Abstract: A semi-submersible floating structure includes a horizontal platform with a symmetrical arrangement of buoyant bodies extending vertically downwardly from the platform. The buoyant bodies consist of a tubular column secured by a bending-resistant connection to the platform with a closed container secured to and extending downwardly from the lower end of the tubular column. The horizontal cross-sectional area of the closed container is for most of its vertical height greater than the transverse cross-sectional area of the tubular column. At least the lower portion of the closed container has a curvilinear surface. An annular wall extends around and is spaced radially outwardly from each of the closed containers and the wall, in combination with the enclosed container, forms an annular chamber therebetween open at the bottom and closed at the top. The platform and the buoyant bodies are formed of reinforced concrete or prestressed concrete.

Abstract: A semi-submersible pipelaying watercraft is disclosed, which is particularly suitable for operating under particularly hostile marine environments, said watercraft comprising a composite ramp of special construction for launching the pipe to be laid, a system for determining the craft's position and a control system, governed by electronic computers for automatically positioning the craft.An internal inclinable ramp is coactively combined with an external ramp and the internal ramp is equipped with a locking system and with a displacing system, hydraulic controls being provided for moving both the internal and external ramps. The electronic computers are two and one of them makes the calculations for determining the design parameters, whereas the other computer receives the actual data provided by the several sensors mounted aboard and processes them.

Abstract: The vessel comprises a pair of laterally spaced elongated hulls having a pair of upstanding columns at opposite ends thereof supporting a working platform and a drilling mast in spaced relation above the hulls. The hulls buoyantly support the vessel in a low draft in-transit floating condition with the hulls having freeboard. The hulls have ballast compartments to submerge the hulls and portions of stabilizing columns such that the waterline lies intermediate the height of the columns with the platform and drilling mast elevated above the waterline. The columns stabilize the vessel in the high draft condition and the number, cross-sectional area and configuration of the columns, the weight distribution of the vessel and the geometry of the submerged hulls and portions of the columns are such that the vessel obtains motion minimizing characteristics in the high draft condition.

Abstract: A vessel comprising a pair of laterally spaced elongated buoyancy hulls and vertically mounted thereon a plurality of hollow columns, distributed around the outer circumferential area of the vessel and supporting a work platform above the water level when the hulls are submerged, the hulls containing water ballast compartments. The platform supports one or more heavy duty cranes, adapted for outboard handling of loads. At the lower end of the columns, air chambers are provided in open connection with the surrounding water at their bottom ends. At their upper ends these chambers have air valves for discharging air from and supplying air to the chambers selectively controlled by directions from a computer which is added to the crane operating device.

Abstract: A semi-submersible pipelaying vessel has an improved configuration and structure for laying pipe wherein the pipeline path extends along a port or starboard side of the vessel. The pipeline path passes through the upper deck member of the vessel and then through a supporting column member of the vessel. A cantilevered overhang or deck member extension is not required. The pipe is supported along the pipeline path by a plurality of pipeline supports for providing the pipe at the stern of the vessel with the correct inclination with respect to the water surface. The slotted column advantageously provides protection for the pipeline below the deck level with respect to lateral wave action forces and added vessel stability and/or work area efficiency.

Abstract: A stabilizing system for a crane vessel of the twin hull semi-submersible type having a working platform supported above sea level by columns on submersible hulls. Water ballast compartments above sea level on the corner columns are discharged selectively in order to stabilize the vessel during handling of heavy outboard loads by cranes. The water is discharged through controlled valves of special construction. This control is regulated in dependence of measured values of the moment of force applied on the vessel by the crane load, and effects the operation with the help of a computer.Lower water ballast compartments in the columns have an additional "passive" function and the water can be discharged therefrom by pressurized air or by pumping it into the upper ballast compartments.

Abstract: Control forces for stabilizing semi-submersible platforms are provided outboard the platform columns, at a point approximately where the free surface of the water intersects the columns, without altering the internal arrangements or structure of the platform and employing equipment which develops pressures needed to impose control forces only. In a similar manner, control forces for stabilizing pitch and roll motions in ships and to effectively damp the oscillatory motion of the water level in a "moon pool" are provided.

Abstract: A marine vessel is provided which comprises a platform member, two parallel hulls disposed below the platform and adapted to be below the water surface when the ship is in operation, each of the hulls consists of an after section, a forward section having a smaller cross-sectional area than the after section and a central section having a cross-sectional area substantially smaller than that of the forward section and supported only by the junctions with the forward and after sections. Both forward sections and both after sections are joined to the platform member by strut-like members which are tapered so that their waterplane areas increase rapidly between the waterline and their junctions with the platform member.

Abstract: Semi-submersible vessels are described comprising a sealed chamber with curved surfaces, a partially immersable support structure secured to the chamber and a platform or deck carried by the support structure. Preferably the sealed chamber comprises a plurality of toroidal storage reservoirs and ballast tanks. The lower portion of the vessel formed by the closed chamber opens at its upper portion toward the support structure and at its lower portion through an opening for communication with the liquid of the environment. The vessel additionally comprises a plurality of openings in the proximity of the larger perimeter of the chamber. According to another embodiment, the concavity of the chamber is directed downwardly.

Abstract: A tension leg buoyancy structure for use in seas exposed to wave action including a buoyancy section, an anchor section which rests on the sea bed, and a plurality of parallel tethers connecting the buoyancy section with said anchor section to permit the buoyancy section to move relative to the anchor section, in which the natural periods of oscillation follow specified equations such that the value of the parameters is so selected that the natural period of the buoyancy section for linear oscillation in the direction of wave travel, the natural period of the buoyancy section for linear oscillation in a horizontal direction perpendicular to the direction of wave travel, and the natural period of the buoyancy section for rotational oscillation about a vertical axis of said buoyancy section structure are greater than 50 seconds.

Abstract: A floating island for the extraction of gas from the sea having a plurality of buoyancy units positioned on a base plate with columns extending upward therefrom, a height approximately the wave height expected. A platform containing gas liquefaction apparatus is positioned on the top of the columns. The buoyancy units are selected so that when the island is free floating, the columns project more than half way from the water.

Abstract: A semi-submersible floating apparatus for operating at sea and a method of assembling the same are disclosed. The apparatus comprises two or more submerged or bottom hulls supporting, by pillars, one or more working platforms or top hulls all of which are elongate floating bodies adapted to be individually constructed. The top hull is arranged transversely of the bottom hulls and is affixed by lateral connections adjacent the tops of the pillars. In assembling the apparatus, the bottom hulls are interconnected and fitted with the pillars and then ballasted until the bottom hulls are submerged. The top hull is floated until centered transversely of the bottom hulls and raised to a position for the lateral connection thereof. Alternately, the top hull is connected to the pillars and the bottom hulls are deballasted to raise the top hull above the level of the sea.

Abstract: A floating semi-submersible platform is heave stabilized by velocity damping of platform motion. Vertical velocity of the platform is sensed and a force is applied to the platform as a function of and in opposition to the sensed heave velocity. The system may be passive, as by provision of velocity damping in tethering cables. It may be actively hydrostatic by employing variable ballast tanks and water pumps or air pressure for displacement of water, or it may be actively hydrodynamic by employing propellers or rotor blades for thrust generation. By applying a heave opposing force that is proportional to heave velocity, the platform response to waves at the platform resonant period is greatly reduced with exertion of relatively small magnitude opposing forces, whereby the platform may be designed with a considerably smaller resonant period for a given set of expected conditions.

Abstract: The derrick barge comprises a pair of laterally spaced elongated hulls having a plurality of upstanding columns spaced therealong supporting a working platform and a heavy duty derrick or crane in spaced relation above the hulls. The hulls bouyantly support the vessel including its deck load in the floating condition with the hulls having freeboard. The hulls have ballast compartments to submerge the hulls and portions of the stabilizing columns to a distance of approximately one-half the effective height of the stabilizing columns to maintain the vessel in a semisubmerged floating condition with the platform and derrick elevated above the waterline. However, the vessel also may be ballasted or deballasted to submerge or emerge to a greater or lesser extent from the semisubmerged condition such that the distance between the mean water surface and either the underside of the deck or top side of the hull is not less than 0.75 of the mean wave height.

Abstract: A self-propelled drilling tender has mounted therewith a drilling rig and a jack-up platform adapted to be mounted on the drilling tender or ship for transportation from one drilling site to another site. Thereafter drilling operations occur with the drilling on the ship thus enabling the ship to operate as a drilling ship or the platform legs can be lowered to jack the platform off the ship to thereby enable the platform to operate independently as a drilling platform. Further, if desired, the rig can be disassembled or lifted from the drilling platform and moved to land operations adjacent or in the vicinity of the drilling platform and ship to thereby enable land drilling operations to occur.

Abstract: This invention relates to a vertically moored platform which is a floating structure anchored only by essentially parallel and vertical elongated members such as riser pipes under tension. Up to 32 or more such riser pipes are connected between the floating structure and anchor means on the sea floor. Special riser pipe/jacket vertical bearing assembly is provided to place the riser pipes under proper tension and to transmit force from the riser pipes to the floating structure.

Abstract: Handling and racking of riser pipes in a drilling derrick on a platform by means of manipulators. The pipes are racked vertically on a set back platform and are displaced to and from a position above the rotary table by manipulators.

Abstract: Semi-submersible offshore drilling platforms are stabilized to reduce heave at wave periods which are shorter than those at which heave resonance occurs. Platform structures include supporting columns and pontoons. The pontoons extend outboard of the columns and have non-uniform cross sections. In addition, the pontoons may be shifted outwardly from the column center-lines. Reduced heave response to head-on, stern-on and beam waves is achieved.

Abstract: The vessel comprises a pair of laterally spaced elongated hulls having a plurality of upstanding columns spaced therealong supporting a working platform in spaced relation above the hulls a distance slightly greater than the maximum anticipated wave height. The hulls buoyantly support the vessel in a low draft floating condition with the hulls having free-board. The hulls have ballast compartments to submerge the hulls and portions of the stabilizing columns to a distance of approximately half the effective height of the stabilizing columns which is slightly greater than maximum anticipated wave height, to maintain the vessel in a high draft floating condition with the platform elevated above the waterline. The columns stabilize the vessel in the high draft condition about roll and pitch axes. The working platform mounts either a drilling rig or a heavy duty crane or like operational equipment along the centerline of the vessel.

Abstract: This invention relates to the installation of a Vertically Moored Platform over a selected well site. The platform or structure is supported on a buoyant gravity base and floated to a position over the subsea well site. The gravity base is then ballasted to effect tilting in a controlled manner. Ballasting is continued to bring the gravity base and platform back to a vertical position. Then the gravity base is lowered from engagement with the floating structure with cables to the sea floor while maintaining the floating structure in a positive buoyancy state. In the preferred embodiment a large-diameter drive pipe is inserted through each receiving passage in the gravity base and into the soil or rock beneath the gravity base where it is anchored. A conductor is then inserted through the drive pipe and anchored or cemented to the soil or rock beneath the drive pipe. A riser pipe is then inserted into the drive pipe and secured to the conductor.

Abstract: An elongated deck section having two rows of legs with several legs per row is fabricated with the legs hingedly mounted on footings adapted to receive fluid bearings and is transported from the fabricating yard to a dock head over a smooth concrete slab of minimal slope and thence longitudinally via fluid bearing adapted gang planks and tracks onto and along a barge disposed with its stern adjacent the dock head and grounded thereat, the platform being transported by placing fluid bearings under the footings which allow the section to be moved sideways, lengthways, or rotated or turned, as desired, the deck's horizontal truss stresses and the fluid bearing loads being controlled by actuating fluid elevators between each leg and the fluid bearing thereunder, the barge being initially ballasted so that change of ballast during loading is unnecessary to maintain minimal slope of the barge, the section then being anchored to the barge and the barge reballasted to float its stern and trim the barge preparatory to

Abstract: An improved leg construction is disclosed for jackup barges. The barge leg is typically of triangular construction. The members of a leg including the three verticals extending along the leg are preferably constructed of tubular members. The vertical tubular members include on the inside a rack formed of teeth to engage an elevating gear drive unit. Adjacent to the teeth, an undercut on both sides of the slot in the exterior of the tubular member is formed, locking the guide mechanism to the tubular member. This construction measurably improves the profile of the jackup leg to impinging wave action from any direction, thereby reducing the resistance of the leg to water and permitting a reduction in the leg weight and hull size.

Abstract: A double-ended, flat-bottomed hull, having a length to beam ratio of approximately 2 to 1+, with sides tapering from amidships to the pointed ends respectively. Two octagonal (in cross-section) end columns and two larger rectangular beam columns are equally spaced around the perimeter of the hull for supporting a work deck thereabove, for providing columnar storage rather than work deck storage and a lower center of gravity, and for eliminating external trussing. The configuration of the hull substantially increases its natural heaving period, and, coupled with an added-mass factor increased by chamfering the hull perimeter between columns and breakwaters mounted on an end and a beam, extend the range of wave height and period range of seas in which the barge can operate and avoid resonance and substantial beam wave effect.

Abstract: Improved method and apparatus for assembling and completing the fabrication of a multilegged structure of extended length at an offshore site wherein separate multilegged structural modules are selectively floated, disposed end-to-end, and aligned relative to each other at the offshore site such that the ends of aligned legs of the individual sections can be drawn and clamped together and then welded while in a clamped condition whereby the several welded-together sections can form an elongated unitary structure. .Iadd.

Abstract: The vessel comprises a pair of laterally spaced elongated hulls having a plurality of upstanding columns spaced along outboard portions of the hulls. In the preferred form, a central column supports a working platform in spaced relation above the hulls. The hulls buoyantly support the vessel in a low draft condition with the hulls having freeboard. The hulls and outboard columns have ballast compartments for ballasting and deballasting the vessel to respectively submerge the hulls, outboard columns, and a portion of the central column to provide a high draft condition with the mean waterline located intermediate the height of the central column and between the platform and the upper ends of the outboard columns, and return the vessel to a low draft condition. The outboard columns provide stability to the vessel during the initial portion of its transition from the low draft condition to the high draft condition and in the final portion of its transition from the high to the low draft condition.

Abstract: This invention relates to a structure floating on a body of water. Three or more spar buoy-type floats support the structure above the water. The structure is connected to anchors in the floor of the body of water by .[.elongated members such as.]. large diameter pipe .Iadd.for example.Iaddend.. There are no other anchoring connections in the system. Each spar buoy has a unique structure so that vertical forces and overturning moments on the floating structure are minimized. .[.The spar buoys have a buoyancy means having a volume of two parts..]. g The buoy of each spar buoy has a volume of two parts. The first part can be defined as resulting from a straight, vertical, prismatic shape which runs the entire vertical length of the .[.buoyancy means..]. .Iadd.buoy.Iaddend.. The volume of this prismatic portion comprises between about 40 and 80 percent of the total displacement. The .[.buoyancy means have a second or.]. .Iadd.second part has an .Iaddend.