Abstract: A motion damper for structures includes a housing coupled to a structure such that the housing moves in correspondence with the structure. The housing includes a wall with a vent, and has an air chamber therein in fluid communication with the vent. A piston is sealed within the housing for one-dimensional motion therein. A rigid plate is disposed within the housing's air chamber. The plate is disposed between the piston and the vent, and is spaced apart from and fixedly coupled to the piston such that the plate moves in correspondence with the one-dimensional motion of the piston. At least one spring is mounted in the housing and is coupled to the plate for applying a force thereto that is in opposition to the one-dimensional motion of the piston.

Abstract: A floating ocean platform stabilized in position by energy produced from wave energy. In one embodiment, the platform may be used to support a roadway to build a floating bridge. The platform may also include a wave break mechanism for additional stability and may submerge for storm survival. The platform may be constructed in modules to permit reconfiguration and management of resources. In other embodiments, the platform may support communities. The bridge may also provide transmission lines for conducting wave generated electricity back to the mainland.

Abstract: A method of connecting a member to a floating structure, the method includes disposing the floating structure in a body of water and attaching the member to the floating structure. The method also includes changing an orientation of the floating structure and aligning the member with a connection device disposed on a lower portion of the floating structure.

Abstract: The invention provides a sub-structure (2) comprising at least one leg (4) having first buoyancy means (4a) arranged in a lower part of the at least one leg to provide a first buoyancy, and a float element (3) having second buoyancy means to provide a second buoyancy, wherein the sub-structure and the float element are constructed to allow relative wave induced motion with respect to each other in a substantially vertical direction wherein the leg is movable from a pre-installation position to an installation position by a substantially downwards movement of the leg with respect to the float element, and wherein during at least a second part of the downwards movement of the leg towards the installation position and/or in the installation position the first buoyancy means are substantially located below a wave zone to substantially decrease heave action on the first buoyancy means.

Abstract: A modified spudcan with optimal peripheral skirt for enhanced performance of jackup operations comprises a spudcan top part, a spudcan bottom part, wherein the spudcan bottom has a central tip protruding from the central part of the spudcan bottom; wherein the top and bottom parts are coupled at their peripherals or through a spudcan side wall to form a hull structure, and a peripheral skirt having an upper end being coupled to the spudcan bottom part and a lower end extending downwardly, wherein the tip of the lower end of the peripheral skirt is higher than the distal end of the central tip.

Abstract: A system includes a vessel configured to contain a substance therein having a top end and a bottom end with a center-of-gravity for the vessel disposed between the top end and the bottom end, a frame connected to the vessel, a cable link connected to the frame configured to connect a cable thereto, and a cable support connected to the vessel or the frame. The cable support disposed above the center-of-gravity of the vessel with respect to the top end and the bottom end of the vessel. As the vessel moves from a first position to a second position, the cable engages the cable support such that a lifting force is translated from the cable and through the cable support to have the cable move the vessel through the cable support, the cable support attached to the frame or the vessel with the cable support disposed above the center-of-gravity.

Abstract: A method for installation of an offshore wind turbine. The method includes prefabrication of a foundation that provides buoyant force and uprighting force to the foundation so as to keep it upright without external forces. The method further includes installation on a dock that includes assembling the offshore wind turbine into a complete set, and finishing testing in a state of the complete set. The method further includes transporting the complete set to an offshore site in a way of floating on the water, and then offshore installation that includes sinking the complete set onto a sea bed by gravity on the offshore site, and fixing the foundation to finish the installation. The present invention also provides a method for recovery of an offshore wind turbine, which is performed generally in steps reversed to the method for installation.

Abstract: An offshore structure comprises a hull having a longitudinal axis and including a first column and a second column moveably coupled to the first column. Each column has a longitudinal axis, a first end, and a second end opposite the first end. In addition, the offshore structure comprises an anchor coupled to the second end of the second column and configured to secure the hull to the sea floor. The first column includes a variable ballast chamber and a first buoyant chamber positioned between the variable ballast chamber and the first end of the first column. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. The second column includes a variable ballast chamber. Further, the offshore structure comprises a topside mounted to the hull.

Abstract: A load out and float off method for a spar type structure or another structure such as a deck. The invention enables the load out and float off of a large diameter spar using existing Heavy Lift Vessels (HLV's). A U-shaped tank (U-tank) is utilized to artificially extend the length of the HLV and provide supplemental buoyancy to help lift the spar off the land ways. The U-tank provides supplemental buoyancy and water plane area to float the spar off the HLV. After HLV departure the U-tank is moved and placed beneath an adapter frame on the spar's hard tank. The U-tank is ballasted upward to reduce the hard tank draft and have the strake tips clear the channel bottom. The spar can then be brought alongside the fabrication yard quay for additional work and then towed down the channel to the open sea.

Abstract: A method of constructing a semi-submersible unit with a side wall. To construct the semi-submersible unit, the method can include placing a hull in a body of water and connecting a deck structure to the hull. In addition, there is a kit for constructing a semi-submersible unit, with a side wall.

Abstract: A hull, suitable for use as a tension leg platform (TLP) or as a semi-submersible vessel, comprises columns having a generally polygonal transverse cross section at least one axis of which is generally radially aligned with the central vertical axis of the hull. Buoyant, subsurface pontoons interconnect adjacent columns. The pontoons are generally rectangular in cross section and the outboard, generally vertical surface of each pontoon is connected to a side surface of an adjoining column at a location which is substantially inboard of the outermost face of the column. In certain embodiments of the invention, tendon porches (configured to receive the upper tendon connectors of a TLP) are mounted to the outboard surface of one or more pontoons.

Abstract: Measurement platform for installing in water, very light and easy to transport, which comprises a foundation of improved suction anchor type constituting the platform base. It is driven into the seabed by the pressure difference between outside and inside, and by reversing the pressure gradient it can be extracted for reutilization. The measurement platform also has a series of telescopically connected tubes, a house located on these tubes containing the devices, a vertical shaft wind turbine for powering the assembly, a device for transmitting data (wi-max or equivalent) to the on-land station, a Doppler laser anemometer, security cameras and the terminal of a Doppler current meter. All data recorded by the devices as well as pictures from security cameras will be continuously sent to the on-land station. Thus the security of the facility is increased, and possible sabotages are forecasted.

Abstract: A floating system comprising a plurality of buoyant columns, a top portion of the columns extending above a water surface, and a bottom portion of the columns submerged in a body of water; a deck connected to the top portion of the columns; at least one pontoon connected to the bottom portion of at least two of the columns; a plurality of heave plates, each heave plate connected to the bottom portion of at least one of the columns; and a conduit connected to the deck and extending to a bottom of the body of water.

Abstract: An offshore structure comprises a hull having a longitudinal axis and including a first column and a second column moveably coupled to the first column. Each column has a longitudinal axis, a first end, and a second end opposite the first end. In addition, the offshore structure comprises an anchor coupled to the second end of the second column and configured to secure the hull to the sea floor. The first column includes a variable ballast chamber and a first buoyant chamber positioned between the variable ballast chamber and the first end of the first column. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. The second column includes a variable ballast chamber. Further, the offshore structure comprises a topside mounted to the hull.

Abstract: An offshore structure comprises a hull having a longitudinal axis, a first end, and a second end opposite the first end. In addition, the structure comprises an anchor coupled to the lower end of the hull and configured to secure the hull to the sea floor. The anchor has an aspect ratio less than 3:1. The hull includes a variable ballast chamber positioned axially between the first end and the second end of the hull and a first buoyant chamber positioned between the variable ballast chamber and the first end of the hull. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. Further, the structure comprises a ballast control conduit in fluid communication with the variable ballast chamber and configured to supply a gas to the variable ballast chamber. The structure also comprises a topside mounted to the first end of the hull.

Abstract: A method for providing a sustainable offshore community that includes a floatable, low cost platform structure which covers a large amount of real estate and is supported above the surface of the ocean from columns which pass through the structure such that the extremities of the structure are supported with stays that run from the top of the columns to the extremities of the platform. This type of staying structure permits the formation of the large floatable platform for supporting self sustaining communities by providing sizeable living and recreational areas, thus to permit an offshore community to exist at sea for a number of years.

Abstract: A semi-submersible structure. The hull includes four columns that are supported by two pontoons. The columns support the topsides and the topsides structural framing serves as horizontal framing between the columns. A truss frame is attached to the columns. The truss frame preferably includes heave plates. The truss frame extends downward below the pontoons a sufficient distance in the water such that it minimizes motions caused by environmental forces. The hull section and the truss space frame are constructed separately and assembled together at the offshore site where the structure is used for drilling and/or production.

Abstract: A building over the water, maneuvering methods for the building and hosting sites of the building. The buildings including a superstructure (A) provided a floor structure (1) that is placed over a water surface (2) on which an inhabitable subassembly (3) is positioned, a support (B) sitting on ground (4) positioned under the floor structures (1), and mobile floating docks (C) with variable and controllable buoyancy that includes a load carrying platform (5) positioned under the floor structure (1). The superstructure (A) is held above the water surface (2) by the supports (B), that sit on the ground (4), and respectively carried by the floating docks (C), the superstructure being detachable from the ground (4), and transportable on water on the mobile floating docks (C), thus being possible to reposition the superstructure (A) on ground (4), at a destination of choice.

Abstract: A heave compensation apparatus and method for a winch or crane system, the winch or crane system preferably for a vessel and including a lift wire for attachment to a load. The apparatus includes a vessel motion measurement device which may be in the form of a motion reference unit for measuring the motion of the vessel, and a control device or computer capable of receiving an output from the vessel motion measurement device and controlling the winch or crane system according to the movement of the vessel, so as to stabilise the load. The apparatus may further optionally include one or more of a lift wire tension measuring device for measuring the tension in the lift wire; a lift wire distance measurement device which measures the length of lift wire that has been paid out; and a load motion measurement device for measuring the motion of the load.

Abstract: A riser assembly and method for providing buoyancy to a riser assembly are disclosed. The riser assembly which is of the type for transporting fluids from a sub-sea flowline to a floating structure comprises a first segment of flexible pipe, a further segment of flexible pipe and a rigid buoyancy support for providing at least one buoyancy element at the support.

Abstract: A floating platform includes a hull and a deck mounted on the uppermost end of the hull. The platform is anchored to the seabed by a plurality of tendons connected to the hull at the upper ends thereof and secured to the seabed at the lower ends thereof. The platform includes detachable buoyancy means providing supplemental buoyancy for hydrostatically stabilizing the platform without utilizing a derrick barge while ballasting the platform during installation.

Abstract: An extendable draft platform, having a deck and buoyancy columns installed in leg wells in the deck for vertical movement from a raised position to a submerged position, includes a connection arrangement for securing the columns to the deck when the columns are in the submerged position. In the connection arrangement, a plurality of first guide elements near the top of each column is engageable by a plurality of complementary second guide elements secured to the deck around each leg well when the column is lowered to its submerged position. A locking mechanism is operable between the columns and the deck when the first guide elements are engaged with the second guide elements. The first and second guide elements may be configured so that the connection between the deck and the columns may be enhanced by over-ballasting the columns and/or by welding the columns to the deck.

Abstract: An extendable draft offshore oil and gas drilling and production platform (“EDP”) includes a buoyant deck having a central opening, an adjustably buoyant pontoon, and a single, adjustably buoyant column. The column is mounted upright on the pontoon, and is vertically movable through the central opening of the deck. The deck is supported on an upper end of the column above a body of water for offshore operations. The pontoon, and optionally, the column, have compartments with a buoyancy that is adjustable by pumps or sea water ballast and pressurized air. In one embodiment, the compartments can comprise a plurality of tubes. In another embodiment, a lower end of the column may comprise an open truss structure. The platform combines the advantages of a SPAR platform with those of a deep draft extendable draft platform.

Abstract: A semi-submersible, multicolumn, deep draft, floating offshore oil and gas drilling and production platform comprises a floating hull having an adjustably buoyant base, a plurality of columns vertically upstanding from the base, and an equipment deck that is supported atop the columns when the platform is operationally deployed. Each of the columns comprises a cellular structure that includes a plurality of elongated tubes having a variety of cross-sectional shapes extending from the base to the top of the column. Each of the tubes defines one or more closed compartments. At least one of the compartments has a buoyancy that is fixed, and at least another one of the compartments has a buoyancy that is adjustable. The buoyancy of the compartments and the base can be controllably adjusted with pressurized air to provide a safer and less costly method for deploying the platform for offshore operations.

Abstract: The invention is a method for lifting and transporting a heavy load by using a heavy lift vessel with at least two heavy lift cranes adapted to operate simultaneously; mounting fly-jibs on the heavy lift crane to increase reach and height of the heavy lift crane; picking up a load from a first location using the fly-jib modules simultaneously; shifting the load from the first location to over a second location on the heavy lift vessel; placing the load on the second location; moving the heavy lift vessel to a second position; using a mooring system to maintain the heavy lift vessel at the second position; picking up the load from the second location using the fly-jib modules simultaneously; shifting the load from a second location to over a third location; and placing the load on the third location.

Abstract: A marine buoy for the offshore support of subsea production and drilling activities that has a closed-bottomed base section with a solid ballast and variable ballast chambers, a chamber in the base section for storing equipment and supplies, and an upper section with a smaller cross-sectional area than the base section having an elevator shaft leading from the top of the upper section to the chamber in the base section. The upper section supports a deck for housing process equipment for operations that the marine buoy is supporting.

Abstract: The present invention provides a large transport ship in which the shape of a ship bottom 1a from a bow 1h to a stern 1t, when viewed on a cross-section perpendicular to the longitudinal direction of the ship bottom 1a, is tapered towards the center CL of the ship bottom in the widthwise direction. Consequently, it is possible to resolve problems associated with changes in the draft corresponding to the state of the load, without using ballast water.

Abstract: An apparatus for controlled deployment of ballast material onto a subsea location, preferably a subsea structure, comprising at least one chute for conveying said ballast material, said chute having a first end and a second end; at least one buoyancy element associated with the chute such that the chute may assume a generally vertical orientation in the water, supported by said buoyancy element; a support element associated with said chute and adapted for cooperation with an installation weight, said chute second end being adapted for connection to an element associated with the seabed.

Abstract: A system for drilling wells includes a plurality of platform modules, which are interconnected to one another on site to form a unitary platform structure. The interconnected platform modules are elevated above a surface on plurality of legs coupled to at least some of the platform modules. The elevated interconnected platform modules support drilling and auxiliary equipment. The system is well adapted for use in arctic, inaccessible, shallow water or environmentally sensitive locations.

Abstract: A marine platform (and method of installation) provides a plurality of buoys, a platform having a peripheral portion that includes a plurality of attachment positions, one attachment position for each buoy, and an articulating connection that connects each buoy to the platform at a respective attachment position, the connection allowing for sea state induced buoy motions while minimizing effect on the platform. A method of installation places the platform (including oil and gas drilling and/or production facility next to the buoys. Ballasting moves the platform and buoys relative to one another until connections are perfected between each buoy and the platform.

Abstract: There is provided a buoyancy system for a structure having at least one component being substantially stationary with respect to the bottom of a water covered area. The system comprises a set of buoyancy modules of engineered materials to apply an identified amount of buoyancy. The set of buoyancy modules is attached to the structure at a set of buoyancy load transfer locations. The set of buoyancy modules comprises layers of the engineered materials. The engineered materials comprise a substantially reinforced axial layer, a substantially reinforced hoop layer; and a leak prevention layer.

Abstract: A floating platform for offshore drilling or production of hydrocarbons comprises a topsides with drilling and/or production equipment (8), and a substructure comprising a lower pontoon (3) and columns (4) connecting the pontoon (3) to the topsides (1). During its operation the platform is exposed to wave forces (9) which cause heave motion (v) and roll and pitch motion (p) of the platform. The substructure has a draught (11) which is at least 40 metres, preferably at least 50 metres and most preferred at least 60 metres, and the ratio between the distance (16) between the columns' centre axes (25), measured along a side of the substructure, and the lower substructure's draught (11) is between 1.0 and 1.5, preferably between 1.2 and 1.4 and most preferred between 1.3 and 1.35.

Abstract: A marine platform provides a plurality of buoys, a platform having a peripheral portion that includes a plurality of attachment positions, one attachment position for each buoy, and a connection that connects each buoy to the platform at a respective attachment position, the connection allowing for sea state induced buoy motions while minimizing effect on the platform. Each connection can provide first and second portions (or devices) and a load transfer mechanism that transfers load from the first portion to the second portion so that one of the portions (or devices) can be serviced.

Abstract: A marine buoy for the offshore support of subsea production and drilling activities that has a closed-bottomed base section with a solid ballast and variable ballast chambers, a chamber in the base section for storing equipment and supplies, and an upper section with a smaller cross-sectional area than the base section having an elevator shaft leading from the top of the upper section to the chamber in the base section. The upper section supports a deck for housing process equipment for operations that the marine buoy is supporting.

Abstract: An offshore well platform is towed in an upright condition to a well site by the use of a temporary flotation device. The flotation device mounts to a portion of the platform and is partially submerged, increasing the ability and buoyancy of the platform. At the site, the engagement of the flotation device shifts to a deploying position. In the deploying position, the ballast of the platform is increased to cause it to more deeply submerge. The flotation device remains at least partially surrounding the platform and floating while the platform moves downwardly relative to it. This provides lateral support if needed to prevent heeling while being submerged. The flotation device is disengageable from the platform when the platform is fully submerged.

Abstract: A marine platform provides a plurality of buoys, a platform having a peripheral portion that includes a plurality of attachment positions, one attachment position for each buoy, and a connection that connects each buoy to the platform at a respective attachment position, the connection allowing for sea state induced buoy motions while minimizing effect on the platform. Each connection can provide first and second portions (or devices) and a load transfer mechanism that transfers load from the first portion to the second portion so that one of the portions (or devices) can be serviced.

Abstract: A marine platform provides a plurality of buoys, a platform having a peripheral portion that includes a plurality of attachment positions, one attachment position for each buoy, and an articulating connection that connects each buoy to the platform at a respective attachment position, the connection allowing for sea state induced buoy motions while minimizing effect on the platform.

Abstract: A submersible floating dock which can be sunk beneath the water line in the event of the approach of a violent storm for protection of the dock against wave action, storm surge, and high winds. A dock with a deck supported on hollow floatation chambers is attached to pilings by rings. The rings allow the dock to move up and down in response to changes in the water level. As a storm approaches water is allowed to enter the hollow floatation chambers which are ordinarily filled with air. This causes the dock and deck to sink beneath the water line making it resistent to damage from storm surge, wave action, and high winds. After the storm has passed, pressurized air is introduced into the floatation chambers forcing the water in the floatation chambers out of the chamber. The air increases the buoyancy of the floatation chambers, hence, of the dock so that it rises above the water line for use by an owner after the danger of storm surge, high winds, and waves has passed.

Abstract: In a floating structure, a ballast weight is suspended at a truss angle from an upper section of the floating structure using at least three tension members. This ballast weight is suspended at such a depth and in such a manner that the center of gravity of the floating structure is below the center of buoyancy of the floating structure. The suspension of the ballast weight allows the floating structure to maintain greater stability and achieve desirable motions in response to environmental conditions such as wind and waves.

Abstract: The invention relates to a semi-submersible vessel designed to operate in harsh environment. The vessel has a twin-hull pontoon structure that supports four corner caissons extending vertically from the pontoons above an operational draft of the vessel. A pair of slender parallel horizontal braces connects each pair of opposing caissons, the braces extending in a general plane perpendicular to longitudinal axes of the pontoons. One of the pair of braces is secured between the forward columns and another of the pair of braces is secured between the aft columns. The braces reduce spreading and torque-induced forces acting on the columns, while not substantially increasing water plane area of the vessel. Each brace has an internal “redundancy” feature, being divided into two independent watertight compartments to continue providing buoyancy to the structure if one of the compartments is breached.

Abstract: An apparatus and method for installing a deck on an offshore substructure is provided. The apparatus comprises a deck supported by lifting mechanisms that are in turn attached to pontoons. The apparatus floats on the water with the lifting mechanisms compressed until transported to an offshore substructure having an upper end located above the water surface. The lifting mechanisms are then extended and the apparatus moved on the surface of the water to position the deck over the substructure. The deck is then lowered onto the substructure and the pontoons are lifted out of the water.

Abstract: An exemplary floatable vessel is described having an upper tower section with a reduced diameter or width and an affixed lower base section having an enlarged diameter or width. The lower section contains weighted ballast distributed upon its lower floor. The lower section also includes flotation tanks which can be filled with air to raise the vessel in the water such that portions of the lower section are raised above the water line. Alternatively, the flotation tanks can be flooded to dispose the lower section and a portion of the upper section below the water level. The upper tower section of the vessel supports a deck structure upon which rig components can be constructed or secured. The tower section includes flotation tanks as well. In preferred embodiments, these tanks are variable tanks that can be partially filled with air and partially flooded with water.

Abstract: An oil drilling barge stabilization system and method provide that an array of substantially vertically-oriented piles is formed in the sea bed to a depth beneath the sea bed that finds solid support. A barge is towed into position over the array of piles, and the barge is partially flooded with ballast to lower it in the water so that a set of cylindrical tubes is positioned to surround top ends of at least some of the piles. Air is then forced into the tubes to force the water out the bottom of the tubes, to create a dry environment for workers. Workers weld the tubes to the piles. The air pressure is removed from the interior of the tubes so that water may again flood the bottom of the tubes. The joints between the tubes and piles secure the barge to the array of piles, even in the face of varying tides, currents, and ice flow conditions. The barge may be used to support oil rigs and a variety of other support facilities.

Abstract: A buoyancy assembly suitable for supporting, either alone or in combination, a load deck or other marine body, said assembly comprising: i) a first portion adapted to be connected to or form an integral part of the marine body, said portion incorporating a piston; ii) a second portion adapted to envelope the piston and thus create a variable volume chamber, the first and second portions being moveable with respect to each other; iii) sealing means adapted to form a fluid tight seal between the piston and the second portion; iv) a constant pressure source adapted to maintain a constant pressure within the variable volume chamber; v) tether means adapted to tether the second portion to the sea bed; wherein the buoyance assembly is adapted such that displacement of the marine body from its hydrostatic equilibrium position results in the generation of a restoring force, upwards or downwards, tending to restore equilibrium.

Abstract: A deep draft semi-submersible offshore structure suitable for conducting mineral exploration and production operations in deep waters of the oceans. The structure uses three or more caissons or columns equidistantly spaced from adjacent columns. The weight distribution and provision of liquid or solid permanent balance in the lower ends of each column make the structure stable without reliance upon water line displacement or tendons, as compared to conventional vessels. The center of gravity of the structure is maintained below its center of buoyancy, thus imparting an inherent absolute stability to the structure. The columns are retained in spaced relationship to each other by a plurality of horizontal braces or a combination of horizontal braces and diagonal braces. The major part of the structure is positioned below the water surface at sufficient depth to minimize the reaction to surface changes, thereby greatly reducing heave and angular response to surface wave action.

Abstract: A method and apparatus for an improved drilling rig of jack-up type is provided. The drilling rig has a frame part comprising a working deck and an essentially plane-shaped bottom. Three feet are provided in the frame and are operated by lifting devices. The feet support the frame on the sea bottom during a drilling operation and are lifted off the sea bottom when the drilling rig is transported. A drilling unit is movably arranged on the frame part and can be moved substantially outside the frame during a drilling operation. A residence unit is also provided on the frame and is movable in a direction opposite that of the drilling unit at least during the drilling operation. An air bed is blown into an airspace which is arranged below the frame part of the drilling rig. The air bed is dischargeable for transportation of the drilling rig.

Abstract: Improvements to a ring pontoon semisubmersible vessel. The centerlines of the corner columns ar displaced with respect to the axial centerlines of the forward and aft portions of the ring pontoon. Additionally, the centerlines of the corner columns may be displaced with respect to the axial centerlines of the starboard and port portions of the ring pontoon. The superstructure deck may be supported by radial braces extending from the ring pontoon to locations on the superstructure deck which are inward of the ring pontoon.

Abstract: A buoyancy assembly suitable for supporting, either alone or in combination, a load deck or other marine body, said assembly comprising a first portion adapted to be connected to the marine body and a second portion (1) adapted, in combination with the first portion, to contain a variable volume (4) of compressed gas, characterised in that the first portion is moveable, in use, relative to the second portion (1), said movement tending to maintain hydrostatic equilibrium such that when disturbed from its position of equilibrium the marine body will develop a restoring force, upwards or downwards.

Abstract: A tension leg caisson is disclosed for supporting surface facilities on a deck for conducting hydrocarbon recovery operations in deepwater location applications. The tension leg caisson has an elongated, buoyant central vertical column or caisson with a plurality of outrigger pontoons. A plurality of tendons are connected on one end to the outrigger pontoons at a location which is spaced apart from the vertical. The other end is anchored to the ocean floor. Another aspect of the invention is a method of improving the dynamic response of a buoyant central caisson type platform.

Abstract: Apparatus for locating a floatable platform, comprises upstanding support members arranged to be adjacent to an article submerged in a liquid, and extendible members depending from the platform. The extendible members on initial extension are arranged to locate on the support members, and further extension of the extendible members raises the platform from a buoyant to a partially-buoyant state. A laser device on the platform is arranged to scan a stationary coded target so as to determine the position of the platform.