Ships – Building – Antifriction surfaces
Reexamination Certificate
1999-11-16
2001-09-25
Avila, Stephen (Department: 3617)
Ships
Building
Antifriction surfaces
C114S289000, C114S290000
Reexamination Certificate
active
06293216
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of surface effect vessels. More particularly, the invention relates to a hull configuration and engine/blower arrangement for a high speed surface effect vessel that utilizes cushions of air to reduce friction between the boat hull and water surface.
BACKGROUND OF THE INVENTION
Surface effect vessels which use cushions of air to reduce friction between the boat hull and the water are well known in the prior art. Basically, surface effect vessel technology involves injecting pressurized air under the hull of a boat so that at least a portion of the boat hull rides upon a cushion of air. By utilizing gas pressure contained within a pocket under the hull, a surface effect vessel can operate at higher speeds and reduced power levels as compared to conventional vessels. This increased performance is due to the fact that the friction between the air cushion and the boat hull is substantially less than the friction between the water and the boat hull. Thus, riding upon a cushion of air allows a surface effect vessel to reach higher speeds and operate more efficiently with a smaller engine than a typical vessel.
There are many prior art designs which utilize this surface effect. For examples, see U.S. Pat. Nos. 5,860,380, 5,611,294, 5,415,120 and 5,176,095 to Burg, U.S. Pat. No. 5,570,650 to Harley, U.S. Pat. No. 4,574,724 to Stolper and U.S. Pat. No. 3,968,763 to Mason, the disclosures of which are hereby incorporated by reference. One of the primary problems with these and all other prior art designs is that the water/air seal that is maintained by the displacement of the hull allows excessive amounts of air to escape. This air loss increases the volume and pressure of the air required to maintain an air cushion under the vessel. Producing and providing pressurized air requires power from the vessel's engines and blowers. Thus, the efficiency and performance of the vessel are greatly diminished when air escapes from the supporting air cushion.
Prior art surface effect vessels, such as those discussed above, further suffer from a number of other additional problems. For example, prior art surface effect vessels have a greater tendency to loose their supporting cushion of air in choppy or rough seas. As the surface effect vessel rolls in the rough seas, air in the supporting cushion tends to escape from the sides of the boat hull. In addition, air tends to escape from the supporting air cushion when the aft and bow portions of the surface effect vessel are lifted out of the water as the vessel rides over wave peaks. When air from the air cushion is lost, a larger portion of the vessel's hull comes into contact with the water's surface. This air loss results in dramatically increased friction between the vessel and the water and causes the vessel to slow down or lurch. Thus, maintaining the low friction air cushion beneath a vessel's hull under adverse conditions is an important aspect of the design of surface effect vessels.
One prior art approach to maintaining the air cushion utilizes a flexible skirt positioned around the edges of the boat hull to help contain the air cushion. An example of such an embodiment is a hovercraft. Unfortunately, the flexible skirts used in these types of applications increase the resistance of the vessel through contact with the water's surface. In addition, these flexible skirts require extensive and expensive maintenance. Furthermore, these skirts are still prone to allow more air to escape from the air cushion in rough seas.
Yet another problem with prior art surface effect vessels is that their hulls are substantially planar in the area in front of the air cavity. The hull is constructed to be planar in the region in front of the air cavity to allow the air cushion to extend as far as possible to the sides of the vessel. However, at high speeds or in rough seas, this planar hull section will tend to ride up on wave peaks. The bouncing of the vessel results in a rough bumpy ride and decreased stability. In addition, as the planar hull section rises and falls in the heavy seas, air tends to vent from the supporting air cushion. Therefore, what is needed is a surface effect vessel that is configured to operate in heavy seas.
V-shaped hulls are designed to provide an improved ride in rough water, as compared to relatively flat hulls, by deflecting wave energy away from and to the sides of the hull. Thus, traditional V-shaped hulls provide improved ride qualities at the expense of low speed planing and fuel efficiency. However, if the hull of a surface effect ship is made a moderate to deep V-shape, air from the air cushion tends to vent from the sides of the V-shaped hull when the vessel's speed increases and the edges of the V-shaped hull rise out of the water. Thus, prior art surface effect vessels have not utilized deep-V hulls. Therefore, what is needed is a deep-V hull configuration for a surface effect vessel that provides improved high speed handling characteristics without substantially increasing the amount of air venting from the air cushion.
SUMMARY OF THE INVENTION
The present invention is designed to address the above discussed problems with the prior art by providing an improved surface effect boat hull configuration and layout that minimizes the friction between the boat's hull and the water while providing an improved degree of stability in rough seas. In particular, one embodiment of the present invention is directed toward a vessel for moving across the water's surface wherein the vessel has a V-shaped hull for supporting the vessel upon the water's surface. The V-shaped hull has a gas cavity. The gas cavity is preferably concave with respect to the water's surface and is adapted to receive pressurized gas from a gas blower. The V-shaped hull further includes air restricting side hull portions adapted to reduce gas loss from the gas cavity. The air restricting side hull portions extend substantially parallel to the vessel's direction of movement along the V-shaped hull. The V-shaped hull also has water redirecting projections positioned near a leading edge of the air restricting side hull portions. The water redirecting portions are adapted to direct a flow of water toward a blow through area of the V-shaped hull such that a portion of the pressurized gas is prevented from venting from the air cavity through the blow through area. While not preferred, it is appreciated that, for specialized applications, the water redirecting portions may be manually or automatically controllable such that the turbulent water flow can be adjustably directed toward one of a multitude of blow through area locations.
The provision of water redirecting portions improves upon the prior art by allowing the vessel to travel at a higher rate of speed without venting air from the supporting air cushions. In addition, the water redirecting portions allow a surface effect vessel to be constructed with a more steeply sloped V-shaped hull having a higher dead rise angle. As discussed in more detail below, a steeply sloped V-shaped hull improves the handling and ride quality of a surface effect vessel in rough seas by allowing the hull of the vessel to pierce through the wave peaks.
The present invention further comprehends another embodiment wherein a pair of blow through areas are located on opposite sides of the V-shaped hull adjacent to the leading edges of the air restricting side hull portions and the pair of blow through areas are lifted above the water's surface when the vessel reaches a critical blow through speed. In this embodiment, the water redirecting portions are curved extensions of the air restricting side hull portions that create a turbulent high velocity water flow directed toward the blow through areas. Cornering chines extend from the sides of the hull and increase the stability of the vessel in hard turns. A dividing portion is positioned in the gas cavity such that the gas cavity is divided into at least two
Avila Stephen
Luedeka Neely & Graham PC
LandOfFree
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