Abstract: A submersible/semi-submersible dry lift carrier for transporting a jack-up drilling rig in a body of water includes a hull, a deck, at least one stability column, and a plurality of ballast compartments capable of being flooded and emptied for lowering and raising the carrier. The carrier further includes at least three leg wells, each well sized and spaced for receiving a leg from a jack-up drilling rig, and each of said wells comprising a vertical passageway having a first end opening through the deck and a second end opening through the bottom of the hull. The carrier further includes at least three pinning receptacles, each receptacle sized and spaced for receiving a spud can and leg from a jack-up drilling rig. In operation, the dry lift carrier is partially submerged by flooding the ballast compartments and then positioned beneath the floating jack-up rig. The carrier is de-ballasted thereby lifting the jack-up rig from a floating "wet" mode to a "dry" mode on the deck of the carrier.

Abstract: An elevating unit for a jack-up rig provides a pinion gear that rotates upon a support frame for engaging a toothed rack of each leg of the jack-up rig. Each pinion gear is mounted on a gear shaft that extends in opposite directions from a plane of rotation of the gear. First and second roller bearings are mounted upon the frame for supporting the pinion gear at first and second pinion gear shaft end portions. On one shaft end portion, a planetary gear box engages the shaft, the gear box being motor driven. On the opposite side of the shaft end portion a brake hub is attached to the pinion gear shaft and carries a brake drum. A brake band extends about the drum, the band being operable to frictionally engage the brake drum to retard movement of the drum, hub and pinion gear shaft relative to the frame.

Abstract: A high speed ship is disclosed which includes a hull structure having a bow portion and a stern portion with the hull being normally supported above the surface of the water when in operation. A forward strut depend from the bow portion of the hull structure and is subtended by a first transverse displacement foil. A set of midship dual struts depend from the hull structure aft of the forward strut; the aft dual struts are subtended by a second transverse displacement foil extending laterally between and connected to each of said struts. The second transverse displacement foil has a beam equal to or greater than its length and provides 70% or more of the major buoyancy for the ship during operation to maintain the hull above the surface of the water during operation. The forward foil provides less than 30% of the buoyancy of the vessel and has a beam less than the spacing between the aft struts.

Abstract: A floating platform comprising in combination a semisubmersible vessel (40) having two or more pontoons, buoyant columns upstanding from those pontoons and a deck supported on the columns (the semisubmersible vessel being a kind known per se); and a raft (41) comprising a hull portion and two or more buoyant caissons arranged so that the raft is capable of floating in a stable configuration with the hull portion of the raft submerged to such a depth that the semi submersible vessel (40) can float over the hull portion and with only the buoyant caissons piercing the water surface, in which the pontoons of the semisubmersible vessel (40) are secured to upper surfaces of the hull of the raft (41).

Abstract: Modular floating structures suitable for supporting offshore oil drilling and production platforms may be fabricated utilizing a Y-shaped joint interconnecting plural legs of a space frame. The space frame may be made up of plural frame members where each corner of the frame includes a Y-shaped joint. Stable offshore floating structures for drilling and production platforms may utilize the integral space frames in a truncated dodecahedral, inverted pyramid or tetrahedral configuration. The Y-shaped joint may be formed of three channel members each having opposed legs which may be secured to the opposed legs of the other channel members in a back-to-back or face-to-face configuration to form the Y-shaped joint. The channel members may be fabricated of flat plate folded and cut along predetermined lines to form the channel members. If the channel members are secured to each other face-to-face, they may form hollow flotation chambers suitable for use with the floating structures.

Abstract: Semi-submersible platform comprised particularly of semi-immersed columns and totally immersed elongate elements or pontoons (4) having a substantially horizontal axis, at least some of them having porous walls, the porosity being obtained by a large number of small holes in said walls. The porosity degree, in other words the ratio between the total surface of the holes and the total surface of the walls is preferably at the most equal to 30%.

Abstract: A tension leg platform system includes a relatively small platform (12, FIG. 3 ) and relatively low capacity tendons (16), despite providing sufficient tension to risers (34) that carry hydrocarbons from seafloor wells to the platform. With the platform floating at the sea surface and held in position by the tendons, seafloor wells can be connected through risers to a side of the platform, with the tension of each riser compensated by adding buoyancy to the corresponding side of the platform, as by using pressured air (at 100) to blow water out of a platform compartment (94).

Abstract: A method and apparatus for an OTEC platform are disclosed. The platform provides the high stability needed for OTEC applications. The platform includes a centrally located cold water pipe. The cold water pipe is suspended from a center column that is open at both the top and the bottom. The platform further includes multiple columns surrounding the cold water pipe. The columns extend from above the sea surface to deep depths below the sea surface. The OTEC platform also includes multiple power modules. The power modules are submersed below the sea surface and are utilized to provide stability to the platform. Moreover, the power modules are dispersed around the columns to provide additional stability. Various embodiments of the arrangement of the columns are also disclosed. The columns may be proximate the center column or may be placed an extended distance from the center column.

Abstract: A small water plane area vessel is disclosed which includes at least one normally submerged hull, a superstructure normally located above the level of the water during operation of the vessel and at least one strut connected between the superstructure and the submerged hull. The vessel has a design draft water line located between the normally submerged hull and the superstructure and at lease one buoyancy pod on the strut located above the design draft water line and below the superstructure. The strut has a water plane area at the water plane of the pod which is larger than the water plane areas thereof above and below the pod.

Abstract: A non-rotatable fairing for suppression of vortex-induced vibration of a marine tubular is provided, the tubular having a circular cross section and a centerline that is normal to the circular cross section, the fairing comprising:shaped sides that extend essentially tangentially from the outer surface of the tubular toward a point that is about a distance equal to the outside diameter of the tubular or less from the centerline of the tubular; anda means to fix the fairing to the tubular so that the fairing cannot rotate around the tubular, wherein the maximum length of the cross section of the combined fairing and tubular is between about 1.25 and about 1.5 times the outside diameter of the tubular.

Abstract: A method for building and assembling an offshore platform whose normal draft exceeds the depth of waterways between the building site and use location of the platform. The hull and deck of the platform are built separately in a shallow graving dock. The deck is then elevated, the graving dock partially flooded and the hull floated into position and mated to the deck. A modified form of the invention is the building of the hull and deck as a single structure and use of the barge to support a portion of the weight of the platform. The graving dock is then flooded to maximum depth, a barge is floated under the deck and ballasted down to a select draft. The barge is attached to the deck and then deballasted to partially support the platform structure and reduce its overall draft.

Abstract: A tension leg platform which can be a heave restrained platform and drilling system (HRP/DS) is taken to the heave restrained mode by rapidly sluicing ballast by gravitational force from a reservoir above the water line.

Abstract: A device for the integrated suspension and manipulation of legs supporting a jack-up oil platform having a hull mounted displaceably on the legs by drive mechanisms having at least two opposite units each formed by a motor associated with at least one speed reducer driving an output gear co-operating with opposite racks mounted on at least part of the length of the legs. The opposite units of each drive mechanism are mounted in articulated fashion on a structure supporting them via at least one bearing allowing a determined angular deflection of the units and of each corresponding output gear. The motor and the speed reducer of each opposite unit are housed in a member for absorbing energy, used, in particular, at the moment of the placement of the legs on the sea bed and for limiting the stresses due to the flexure of the legs under the action of swells and the wind.

Abstract: A composite tubular tendon containing axial fibers and helical fibers laid on an inner liner is connected to a circular opening in a hollow termination body having an opposite curved end which is connected with an elongated member smaller than the termination body. The inner liner of the composite tubular tendon abuts the circular opening in the hollow termination body and fibers of the composite tubular tendon are extended over and cover the termination body from the point of abutment to the elongated member which is smaller than the termination body. The axial fibers of the composite tubular tendon are continued over the termination body in a geodesic path and the helical fibers are continued over the termination body in a helical path.

Abstract: A Kevlar.RTM. rope termination in which the rope is passed through an opening in a tension leg termination, is divided and laid over a rigid pin, being sealed around the pin with a resin. A flexible bearing member is located between the rope covered pin and a rigid support member contiguous with the inside of the termination, adjacent to the opening so that the rope covered pin can easily rotate within the bearing member without kinking the rope.

Abstract: A semi-submersible platform supported on columns with pontoons extending between and outboard of the columns. Damper plates are provided by flat surfaces either on top of the outboard section of the pontoons or by plates positioned on the columns above the pontoons to provide heave and pitch stabilization and motion phase control in relation to the wave action such that when the platform is in the drilling mode, the heave phase of the platform is approximately one hundred eighty degrees out of phase with wave action, and in the survival mode, heave action of the platform is substantially in phase with wave action, such that the platform will ride with the storm waves allowing the use of shorter columns than the current art.

Abstract: A method for converting an existing semi-submersible drilling- or accommodation rig into a floating production plant having apparatus for extracting and processing oil and/or gas, or other heavy and bulky deck load. These vessels comprise at least two submerged pontoon bodies, a work deck raised to a secure level above the surface of water having personnel accommodation areas and upright support columns between the bodies and the work deck. A module is prefabricated which contains the main part of the processing apparatus. The vessel is provided with a steel structure to carry the module near the level of the work deck. Also, the vessel is provided with a displacement increasing device, substantially corresponding to the dead weight of the module and the steel structure. Further, the water line area of the vessel is increased until the necessary deck load capacity and stability is achieved.

Abstract: A floating structure (11) with completely or partially submersible pontoons that provide the buoyancy for an offshore drilling platform, with a deck that is located on columns (13) attached to the pontoons. A separate, submerged ballast unit (15) is attached to the pontoons to help stabilize the floating structure and improve its motion in waves. The ballast unit (15) is approximately the same size in the horizontal plane as the extent of the pontoons (14) and is attached to the floating structure at each corner by at least three vertical struts (16) that extend through and below the pontoons. The struts being attached so that they can be connected or removed from a locking device on the top side of the pontoons. At the upper end of the struts (16) there is an attachment head (24) which can be connected and removed from a lifting device such as a wire (25) driven by a winch mounted on the platform.

Abstract: A stable racing catamaran with hydrofoil qualities is disclosed. The stable racing catamaran with hydrofoil qualities includes a deck, a pair of forward pylons affixed to the deck, a pair of aft pylons affixed to the deck, a pair of forward hulls affixed to the pair of forward pylons, respectively, a pair of aft hulls affixed to the pair of aft pylons, respectively, a pair of forward skags affixed to the pair of forward hulls, respectively, a pair of aft skags affixed to the pair of aft hulls, respectively, a pair of forward rudders disposed in close proximity to the pair of forward hulls, respectively, a pair of aft rudders disposed in close proximity to the pair of aft hulls, respectively, a pair of forward rudder shafts for rotatably mounting the pair of forward rudders, respectively, and a pair of aft rudder shafts for rotatably mounting the pair of aft rudders, respectively.

Abstract: A vessel is provided, adapted for operating at the surface of the ocean, useful for a combination of functions, including providing food, fiber for clothing, living space, fresh water, transportation, and domestic energy for at least one person, as well as excess energy, food, fiber and fresh water for sale. The vessel comprises at least two hulls coupled with streamlined struts, the upper hull vertically aligned with the lower, the lower hull being fully submerged and the upper hull being fully unsubmerged, and both hulls having substantially the same volume. The vessel is stabilized by a combination of passive lift and stabilization surfaces while the vessel is in motion, and laterally mounted stabilization reservoirs for use when the vessel is not moving. The vessel is controlled and stabilized against wave-generated motion by a combination of actively controllable moveable surfaces, and is propelled by a sail and a water propellor.

Abstract: A lightweight, high modulus mooring element for a tension leg platform comprises a pretensioned composite member in fixed attachment to and surrounded by a metallic tubular member in compression prestress. The hybrid composite assembly offers significant cost and weight savings over an all steel mooring system for use in deep water tension leg platform mooring.

Abstract: A column belt is between upper and lower reduced-diameter columns and is only in the vicinity of and across the water surface so that the heave resonant period is increased which is due to the effect of the shape of the column belt.

Abstract: A pontoon float has a flexible collapsible structure which may be extended by interlinking pontoon float platforms to form an elongated platform as for a dock or pier. Each pontoon float platform is supported by a rectilinear array of removable, stackable hollow floats, removably fastened to permanently affixed lid sections, forming an air tight seal. The individual floats are secured to the platform only by removable upper ends, and are otherwise free. The floats may be readily removed and stacked, reducing each pontoon platform to a planar section and a stacked, compact array of float members. The pontoon sections are reinforced by a grid of stringers, providing adequate rigidity without undue stiffness. Preferably, each pontoon sections is provided with interlocking extension plates on an end and a side and a mating pattern of interlocking holes on a second end and side so that they can be adjoined to form complex large floating structures as required.

Abstract: A floating structure to support maritime operations is constituted by a metallic platform, in the shape of an internally open square (10) floating in the ocean being moored to the bottom of the ocean by a cable system (C.sub.1, C.sub.2, C.sub.3 . . . C.sub.n) tied to a pile system (E.sub.1, E.sub.2, E.sub.3 . . . E.sub.n). It retains in its interior a portion of the sea which is communicated to the outside ocean through an opening (11) in the walls of the said metallic platform (10) in such a way that, in that confined part of the ocean, the support boats to the sea work, may be moored due to the fact the interior of the open square is calm in respect to the rough sea outside the structure (10).

Abstract: A tension leg platform for drilling and/or production, processing and transporting hydrycarbons from sub sea wells or installations, and methods for installation of such platform. The platform comprises in operational position the following: a working platform which has position above the sea level, a buoyant body (1) which is connected with the underside of the platform and has substantially position below the surface, and a number of tension legs (13) which connect the buoyant body (1) with a fundament anchored to the sea bed. The invention is characterized in that the lower parts of the tension legs (13) in per se known fashion are anchored to the fundament (14) and at their upper ends are controlled in guides (20, 21) on the outside of the buoyant body and are attached to the buoyant body (1) above or just below the water line.

Abstract: The floating structure comprises one or more catenary mooring cables for anchoring the structure to the seabed. An extensible dynamic tensioner system is provided for maintaining a predetermined dynamic tension in each mooring cable, as the structure responds to cyclic wave forces, and for increasing the natural periods of oscillation of the pitch, roll, heave, surge, sway, and yaw motions of the moored floating structure by reducing the spring stiffness of the mooring system. A motion damping system is coupled between the dynamic tensioner system and the structure for damping the linear and angular displacements of the structure relative to the tensioned cables. The damping system selectively applies frictional forces against a movable member in the tensioner system. The movable member does not move relative to the cables.

Abstract: A mobile marine drilling assembly has a horizontally disposed pontoon which floats on or is submerged below the surface of a marine environment. A first vertically disposed column is secured to the pontoon and extends upwardly therefrom. A work platform has an opening through which the column extends, and the platform overlies the pontoon and is vertically movable relative thereto along the column. A jack system is operably connected with the work platform and with the column for jacking the work platform along the column between a first position wherein the pontoon floats on the surface of the marine environment and a second position wherein the pontoon is disposed a substantial distance below the surface of the marine environment. An anchor is secured to the floor of the marine environment.

Abstract: A semi-submersible platform supported on columns with pontoons extending between and outboard of the columns. Damper plates are provided by flat surfaces either on top of the outboard section of the pontoons or by plates positioned on the columns above the pontoons to provide heave and pitch stabilization and motion phase control in relation to the wave action such that when the platform is in the drilling mode the heave phase of the platform is approximately one hundred eighty degrees out of phase with wave action and in the survival mode heave action of the platform is substantially in phase with wave action, such that the platform will ride with the storm waves allowing the use of shorter columns than the current art.

Abstract: The semisubmersible drilling vessel has two spaced, parallel, horizontal, elongated submersible hulls which support a deck and a deck mounting structure. The deck has a central opening overhanging the space between the two hulls and is surmounted by a derrick. The mounting structure includes at least two vertical columns which connect the ends of the hulls to the deck and at least two hollow columns facing and spaced from one another substantially in the center of each hull. These central hollow columns form caissons on the interior of which is provided pipe manipulation apparatus which accommodates the handling and vertical storage of pipes associated with drilling a well.

Abstract: Described herein are a system for securing and tensioning the tethers 12 of a tension leg platform 10 and a TLP installation method incorporating such a system. The tethers 12 preferably extend upward from the ocean bottom 16 to a position slightly below the bottom of the unballasted TLP hull 20. At least one tether tensioning tool 26 is situated within the hull 20 for lowering a tether extender 22 to each tether 12 and then biasing each tether-tether extender unit upward to tension the tether 12. The use of a removeable tensioning tool 26 avoids the need for a dedicated tensioning system for each tether 12. The tensioning system 28 of the present invention permits use of a simplified method for installing a TLP 10. Because the tethers 12 extend to an elevation which, at least initially, is below the draft of the TLP hull 20, the tethers 12 may be installed offshore prior to hull installation.

Abstract: A node intersection between circular columns and pontoon members at a tendon-moored semisubmersible offshore platform. The pontoon members have a box shape, defined by vertical side walls, a horizontal deck and a horizontal bottom skin, joined together into a foursided frame, via the columns. The node intersection comprises vertical bulkheads within the lower ends of the columns, forming internally intersecting continuations of the vertical sidewalls.

Abstract: A tension leg floating platform for offshore drilling has a plurality of tendons extending from the sea floor to the platform in tension. The upper connector for each tendon includes a housing with a conical shoulder located therein. A terminal segment on the upper end of each tendon extends through the housing. Dogs are carried on the shoulder of the housing, each having threads on the interior for mating threads formed on the terminal segment. A cam ring moves the dogs from an outer retracted position to an inner engaged position. The cam ring also will rotate the dogs relative to the terminal to mesh the threads of the dogs with the threads of the terminal segment.

Abstract: There is described a vessel such as a semi-submersible drilling unit having a drilling deck structure with a plurality of columns depending from the deck. Pontoons are provided at the ends of the columns and a buoyant configuration modifying sleeve-like element is mounted around the columns. The sleeves are annular in cross-section and of generally cylindrical form and terminate at their lower ends in cuffs of reducing outer diameter. This provides an inwardly tapered or curved end to the sleeve. A cable and pulley arrangement is provided for vertically moving the sleeves along the columns and for locating them on the columns close to the unit transit waterplane and at a survival waterplane position.

Abstract: A system for stabilizing floating semi-submersible platforms and compensating ship motion of monohull ships is based on a design protecting waterplane from vertical movement during wave actions. Each vertical strut of the semi-submersible platform utilizing this system consists of a vertical hollow column with its upper end connected to the platform upper structure and lower end open to the surrounding water. Inside the vertical hollow column is inserted a buoyancy vessel which is connected to the upper platform structure by its upper part and which serves as a means of forming a waterplane. During passive mode of this system operation, the roll and pitch of the floating platform (ship), due to wave induced forces, will be introduced because the vertical movement of the water level inside the vertical hollow column will be considerably less than the vertical movement of the water outside the vertical hollow column.

Abstract: The semi-submersible, deep-drafted platform includes a fully submersible lower hull, and a plurality of stabilizing columns which extend from the lower hull to an upper hull. At least one column has means adapted to reduce the water plane area within a portion of the dynamic wave zone of the column and to increase the natural heave period of the platform.

Abstract: Apparatus for attaching a floating tension leg platform to an anchoring base template on the subsea floor. The apparatus includes an external mooring porch for each tendon, the porches being mounted on the outside surfaces of the platform's columns.

Abstract: A buoyant support unit and platform employing the same which includes at least five substantially cylindrical floatable pipes having a diameter of less than about 5 meters which are arranged parallel to each other in spaced-apart relationship, wherein the edge to edge distance between adjacent pipes is from 0.25 to 2.0 times the diameter of the pipe.

Abstract: An ocean platform has a negatively buoyant pontoon suspended from the balance of the platform to increase the heave resonant period to at least 25 seconds. Tendons suspend the pontoon to a depth where dynamic wave forces do not materially act directly on it in seas of normally occurring periods of up to about 15 seconds but do in seas of periods above about 15 seconds. Columns and an upper pontoon provide buoyancy for the platform.

Abstract: A semisubmersible, stationary positioned vessel for offshore work, e.g. development of oil and gas fields and having a device for, in operational condition, increasing stability and dampen motion. The vessel has at least one submerged body as well as a number of legs supported thereby for carrying a work deck at a secure level above the operational water line. The waterline area of the vessel is increased at at least some of the legs. The vessel also comprises a device for rigidly connecting at least one horizontal plate below the submerged body. The area of the plate and the vertical distance from the body determining the volume of the added mass of water vacillating well below the water line following the elastic movements of the vessel.

Abstract: An offshore complex comprises a substantially ring-shaped structure (1) which is intended to rest at its lower end on the sea bottom with the upper end of the complex located above the surface of the water. The structure incorporates water-filled ballast chambers to an extent such that the structure can be caused to float by pumping water from the chambers. The upper ring-shaped end of the structure (1) supports an aircraft take-off and landing strip (3), which rises helically along a part of the perimeter of the ring-shaped structure (1). The area of water (5) enclosed by the ring-shaped structure (1) can be used as a harbor, into which sea-going vessels can enter through an opening (6) provided in the wall of the ring-shaped structure (1) at its upper end. An advantage is gained when the ring-shaped structure (1) is made substantially of concrete, and the structure may incorporate a large number of interconnected, upstanding cylindrical concrete bodies (2).

Abstract: A single leg tension leg platform is a semi-submersible structure moored at a deep water site by hybrid mooring consisting of a single tension leg or cluster of tendons attached to a central column and, optionally, a conventional spread mooring system. The central column is surrounded by peripheral stability buoyant columns symmetrically arranged and typically in number from about 3 to 8. All the vertical tendons are located in a tight cluster at the center of the platform. This means that the tendons no longer effectively restrain pitch/roll or yaw motion. The role of the tendon cluster is essentially the direct, stiff elastic restraint of heave and compliant restraint of horizontal offset. Pitch/roll response is controlled primarily by careful distribution of peripheral buoyancy and detuning.

Abstract: A method for securely mooring a floating tension leg platform to an anchoring base template. The method involves swinging an end of a neutrally bouyant, one piece tendon which has an enlarged connector downwardly into position adjacent an anchoring receptacle, pulling the enlarged connector through a side-entry opening in the receptacle, lifting the tendon to seat the enlarged connector in a load ring of the receptacle, adjusting the effective length of the tendon to place it in tension and repeating these steps for each of the mooring tendons.

Abstract: The construction of a joint portion between a column and a bracing in a semi-submerged marine structure which consists of a platform, a column, a submerged body and a bracing to which the column is joined. The bracing consists of a portion having a small cross-sectional area, a tapering portion the cross-sectional area of which increases gradually toward a free end of the bracing, and a free end portion having a larger cross-sectional area. In a joint portion between the column and bracing, the portion of the bracing which has a larger cross-sectional area is in the interior of the column. If the tapering portion of the bracing is welded to the outer plate of the column, the stress in the joint portion can be dispersed into the outer plate and the same portion of the bracing.

Abstract: A composite structure of lightweight is used as a tensioned tether element for mooring of offshore facilities. The composite structure comprises bonded inner and outer tubular members having an annular space therebetween. Aramid or other fibrous, high strength material is bonded to the inner surface of the outer tubular member to provide additional tensile strength thereto. The remainder of the annulus between the inner and outer tubing may be filled with a foam material such as polyurethane foam. The composite structure can be made so as to be of neutral, positive or negative buoyancy. The composite allows greater tensile loadings than steel materials by themselves at greatly reduced weight.

Abstract: A semisubmersible water surface navigation ship with even draft comprising at least two lower hulls, which can be submerged under water to reduce resistance and have a shape affording low friction resistance, and which are equipped with lifting and diving planes, at the bow and stern parts, and an upper hull above the water surface being connected to the lower hulls by way of water breakers. In order to keep an even draft or trim during navigation, the lifting/diving force capacity of the lifting and diving planes is designed to be greater than the buoyancy change of the water breakers owing to loads such as waves and wind. Steering rudders, propellers and water ballast tanks are installed in order to cause the ship to navigate or lie to under any one of a shallow draft state, a semisubmerged state and a deep submerged state. The upper hull is provided with superstructures with sufficient reserve buoyancy for maintaining the stability of the ship under the deep submerged state.

Abstract: A vessel (10) is provided for installing or removing a module (16) on or from a support structure (30) erected in a body of water. The vessel is able to suspend the module over the support structure by cranes (14, 15), enabling installation or removal of the module to be accomplished while the module is being suspended.

Abstract: An offshore multiple tendon compliant buoyant tower construction for well operations in which a plurality of tendons are arranged in parallel, vertical, closely spaced assembled relation and have top and bottom ends, the bottom ends being connected to a base module at the sea floor, the top ends being connected to a buoyant structure which includes conductor tubes therein for each of said tendons and which serves to restrict bending of the top portion of said tendons to provide a relatively stiff, unbending, noncompliant tendon top portion which extends below the sea surface, the portion of the assembled tendons below the stiff to portion being relatively compliant; the buoyant structure imparting tension to said plurality of assembled tendons at the top ends thereof whereby the tensioned tendons provide lowering of the effective center of gravity of the tower construction below the center of buoyancy and whereby cyclic stresses in the assembled tendons resulting from roll or bending of the tower construction

Abstract: A relatively inexpensive, mobile type of offshore structure has truss-type legs constructed of smoothly cylindrical chords and braces whereby the portions of the legs exposed to wave and wind forces, when the unit is in operation, are practically free of the usual turbulence-producing protuberances and recesses. The legs are powered to move vertically in relatively large guides which are pivoted to the support platform. Wedges may be operated to tilt and/or hold the legs in desired slant position as the legs approach bottom. Also, as the legs approach bottom, they are released from the platform and their rate of descent is sharply increased so that all legs will impact the bottom at substantially the same time. The leg slant holding wedges are released as the legs strike bottom so that the platform is free to rock, rise, and fall independently of the legs, under wave action.

Abstract: Emergency escape platform apparatus including an escape platform disposed in spaced apart relation from a drilling platform and joined to the drilling platform by escape bridge apparatus. Two flexible base cables are connected in tension horizontally adjacent between the escape platform and the drilling platform. Two flexible hand cables are connected in tension horizontally adjacent to one another and vertically adjacent respectively above the base cables. A plurality of vertical spacer bars are vertically connected between a respective base cable and a respective hand cable at selected intervals. Cable tensioning apparatus connects the base cables and the hand cables for maintaining the cables under selected tension while permitting relative movement between the escape platform and the drilling platform. Light weight walkway structure is horizontally disposed between and connects the base cables to provide a walkway for individuals between the drilling platform and the escape platform.

Abstract: A floating semisubmersible off-shore drilling platform or the like comprises an upper working level portion and a lower pontoon portion. When the platform is transported from one place to another, it floats on the pontoon portion, but when it is working as a stationary unit in open water, it is submerged deeper, so that the pontoon portion is at a considerable distance below the water surface and the working level portion is at a considerable distance above the water surface. The platform is adapted to withstand ice pressure from ice occurring in the ambient water by giving the pontoon portion of the platform a form particularly advantageous in ice conditions. When ice occurs, the platform is lifted to such a position, that its pontoon portion comes to float at the water surface level.