Pneumatic system reducing friction between a vessel hull and the surrounding water
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A pneumatic system designed to minimize the high coefficient of water friction, known in the nautical industry as “skin resistance” or “drag,” against the submerged hull (10) area of a vessel. This system directs pressurized air from a shipboard compressor (30) through many distributing pipes (60). These distributing pipes (60) are arranged longitudinally and are evenly spaced transversely, adjacent to the internal hull (10) section that lies below the waterline. A plurality of smaller ejection pipes (70) project from the distributing pipes (60). Calibrated nozzles (80) connect the ejection pipes (70) to the vessel's exterior, releasing a constant flow of pressurized air as bubbles between the water (A) and the hull (10) surface. This layer of bubbles reduces the undesired effect of skin resistance (drag) caused by the viscosity of the medium through which the vessel navigates.

Iglesias Schoo, Raul Alberto (Buenos Aires, AR)
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Primary Examiner:
Attorney, Agent or Firm:
Alberto Iglesias Schoo (Gallo 1577 - piso 8 "17", Buesnos Aires, null, null, AR)
What is claimed is:

1. A pneumatic system to deliver compressed air to water adjacent to a vessel's hull whereby friction between the water and said hull is reduced, comprising: A. an onboard compressor, B. a web of distribution pipes connected to said compressor, said distribution pipes arranged longitudinally along the interior of the submerged portion of said vessel's bulkhead, C. a plurality of ejecting pipes, smaller than the distribution pipes, and connected to said distribution pipes, D. a calibrated nozzle at the distal end of each of said ejecting pipes, said calibrated nozzles penetrating the hull's exterior surface, with said nozzles homogeneously distributed along the hull's exterior surface to expel into the water to form bubbles.

2. The pneumatic system of claim 1, further including a compressor powered by a motor driven by the vessel.

3. The pneumatic system of claim 1, further including a compressor powered by the vessel's engine.

4. A pneumatic system according to any one of claims 1, 2, or 3, wherein said compressor has a pressure control valve.

5. The pneumatic system of claim 4, further including the portion of the vessel's hull found below the waterline.



Jun. 30, 2006 [AR] Argentina No. 20060102831


Not applicable.


Not applicable.


1. Field of Invention

This invention generally relates to marine vessels, specifically to a system to increase a marine vessel's efficiency by using air bubbles under the hull to reduce friction or drag.

2. Prior Art

Previously, in an attempt to overcome the effects of friction between vessel hull and water, designs have included vessels such as the hovercraft (such as one described in U.S. Pat. No. 7,032,698 to Lee, et. al., Apr. 25, 2006), which is a watercraft that traps a generated cushion of air, and moves upon that air. In some cases, the air cushion acts as a means of propulsion. The hovercraft's hull glides over this air cushion, which has a lower friction coefficient than water. However, the functionality of this technique is restricted to relatively small vessels, because it demands a large quantity of highly compressed air, which, in turn, requires a high power compressor, thus making it impractical for larger vessels.

Some inventions seeking to exploit the low-drag property of air bubbles under a hull have incorporated components unnecessary to achieve the ultimate purpose. For example, the invention claimed in U.S. Pat. No. 5,967,071 to Wipper, Oct. 19, 1999, required a means to recover the expelled air, a means to separate water from the recovered air, and a recycling means to return the recovered air to the distribution system. Each additional means requires additional energy input, resulting in loss of the energy advantage gained by reducing the drag imposed by the water, which compromises the practicality of such an invention.

Another invention presented in U.S. Pat. No. 4,926,771 to Hull, May 22, 1990, consists of a ship hull with two keels forming a channel in between them. A shipboard compressor provides air through large diameter pipes. The air flows through the channel. This system, however, has the disadvantage of having a large volume of air requiring considerable energy, and thus, its use in small vessels is impractical. Furthermore, the efficiency of this system is limited to its effect in the channel, and has no measurable effect on the sides of the hull. It thus results in low efficiency.

Some inventions have attempted to lubricate the hull surface with substances other than pure air. For example, U.S. Pat. No. 5,456,201 Oct. 10, 1995, and U.S. Pat. No. 5,524,568, Jun. 11, 1996, both to Bobst, or U.S. Pat. No. 5,575,232 to Kato, et. al., Nov. 19, 1996, describes the use of a layer of air bubbles intermixed with water. However, water has a much higher friction coefficient than water. Consequently, the lubrication layer will be less effective at reducing drag if a high viscosity substance is present. The introduction of water to the lubrication layer impedes the advantages provided by water's low friction coefficient. This short-coming can be circumvented by requiring that the lubricating layer be made exclusively of air.

Previous inventions are less energy-efficient, because the air-producing portions of the hull do not remain submerged. To illustrate, U.S. Pat. No. 5,967,071, mentioned above, releases air from the bow, such that the air bubbles will drift astern. With faster watercraft, such as speedboats, it is well known that increased speed lifts the bow above the water's surface. Therefore, air bubbles could not be released to areas of the hull that remains submerged. Faster watercraft would benefit from air release areas at, or near the stern.


It is widely known that water has a much higher viscosity than air. Thus, in water, friction produces a significant resistance to a vessel's hull as it navigates through water (known in nautical terms as “hull skin resistance” or “drag”). This opposition to the vessel's propulsion is the primary cause of fuel consumption; air resistance upon the vessel's remaining surface consumes one hundred times less fuel.

Due to significant drag, a hull's design is of great importance, particularly concerning the keel's capacity to dynamically penetrate the water. However, hull design alone does not completely solve the problem, because it will not reduce the lateral and underside surface area of the hull, which is still subject to the water's friction. This problem is magnified in large cargo vessels, because their hull design is limited by the need for interior holding capacity and their stability.

Accordingly, several objects and advantages of the invention are that it reduces the resistance or drag upon the skin of a vessel's hull. The object of this invention is to present a pneumatic system that constantly delivers pressurized air through pipes and calibrated nozzles, which are homogeneously distributed along the submerged exterior of a vessel's hull. As the air leaves the nozzles, it dissipates as small bubbles, which form a layer of lubricating micro-spheres between the hull and the water.

Another object is to optimize air output while preventing deterioration of the pipes delivering the air due to the constant high-pressure stresses.

In addition, another object is to minimize excessive waste of compressed air, which can be economically costly.

It is a further object is to provide a pneumatic system for friction reduction to high speed crafts, such as those used in nautical competition. In those cases, the bow's elevation results in a smaller portion of the hull remaining underwater.

Further objects and advantages will become apparent from a consideration of the ensuing description and drawings.


In accordance with the invention, a pneumatic system of pipes delivers compressed air to the layer of water adjacent to a vessel's hull to reduce friction between the water and the hull. The system includes an onboard compressor connected to distribution pipes. Smaller ejection pipes deliver the compressed air from the distribution pipes to calibrated nozzles, which penetrate through to the exterior of the hull. The compressed air forms bubbles along the underside of the hull as the vessel travels through water. The layer of air reduces the friction between the hull and the water, thus increasing the vessel's efficiency.



FIG. 1 is a vertical longitudinal section view of a vessel's hull and the preferred embodiment of the present invention installed therein.

FIG. 2 is a transverse section view of a vessel's hull and the preferred embodiment of the present invention installed therein.

FIG. 3 is a transverse section view of a distribution pipe and its ejection pipes leading to the exterior of the hull.

FIG. 4 is a lateral view of a section of a distribution pipe on a section of the hull.

FIG. 5 is a lateral view of a speedboat with the preferred embodiment of the present invention installed therein.


Reference Numerals

  • 10—hull
  • 20—engine room
  • 30—compressor
  • 40—pressure-regulating valve
  • 50—manifold
  • 60—distributing pipe
  • 70—ejection pipe
  • 80—nozzle
  • A—water
  • S—direction of vessel travel


Preferred Embodiment

In the following, preferred embodiments will be presented with reference to FIGS. 1-5.

As seen in FIG. 1, the hull 10 of a large vessel has, next to the engine room 20, a compressor 30, fed by available energy located in its proximity. Said compressor 30 has a pressure-regulating valve 40, which regulates the flow going to a manifold 50. The distributing pipes 60 branch out from the manifold 50 in an evenly-spaced fashion and extend parallel to the vessel's hull 10 below the waterline, adjacent to the hull 10. Ejection pipes 70 are elbow-shaped pipes with a small diameter, and direct air flow from the distributing pipes 60 to a narrow calibrated nozzle 80, dispersing air between the water and the outside surface of the hull 10. The resulting bubbles serve as lubricating micro-spheres of air that will facilitate the ship's movement through the water.

FIG. 2 is a transverse section view of the vessel, taken from the II-II plane in FIG. 1, and shows how the distributing pipes 60 are evenly spaced next to the interior of the hull 10, covering the immersed area of the vessel. Air is distributed at a constant pressure to the ejection pipes 70, and passes through the calibrated nozzles 80 which are homogeneously distributed throughout the hull 10. This causes a thin flow of air to the exterior of the hull 10. Said air flow creates tiny air bubbles which will tend to rise, and position themselves between the water A and the exterior of the hull 10 as a layer of lubricating micro-spheres that minimize friction or drag.

FIG. 3 is a cross section of a distributing pipe 60 connected to ejection pipes 70. Ejection pipes 70 are smaller in diameter than distributing pipes 60, and are distributed along the length of the distributing pipes 60. Ejection pipes 70 are elbow-shaped connections that assist in the homogeneous distribution of the calibrated nozzles 80. The calibrated nozzles 80 allow a thin layer of pressurized air to flow from the ejection pipes 70 to penetrate the hull 10, forming the lubricating layer of micro-bubbles in the water.

Similarly, FIG. 4 shows a longitudinal section of a distributing pipe 60, the derivative ejection pipes 70, and the calibrated nozzles 80 connected to the hull 10 exterior that supply the lubricating coat of micro-bubbles. These micro-bubbles flow astern, according to the direction in which the vessel is navigating S.

FIG. 5 reveals a lateral view of a speedboat. Its navigating speed causes the vessel's bow to rise and, conversely, the stern to remain submerged. The calibrated nozzles 80 are distributed at the stern to improve the vessel's efficiency through the water.


Accordingly, the reader will see that, according to the invention, I have provided a simple, efficient system to reduce water friction upon a vessel hull.

While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but as exemplifications of the presently preferred embodiments thereof. Many other ramifications and variations are possible within the teachings of the invention.

Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given.