Abstract: A riser joint keel assembly. A tapered riser joint is connected to a larger diameter outer sleeve through a connection that allows the tapered section and outer sleeve to function as one unit. In the combined design, the outer sleeve provides the required sliding interface between the riser and the guide at the keel of the hull while also providing some of the bending compliance needed to transition from the riser supported in the hull to the riser unsupported below the hull. The tapered section also provides the remaining bending compliance needed for the transition. The connection between the tapered and sleeve sections is a forged, machined ring plate welded to the bottom end of the sleeve, which provides a base for either bolted or threaded type attachment points for the tapered riser joint below the ring plate and the internal riser joint that continues to the surface.

Abstract: An improved floating circular hull construction arrangement. The hull is divided into sections by watertight flats. The flats are stiffened with angles or bulb tees curved to form concentric circles that are in turn supported by the radial girders spaced around the flats and spanning between the inner and outer-shells. In each section, longitudinal girders spaced radially around the inside of the outer-shell terminate at the flats and attach to the flats and do not penetrate the flats. The longitudinal girders are attached to flats aligned with the locations of the radial girders that extend across the flats to the inner and outer shells. A panel stiffening arrangement on the inner circumference of the outer shell is attached to the outer shell and the longitudinal girders. Longitudinal girders spaced around the outer circumference of the inner shell extend along the length of the inner shell and are attached to the radial girders.

Abstract: An improved floating circular hull construction arrangement. The hull is divided into sections by watertight flats. In each section, longitudinal stiffeners spaced around the inside of the outer shell terminate adjacent the flats and do not penetrate the flats. The longitudinal stiffeners are supported by full rings that are concentric with the center of the hull. The rings are received over the longitudinal stiffeners, extend radially inward and are laterally supported with members configured to act in tension in either axial direction and which are parallel to the longitudinal axis of the hull. Rings on the inner shell extend radially outward toward the outer shell and may be laterally supported similarly to the lateral supports of the outer shell. The flats are stiffened with angles or bulb tees curved to form concentric circles that are in turn supported with radial girders spaced around the flats and spanning between the inner and outer shells.