Patent ID: 7984683

Claim:
A compound hull for powered vessels having a fore end prow, an aft end stern, a mid-ship line, a keel and developing a wave form at displacement hull speed, defined as the wave shape formed by a lower hull at a speed at which the wave length matches the waterline length of the vessel and develops a crest adjacent said stern, comprising: a) a displacement hull having: i) an upper hull portion having a bottom and hull sides joined at a stem at said vessel fore end and terminating at said vessel aft end in a generally square stern, said bottom having a generally flat aft section extending from said mid-ship line to said stern, each said hull sides having a top edge which forms a sheer and a bottom curve which joins said bottom along a hard chine; said bottom aft section of said upper hull matching said wave form at hull speed from said mid-ship line to said stern, said bottom flat aft section providing a plane on which said hull surfs on the developing crest of said wave form; and ii) a lower hull portion consisting of a pair of angled side planes joined continuously along a bottom keel margin from said fore end to said aft end which together form a double ended V-bottom displacement hull having a varying dead-rise angle, a length the same as said upper hull portion and a beam less than the beam of the upper hull portion; b) said upper and said lower hull portions being joined along a faired line that begins at said fore end of said vessel at said intersection of said hard chine and said stem and terminates at a midpoint of said stern; and c) said upper and said lower hull portions cooperate to recover energy from said wave form by surfing downhill on the developing crest of said wave form thereby resulting in lower power requirements for long-period cruising at displacement hull speed while providing greater aft beam and load capacity, as compared to compound hull shapes not having a double ended V-bottom displacement lower hull portion, and said bottom flat aft section with square stern providing stability against roll and pitch of said vessel and damping turbulence.