Hull modification to minimize porpoising of a boat

Details Hull modification to minimize porpoising of a boat Hull modification to minimize porpoising of a boat

2000-06-30

2001-12-25

Basinger, Sherman (Department: 3617)

Ships

Hull or hull adjunct employing fluid dynamic forces to...

C114S291000

Reexamination Certificate

active

06332422

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the construction of a boat hull. More specifically, the present invention concerns a modification to a boat hull to minimize porpoising of the boat when underway.
BACKGROUND OF THE INVENTION
In the prior art, boats are known with a wide variety of hull configurations. While the exact shape of the hull often differs from one boat to the next, most boat hulls may be characterized as having a V-shape (in lateral cross-section). In addition, most hulls are adorned with raised or recessed ridges that extend longitudinally along the hull. These ridges are referred to in the art as “chines.” Some boat hulls may also incorporate laterally extending ridges or recesses, which are also referred to as chines.
Regardless of their placement and orientation, chines are included on a boat's hull to improve its performance and stability during operation. For example, chines are useful to control lateral motion of the vessel when underway.
Lateral motion, however, is not the only type of motion experienced by boats, especially speed boats. Speed boats operate across a wide range of different speeds. Accordingly, it is possible that a hull that operates acceptably at low speed may not operate acceptably at higher speeds.
One type of motion that may become pronounced at higher speeds is a phenomenon known as “porpoising,” which means that the boat tends to rhythmically move up and down while travelling forward. (“Porpoising” refers to the motion of the boat that is like the movement of a porpoise jumping out of the water.)
Porpoising occurs when the center of gravity and the center of buoyancy of the boat are close together but are not in equilibrium with one another.
In most cases, porpoising is more likely to occur when the boat is at a higher speed than when the boat is at a lower speed. At lower speeds, a majority of the hull of the boat is in contact with the water, so the boat is in a condition where the equilibrium between the center of buoyancy and the center of gravity of the boat is not in question. However, as the boat's speed increases, the hull generates greater lift (which is a function of the boat's speed). This means that, at higher speeds, less of the boat's hull contacts the water as the bow of the boat rises out of the water. As a result, equilibrium between the center of gravity and center of buoyancy may not be established, resulting in porpoising of the boat when underway.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a modification to a boat hull that helps to minimize porpoising of a vessel when underway.
It is a further object of the present invention to provide a modification to the chines on the hull of a boat to minimize the porpoising of a boat.
It is still a further object of the present invention to provide a hull with bow, stern, port and starboard sides. At least one chine extends longitudinally from a first point near the bow to a second point near the stern. At least one wedge section is disposed along the at least one chine where the at least one wedge is adapted to minimize porpoising of the hull when in operation.
It is still another object of the present invention to provide a hull that includes two chines, one disposed on the port side and the other disposed on the starboard side, where each chine is V-shaped in cross-section. In addition, each chine has an inner side facing a centerline of the hull and has an outer side facing a side of the hull. Furthermore, two wedge sections are provided, each one disposed at the second point on the two chines.
Another object of the present invention is to provide a hull where the two wedge sections are triangular, are disposed on the inner sides of the chines, and face inwardly toward the centerline of the hull.
It is still another object of the present invention to provide a hull with chine end sections disposed at the second point of each chine, forming a triangular end to each chine, where the wedge sections are disposed adjacent to the chine end sections.
A further object of the present invention is to provide a hull where the wedge sections and chine end sections share a common edge.
Additionally, it is an object of the present invention to provide a hull where the wedge sections are disposed longitudinally about 1800 mm from a forward-most portion of the bow.
Further, it is an object of the present invention to provide a hull where the wedge sections are disposed laterally about 230 mm from the centerline of the hull.
It is still another object of the present invention to provide a hull where the wedge sections have a length of 150 mm along a first edge, 160 mm along a second edge, and a predetermined length along a third edge.
Another object of the present invention is to provide a hull where the chine end sections are triangular in shape with a length of 115 mm along a first edge, 100 mm along a second edge, and, along a third edge, are equal in length to the third edge of the wedge sections.
A further object of the present invention is to provide a boat with at least one wedge section disposed on at least one chine of a hull having the characteristics detailed above.


REFERENCES:
patent: 4398483 (1983-08-01), Wood et al.
patent: 4790783 (1988-12-01), Karls
patent: 4903626 (1990-02-01), Haines

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