Autonomous In-Water Marine Antifouling Apparatus, System and Method

Biofouling, defined as the accretion of organisms on submerged, man-made surfaces, has been the bane of ship operators for at least 2500 years. Initial attempts to control biofouling using metal sheathing or various mixtures of waxes, tars, and toxic chemicals were aimed at making wooden hulls both water-tight and protecting against marine boring organisms. With increased use of metal-hulled ships beginning in the 1800s, however, the rationale for protective treatments shifted from ensuring hull integrity to improving vessels' performance. The adverse effects of biofouling on ships' performance have long been recognized. Attachment of biofouling organisms, such as macroalgae, hydrozoans, bryozoans, barnacles, polychaete tubeworms, mollusks, and ascidians, increases the frictional resistance of a ship's hull, resulting in an increase in the power and in the fuel consumption required to move through the water as well as a reduction in the maximum speed through the water. The negative economic impact of this degradation in performance is widely recognized as enormous.

Biofouling is a complex process that involves colonization by microfouling organisms, such as viruses, bacteria, cyanobacteria, fungi, protozoa and microalgae, and larger macrofouling organisms, including macroinvertebrates and macroalgae. Macrofouling includes calcareous hard-fouling organisms such as acorn barnacles, mussels and tubeworms and soft-fouling organisms such as non-calcareous algae, sponges, anemones, tunicates and hydroids.

The colonization process is often broadly described as a succession of four main stages, as described in a published article by Vinagre, P. A., et. al., Marine Biofouling: a European Database for the Marine Renewable Energy. Sector. Journal of Marine Science and Engineering 2020; 8: 495-521. As described by Vinagre, the four main stages are:

Marine biofouling is a worldwide problem that affects both commercial and military interests in the form of cost, schedule and maintenance impacts. It also affects the environment, as invasive species can be transported across the world from the location of initial attachment to a ship hull to a subsequent location where they reproduce and/or become detached, either spontaneously or during the process of in-water cleaning of the hull of biofouled ships. For many years, efforts to control biofouling species transport have focused on ballast water management. More recently, research has identified biofouling as a significant mechanism for transporting biofouling species, with ships and boats as vectors, and there is an increasing awareness that comprehensive efforts are needed in both areas (biofouling and ballast water management) to successfully address spread of biofouling species, particularly invasive species.

Biofouling is the attachment of organisms to a surface in contact with water over time, and begins with the growth of a biofilm (slime layer), which rapidly occurs on a marine surface. Biofilm formation occurs within hours after a new or cleaned ship hull enters seawater. Biofilm growth rapidly progress to a point where it provides a foundation for seaweed, barnacles, and other organisms, some of which may be invasive species. Biofouling management can take the form of preventive actions, such as using antifouling coatings for vessels hulls, or remedial actions, such as physically removing biofouling by cleaning the hull in the water or in a drydock facility. Antifouling coatings initially focused on incorporating toxic compounds in the paint. Over time, however, these compounds were found to concentrate in harbor sediment, causing environmental concerns, and different approaches to antifouling coatings on the hulls of ships have been adopted as once widely used biocide antifouling coatings have been banned internationally.

In 2009, the Coast Guard Office of Operational and Environmental Standards (CG-OES), formerly CG-523, funded an overview study on biofouling management, viz., U.S. Coast Guard Biofouling Assessment published in September 2010. The study noted that shipboard biofouling impacts vessels in two general ways; decreasing revenue and increasing expense. The total cost associated with biofouling in the United States alone was estimated to be as much as $120B per year. World-wide in 2013, there were over 29,000 merchant vessels in service including over 15,000 large (25,000 to 60,000 gross tons) and very large (>60,000 gross tons) merchant vessels. All of these merchant vessels must repeatedly manage the problem of biofouling throughout the life of each vessel. In this regard, see McClay, T. et. al. Vessel Biofouling Prevention and Management Report, Report No. CG-D-15-15. March 2015: Table 1.

The conventional methods of cleaning ship hulls having significant biofouling deposits require re-locating the ship out of the water in a dry dock facility. Once in the dry dock facility, pressurized water jets combined with mechanical cleaning methods are used to remove all marine fouling deposits prior to the application of a new antifouling coating on the clean hull of the ship. It has been reported that the amount of biofouling removed can amount to as much as 200 tons from a single large ship hull. Importantly, environmental protection regulations in most harbors of the world require that all removed biofouling is safely and completely captured and disposed along with the requirement for filtering all wash water to prevent any contamination of the environment at the location of hull cleaning including both dry dock and in-water hull cleaning locations.

Because of environmental restrictions, antifouling approaches for ship hulls are shifting from managing the release of toxic compounds previously used in antifouling coatings to more frequent cleaning of minor accumulations before biofouling deposits can adversely impact the power requirements and ship's speed through the water. As a result, hull coating manufacturers are increasingly abandoning toxic antifouling formulations in favor of biocide-free, silicone-based coatings whose surfaces resist attachment of marine organisms, but require frequent cleanings as well as special care when cleaning. By way of example, a commercially available silicone-based antifouling coating is available that claims a useful life of about seven years. However, ship hulls with this silicone-based coating require frequent in-water cleaning using less aggressive methods that will minimize damage to the silicone-based coating. In this regard, see the Sigmaglide 2390 biocide-free fouling release coating that is available from PPG Protective and Marine Coatings, Alexander, Arkansas.

By way of another example, one of the more advanced types of hull coatings are the hard, non-toxic coatings such as Ecospeed available from Hydrex Group/Subsea Industries based in Antwerpen, Belgium. The Ecospeed coating includes glass flakes within a vinyl-ester resin, a hard coating that is intended to last the life of the ship. Although this biocide-free coating also requires more frequent in-water cleaning, it is much more durable with regard to various hull cleaning methods as compared with conventional hull coatings such as the increasingly popular silicone-based coatings.

These newer generation of antifouling coatings require frequent in-water interim cleanings between the need for placing the ship in a dry dock for more thorough removal of biofouling deposits. However, the process of in-water hull cleaning has come under increasing regulatory scrutiny in view of environmental protection requirements. The U.S. regulations governing in-water cleaning of ship hulls are fully disclosed in the previously cited report by McClay (2015). As stated in the report by McClay, all in-water cleaning methods are required to collect all removed biofouling products and filter all effluents unless the cleaning method is proven to kill all organisms treated and removed.

Prior art in-water methods for removing early stages of marine biofouling deposits from ship hulls are described in previously cited report by McClay (2015) as well as a report by C. Zabin, et. al., In-Water Vessel Cleaning: Current and Emerging Technologies, Associated Risks and Management Options December 2016. The prior art in-water cleaning methods and systems disclosed in these two reports include mechanical cleaning with brushes, water jet cleaning and a heated water method to kill biofouling organisms. All prior-art methods for in-water cleaning of ship hulls are required to collect all removed biofouling products and filter all effluents except for the method that uses heated water at 72 C that is claimed to kill all organisms treated and removed. Examples of in-water cleaning methods and systems described in these two reports are briefly described as follows.

An object of the present disclosure is to provide an apparatus, system and method for use in seawater environments for in-water, autonomous ablation of marine organisms, including marine microorganisms, to remove marine organisms that attach to the hulls of ships during each period of two to four weeks following the previous removal of biofouling from the ship's hull. As used hereinafter, the term “ablation” refers to the purposeful devitalization (e.g., killing) and removal of targeted species. The ablation process as applied in the present disclosure utilizes the process of molecular dissociation to induce irreversible cell death within marine organisms, including marine microorganisms, that are targeted and removed from the hull of the ship. Hereinafter, marine organisms, including marine microorganisms, that attach to the hulls of merchant ships are also referred to as marine biofouling.

A further object of the present disclosure is to provide an apparatus, system and method that overcomes the disadvantages of current in-water methods for ablation of marine biofouling from ship hulls by eliminating the need for the collection of all marine organisms, including microorganisms, that are removed from the hull of the ship. In addition, the present disclosure provides an autonomous apparatus, system and method that eliminates the requirement for manual operation or maintenance by underwater divers. The system is programmed and controlled to ablate marine deposits from a selected area of the hull of the ship following a pre-programmed and/or machine learning enabled sequence of paths that assure complete coverage of the hull below the water line of the ship that can potentially be exposed to marine organisms and susceptible to marine biofouling.

The present disclosure is addressed to apparatus, systems and methods for use in seawater environments for the in-water, ablation and removal of marine organisms, including marine microorganisms, that attach to the hull of ship. The marine antifouling system of the present disclosure employs one or more biofouling ablation vehicles to repeatedly traverse the hull of a ship below the water line to ablate marine organisms and microorganisms on a recurring basis. Each biofouling ablation vehicle may incorporate a rechargeable battery or may be connected to an external source of electrical power though a reinforced tether that enables the ablation of marine biofouling to be performed in an automated and recurring manner following pre-programmed and/or machine learning enabled paths that, collectively, cover the exposed surfaces of the hull of a ship below the water line.

In a preferred embodiment of the present disclosure, the reinforced electrical power and communication tether that extends from a tether reel mounted at the deck level of the ship incorporates 440 volt, 3-phase, 60 Hz power lines, fiber optic and/or data cable for transmission of video signals from a plurality of digital image sensors located on the bottom surface each biofouling ablation vehicle and a flexible load-bearing cable.

The plurality of digital image sensors on the bottom facing surface (i.e., hull facing surface) of the biofouling ablation vehicle that are positioned along the front end and back end, respectively, of the biofouling ablation vehicle enable the inspection of the surface of the hull both immediately before and immediately after the in-water, ablation of marine organisms attached to the antifouling coating adhered to the hull of the ship. In addition, the biofouling ablation vehicle can be used for the purpose of inspection of the hull of the ship (e.g., assess the extent and depth of pitting corrosion and associated hull thinning), the condition of its antifouling coating and the extent of biofouling using the plurality of digital image sensors mounted on the biofouling ablation vehicle. This also enables the determination of the extent of biofouling accumulation between hull cleaning cycles using an intelligent image recognition system combined with incremental machine learning to automate the assessment of biofouling and guide the frequency of hull cleaning operations as well as the condition of the ship's hull and antifouling coating. In this regard, refer to Mittendorf, M. et. al., Capturing the Effect of Biofouling on Ships by Incremental Machine Leaning. Applied Ocean Research 2023; 138:1-15. Also refer to Bloomfield, N. et. al., Automating the Assessment of Biofouling in Images Using Expert Agreement as a Gold Standard. Scientific Reports 2021; 11: 2379-2388. In addition, also refer to Chin, C. S., et. al., Intelligent Image Recognition System for Marine Fouling Using Softmax Transfer Learning and Deep Convolutional Neural Networks. Complexity; Volume 2017; 1-9 (published by Hindawi). All three references listed above are incorporated herein, in their entirety, by reference.

By way of example, four or more biofouling ablation vehicles can be deployed with a first half of the biofouling ablation vehicles deployed on the port side of the ship's hull and a second half of the biofouling ablation vehicles deployed on the starboard side of the ship's hull. Each biofouling ablation vehicle automatically traverses, inspects and records the extent of marine fouling and removes marine organisms, including marine microorganisms, that attach to the hull of the ship as well as the condition of the ship's hull and antifouling coating. The biofouling ablation vehicle automatically traverses and removes marine organisms following a pre-programmed sequence of paths that are customized to the specific size and shape of the intended surface area to be cleaned for each unique ship hull.

The apparatus, systems and methods of the present disclosure for the in-water, ablation of marine organisms, including marine microorganisms, enables the removal of biofouling from the ship's hull on a recurring basis whether the ship is stationary at a dock, at anchor or otherwise stationary or while the ship is underway. By enabling a recurring process for ablation of marine biofouling from the hull of the ship, the marine organisms are removed at an early stage of their life cycle and prior to marine biogenic calcification that results in marine biofouling that requires much more aggressive methods for the removal of biofouling from the ship's hull such as pressurized water jets, mechanical scraping and powered aggressive brushing methods.

According to the present disclosure, one or more biofouling ablation vehicles are deployed to enable the repeated removal of biofouling from the hull of the ship below the water line, referred to hereinafter as a complete cycle of biofouling removal from the hull of a ship, within a period of two to four weeks following the previous removal of biofouling from the ship's hull or for the hull of a ship having received a marine antifouling coating (e.g., a silicone coating such as the PPG SigmaGlide 2390 coating). The repetition of a complete cycle of biofouling removal from the ship's hull as frequently as every two to four weeks assures that the marine organisms newly attaching to the hull have not yet formed a calcareous body or shell and therefore can be efficiently and effectively removed using the molecular dissociation-based ablation method employed in the present disclosure. Thus, the process disclosed herein contemplates repeatedly cleaning the ship hull, while it is in water, at the early stages of marine fouling (known as slime) before calcareous (hard shell) organisms form during the macrofouling stage. The technology utilized in the process is capable of removing early stage marine fouling from ship hulls without damaging the underlying antifouling coating that is previously applied to the hull of the ship. The biofouling ablation vehicles may be pre-programmed to autonomously traverse the hull of the ship and remove a layer of microfouling from an initially clean hull at various intervals. In some instances, the layer of microfouling that is removed from the hull of the ship is about 2 mm or about 2 mm (i.e., about 0.1 or 0.1 inch) thick. The rate of deposition and growth of microfouling and macrofouling increases with increasing temperature. Accordingly, cleaning intervals are dependent upon water temperature and may occur every four to eight weeks. The biofouling ablation vehicles function as magnetically secured “crawlers” which clean the hull on both the port and starboard sides of the ship and are capable of cleaning the hull of the ship while the ship is in port, at anchor or travelling (i.e., in-motion in the sea).

The apparatus, system and methods of the present disclosure utilizes molecular dissociation of the marine organisms, including marine microorganisms, that attach to the hull of the ship. Molecular dissociation of organic species within attached marine organisms is achieved by placing a plurality of active electrodes in confronting adjacency with marine organisms attached to the antifouling coating adhered to the hull of the ship. One or more common electrodes are positioned adjacent to a plurality of active electrodes and are in electrical communication with the plurality of active electrodes through electrically conductive sea water interposed between the plurality of active electrodes and the one or more common electrodes. The total combined surface area of the common electrodes in contact with sea water is substantially greater than the total combined surface area of all of the active electrodes in contact with sea water.

A radiofrequency voltage is applied between the plurality of active electrodes and one or more common electrodes wherein marine organisms are located between the plurality of active electrodes and the one or more common electrodes. A region of high electric field intensity at the interface between the distal end face of each active electrode and the marine organisms results in the formation of a plasma in a vapor layer between the distal end face of each active electrode and the marine organisms. The plasma formed within the vapor layer is result of the applied electric field in combination with the presence of sodium ions present in seawater. The sodium ionized in the presence of the intense electric filed generates free electrons. The free electrons within the ionized vapor layer are accelerated within the high electric fields near the distal ends of each active electrode thereby generating energetic electrons. The energy evolved by the energetic electrons that bombard each organic molecule can break its chemical bonds. As a result, all organic molecules within the marine organisms attached to the hull of the ship (i.e., the targeted marine organisms) are molecularly dissociated into free radicals that combine into final, nonviable gaseous or liquid byproducts. Since the resulting products of the molecular dissociation of the targeted marine organisms are nonviable, there is no requirement to capture any of the removed gaseous, liquid or solid products generated by molecular dissociation.

The system for in-water, autonomous and recurring ablation of marine organisms, including marine microorganisms, that attach to the hull of ship includes one or more battery-powered or externally powered and tethered biofouling ablation vehicles and one or more ship-powered biofouling ablation vehicle maintenance stations located above the water line of the ship and accessible by pre-programmed movement of the biofouling ablation vehicles. Each battery-powered or externally powered and tethered biofouling ablation vehicle includes [a] a support frame, [b] four or more independently-suspended drive wheels for advancement of two or more traction belts, [c] a traction belt attached to each set of two or more drive wheels on either side of biofouling ablation vehicle and incorporating magnets within each traction belt to secure the biofouling ablation vehicle to the hull of the ship while simultaneously allowing the biofouling ablation vehicle to traverse the hull of ship as the traction belt is advanced by its drive wheels, [d] four or more motors, preferably hub motors, for the independent actuation and control of the rotation of each of the two or more drive wheels, [e] a plurality of permanent rare-earth magnets imbedded within traction belt to secure biofouling ablation vehicle to hull of ship while traversing the hull for hull surface orientations ranging from vertical to horizontal, [f] a control and communication system incorporating one or more microcomputers, [g] a power supply for supplying a high voltage to energize a plurality of active electrodes in a salt water environment to create a plasma within a vapor layer generating energetic electrons produced at the interface with the marine organisms to effect or cause the molecular dissociation of the targeted marine organisms, [h] one or more removably attachable active electrode modules for the molecular dissociation of targeted marine organisms, [i] a rechargeable battery or a tether connected to an external source of power and [j] an enclosure surrounding the battery or back-up battery supplied by external power source, control and communication systems, battery management system and power supply that provides a thermally insulating barrier to prevent overheating of the enclosed components during a predetermined period of forced convection heating of the biofouling ablation vehicle within the biofouling ablation vehicle maintenance station for the purpose of cleaning the biofouling ablation vehicle.

Each ship-powered biofouling ablation vehicle maintenance station includes [a] an enclosure sufficiently large to receive and secure a single biofouling ablation vehicle and having a closable door at the entrance of the biofouling ablation vehicle maintenance station, [b] receptacle for a water-tight electrical connection to a mating charging plug secured to the biofouling ablation vehicle (for case of battery-powered biofouling ablation vehicle embodiment), [c] a battery recharging current source (for case of battery-powered biofouling ablation vehicle embodiment), [d] a forced air convection heater programmed to heat all exterior surfaces of the biofouling ablation vehicle to a temperature of at least 72° C. (162° F.) for a predetermined heating cycle duration to devitalize (e.g., kill and render nonviable) all marine organisms on the exterior surfaces of the biofouling ablation vehicle, [e] an array of water jet nozzles surrounding all sides of the exterior of the biofouling ablation vehicle and having a source of cleaning water (e.g., filtered water) to remove any solid or liquid devitalized marine organisms and [f] one or more microcomputers. The predetermined duration of the heating cycle for removal of marine organisms and microorganisms is selected to be sufficiently long to increase the temperature of all exterior surfaces of the biofouling ablation vehicle to at least 72° C. for a period, twhile maintaining the temperature of the battery or back-up battery below 50° C. During the heating cycle, the door at the entrance into the biofouling ablation vehicle maintenance station is preferably closed to improve the efficiency of the force air convection heating process.

The ablation of targeted marine organisms and microorganisms through the process of molecular dissociation of marine organisms results in a predictable rate of erosion of the active electrodes incorporated in the one or more removably attachable active electrode modules within the biofouling ablation vehicle. The predictable rate of erosion of the active electrodes enables the control and communication system within the biofouling ablation vehicle to continuously compare usage time with a predetermined maximum allowable usage time. In this manner, the one or more removably attachable active electrode modules can be replaced at predetermined time intervals based on the duration of their use for the ablation of marine organisms and microorganisms.

A predominant characteristic of the present disclosure resides in the molecular dissociation of targeted marine organisms and microorganisms that become attached to the hull of a ship in a seawater environment. Molecular dissociation is achieved through the ionization of atoms within a vapor layer produced in seawater (containing sodium chloride) that leads to the generation of energetic photons having wavelengths in the range from 306 to 315 nanometers (ultraviolet spectrum) and from 588 to 590 nanometers (visible spectrum). In addition, the free electrons within the ionized vapor layer are accelerated in the high electric fields at the distal end of each active electrode incorporated in a removably attachable active electrode module. When the density of the formed vapor layer (or within a bubble formed in the electrically conducting seawater) becomes sufficiently low (i.e., less than approximately 1020 atoms/cmfor aqueous solutions), the electron mean free path increases to enable subsequently injected electrons to cause impact ionization within these regions of low density (i.e., vapor layers or bubbles). Energy evolved by the energetic electrons (e.g., 4 to 5 eV) can subsequently bombard a molecule within the marine organisms or microorganisms and break its organic chemical bonds, dissociating the molecule into free radicals, which then combine into final nonviable gaseous and/or liquid species.

The energy of the generated photons produces photoablation through photochemical and/or photothermal processes to disintegrate biofouling thicknesses as small as several cell layers at the targeted biofouling ablation site. The “fragments” of disintegrated marine organism molecules carry away much of the energy thereby limiting the amount of energy transferred to and potentially damaging the biofouling coating on the hull of the ship.

In addition. other mechanisms contribute to the ablation of the targeted marine organisms and microorganisms. For example, ablation of the marine organisms may also be caused by dielectric breakdown of structural elements or cell membranes within the marine organisms as a result of the generation of highly concentrated intense electric fields at the distal end of the active electrodes within each removably attachable active electrode module. The distal ends of the active electrodes are sized and have exposed surfaces areas which, in the presence of the applied voltage, cause the formation of a vaporized region or layer over at least a portion of the surface of the active electrode. This layer or region of vaporized electrically conducting seawater creates the conditions necessary for ionization within the vaporized region or layer and the generation of energetic electrons and photons. In addition, this layer or region of vaporized electrically conducting seawater provides a high electrical impedance between the electrode and the adjacent tissue so that only low levels of electric current flow across the vaporized layer or region into the targeted marine organisms or microorganisms, thereby minimizing Joulean heating within the antifouling coating on the hull of the ship.

The density of the electrically conducting seawater at the distal tips of the active electrodes is locally heated by the applied electric current thereby forming a vapor layer. Once the density in the vapor layer formed within the seawater reaches a critical value, electron avalanche occurs. The electrons accelerated in the electric field within the vapor layer become trapped after one or a few scatterings. These injected electrons serve to create or sustain a low-density region with a large mean free path to enable subsequently injected electrons to cause impact ionization within these regions of low density. The energy evolved at each recombination is on the order of half of the energy band gap (i.e., 4 to 5 eV). This energy can be transferred to another electron to generate a highly energetic electron. This second, highly energetic electron has sufficient energy to bombard an organic molecule to break its chemical bonds, i.e., dissociate the organic molecule into free radicals.

Referring to, a first embodiment of the marine antifouling system according to the present disclosure is represented in general at. The marine antifouling systemincludes one or more battery-powered biofouling ablation vehiclesand one or more biofouling ablation vehicle maintenance stations. The one or more battery-powered biofouling ablation vehiclesare in wireless communication with a command and control centerand its operatorlocated on shipas seen along second communication pathin. Although frequently referenced throughout the Detailed Description, shipis only seen in. Likewise, the one or more biofouling ablation vehicle maintenance stationsare also in wireless communication with a command and control centerand its operatorlocated on shipas seen along first wireless communication pathin.

The maintenance station enclosureof each biofouling ablation vehicle maintenance stationis secured to the exterior surface of the hullof the ship and is located well above, preferably at least 20 feet above, the water line of the ship. Also, each biofouling ablation vehicle maintenance stationis positioned so that it is accessible by pre-programmed movement of the biofouling ablation vehiclefor the purpose of [a] replacing used removably attachable active electrode modules(not shown), [b] re-charging the battery within the biofouling ablation vehicleand [c] removing any marine organisms that become attached to the exterior surfaces of the biofouling ablation vehicle. As seen in, an openable dooris pivotably supported by the maintenance station enclosureand is positioned at the entranceof the biofouling ablation vehicle maintenance station. Dooris wirelessly and remotely openable by a control system (not shown) within the biofouling ablation vehicleto enable entrance into and exit from the biofouling ablation vehicle maintenance station. In a preferred embodiment, dooris closed during the period of forced air convection heating of the exterior of the biofouling ablation vehicleto at least 72° C. for the purpose of removing marine organisms from the exterior of the biofouling ablation vehicle. The forced air convection heating unit located within the biofouling ablation vehicle maintenance stationis not shown in.

Still referring to, the directions of travel of the biofouling ablation vehicle for the purpose of entering and exiting the biofouling ablation vehicle maintenance station is seen at. First and second wheelsandare seen on one side of biofouling ablation vehicle. Third and fourth wheelsandlocated on the side of the biofouling ablation vehicleopposite first and second wheelsandare not seen in. Several of a plurality of water jet nozzlesare visible at the entranceof the biofouling ablation vehicle maintenance station. Following the forced air convection heating of the exterior of the biofouling ablation vehicle, pressurized water (e.g., filtered water) is sprayed over the exterior of the biofouling ablation vehicleto remove the devitalized marine organisms and microorganisms from the surfaces of the biofouling ablation vehicle.

Referring next to, a second and preferred embodiment of the marine antifouling system according to the present disclosure is represented in general at. The marine antifouling systemincludes one or more biofouling ablation vehiclesand one or more biofouling ablation vehicle maintenance stations. Each biofouling ablation vehicleis individually connected to an external source of power by a reinforced electrical power and communication tether. The one or more externally powered biofouling ablation vehiclesare in communication with a command and control centerand its operatorlocated on shipas seen along second wireless communication pathas well as through fiber optic and/or data cablein. Likewise, the one or more biofouling ablation vehicle maintenance stationsare also in wireless communication with a command and control centerand its operatorlocated on shipas seen along first wireless communication pathin.

The maintenance station enclosureof each biofouling ablation vehicle maintenance stationis secured to the exterior surface of the hullof the shipand is located well above, preferably at least 20 feet above, the water line of the ship. Also, each biofouling ablation vehicle maintenance stationis positioned so that it is accessible by pre-programmed movement of the biofouling ablation vehiclefor the purpose of [a] replacing used removably attachable active electrode modules(not shown) and [b] removing any marine organisms that become attached to the exterior of the biofouling ablation vehicle. As seen in, an openable doorwith slotis pivotably supported by the maintenance station enclosureand is positioned at the entranceof the biofouling ablation vehicle maintenance station. Dooris wirelessly and remotely openable by a control system (not shown) within the biofouling ablation vehicleto enable entrance into and exit from the biofouling ablation vehicle maintenance station. In a preferred embodiment, dooris closed during the period of forced air convection heating of the exterior of the biofouling ablation vehicleto at least 72° C. for the purpose of removing marine organisms from the exterior of the biofouling ablation vehicle. The forced air convection heating unit located within the biofouling ablation vehicle maintenance stationis not shown in.

Still referring to, the directions of travel of the biofouling ablation vehicle for the purpose of entering and exiting the biofouling ablation vehicle maintenance station is seen at. First and second wheelsandare seen on one side of biofouling ablation vehicle. Third and fourth wheelsandlocated on the side of the biofouling ablation vehicleopposite first and second wheelsandare not seen in. Several of a plurality of water jet nozzlesare visible at the entranceof the biofouling ablation vehicle maintenance station. Following the forced air convection heating of the exterior of the biofouling ablation vehicle, pressurized water (e.g., filtered water) is sprayed over the exterior of the biofouling ablation vehicleto remove the devitalized marine organisms and microorganisms from the surfaces of the biofouling ablation vehicle.

Tuning now to, the biofouling ablation vehicleof the first embodiment is seen in greater detail. A partially sectioned and cut away perspective view of the interior of a biofouling ablation vehicle enclosurereveals the principal components within a biofouling ablation vehicle. The principal components within the biofouling ablation vehicle enclosureinclude a battery, a battery management system, a power supply, a control and communication system(for example, a control and wireless communication system) and a support framecontaining an array of ablation module assemblies(not shown). The biofouling ablation vehicle enclosurealso provides a water-tight seal around the battery, battery management system, power supply, control and wireless communication systemand support framethereby preventing the ingress of sea water into the interior of the biofouling ablation vehicle enclosure.

Biofouling ablation vehicle enclosurealso supports four wheels-having a diameter Dof which only first and second wheelsand, respectively, are seen on first sideof biofouling ablation vehiclein. One wheelon first and second sideand, respectively, of biofouling ablation vehiclefunctions as a drive wheel and is actuated by a motor, preferably a hub motor. The perimeter of each wheelincorporates a plurality of uniformly spaced ribsthat engage corresponding uniformly spaced slots(not shown) located on the interior surface of flexible traction beltas the wheels rotate, wherein traction belthas width, W(wherein only first drive beltis seen. In). Each of the four wheels-are supported by suspension system secured to the biofouling ablation vehicle enclosure. A plurality of permanent magnets is securely contained within the flexible traction beltto enable the biofouling ablation vehicle to be magnetically secured to the steel hullof the shipas the biofouling ablation vehicletraverses the hullof the shipduring the ablation of marine fouling on the surface of the hullof the shipbelow the water line. By way of example, neodymium Grade 52 magnets composed of NdFeB are characterized by a strong magnetic field having strong associated attractive forces. By way of example, neodymium Grade 52 magnets are commercially available from K&J Magnetics, Pipersville, Pennsylvania.

By way of example, each of drive wheelsmay have a diameter, Dof 8.0 inches and width, Wof 2.5 inch. Each drive wheelmay have 24 equally spaced ribshaving a nominal rib width of 0.25 inch and rib height of 0.25 inch. In the present example, a traction belthaving a width of 2.5 inches and a thickness of 0.70 inch is seen in partial sectional view in. A plurality of slotshaving a nominal width of 0.26 inch and depth of 0.25 inch are located on the inner surfaceof traction beltat a spacing of L. The size of the slotsare dimensioned to receive the ribson the perimeter of each drive wheel. For the present example of drive wheelshaving a nominal diameter of 8.0 inches, a preferred slot spacing, Lbetween slotsis nominally 1.0 inch. By way of example and as seen in, permanent magnetscan be positioned between slotsat a nominal magnet spacing, Lis. In this example, the nominal magnet spacing, Lis substantially the same as the slot spacing, Lof 1.0 inch. For the case of a spacing between drive wheelsof 25 inches, the number of permanent magnetsthat can be incorporated into each traction beltalong the length of contact with the hullat a nominal magnet spacing, Lis of 1.0 inch is 25. Hence, a total of 50 permanent magnets can be incorporated within first and second traction beltsand

By way of further example, assume the permanent magnetsincorporated or imbedded within first and second traction beltsand, as seen in the partial sectional view in, are rectangular magnets having a width of 0.30 inch, a length of 2.0 inches and a thickness of 0.30 inch. The length of each permanent magnetextends across the width of the traction belt. This example width of permanent magnetsand their positioning between slotsenables the traction beltfollow the curvature of the drive wheels. As seen in, assuming a combined thickness of 0.30 inch for the intervening layers of traction belt, layer of marine organismsand antifouling coating, then the total spacing between the permanent magnetand the steel hullof the shipis 0.30 inch. Based on the above dimensions of the permanent magnetsand its distance from the steel hullof the ship, the attraction force between each magnetwithin the traction beltand the hullcalculated by a permanent magnet manufacturer, K&J Magnetics, is 5.3 pound per magnet. This calculation is based on the use of neodymium Grade 52 magnets composed of NdFeB. In the present example incorporating a total of 50 permanent magnetsalong the length of contact with the hull, the combined magnetic attraction force is 50 magnets×5.3 pounds attraction force per magnet or a total attraction force of 265 pounds. This level of magnet attraction force should be sufficient for the preferred size of the biofouling ablation vehicleor. In this regard, neodymium Grade 52 magnets are commercially available from K&J Magnetics, Pipersville, Pennsylvania.

Still referring to, first and second battery plug recharging terminalsand, respectively, are seen at the front endof the biofouling ablation vehicle enclosureand extend from battery. First and second electrically insulative sleevesand, respectively, surround the first and second battery plug recharging terminalsand, respectively, within the interior of the biofouling ablation vehicle enclosure. In a preferred embodiment, the portions of the first and second battery plug recharging terminalsandthat are exterior to the biofouling ablation vehicle enclosuremay be first and second compressible elastomeric shroudsand, respectively, that elastically compress and retract when first and second battery plug recharging terminalsandare inserted into and come into electrical communication with the corresponding first and second charging receptaclesand, respectively, within the biofouling ablation vehicle maintenance stationas seen in.

Tuning now to, a biofouling ablation vehicleof the second and preferred embodiment is seen in greater detail. A partially sectioned and cut away perspective view of the interior of the biofouling ablation vehicle enclosurereveals the principal components within a biofouling ablation vehicle. The principal components within the biofouling ablation vehicleinclude a reinforced electrical power and communication tether, an AC to DC converter, back-up battery, battery management system, power supply, control and communication systemand support framecontaining an array of ablation module assemblies(not shown). The biofouling ablation vehicle enclosurealso provides a water-tight seal around the AC to DC converter, back-up battery, battery management system, power supply, control and communication systemand support framethereby preventing the ingress of sea water into the interior of the biofouling ablation vehicle enclosure.

Biofouling ablation vehicle enclosurealso supports four wheels-having a diameter Dof which only first and second wheelsand, respectively, are seen on first sideof biofouling ablation vehiclein. One wheelon first and second sideand, respectively, of biofouling ablation vehiclefunctions as a drive wheel and is actuated by a motor, preferably a hub motor. The perimeter of each wheelincorporates a plurality of uniformly spaced ribsthat engage corresponding uniformly spaced slots(not shown) located on the interior surface of flexible traction beltas the wheels rotate, wherein traction belthas width, W(wherein only first drive beltis seen. In). Each of the four wheels-are supported by suspension system secured to the biofouling ablation vehicle enclosure. A plurality of rare-earth magnets is securely contained within the flexible traction beltto enable the biofouling ablation vehicle to be magnetically secured to the steel hullof the shipas the biofouling ablation vehicle enclosuretraverses the hullof the shipduring the ablation of marine fouling on the surface of the hullof the shipbelow the water line. By way of example, neodymium Grade 52 magnets composed of NdFeB are characterized by a strong magnetic field having strong associated attractive forces. By way of example, neodymium Grade 52 magnets are commercially available from K&J Magnetics, Pipersville, Pennsylvania.

Still referring to, reinforced electrical power and communication tetheris seen at the front endof the biofouling ablation vehicle enclosureand is in electrical communication with AC to DC converter. The AC to DC converteris in electrical communication with back-up battery, battery management system, power supplyand control and communication system. In addition to 440 volt, 3-phase, 60 Hz power lines and flexible load-bearing cable, the reinforced electrical power and communication tetheralso incorporates fiber optic and/or data cable for transmission of signals from digital image or other sensors located on bottom surface of support frameseen inbut not seen in.

By way of example, a preferred neutrally buoyant reinforced electrical power and communication tetheris seen inhaving a diameter, Dranging from 6 mm to 15 mm and including first, second and third conductor lines,,, respectively, fiber optic and/or data cable, buoyancy filler, Kevlar strengthening layerand outer covering. Preferably, first, second and third conductor lines,,, respectively, within reinforced electrical power and communication tetherthat carry 440 volt, three phase power at 60 Hz are copper wires with electrically insulative coverings. Also, the outer coveringof reinforced electrical power and communication tetheris polyethylene to confer resistance to abrasion, ultraviolet light and sea water. The buoyancy fillerwithin reinforced electrical power and communication tetheris preferably a foam elastomer to confer neutral buoyancy to reinforced electrical power and communication tetherthereby improving maneuverability within the sea water as the biofouling ablation vehicletraverses the hullof the ship. In this regard, see commercially available tethers for use in sea water manufactured by Invocean, a division of the Marmion Group, Houston, Texas.

Turning now to, the biofouling ablation vehicle maintenance stationof the first embodiment that is securely attached to hullof shipis seen in greater detail. A partially sectioned and cut away perspective view of the interior of the biofouling ablation vehicle maintenance station enclosurereveals forced-convection heating unithaving fanto circulate heated air and air intake vent, battery recharging unithaving first and second recharging receptaclesand, respectively, cleaning water pressurization and control unitthat is connected to liquid flow lines (not shown) leading to a plurality of water jet nozzlesused for cleaning the exterior of the biofouling ablation vehiclefollowing its return to the biofouling ablation vehicle maintenance stationand after the biofouling ablation vehicleis exposed to forced-convection air heating to enable the removal of any surface accumulation of marine fouling on the exterior surfaces of the biofouling ablation vehicle. Power lineconnected to ship electrical utility source (not shown) supplies electrical power (e.g., 440 volts, 3 cycle power at 60 Hz) to battery recharging unit. Water supply lineis connected to cleaning water pressurization and control unitat water inlet port receptaclewith removably connectable water supply fitmentlocated at distal end of water supply line. An openable doorthat is motor-actuated is pivotably supported by the maintenance station enclosureand is positioned at the entrance(not shown) of the biofouling ablation vehicle maintenance station. Dooris wirelessly and remotely openable by a control system (not shown) within the biofouling ablation vehicleto enable entrance into and exit from the biofouling ablation vehicle maintenance station.

In a preferred embodiment, dooris closed during the period of forced-convection air heating of the exterior of the biofouling ablation vehicleto at least 72° C. for the purpose of removing marine organisms from the exterior surfaces of the biofouling ablation vehicle. An air gap or other insulative material thickness of at least 0.25 inch is maintained between the inner surfaces of the biofouling ablation vehicle enclosureand the principal components contained within the biofouling ablation vehicleincluding the battery, battery management system, power supplyand control and wireless communication system. A thickness of at least 0.25 inch assures that the principal components contained within the biofouling ablation vehicleare maintained at acceptably low temperatures to prevent any thermal damage to these principal components during the forced-convection heating procedure. The use of forced-convection air heating within the enclosed biofouling ablation vehicle maintenance station enclosureenables the exterior surfaces of the biofouling ablation vehicleto be heated to at least 72° C. within a period of preferably less than 30 minutes.

Still referring to, a hinged dooris seen on the bottom surface of enclosuresupported by a plurality of hinges. Only hingesandare seen in. The hinged doorand the perimeterof the base of the maintenance station enclosureare fabricated using a ferromagnetic material (e.g., steel). The ferromagnetic material (e.g., steel) used to fabricate the perimeterof the base of the maintenance station enclosureenables the magnetswithin first and second traction beltsandas seen in(traction beltnot seen in) to remain magnetically attached to the base of the maintenance station enclosureas it enters the biofouling ablation vehicle maintenance station. The width the hinged dooris less than the width between the inner edges of the first and second traction beltsand, respectively, on the biofouling ablation vehicleso that hinged doorcan be opened without the requirement to overcome the attraction forces of the magnets imbedded within the traction beltsand. The hinged doorprovides operator access to the bottom surface of support frameto enable access to and replacement of the removably attachable active electrode modulesseen inwithin the array of ablation module assembliesshown in.

Turning next to, the biofouling ablation vehicle maintenance stationof the second and preferred embodiment that is securely attached to hullof shipis seen in greater detail. A partially sectioned and cut away perspective view of the interior of the biofouling ablation vehicle maintenance station enclosurereveals forced-convection heating unithaving fanto circulate heated air and air intake ventand cleaning water pressurization and control unitthat is connected to liquid flow lines (not shown) leading to a plurality of water jet nozzlesused for cleaning the exterior of the biofouling ablation vehiclefollowing its return to the biofouling ablation vehicle maintenance stationand the biofouling ablation vehicleis exposure to forced-convection air heating to enable the removal of any surface accumulation of marine fouling on the exterior surfaces of the biofouling ablation vehicle. Power lineconnected to ship electrical utility source (not shown) supplies electrical power (e.g., 440 volts, 3 cycle power at 60 Hz) to the forced-convection air heating unitas well as the cleaning water pressurization and control unit. Water supply lineis connected to cleaning water pressurization and control unitat water inlet port receptaclewith removably connectable water supply fitmentlocated at distal end of water supply line. An openable doorthat is motor-actuated incorporates slot(to accommodate reinforced electrical power and communication tetherattached to biofouling ablation vehicle) and is pivotably supported by the maintenance station enclosureand is positioned at the entrance(not shown) of the biofouling ablation vehicle maintenance station. Dooris wirelessly and remotely openable by a control system (not shown) within the biofouling ablation vehicleto enable entrance into and exit from the biofouling ablation vehicle maintenance station.

In a preferred embodiment, doorhaving slotis closed during the period of forced air convection heating of the exterior of the biofouling ablation vehicleto at least 72° C. for the purpose of removing marine organisms from the exterior surfaces of the biofouling ablation vehicle. An air gap or other insulative material thickness of at least 0.25 inch is maintained between the inner surfaces of the biofouling ablation vehicle enclosureand the principal components contained within the biofouling ablation vehicleincluding the back-up battery, battery management system, power supplyand control and wireless communication system. A thickness of at least 0.25 inch assures that the principal components contained within the biofouling ablation vehicleare maintained at acceptably low temperatures to prevent any thermal damage to these principal components during the forced-convection heating procedure. The use of forced convection heating within the enclosed biofouling ablation vehicle maintenance station enclosureenables the exterior surfaces of the biofouling ablation vehicleto be heated to at least 72° C. within a period of preferably less than 30 minutes.

Still referring to, a hinged dooris seen on the bottom surface of enclosuresupported by a plurality of hinges. Only hingesandare seen in. The hinged doorand the perimeterof the base of the maintenance station enclosureare fabricated using a ferromagnetic material (e.g., steel). The ferromagnetic material (e.g., steel) used to fabricate the perimeterof the base of the maintenance station enclosureenables the magnetswithin the traction beltsandseen in(traction beltnot seen in) to remain magnetically attached to the base of the maintenance station enclosureas it enters the biofouling ablation vehicle maintenance station. The width the hinged dooris less than the width between the inner edges of the first and second traction beltsand, respectively, on the biofouling ablation vehicleso that hinged doorcan be opened without the requirement to overcome the attraction forces of the magnets imbedded within the traction beltsand. The hinged doorprovides operator access to the bottom surface of support frameto enable access to and replacement of the removably attachable active electrode modulesseen inwithin the array of ablation module assembliesseen in.

A sectional view of an active electrode assemblyincluding a removably attachable active electrode moduleand an interconnection terminal array moduleis shown in. A plurality of interconnection terminal array modulesare secured to support frameand enable the removably attachable active electrode moduleto be replaced once the active electrodeswithin the removably attachable active electrode modulehave become eroded as a result of the ablation process used to molecularly dissociate marine fouling that has become attached to the hullof the shipbelow the water line. The interconnection terminal array moduleincorporates a plurality of connector pinsthat are individually attached to a connector pin base. Each a connector pin baseis in electrical communication with a cable harnessincluding an individual active electrode lead wirefor each connector pin basewithin the interconnection terminal array module. The interconnection terminal array modulealso supports common electrode connector pin. Upon attachment of a removably attachable active electrode moduleto the interconnection terminal array module, the common electrode connector pinremovably attaches to a mating receptacle within and the common electrodethat surrounds and is electrically insulated from the active electrodesas seen in. The cable harnessis in electrical communication with each interconnection terminal array moduleand extends to multiplexerwithin power supply(not shown). In addition, individual electrically isolated electrical lead wires within the cable harnessare in electrical communication with each connector pinwithin the interconnection terminal array module. As seen in, common electrode connector pinis also in electrical communication with common electrode leadthat extends to a radiofrequency generator(as seen in).