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: Apparatus for substantially reducing the roll and pitch motions of a floating vessel in commonly occurring seas is described. The apparatus comprises a recessed cavity formed in a substantial area of the bottom of the hull of the vessel and has an airblower coupled to the cavity for introducing air into it. The apparatus may include horizontal planes for restoring the effect of the added mass of the water on the stability of the vessel.

Abstract: A heave resonant damper for semisubmersible platforms includes tanks and ducts constructed so that their resonant period approximately equals the resonant heave period of the platform, wherein the ducts have selectively varied cross-sectional area to optimize damping.

Abstract: Apparatus for substantially reducing the roll and pitch motions of a floating vessel in commonly occurring seas is described. The apparatus comprises a recessed cavity formed in a substantial area on the bottom of the hull of the vessel and has an airblower coupled to the cavity for introducing air into it. The apparatus may include horizontal planes for restoring the effect of the added mass of the water on the stability of the vessel.

Abstract: A seagoing vessel is stabilized by a passive system including tanks symmetrically disposed on the vessel below the water line. The tanks are connected by a conduit and pressurized with air to a selected pressure level. During each oscillatory roll and/or pitch cycle of the vessel, the tanks alternately fill and drain with selected volumes of water to reduce the righting moment of the vessel. The period of oscillation of the vessel is thus lengthened beyond the period of wave motion.

Abstract: A seagoing vessel is stabilized by a passive system including tanks symmetrically disposed on the vessel below the water line. The tanks are connected by a conduit and pressurized with air to a selected pressure level. During each oscillatory roll and/or pitch cycle of the vessel, the tanks alternately fill and drain with selected volumes of water to reduce the righting moment of the vessel. The period of oscillation of the vessel is thus lengthened beyond the period of wave motion.

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 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: A seagoing vessel is stabilized by a passive system including tanks symmetrically disposed on the vessel below the water line. The tanks are connected by a conduit and pressurized with air to a selected pressure level. During each oscillatory roll and/or pitch cycle of the vessel, the tanks alternately fill and drain with selected volumes of water, thereby to reduce the righting moment of the vessel. The period of oscillation of the vessel is lengthened beyond the period of wave motion.

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.