Patent ID: 8567332

Claim:
A ship with passive roll stabilization, comprising: a hull having; a forward end, an aft end, a port side, and a starboard side, a waterline region along the hull having a waterline that coincides with the level at which the hull floats in open water; first and second bilge keels mounted along the hull within or below a waterline region representing a region of possible waterlines on the hull, the first bilge keel positioned along a streamline side portion of the hull along the waterline regio the port side of the hull extending from the forward end to the aft end, and the second bilge keel positioned along a streamline side portion of the hull along the waterline reign of the starboard side of the hull extending from the forward end to the aft end, wherein each of the first and the second bilge keels comprise: an attachment end attached to the hull; a free end; a curved upper surface extending from the attachment end to the free end; and a curved bottom surface below the curved upper surface, extending from the attachment end to the free end, wherein in each of the first and the second bilge keels, the upper surface is curved downwards forming a central trough region, and the bottom surface is curved upwards forming a central crest region, with the central trough region of the upper surface and the central crest region of the lower surface aligned so that the bilge keel has a substantially biconcave cross section.