WO2013013679A1

WO2013013679A1 - A ship hull cleaning system for removing fouling

Info

Publication number: WO2013013679A1
Application number: PCT/DK2012/050281
Authority: WO
Inventors: Jørgen Hansen
Original assignee: Mms Equipment A/S
Priority date: 2011-07-27
Filing date: 2012-07-27
Publication date: 2013-01-31
Also published as: DK201170408A; EP2736799A4; EP2736799A1; DK177265B1

Abstract

A hull cleaning system (1) for removing fouling from a ship comprises an underwater cleaning unit (2) having cleaning brushes (3) rotatable by at least one drive (4). A water suction line (5) connects the cleaning unit with a centrifugal pump (6), and a water pressure line (7) from the pump passes via at least one filter device (8) to the drive (4) for the brushes. A water outlet (9) from the drive (4) acts to drive the cleaning unit along the hull. The removed fouling is transported via the water suction line and the pump to the filter device (8).

Description

A Ship hull cleaning system for removing fouling

The present invention relates to a ship hull cleaning system for removing fouling, the ship hull cleaning system comprising an underwa- ter cleaning unit having cleaning brushes rotatable by at least one drive, a water suction line connecting the cleaning unit with a pump, and a water pressure line from the pump to the cleaning unit, cleaned off fouling being transportable via the water suction line to at least one filter device.

Such a system is disclosed in EP 0 275 605, in which the water pressure line to the cleaning unit is fed from a pressurized tank, and the pump suction side is connected with the water suction line via the filter device. US 6,070,547 discloses a cleaning unit in which a water suction line leads to a filter for removing cleaned off fouling. US 7,905,192 discloses a cleaning unit powered by separate motors and driven by an en- gine unit holding the cleaning unit. The cleaning unit is provided with a water recirculation system ejecting water in around the brushes of the cleaning unit and drawing water out via a suction line provided with a filter and a pump. The pressure line is connected with a hydro-cyclone phase separator device or with a large shore based processing facility. US 5,628,271 relates to a recirculation system for cleaning of vessels in dry- dock. A pressure pump draws water from a holding tank to a cleaning device. Dirty water is pumped via a filter and clean water from the filter is pumped to the holding tank for reuse.

It is an aim of the present invention to provide a reliable and easy to operate ship hull cleaning system.

In view of this, the ship hull cleaning system according to the present invention is characterized in that the pump is a centrifugal pump, that the at least one filter device is located downstream of the centrifugal pump and is connected with the water pressure line leading to the at least one drive, and that the at least one drive has a water outlet positioned for driving the cleaning unit along the hull.

The centrifugal pump is insensitive to the presence of fouling parts in the pumped water, and the centrifugal pump can deliver high volumes of water at a significant pressure. The at least one filter device in the water pressure line is very reliable in operation because it is supplied with water at high pressure. The pressure and volume delivered by the centrifugal pump allows effective filtration in the filter device provided downstream of the pump and furthermore allows the water flow from the filter to continue via the water pressure line to the drive rotating the brushes, and furthermore to exit from the drive through the wa- ter outlet positioned to drive the cleaning unit along the hull.

The water pressure line from the filter device delivers water to the at least one drive for the brushes in the cleaning unit, and if the filter for one reason or another should be restricting or blocking for water flow, then the brushes will slow down in rotation or even stop operating. The cleaning unit is thus automatically slowed down or stopped if the filter device is clogged. After the water from the pressure line has driven the drive for the brushes it exits to sea via a water outlet for driving the cleaning unit forward in the cleaning direction. This provides a simple means for driving the cleaning unit forward and the cleaning unit is easy to operate. The single centrifugal pump is providing pressurized water for filtration, driving of brushes, and driving of the cleaning unit along the cleaning path on the underwater hull portion of the ship.

The surface to be cleaned is the outside surface of the hull, and this surface is either vertical on major parts of the side of the ship, or facing more or less downwards on the side parts curving towards the bottom of the hull, or facing directly downwards at the bottom of the ship hull. Gravity thus tends to remove the cleaning unit away from the surface. The centrifugal pump can deliver high volumes of water, at in operation it can thus also draw a high volume of water through the wa- ter suction line, and this high volume on the one hand provides for an efficient removal of brushed off fouling and on the other hand provides a flow around the cleaning unit that helps keeping the cleaning unit on the working track along the outer surface of the hull.

The water outlet may be fixed in a position, which by experience is suitable for providing forward motion of the cleaning unit. However, it is preferred that the water outlet from the at least one drive is direction- ally adjustable in relation to the cleaning unit. This provides a diver with the possibility for changing the direction of movement of the cleaning unit in a very easy manner. In order to clean a large underwater surface the cleaning unit has to pass in the forward direction and in the aft direction many times in parallel paths, and it is easier to change the direction of the water outlet than to turn with the complete cleaning unit.

In an embodiment the underwater cleaning unit has a water suction line to the centrifugal pump with a larger diameter than the water pressure line from the centrifugal pump. The centrifugal pump is thus met with lower flow resistance on the suction side than on the pressure side, and it may furthermore be an advantage to let the pump cause a larger water flow volume in the water suction line than in the water pressure line to the underwater cleaning unit. The difference in flow volume can be obtained by opening a by-pass valve or a waste valve located in the pressure line, preferably downstream of the filter device. The by-pass valve can be used if pressurized water can be used for other purposes than supplying the underwater cleaning unit, and a waste valve can be used if the pressurized water is simply let out to sea.

In another embodiment the underwater cleaning unit has a circumferential hollow structure providing buoyancy to the cleaning unit. The circumferential structure can be formed as a pipe, preferably a pipe of a material having a density lower that 1, such as a density of 0.98, so that material in the structure itself also provides positive buoyancy in sea water. The hollow structure may be dimensioned so that the cleaning unit has a negative buoyancy of less than 10 kg, and preferably in the range from 4 to 0.5 kg, and more preferably about 2 kg. When the cleaning unit is in operation it has a tendency to be directed by suction towards the outer surface being cleaned, and a small negative buoyancy is favourable for easy operation by the diver.

In a preferred embodiment the at least one filter device is mounted at a container, the container being provided with at least one buoyant body for positioning below the container. The filter device is preferably maintained above sea level while the cleaning unit is used for underwater hull cleaning. Although it is possible to locate the filter on shore, it is very advantageous to mount it at a container, which is a moveable object, and to support the container by at least one buoyant body, as this makes it possible to position the filter in vicinity of the working position of the cleaning unit. The at least one buoyant body may just support the container from below and the container may be partially self-floating, but preferably the at least one buoyant body has sufficient size to hold the container and the equipment therein in a position where the bottom of the container is above sea water level. To achieve this, the buoyancy of the at least one buoyant body is larger than the combined weight of the container, the buoyant body itself and the equipment and personnel present at the container. The container with the equipment may be floated to a position next to the ship to be cleaned with the re- suit that the water suction line and the water pressure line may have shorter lengths as the distances between the pump and the filter device on the one hand and the cleaning unit on the other hand are smaller when the container is close to the ship.

In an embodiment the at least one buoyant body has a length and a width corresponding to the length and width of the container, and the at least one buoyant body has corner fittings. The corner fittings on the buoyant body can be locked to similar corner fittings on the container, such as by using twist-locks or other standard container corner locking equipment. An advantage of this is that the buoyant body can be connected with the container by standard means and without exceeding the footprint of the container, such as 6.1 m x 2.44 m (20' x 8') for a 20' ISO standard container, or 12.2 m x 2.44 m (40' x 8') for a 40' ISO standard container. When not in use, the hull cleaning system is thus easy to store as it fits into standard container systems, and it is easy to move as standard container cranes can be used.

In an embodiment the container is provided with two buoyant bodies. The stability of the system in floating condition is improved by using two buoyant bodies instead of only a single buoyant body, because the two buoyant bodies may be located with mutual separation below the container and thus provide a higher righting moment.

In an embodiment either end of the container is locked to one of the two buoyant bodies, the buoyant bodies being located with their length direction extending in the width direction of the container, when the system is in its floating operating condition. The container and the two buoyant bodies are thus in an H-type configuration when viewed from above, and this provides a high degree of floating stability. This configuration also provides free deck space outside the footprint of the container, and better ability for personnel to move around and assist di- vers and handle moorings etc. during the cleaning operation.

In a further development the two buoyant bodies are spaced apart and a floor structure, preferably a grating, extends between the buoyant bodies in the area next to the container. The grating increases the available deck space.

The hull cleaning system preferably has an inactive condition, in which at least the cleaning unit, the water suction line, the water pressure line, the centrifugal pump, the at least one filter device, a generator and possibly diving equipment are stored within the container. As an option, the at least one buoyant body can be positioned on the container with the length direction extending in the length direction of the container. The at least one buoyant body can be positioned on top of the container or on the bottom side of the container, or in case of two or more buoyant bodies both on the bottom side and on the top side of the container. Two buoyant bodies can alternatively be locked together on top of one another. This alternative is preferred in cases, where the buoyant bodies have a height corresponding to about 50% of the height of the container. In the inactive condition the complete hull cleaning system is easily stored in a safe manner.

In an embodiment the container is provided with diving equip- ment. By including diving equipment in the container of the hull cleaning system it becomes possible to dispense with using a separate diving ship.

In an embodiment the container is provided with communication equipment and recording equipment for the underwater operation of the cleaning unit. The communication equipment allows easy communication with the diver or divers operating the cleaning unit, and the recording equipment, such as video recording, may document the cleaning operation.

In an embodiment the hull cleaning system is self-propelled by providing one of the buoyant bodies with an engine driving a water pump, and providing the buoyant bodies with submerged nozzles for ejecting pressurized water delivered by the water pump.

Illustrative examples of embodiments of the present invention are described in further detail in the following with reference to the highly schematic drawings, on which

Figs. 1 and 2 are side views of the hull cleaning system according to a first embodiment and a second embodiment of the present invention stored in inactive conditions,

Figs. 3 to 5 are illustrations of the embodiment in Fig. 2 as it is shifted to an active, operating condition; where Figs. 3 and 5 are views from above, and Fig. 4 is a side view,

Fig. 6 is an illustration in a view from above of an embodiment in the operating condition,

Figs. 7 and 8 are views from the outside a nd the inside of a cleaning unit of the hull cleaning system of Fig. 2, and

Figs. 9 and 10 are views like Figs. 7 and 8 of a further a cleaning unit of the hull cleaning system of Fig. 2.

A hull cleaning system is generally designated 1 and includes in a stored away condition various parts located inside a container 10 and two buoyant bodies 11 located outside container 10. The two buoyant bodies 11 can be arranged in different ways with respect to the container in the stored away condition. The buoyant bodies can be stored separately from the container. The buoyant bodies can be arranged below and on top of the container, as it is illustrated in Fig. 1, both buoyant bodies can be arranged on top of the container, or both buoyant bodies 11 can be arranged below the container 10. In the first embodiment of Fig. 1 the buoyant bodies have sufficient height to provide the required buoyancy.

In a second embodiment illustrated in Fig. 2 the buoyant bodies have larger height than in the first embodiment, namely a height corresponding to about half the height of container 10. One advantage of this is obtained by locating the buoyant bodies on top of one another during storage so that they occupy the same storage space as a single standard container. Another advantage is a higher freeboard in floating condition, and thus less sensitivity to waves during operation.

The length and the width of the buoyant body 11 correspond to the length and the width of the container 10. Container 10 may have a freely selected size, but it is preferably an ISO standard container of 20' in length, or possibly of 40' in length. The container 10 has standard corner fittings 12, and the buoyant body 11 is provided with the same type of standard corner fittings 12 at each corner in the same manner as such corner fittings are provided on the container. The corner fittings on both the container and the buoyant body 11 may consequently be interlocked by container standard brackets or container standard twist-locks. In the interconnected state a container crane or another container lifting device can in a single operation lift container 10 and buoyant bodies 11, and the management of the system on shore is thus particularly simple.

When the hull cleaning system is to be utilized the container handling or lifting device is activated to lift or transport the interlocked container and buoyant bodies 11 to a shore location nearby a ship to be cleaned from fouling. The buoyant bodies 11 are released by activating the twist-locks or other devices interlocking corner fittings to the un- locked position, and then buoyant bodies 11 are handled to be positioned as illustrated in Fig. 3, where the buoyant bodies 11 are placed in parallel and with such a mutual separation that the four corner fittings on the lower corners of container 10 can be aligned with the two pairs of two corner fittings 12 located within the central portions of the upper surface of each of the buoyant bodies 11. These corner fittings are interlocked with the corner fittings on the lower corners of container 10 by using locking devices, such as twist-locks. The container 10 and the buoyant bodies 11 are then interlocked in the H-shaped configuration illustrated in Figs. 4 and 5. It is possi ble to mount stiffeners to the buoyant bodies 11, such as a horizontal stiffener 30 between the upper corner fittings at the short ends of bodies 11. These horizontal stiffeners are thus located at the bottom and at the top in the H-shape interconnecting the free ends. A horizontal stiffener may also be mounted between the lower corner fittings at the short ends of bodies 11. It is also possible to interconnect two horizontal stiffeners via vertical stiffeners to form a frame shape, and such a frame shape can be strengthened by diagonal stiffening. The frame may be located in between the short ends of the bodies 11 and be locked to the corner fittings of the bodies 11. The horizontal stiffeners may have standard corner fittings at the ends of the individual stiffener, or the stiffeners may at the ends have locking heads to be inserted into and locked to the corner fittings on the bodies 11. The additional strength provided by the horizontal stiffener or stiffeners is advantageous, but not always necessary, and the hull cleaning system may thus in another embodiment be without such stiffeners.

The container can have access doors in the end sides, but preferably is has at least one access door in the longitudinal side. A floor structure 14 is placed between the buoyant bodies 11 along either longitudinal side of the container. The floor structure can be a grating, which is removable and can be stored inside the container. In an embodiment one of the floor structures 14 can be shifted between two positions, namely the active position illustrated in Fig. 6 where the floor structure provides support for personnel, and an inactive position where the floor structure has been moved to a position below container 10. In the inac- tive position there is an open view down into the water over substantially the whole area in between the bodies 11. The floor structure may e.g. be mounted for swinging between the two positions or it may be mounted for sliding between the two positions, such as by being placed with possibility for sliding on supports extending horizontally in below container 10.

In an embodiment container 10 has a window 28 mounted in the vertical side wall in the area located between the two bodies 11, and preferably a control desk 29 within container 10 is placed near the window. It is thus possible from within container 10 to follow the diving op- eration both on equipment located in the container and visually by looking out of the window down into the water. In operation, the right hand ends of bodies 11 in Fig. 6 are located next to the side of the hull and the water surface between the bodies is relatively calm which improves the visibility from above, and the floor structure 14 is typically in the in- active position where it does not block the view from the window into the water.

In order to reduce noise inside the container a power generator 15 can be positioned on the upper side of the one buoyant body 11, and a centrifugal pump 6 can be positioned on the upper side of the other buoyant body 11. As an alternative the power generator 15 can be mounted inside the buoyant body 11, and the centrifugal pump 6 can also be mounted inside buoyant body 11. Such a mounting reduces the noise made by the operation of in particular the power generator. The mounting inside the buoyant body also protects the pump or the power generator against weather. It is also possible to mount the power generator inside the one buoyant body and the centrifugal pump within the other buoyant body.

As an example, the power generator may be a generator del i- vering power at 230 V and 50 Hz, where the generator is driven by a di- esel engine. The diesel engine and the generator are preferably mounted in a frame structure so at to be movable as a unit. A power generator of this type is available from EuroCommerce ApS, Denmark in a 6 kW version. The centrifugal pump may be a FOX Portable Pump from Rosen- bauer International, Austria of the type PFPN having a capacity of 1000 liters per minute at a delivery pressure of 15 bar and 1600 liters per minute at a delivery pressure of 10 bar. This centrifugal pump is a single-stage pump provided with an automatically controlled double action piston pump for priming the centrifugal pump. The pump is driven by a BMW 2 cylinder four-stroke piston engine providing an output of 50 kW at 4500 rpm.

A water suction line 5, typically a steel-armored hose is connected to the suction side of centrifugal pump 6. A water pressure line 7 is connected to the pressure side of centrifugal pump 6 and extends to a filter device 8, such as an automatic filter of the type AF 75 S or AF 76 S and the make Mahle, available from the company Filterteknik, Denmark. It is possible to use only a single filter device 8, but preferably several filter devices are used in series as illustrated in Fig. 6, where the outlet from the first filter device is connected with the inlet of the second filter device, and so forth for the four filter devices. It is also possible to couple the filter devices in parallel.

On the downstream side of filter device 8 the water pressure line 7 extends to a first connection 23 on a cleaning unit 2 (fig. 7). The first connection 23 has an inlet opening to a drive 4 for cleaning brushes 3. The drive is a water turbine where the turbine wheel within the drive housing receives the pressurized water at the periphery of the wheel and delivers spent water at the center of the wheel where a central exit pipe extends via a pipe bend to a water outlet 9. Water outlet 9 is preferably directed to face opposite to the desired path to be followed by the cleaning unit. The pipe bend and the pipe section extending between the bend and water outlet 9 may be mounted onto the exit pipe from the drive housing in a swiveling manner so that the pipe section can be easily turned with the water outlet facing in the opposite direction, as is illu- strated in broken lines in Fig. 7.

The cleaning unit 2 has an inner space between the outer side viewed in Fig. 7 and the inner side viewed in Fig. 8. Within this inner space a toothed drive wheel is mounted on the drive shaft of the turbine wheel and is engaging toothed intermediate wheels which engage with toothed drive wheels on central shafts for cleaning brushes 3. As an alternative a drive belt may be used to drive all cleaning brushes from a pulley mounted on the drive shaft of the turbine wheel, or a drive may be mounted on each brush shaft, and in the latter case with more than one drive the inlet to each drive may be connected to water pressure line 7 via a manifold.

Suction openings 26 on the inner side of the cleaning unit 2 are connected to water suction line 5 via pipes 25, which extend from the individual suction opening 26 to a second connection 24 for water suction line 5. The second connection 24 is common to all suction openings. In the illustrated embodiment there are four suction openings and the second connection 24 is located to one side of the cleaning unit. There can alternatively be two or three suction openings, or more than four suction openings, such as five or six suction openings, and the pipes 25 can be arranged in other manners. The pipe section with the second connection can for example be located at the middle of the cleaning unit.

The cleaning unit 2 may have a protruding skirt along its periphery so that the skirt forms a cup-shaped volume around cleaning brushes 3. The cleaning unit is on its outer side provided with handles 22. The handles may be fixed structures, or they may be flexible structures like pieces of rope, according to what the divers prefer.

The cleaning unit may on its inner side have distance members, such as supports with wheels. The distance members can maintain a distance to the hull surface so that there is a certain free space between the hull and the free end of the skirt. Alternatively, the skirt can have protruding portions along its free end, which protruding portions act as distance members. Another alternative is to provide the skirt with side openings through which water can be drawn into the cup-shaped volume around the cleaning brushes.

The cleaning unit 2 can be stored in the container, and typically two cleaning units are stored. When the cleaning unit is to be used, it is moved out to a buoy 20 located next to the side of the ship to be cleaned. The water pressure line 7 is connected to the first connection 23 and the water suction line 5 is connected to the second connection 24 on the cleaning unit. The cleaning unit may be connected to buoy 20 via a wire having a length sufficient to allow the cleaning unit to follow the cleaning path on the hull. When the unit is in position at the hull surface centrifugal pump 6 is engaged and water is drawn in through suction openings 26 and via water suction line 5 to the pump 6, which delivers the pressurized water via filter devices 8 and water pressure line 7 to the drive 4 for the cleaning brushes. The water jet leaving drive 4 via water outlet 9 propels the cleaning unit in the direction of the cleaning path along the ship hull.

Additional buoys 20 may be provided at the ends of the buoyant bodies where they act as fenders against the hull of the ship. As an alternative a wheel journalled about a vertical axis can be mounted at the side portion of the buoyant body intended to face the side of the ship to be cleaned. Preferably, several such wheels are mounted on the side portion. The wheels can abut the side of the hull and roll along the hull surface as the cleaning system is moved along the hull.

The container has a compressor for providing divers with air via umbilical 19, and other types of diver equipment may be present in the container, such as pressure bottles 17 for scuba diving or pressure ves- sels for special air blends, like helium. Communication equipment 18 allows contact with the divers from the control desk in the container. The communication equipment may include recording equipment, such as video recording. The comm unication equipment may include a laptop computer. Shelves 21 for stores may hold additional diving equipment.

Fouling material scraped off from the filter parts leaves filter devices 8 from a bottom outlet. The fouling material may be collected in bags at the filter devices and carried out of the container, or it may be conveyed in piping or chutes from the filter devices to a storage site outside the container. In one embodiment the storage site is in the buoyant bodies 11. In another embodiment the storage site is a separate container located on top of buoyant body 11 or a separate container floating next to buoyant body 11.

In an embodiment, water suction line 5 is provided with an additional suction opening with a control valve, which may partially or fully open or close the additional suction opening. The additional suction opening may be opened in case the cleaning unit has a need for consuming a higher flow rate of pressurized water from the water pressure line than the flow rate of water from the suction openings 26. The additional suction opening can be located below the water surface at any appropri- ate location. It is also possible to provide pipes 25 leading to the second connection 24 with an additional opening controlled by a control valve. This additional opening may be facing away from the hull, when the cleaning unit is in operation, and the control valve may have a control handle operable by a diver. If the diver observes that the cleaning unit tends to be sucked too much in direction of the hull then it is possible to operate the handle and open for the additional opening, and the parallel i nflow of water throug h this openi ng wi ll red uce the flow of water through suction openings 26. As an alternative, the skirt may have side openings that can be opened or blocked according to need. In an embodiment the water pressure line is downstream of the filter devices provided with a waste gate that may be opened in case the cleaning unit has a need for consuming a lower flow rate of pressurized water from the water pressure line than the flow rate of water from the suction openings 26.

In an embodiment the hull cleaning system has in one of the buoyant bodies an engine driving a water pump. One or both of the bouyant bodies have submerged nozzles for ejecting pressurized water delivered by the water pump. When the hull cleaning system is in the operational condition floating in the water, then the individual nozzle is in submerged position with an outflow opening directed mainly in horizontal direction so that ejected pressurized water produces a water jet that may propel the system. In one embodiment the individual nozzle may be able to turn about a vertical axis in order to control the direction of the water jet, and in that case one or two nozzles may be sufficient for propelling the system. In another embodiment the nozzles are fixedly mounted in bodies 11 and directed in different directions, and the supply of water to the nozzles is then controlled so that only nozzles pointing away from the desired direction of movement is supplied with water. An preferred embodiment has 8 nozzles located with two nozzles at each of the four outermost corners of the bodies 11. The two nozzles at the individual corner have outflow openings directed about 90° apart. One of the openings can e.g. be flush with the short side wall of the body 11 and the other of the openings can e.g. be flush with the long side wall of the body 11. The nozzles are via pressure lines connectable to the pressurized water supply from the water pump. The pressure lines are provided with control valves, and these valves are operable from a control position within container 10.

An embodiment of the underwater cleaning unit 2 is illustrated in Figs. 9 and 10. The unit has circumferentially extending a hollow structure 31 providing buoyancy to the cleaning unit. The hollow structure comprises a closed pipe running along the entire periphery. The pipe is preferably of a plastic material having a density of about 0.98 (980 kg/m³), but other densities higher than 1 are also possible. The volume of the hollow structure is dimensioned so that the cleaning unit as a whole has a little negative buoyancy, preferably at about 2 kg.

The hollow structure 31 is provided with four wheels 32 as illustrated in Fig. 10. In operation the wheels can abut the surface being cleaned. The suction pipes 25 end in suctions openings 26 located between hollow structure 31 and the plate body carrying the brushes.

In an embodiment the cleaning brushes 3 are mounted on their drive shaft with a possibility of moving in the axial direction of the shaft. The rotational movement of the brushes on the side of the hull causes a lower pressure just in front of the brush so that the brush is sucked towards the side of the hull. The floating mounting of the brushes on the drive shafts with the possibility for individual axial movement of the brushes causes the brushes to automatically adapt to curvatures in the ship hull being cleaned. Details from the above-mentioned embodiments may be combined into new embodiments within the scope of the patent claims, and the details may be varied within the scope of the patent claims. It is as an example possible to use a cleaning unit having only one or two cleaning brushes, or four or five or more cleaning brushes. As another example the water suction line may be divided into several parallel suction lines, and/or the water pressure line may be divided into several parallel water pressure lines. It is also possible to simultaneously use two or more cleaning units supplied by the centrifugal pump and the filter devices via separate suction and pressure lines, the suction lines being united in a manifold upstream of the centrifugal pump, and the pressure lines being divided into individual lines in a manifold downstream of the filter devices. The cleaning unit can be driven in the cleaning direction by other means than the water outlet from the drive, such as by being pulled, or by being driven by wheels.

Claims

P A T E N T C L A I M S

1. A ship hull cleaning system for removing fouling, the ship hull cleaning system comprising an underwater cleaning unit having cleaning brushes rotatable by at least one drive, a water suction line connecting the cleaning unit with a pump, and a water pressure line from the pump to the cleaning unit, cleaned off fouling being transportable via the water suction line to at least one filter device, cha racterized in that the pump is a centrifugal pump, that the at least one filter device is located downstream of the centrifugal pump and is connected with the wa- ter pressure line leading to the at least one drive, and that the at least one drive has a water outlet positioned for driving the cleaning unit along the hull.

2. A ship hull cleaning system according to claim 1, cha racter i z e d in that the water outlet from the at least one drive is direc- tionally adjustable in relation to the cleaning unit.

3. A ship hull cleaning system according to claim 1 or 2, cha racterized in that at the underwater cleaning unit the water suction line to centrifugal pump has a larger diameter than the water pressure line from the centrifugal pump.

4. A ship hull cleaning system according to any of claims 1 to 3, cha racterized in that the underwater cleaning unit has a circumferential hollow structure providing buoyancy.

5. A ship hull cleaning system according to any of claims 1 to 4, cha racterized in that the at least one filter device is mounted at a container, the container being provided with at least one buoyant body for positioning below the container.

6. A ship hull cleaning system according to claim 5, cha racter i z e d in that the at least one buoyant body has a length and a width corresponding to the length and width of the container, and that the at least one buoyant body has corner fittings.

7. A ship hull cleaning system according to claim 5 or 6, cha racterized in that the container is provided with two buoyant bodies.

8. A ship hull cleaning system according to claim 7, cha rac- t e r i z e d in that in a floating operating condition either end of the container is locked to one of the two buoyant bodies, the buoyant bodies being located with their length direction extending in the width direction of the container.

9. A ship hull cleaning system according to claim 8, cha racter i z e d in that the two buoyant bodies are spaced apart and a floor structure, preferably a grating, extends between the buoyant bodies in the area next to the container.

10. A ship hull cleaning system according to any of the claims 5 to 9, cha racterized by having an inactive condition, in which at least the cleaning unit, the water suction line, the water pressure line, the centrifugal pump, the at least one filter device, a generator and possibly diving equipment are stored within the container, and in which optionally the at least one buoyant body is positioned on the container with the length direction extending in the length direction of the container.

11. A ship hull cleaning system according to any of the claims 5 to 9, cha racterized in that the centrifugal pump and/or a generator is located within said buoyant body.

12. A ship hull cleaning system according to claim 11, cha racterized by having an inactive condition, in which at least the cleaning unit, the water suction line, the water pressure line, and possibly diving equipment are stored within the container.

13. A ship hull cleaning system according to any of the claims 5 to 12, cha racterized in that the container is provided with diving equipment.

14. A ship hull cleaning system according to any of the claims 5 to 13, cha racterized in that the container is provided with communication equipment and recording equipment for the underwater operation of the cleaning unit.

15. A ship hull cleaning system according to any of the claims 5 to 14, cha racterized in that one of the buoyant bodies has an engine driving a water pump, that the buoyant bodies are provided with submerged nozzles for ejecting pressurized water delivered by the water pump.