Ships – Implements – Hull cleaning
Reexamination Certificate
1998-11-13
2001-08-21
Basinger, Sherman (Department: 3617)
Ships
Implements
Hull cleaning
Reexamination Certificate
active
06276292
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods and devices for controlling foulant organisms on the hull of a ship while the ship is at rest.
BACKGROUND OF THE INVENTION
Throughout history, efforts have been made to control fouling organisms that attach to ships. These efforts have met with varying degrees of success.
Prolonged and untreated fouling results in a degradation in the engineering properties of the ship's components and can lead to eventual destruction of the ship's structure. The plants and animals that constitute foulant material generally occur naturally in shallow waters along coastlines throughout the world. There are approximately 2,000 species of fouling organisms. The dominant type of fouling organism varies with location, air and water temperature, and time of year. Control of these organisms needs to occur before attachment to the surface of the ship, and an effective method of removal of any organisms that do attach is also critical.
Most of the efforts to control fouling in recent years have concentrated on the development of coatings for ships' hulls. Progress has been made in the development of these coatings. However, due to the sheer numbers, variety and complexity of marine organisms, finding one coating that can be effective under all conditions is extremely difficult.
Currently, the most common method of removing foulant once the organisms attach requires the boat to first be dry docked. Once in dry dock, a cavitating jet fouling removal device is used, which consists of high pressure water pumped through nozzles mounted on a carriage that moves along the side of the hull of the ship.
A search has revealed the following potentially relevant issued patents:
U.S. Pat. No. 3,505,758; U.S. Pat. No. 3,570,256; U.S. Pat. No. 3,581,505; U.S. Pat. No. 3,685,477; U.S. Pat. No. 4,026,233; U.S. Pat. No. 4,046,094; U.S. Pat. No. 4,058,075; U.S. Pat. No. 4,215,644; U.S. Pat. No. 4,244,749; U.S. Pat. No. 4,280,436; U.S. Pat. No. 4,280,437; U.S. Pat. No. 4,280,438; U.S. Pat. No. 4,280,439; U.S. Pat. No. 4,282,822; U.S. Pat. No. 4,289,423; U.S. Pat. No. 4,444,146; U.S. Pat. No. 4,693,200; U.S. Pat. No. 4,890,567; U.S. Pat. No. 4,943,954; U.S. Pat. No. 4,998,496; U.S. Pat. No. 5,138,963; U.S. Pat. No. 5,143,011; U.S. Pat. No. 5,152,242; U.S. Pat. No. 5,279,244; U.S. Pat. No. 5,465,676; U.S. Pat. No. 5,651,326; and U.S. Pat. No. 5,735,226.
SUMMARY OF THE INVENTION
The present invention addresses the age old problem of marine fouling and overcomes disadvantages associated with the prior art while providing additional benefits. An exemplary embodiment combines an enclosure of a hull of a ship at rest with the use of ultrasonic transducers. The enclosure material may be a waterproof tarp-like material. The transducers may be mounted on circuit boards placed in a diamond-shaped grid on the interior of the ship's hull. Alternating spacers may be used between the hull of the ship and the enclosure material to maintain a uniform distance. The transducers may be placed on these spacers. Once the hull is enclosed, the transducers induce cavitation between the enclosure material and the hull of the ship which results in the removal of the foulant organisms from the hull of the ship.
Another exemplary embodiment of the present invention includes a deployment system consisting of a storage cart, a deployment track mounted to a railing of a ship and a roller assembly to facilitate deployment of the enclosure. The storage cart is wheeled to the deck railing and secured for deployment. The enclosure material is laid, accordion-style, on the storage rack when stored. The enclosure material is attached to roller assemblies inside the track system and deployed.
Yet another exemplary embodiment of the present invention includes a connecting link at midship for enclosure material that is deployed in two or more pieces from either end of a ship. In accordance with this embodiment, electromagnets are placed at evenly spaced intervals in a strip of UHMW (ultra-high-molecular weight) material along a leading edge of the enclosure. An electromagnetic current is then used to draw the two pieces together.
The present invention provides a dual advantage over the prior art by both preventing the organisms from reaching the coating on a ship's hull and by cleaning, through cavitation, any organisms that have previously become attached. This is contrary to the current approach of either waiting to control the organisms during attachment at the point of contact with a coating on the hull, or placing the ship in dry dock and cleaning the organisms after attachment.
The present invention simultaneously addresses multiple factors that inhibit or prevent the growth of marine organisms. These include temperature, salinity level, water velocity, light level and cleaning by cavitation.
Marine organisms exist within very narrow bands of tolerance for changes in such properties as temperature and salinity level. Temperatures approaching 212° F. (100° C.) and salinity levels lower than 3 ppt are conditions that have been shown to prevent or control fouling. By eliminating or reducing the amount of visible light, many marine organisms are unable to grow or reproduce. In addition, linear velocities in excess of 1.3 knots prevent the attachment of many kinds of organisms. Almost all fouling occurs at low speeds or when the ship is at rest. What appears to be fouling at sea really begins in port.
This invention takes advantage of the biological weaknesses of the organisms by raising the temperature of the water between the enclosure material and the hull beyond the tolerance level of the organisms. This rise in temperature also effectively lowers the salinity level below that needed for marine growth. In addition, the velocity of the water during cavitation is too high for attachment of organisms. Finally, the enclosure material cuts off the light needed by many organisms to grow.
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Basinger Sherman
Seed IP Law Group PLLC
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