Ships – Ballasting – Fins and boards
Reexamination Certificate
2000-04-05
2001-06-05
Swinehart, Ed (Department: 3617)
Ships
Ballasting
Fins and boards
C114S122000
Reexamination Certificate
active
06240869
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to apparatus and methods for stabilizing watercraft, and particularly to finned apparatus for stabilizing watercraft against roll.
BACKGROUND OF THE INVENTION
Many systems for stabilizing watercraft, such as during pitch and roll, are known. The prior art patent literature describes finned apparatus for stabilizing watercraft against roll. U.S. Pat. Nos. 3,896,755 and 4,061,102, British Patent 1,492,905, Russian Patent 524731, Norwegian Patent 7401864 and French Patent 2,282,364 are believed to be representative of the art.
SUMMARY OF THE INVENTION
The present invention seeks to provide novel finned apparatus for stabilizing watercraft against roll.
There is thus provided in accordance with a preferred embodiment of the present invention stabilization apparatus for a watercraft having a hull, including at least one hydrofoil with a leading edge and a trailing edge, the edges defining a chord extending therebetween, the at least one hydrofoil being mounted below an underside of the hull and arranged for rotation about an axis that is generally perpendicular to the chord and directed towards the underside of the hull, and control apparatus that rotates the at least one hydrofoil about the axis in response to roll of the watercraft so as to stabilize the watercraft against the roll. Preferably the axis passes generally through the chord's center.
In accordance with a preferred embodiment of the present invention the at least one hydrofoil has cambered side surfaces extending from the leading edge to the trailing edge. Additionally or alternatively the at least one hydrofoil has cambered upper and lower surfaces extending from the leading edge to the trailing edge.
Further in accordance with a preferred embodiment of the present invention the control apparatus includes a clinometer that measures roll of the watercraft and the control apparatus receives data from the clinometer and rotates the at least one hydrofoil about the axis in response to the data.
Still further in accordance with a preferred embodiment of the present invention the control apparatus includes a processor that calculates a steady state roll angle of the watercraft and a time derivative of an angle of roll of the watercraft about the steady state roll angle, and the control apparatus rotates the at least one hydrofoil about the axis in response to the time derivative.
Additionally in accordance with a preferred embodiment of the present invention the control apparatus rotates the at least one hydrofoil to at least one predetermined discrete angular position about the axis.
In accordance with a preferred embodiment of the present invention the control apparatus is vibration-isolated mounted to a portion of the watercraft.
The hydrofoil may be mounted on any portion of a keel of the watercraft, such as in front of the keel, aft of the keel, on a starboard or port surface of the keel, or underneath the keel.
Further in accordance with a preferred embodiment of the present invention the at least one hydrofoil is additionally gimbaled for rotation about a fore-and-aft axis of the watercraft.
REFERENCES:
patent: 3324815 (1967-06-01), Morales
patent: 3373710 (1968-03-01), Steinberg
patent: 3727572 (1973-04-01), Nelson et al.
patent: 3896755 (1975-07-01), Marbury
patent: 3937423 (1976-02-01), Johansen
patent: 3990384 (1976-11-01), Reynolds, III
patent: 4061102 (1977-12-01), Bissett
patent: 4077077 (1978-03-01), Harper
patent: 4380206 (1983-04-01), Baitis et al.
patent: 4628853 (1986-12-01), Hoyt
patent: 4686923 (1987-08-01), Greene
patent: 4718872 (1988-01-01), Olson et al.
patent: 5029548 (1991-07-01), Bernitsyn et al.
patent: 5408948 (1995-04-01), Arii et al.
patent: 5452674 (1995-09-01), Melville et al.
patent: 5488919 (1996-02-01), Ferreiro et al.
patent: 7303664 (1973-07-01), None
patent: 0 591 366 (1996-10-01), None
patent: 2282364 (1976-03-01), None
patent: 1350451 (1974-04-01), None
patent: 1492905 (1977-11-01), None
patent: 2116242 (1976-08-01), None
patent: WO 89/11414 (1989-11-01), None
patent: WO 93/00255 (1993-01-01), None
Abstract of GB 768127.
Abstract of GB 7435635.
Derwent Abstract of FR2282364A of Mar. 1976.
Ladas & Parry
Swinehart Ed
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