Abstract: A semi-submersible vessel comprises pontoons having a generally five-sided transverse cross section. In the case of a 4-sided semi-submersible, the columns may be arranged in a generally rectangular form with a column at each corner of the rectangular form, each column having with four sides disposed at a right angle to at least one adjacent side and a fifth side on the exterior of the generally rectangular form disposed at 45 degrees to each adjacent side.

Abstract: A design and construction method reduces the amount of structural material (e.g., steel) required when applying the corrosion allowance to the design of floating offshore structures. The (hull) structural elements involved are typically flat or curved panels where at least one side is wet, e.g.; inside a ballast tank or exposed to seawater. The method minimizes the area to which the largest corrosion allowance is applied. One principle of this method is to have a maximum of one wet side for each hull watertight plating element. The stiffening of this hull structural element is applied to the dry side, i.e., the side that requires the lesser amount of corrosion allowance. Practice of the method typically results in a hull design wherein ballast tanks do not share a common structural element with either another ballast tank or the hull external shell.

Abstract: A floating, offshore drilling and/or production platform such as a tension leg platform, semi-submersible, spar or the like is equipped with a ballast tank system that comprises the traditional tank and a shaft that runs typically vertically from top-of-hull level to the top of the tank. This shaft is large enough to allow the ballast pipe, sounding lines, instrumentation piping, etc. to be installed within it. In certain embodiments, the shaft itself functions as a vent line.

Abstract: A hawser system between a tension leg platform (TLP) and another vessel employs two lines, oriented in a V-shape, to restrict the vertical motion of a hawser near the bow of the other vessel which may be a semi-submersible tender assisted drilling vessel (TAD). Drilling operations may be performed from the TLP while the semi-submersible provides the supporting services for the drilling operation, e.g. drilling fluid and drill pipe storage. The restricted vertical motion of the hawsers significantly reduces the possibility of the hawsers contacting each other. A hawser system according to the invention couples the semi-submersible TAD vessel to the TLP and may be implemented without passing the hawsers through sheaves.

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: A hull, suitable for use as a tension leg platform (TLP) or as a semi-submersible vessel, comprises four columns arranged in a rectangular planform with each column having a generally polygonal transverse cross section at least one axis of which is generally disposed at a 45-degree angle to a line between the center points of adjacent columns. 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: A floating, offshore drilling and/or production platform such as a tension leg platform, semi-submersible, spar or the like is equipped with a ballast tank system that comprises the traditional tank and a shaft that runs typically vertically from top-of-hull level to the top of the tank. This shaft is large enough to allow the ballast pipe, sounding lines, instrumentation piping, etc. to be installed within it. In certain embodiments, the shaft itself functions as a vent line.

Abstract: A hull, suitable for use as a tension leg platform (TLP) or as a semi-submersible vessel, comprises four columns arranged in a rectangular planform with each column having a generally polygonal transverse cross section at least one axis of which is generally disposed at a 45-degree angle to a line between the center points of adjacent columns. 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: 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: A semi-submersible vessel comprises pontoons having a generally five-sided transverse cross section. In the case of a 4-sided semi-submersible, the columns may be arranged in a generally rectangular form with a column at each corner of the rectangular form, each column having with four sides disposed at a right angle to at least one adjacent side and a fifth side on the exterior of the generally rectangular form disposed at 45 degrees to each adjacent side.

Abstract: An offshore platform includes a buoyant hull comprising three or more interconnected pontoons and a plurality of support columns. The support columns support a deck or structure that supports equipment and/or payloads above a water surface. The support columns extend upwardly from respective ends of the pontoons to the deck or structure supported above the water surface. Anchoring members anchor the platform to the seabed.

Abstract: A submerged or partially submerged structure includes one or more non-cylindrical support columns interconnected at the lower ends thereof by horizontally disposed pontoons. The support columns include one or more strakes mounted thereon. The columns and strakes contribute to the stability of the structure during free floating operations and installation by reducing vortex induced motion.

Abstract: A tension leg platform includes a deck supported on the upper ends of three or more columns interconnected at the lower ends thereof by horizontally disposed connecting members. The columns are battered inwardly and upwardly from the platform base to the deck. Tendons connected at the columns anchor the platform to the seabed. The footprints of the base of the battered columns and the tendons are larger than the footprint of the deck supported on the upper ends of the columns.

Abstract: A floating platform system includes a hull design configuration (40, 50) for limiting maximum tendon loads and aiding in inhibiting resonant responses in the platform system leading to better motions for personnel, equipment and riser support, and to lighter and lower cost tendon systems.

Abstract: A submerged or partially submerged structure includes one or more non-cylindrical support columns interconnected at the lower ends thereof by horizontally disposed pontoons. The support columns include one or more strakes mounted thereon. The columns and strakes contribute to the stability of the structure during free floating operations and installation by reducing vortex induced motion.

Abstract: An offshore platform includes a buoyant hull comprising three or more interconnected pontoons and a plurality of support columns. The support columns support a deck or structure that supports equipment and/or payloads above a water surface. The support columns extend upwardly from respective ends of the pontoons to the deck or structure supported above the water surface. Anchoring members anchor the platform to the seabed.

Abstract: A tension leg platform includes a deck supported on the upper ends of three or more columns interconnected at the lower ends thereof by horizontally disposed connecting members. The columns are battered inwardly and upwardly from the platform base to the deck. Tendons connected at the columns anchor the platform to the seabed. The footprints of the base of the battered columns and the tendons are larger than the footprint of the deck supported on the upper ends of the columns.

Abstract: A tension leg platform includes a deck supported on the upper ends of three or more columns interconnected at the lower ends thereof by horizontally disposed pontoons. The columns are battered inwardly and upwardly from the pontoons to the deck. Tendons connected at the columns anchor the platform to the seabed. The footprints of the base of the battered columns and the tendons are larger than the footprint of the deck supported on the upper ends of the columns.

Abstract: In accordance with the present invention, an oscillation suppression system is provided to inhibit vertical and rotational resonance of a floating platform. The oscillation suppression system includes energy absorption chambers mounted in or about the hull of the floating platform. The chambers may be separately attached or integrated as part of the structure. The chambers are comprised of gas in an upper portion, and water mass in a lower portion. The chambers are closed or partially vented at the upper ends and open at their bottom ends. The enclosed gas in the upper portion of the chamber acts as a gas spring reacting against the floating platform and the water mass. The suppression of resonant oscillations of the floating platform system is accomplished through the gas-spring pressure changes acting on the floating platform system in phase opposition to external forces.

Abstract: In accordance with the present invention, an oscillation suppression system is provided to inhibit vertical and rotational resonance of a floating platform. The oscillation suppression system includes energy absorption chambers mounted in or about the hull of the floating platform. The chambers may be separately attached or integrated as part of the structure. The chambers are comprised of gas in an upper portion, and water mass in a lower portion. The chambers are closed or partially vented at the upper ends and open at their bottom ends. The enclosed gas in the upper portion of the chamber acts as a gas spring reacting against the floating platform and the water mass. The suppression of resonant oscillations of the floating platform system is accomplished through the gas-spring pressure changes acting on the floating platform system in phase opposition to external forces.