subsea assembly is provided. The foundation comprises connection points. The connection points permit other components to be connected to the suction anchor and permit loads to transfer from the component connected to the connection points into the foundation. The foundation may be a suction anchor. A method of converting an exploration well using such a foundation to a production well is provided.

A supporting system for a floating unit in shallow water exerts controlled stresses on the floating unit hull and includes supporting structure for the hull. An extendable supporting device operatively connects to the supporting structure and is suitable to support a predetermined weight of the floating unit and load when entirely supported by the extendable supporting device and when the extendable supporting device rests on a bed of a water body. An actuator device connects to the supporting structure and operatively connects to the extendable supporting device for extension or contraction. A control device operatively connects to the actuator device to control the extraction or contraction movement of the extendable supporting device. The system includes at least one hull stress monitoring device operatively connected to the control device. A device to monitor the stress, or load, on the extendable supporting device operatively connects to the control device.

A floating wind power platform for offshore power production, comprising: a floating unit, wherein the floating unit comprises a first, a second and a third interconnected semisubmersible column each being arranged in a respective corner of the floating unit, wherein a tension leg device is arranged to the third semisubmersible column, wherein the tension leg device is adapted to be anchored to the seabed by an anchoring device, and wherein the third semisubmersible column provides a buoyancy force adapted to create a tension force in the tension leg device, wherein the floating wind power platform is further adapted to weather vane in relation to the wind direction.

A buoy (10) comprising a central column (12), an outer frame (14) attached to the central column with buoyancy which may be provided by the outer frame and/or by attached buoyancy units (16). The central column is negatively buoyant and is normally open at one end to allow water to flow in, and create an oscillating water column caused by waves. This water column dampens the effect of wave or other forces on the buoy, thus providing a more stable foundation for a wind powered generator. A further generator may be provided to extract energy from the oscillating water column. The buoy is normally attached to an anchor by one or more tension leg tethers which maintains the buoyancy below the surface of the water which has also be found to increase stability. The anchor may be a modular gravity base anchor.

A floating wind power platform for offshore power production includes a floating unit, wherein the floating unit includes a first, a second and a third interconnected semisubmersible column each having a longitudinal column central axis and each being arranged in a respective corner of the floating unit, a first and second wind turbine, arranged to the first and second semisubmersible columns, respectively, via a first and second tower respectively, wherein the first and second towers have a first and second longitudinal tower central axis, respectively, wherein the first and second semisubmersible columns are arranged in the floating unit with a first and second angle (.sub.1, .sub.2) respectively, with respect to a reference direction (z), and directed away from each other, wherein the first and second longitudinal tower central axes are parallel to the first and second longitudinal column central axes, respectively.

A method for installing a subsea structure at a target installation site in an underwater location is disclosed. The method includes connecting at least one mooring line and at least one leading line to the structure, and towing the structure via the leading line from a deployment position to the target installation site, such that the structure moves both vertically and horizontally between the deployment position and the target installation site. The mooring line is anchored, e.g. to an anchoring device on the seabed, and can incorporate a ballast to apply a sinking force to the structure in proportion to the length of unsupported line. The mooring line and the leading line can together stabilise the structure as it descends to the installation site. The non-vertical installation allows accurate structure placement, e.g. in crowded fields, with less sensitivity to tidal or current forces.

Floating construction comprising: a flotation base, comprising at least one essentially hollow body selectively fillable with ballast, where the maximum horizontal dimension of the flotation base is greater than the maximum vertical dimension of the floating base; a building supported by said flotation base preferably comprising a telescopic tower; downward impelling means; and at least three retaining cables the corresponding upper ends of which are attached to said flotation base, preferably in peripheral positions of the flotation base, and the corresponding lower ends of which are attached to said downward impelling means, such that said retaining cables are taut and apply a downward force on said flotation base that increases the stability thereof. And the installation method for this floating construction.

We have invented a floating platform with 3 canted columns, a new type of fairlead, and a new method of mooring line makeup and installation method, that can be used for canted columns. The platform includes 3 columns having upper ends projecting above water surface. The columns are canted or inclined inward from the corner of hull toward the central vertical axis. The 3 columns converge at the top of column such that each column will lean against the other 2 columns. Each column has two connection points to the other 2 columns. Horizontally disposed pontoons interconnect adjacent columns at the lower ends. The columns and pontoons form a closed structure hull to support a foundation structure directly above the top of column.