Patent ID: 8511246

Claim:
An offshore floating production, storage and off-loading vessel structure for use in producing, storing and transporting oil and/or liquefied gas, comprising: a hull having a top wall defining a deck, a bottom wall, and a generally cylindrical exterior side wall configuration surrounding a central moon pool, said side wall having a lower portion extending upwardly from said bottom wall and an upper portion extending angularly inward and upward therefrom terminating adjacent to a bottom of said deck; ballast compartments and storage compartments contained in said hull; an adjustable ballasting system for ballasting and deballasting selected said ballast compartments and storage compartments to induce heave, roll, pitch and surge motions of said vessel to dynamically position and maneuver said vessel and carry out moving operations; said moon pool having a double tapered conical interior configuration with respect to a vertical axis for entrainment of water to selectively provide added hydrodynamic virtual mass to increase the natural period of the roll and heave modes, reduce dynamic amplification and resonance due to waves and vessel motion, and facilitate maneuvering the vessel; and said hull having a height from said bottom wall to said deck that is less than the largest diameter and less than the smallest diameter of said exterior side wall configuration.