DE102013104278B4 - Floating work platform with a lifting system and method for performing underwater work - Google Patents

Abstract

Floating work platform with a lifting system for lifting the working platform (2) out of the water (4) or lowering the working platform (2) onto the water (4), the lifting system having at least four hydraulically operated supporting members (8), characterized in that Support members (8) each have a hydraulically operated lifting arm (10) and each have a support leg (12), wherein the lifting arm (10) is attached at one end to the working platform (2) and attached to the other end of the support leg (12) is, the working platform (2) an excavator (16) and a working tube (20) having an underwater probe, a suction device and a flushing device, wherein the working tube (20) with the excavator (16) is connectable and thus by means of the excavator (16 ) into the water (4) is lowered.

Description

The invention relates to a floating work platform with a lifting system with the features according to the preamble of claim 1. Furthermore, the invention relates to a method for performing work under water with the features according to the preamble of claim 10.

At the bottom of waters, especially the seabed, are a variety of objects, such as obstacles, foreign objects, mines or the like. Since on the occasion of the construction of offshore wind farms in coastal areas to the shore-side grid connection submarine cables must be laid in the seabed, there is a great interest in recovering or clearing the objects located on the riverbed. In particular, on-ground ordnance such as mines or sunken ammunition present a potential hazard. There is therefore a need to detect, recover or evacuate suspect objects prior to laying submarine cables.

Traditionally, various methods have been used to recover or clear such objects. For example, a technically inexpensive procedure requires divers to identify, salvage or evacuate the object (s). However, the productivity of divers working at the bottom of the river is severely limited due to wind speed, water depth, wave height and tidal current.

In order to work independently of the wave movement and the tides, usually watercraft are equipped with lifting systems. Such lifting systems can lift the vessel out of the water. A watercraft with a lifting system for supplying an offshore wind turbine is, for example, in DE 100 21 163 B4 shown.

In WO 92/08 849 A1 is also a floating construction shown with a plurality of height-adjustable legs for raising and lowering this construction. US 2,600,761 A shows an offshore drilling unit with a plurality of telescopic legs, which are pivotally mounted to the offshore drilling unit.

Such lifting systems, in which at least four lifting stilts are lowered perpendicular to the seabed, however, only achieve a maximum lifting speed of 1 m per minute and are not suitable for a fast, flexible use. For use close to the shore for the removal of earth material adjacent to the water, is in DE 36 40 421 A1 a combination of a web-like, elongated platform, the surface of which has a roadway and having at the bottom at least one end of a support, shown, wherein the support is designed as a floating body.

DE 29 909 329 U1 further shows a quick coupling for excavator tools for coupling a tool to an excavator boom and GB 1 512 525 A shows a method and apparatus for unloading excess water from a bucket of a suction dredger wherein the dredger drags its digger arm across the ground and sucks soil. To protect against sharks is in US 4,166,462 A a shark safety cage shown, which is composed of bars.

The invention is therefore based on the object to provide an efficient and flexible device and a method to increase the productivity of diving work on the river bottom.

The invention solves this problem by the features of a buoyant work platform with a lifting system according to claim 1 and with a method for performing work under water with the features of claim 10.

The buoyant work platform according to the invention, in particular work ship, is designed primarily for performing work on the water and has a lifting system for lifting the work platform out of the water or lowering the work platform to the water, regardless of the sea state and / or tides working from the work platform.

The lifting system has at least four hydraulically operated support organs, which are formed like a spider leg and allow the work platform accurate positioning over ground.

The support members according to the invention each have a hydraulically operated lifting arm and a respective support leg, wherein the lifting arm is attached at one end to the working platform and is attached to the other end of the support leg. In this case, the lifting arm is preferably designed to be angled and attached a hydraulic cylinder in the angular range. As a result, a favorable force is achieved on the supporting organs.

By means of the multi-part running support organs, the working platform is lifted out of the water and can hold their position regardless of the wave motion exactly. The lifting process is advantageously faster than with conventional lifting stilts and is completed within 2 to 3 minutes. The supporting organs are designed in this way to lift the working platform out of the water at a water depth of up to 20 m.

To lift or lower the work platform, the support legs are introduced by means of the hydraulically operated lifting arms laterally of the working platform in the water or brought out. As a result, the working platform advantageously has a safer state than conventional helicopters, such as in DE 100 21 163 B4 shown because the support members are left of the working platform into the water and thus have a greater distance from each other than conventional lifting stilts.

Furthermore, the buoyant work platform on an excavator, in particular a hydraulic excavator, and a working tube with an underwater probe, in particular a magnetic field probe, to detect electrically conductive, metallic contaminated sites or magnetizable ferromagnetic materials. The detection of objects by means of the underwater probe can advantageously also take place when the object is hidden in the sediment of the river bed.

Furthermore, the working tube is preferably made of aluminum and has a suction device and a flushing device in order to expose an object lying in the sediment.

The working tube can be connected to the excavator on board the working vessel and lowered into the water by means of the excavator.

In a preferred embodiment of the invention, the support legs are designed to be telescopic. For this purpose, the support leg on a Tragbeingrundkörper and at least one mounted in the base telescopic stage. One or more telescoping telescopic stages of the support legs advantageously allow a labor input even in deeper water.

To lift the work platform, the support legs are lowered by means of the lifting arms, which are responsible for the stroke up or down, to a predetermined height above the water bottom. Subsequently, at least one telescopic stage mounted in a support base round body is drained off at each support leg.

To release the telescopic stage or telescopic stages, a lock is preferably unlocked and the telescopic stage or telescopic stages sink in a force-free operation to the bottom of the water. Upon reaching the bottom of the river, the telescopic stage or the telescopic stages are locked.

To lower the work platform to the water drained telescopic stages are retracted for storage in the Tragbeingrundkörper.

The retrieval of the telescopic stage or telescopic stages takes place, for example, via a hydraulic cylinder located in the support leg or a drive via an internal rack.

However, the invention is not limited to the above-described operation for discharging or retrieving the telescopic stage or telescopic stages. Rather, any designs for deflation or recovery are conceivable.

Due to the design of the support legs as telescopic legs, the support members can advantageously save space in a transport position of the work platform.

According to a further preferred embodiment of the invention, a foot plate is arranged on each support leg. The foot plate has a diameter of 1 to 5 m, but preferably 3 m, in order to advantageously allow a planar placement of the support member on the bottom of the water and to prevent deep penetration of the support member in the sediment at the bottom of the water.

To detect the exact position when lifting and lowering the individual foot plates, these have corresponding sensors. Furthermore, the foot plates have air and rinse nozzles to allow the release from the sediment at the bottom of the water. Preferably, a joint is arranged between the support leg and the foot plate, which is designed in such a way to compensate for existing bumps and advantageously to allow a secure position of the support leg.

A further preferred embodiment of the invention comprises a computer control unit which is designed to control the movements of the support members during settling and lifting. The movements of the support members are monitored by means of a plurality of sensors and pass the signals of the sensors of the computer control unit. The computer control unit thus advantageously ensures a uniform movement of the supporting organs. As a result, the working platform is vertically straight, evenly and quickly lifted out of the water, or lowered to the water, advantageously no torsional or bending forces acting on the work platform.

According to a further preferred embodiment of the invention, a mechanical locking device of the support members for fixing the support members after completion of the positioning of the working platform and for fixing the support members for producing a transport position is provided. This can be advantageously saved by switching off the hydraulic system energy. Furthermore, a mechanical locking ensures the Supporting organs advantageous for more security, since unwanted loosening of the support members is prevented by the mechanical lock.

According to a further preferred embodiment of the invention, the excavator, in particular the hydraulic excavator, on the excavator on a quick coupling closure to quickly attach or disconnect work equipment, such as a work tube, a flow protection tube or a clamshell grab.

The quick coupling on the excavator arm a quick change of work equipment is feasible, which advantageously allows efficient use of the working platform according to the invention. In this case, a coupling half of the quick coupling is attached to the implement and a second coupling half of the quick coupling on the excavator, so that if necessary, both coupling halves are brought together and locked.

According to a further preferred embodiment of the invention, the excavator on a Global Positioning System (GPS system), which advantageously takes place an accurate position determination of the excavator arm and coupled to the excavator arm working device and thus a precise work is feasible. To increase the accuracy of the position determination as well as the use of differential methods, especially differential GPS, or use of other high-precision navigation systems for position determination is conceivable.

According to a further preferred embodiment of the invention, the buoyant working platform has a flow protection tube which can be lowered into the water and has a multiplicity of water passage openings in the lateral surface of the flow protection tube. The flow protection tube is preferably made of α-magnetic aluminum and is used to protect a diver at the bottom of the water, so that the diver can work independently of the flow.

Through the water passage openings a large part of the flow forces are released, which, for example, caused by ocean currents due to weather conditions and / or by tides. At the same time, the resistance of the flow protection tube is advantageously reduced, whereby a firm state of the flow protection tube is made possible on the bottom of the water.

Furthermore, an inner pedestal is preferably mounted in the flow protection tube on the inner wall, which enables a diver located in the flow protection tube a firm footing when lowering and raising the flow protection tube.

In addition, a Leitergang is arranged in the flow protection tube, which serves the diver to descend from the inner platform to the water bottom.

In a further preferred embodiment of the invention, the buoyant working platform according to the invention has an acoustically operating locating device, in particular a side-scan sonar, which is configured in such a way as to create a soil profile of the body of water. On the basis of such a detection of the conditions of the river bottom can be advantageously control by means of the computer control unit, the supportive organs when lowering and lifting.

The invention solves the above-mentioned. Problem further with a method for raising or lowering a buoyant work platform, in particular a work platform described above, by means of a lifting system with at least four hydraulically operated support members, wherein the support members are made in several parts and each have a lift arm and a support leg.

To raise or lower the work platform, the support legs are introduced by means of the hydraulically operated lifting arm laterally of the working platform in the water or brought out.

If the support legs on the riverbed have a firm footing, the working platform is lifted by means of hydraulically operated lifting arms out of the water or deposited on the water.

In this case, the draining of the support members due to gravity can be done with low hydraulic pressure. When the supporting organs with the support leg are standing on the bottom of the water, the hydraulic pressure is increased slightly to stop the rolling and tamping movements of the buoyant work platform.

If the buoyant work platform is stably supported, the hydraulic pressure of the lift arms is further increased to lift the work platform out of the water. This is lifted out of the water only to the extent that safe working from the platform is possible. Advantageously, the labor input is independent of weather conditions, in particular the height of the waves, feasible because the work platform is held above the water surface by the support members.

When the work to be done from the work platform is completed, the work platform is lowered back onto the water and the support legs lifted out of the water.

The inventive design of the support members advantageously allows a uniform and rapid lifting and lowering of the working platform, whereby this can be preferably brought to Bergen or clearing objects on the riverbed flexibly and quickly from one suspicion point to the next.

• 1 eine schematische Darstellung eines Arbeitsschiffes mit Hubsystem zum Bergen und/oder Räumen von versunkenen Objekten,
• 2 eine schematische Darstellung eines Arbeitsschiffes mit Stützorganen in Transportposition,
• 3 eine schematische Darstellung eines gehobenen Arbeitsschiffes auf Stützorganen,
• 4 eine schematische Darstellung eines positionierten Arbeitsschiffes beim Sondieren und/oder Identifizieren mit einem Arbeitsrohr und
• 5 eine schematische Darstellung eines positionierten Arbeitsschiffes mit abgelassenem Strömungsschutzrohr.

Further embodiments of the invention will become apparent from the claims and from the embodiments explained in more detail with reference to the drawing. In the drawing show:

• 1 a schematic representation of a working ship with lifting system for recovering and / or broaching sunken objects,
• 2 a schematic representation of a work vessel with supporting organs in transport position,
• 3 a schematic representation of a raised work vessel on supporting organs,
• 4 a schematic representation of a positioned work vessel when probing and / or identifying with a working tube and
• 5 a schematic representation of a positioned work vessel with drained flow protection tube.

In 1 is a buoyant work platform according to the invention as a work ship 2 for recovery or clearing in a body of water 4 sunken objects, in particular obstacles, foreign bodies, mines or the like, shown. The work ship 2 Floats at the water surface 6 and according to the invention has a lifting system with four supporting organs 8th on, which are designed to the work ship 2 from the water to lift or lower to the water.

The supporting organ 8th is designed in several parts and has a lift arm 10 , a carrying leg 12 and a foot plate 14 on. The supporting organs 8th are by means of the respective lifting arms 10 displaced in different lifting and setting positions.

Furthermore, the work ship points 2 on board a hydraulic excavator 16 on, which with a quick release coupling 18 is provided and has a counterweight, especially for water depths to about 20 m. The quick release coupling 18 is a connection unit, which is designed such that a connection with little effort is possible. With the quick-release coupling 18 can thus be advantageous various tools, such as. Working tube 20 and flow protection tube 22 , with the lifting linkage or the excavator arm of the excavator 16 connect.

First, there are the supporting organs 8th in a transport position in which the support legs 12 on the deck of the work ship 2 are located and fixed.

2 shows a schematic representation of a work vessel 2 with supporting organs 8th in transport position. The support legs 12 are the side of the work ship 2 lifted out of the water. The work ship 2 moves to a specified position of a suspected point of a sunken object.

Before lowering the support organs 8th a soil profile of the body of water is created by means of a side-scan sonar. The conditions of the river bottom are transferred to a computer program of a computer control unit, which controls the positioning and lowering of the support organs 8th controls. To monitor the lifting process are located on the foot plates 14 Sensors to the exact position of the foot plate 14 capture.

The foot plates 14 are substantially circular in shape and have a diameter of 1 to 5 m, but preferably 3 m, and allow a stable state of the supporting organs 8th , In addition, the foot plates prevent 14 advantageously a deep penetration into the sediment at the bottom of the river. To compensate for uneven floors is between the foot plates 14 and the support legs 12 a joint, in particular a ball joint, arranged.

Furthermore, the foot plates 14 equipped with air and rinsing nozzles to remove the foot plate 14 from the sediment to facilitate.

The lowering of the supporting organs 8th takes place with low hydraulic pressure by means of the lifting arms 10 laterally overboard of the work ship 2 until the foot plates 14 reach the riverbed. Then the pressure in the lift arms 10 increased, possibly caused by the swell rolling and pitching movements of the work vessel 2 to stop.

Indicates the work ship 2 a stable stand on the river bottom, is the working ship 2 by again increasing the hydraulic pressure through the lifting arms 10 lifted out of the water.

3 shows a schematic representation of an upscale work vessel 2 over the water surface 6 a body of water 4 , The lifting process of the working ship 2 is computer controlled so that this process is very even. The work ship 2 is lifted vertically, evenly, evenly and quickly, especially within 2 to 3 minutes, out of the water. The work ship 2 assumes a horizontal orientation in every stroke position.

The lowering process is analog computer-controlled and thus perpendicular, straight, even and fast.

The work ship 2 as it is in 3 is independent of the wave movements of the water and can keep its position accurately. Without a lifting system is a labor input, such as a diving mission for recovering an object, only up to a significant wave height of 0.8 m possible. With the lifting system according to the invention can advantageously by the working ship 2 be worked up to a wave height of 1.5 m or higher. The lifting system according to the invention is further preferably used at a water depth of 0 to 20 m near the coast.

If work is to be carried out at greater depths, there is the option of telescopic support legs 12 to use. For this, the support leg points 12 a Tragbeingrundkörper with at least one mounted in the base telescopic stage.

For lifting the work ship 2 become the support legs 12 side of the ship 2 up to a predetermined depth, in particular about 2 m above the bottom of the river 24 , lowered. Here is the depth of the discharged support legs 12 however, depending on the number and length of telescopic telescopic stages. Then the telescopic stages are released and sink due to gravity on the bottom of the water 24 , When lying on the riverbed 24 there is a locking of the telescopic stages. The work ship 2 can now from the water as described above 4 be lifted.

Lowering the work ship 2 on the water surface 6 takes place in the reverse manner. First, the work ship 2 by depressurizing by means of the lifting arms 10 on the water 4 discontinued. Subsequently, the telescopic stages of the support legs 12 pulled into the Tragbeingrundkörper. This is done, for example, by a drive via a traction system or by an internal hydraulic cylinder. However, other mechanisms for retrieving the telescopic stages are applicable.

An alternative way to reach greater depths is a vertically mounted in a guide mounted suspension of the lift arm 10 on the support legs 12 , When lowering the supporting leg 12 becomes the anchorage 26 of the lifting arm 10 in a guide of the supporting leg 12 moved vertically upwards until the support leg 12 on the riverbed 24 touches down. Subsequently, the anchorage 26 of the lifting arm 10 fixed in this position. The fixation can, for example. Via a locking lug in a on the support leg 12 attached rack done.

After fixing the anchorage 26 can the work ship 2 be lifted out of the water as described above.

Lowering the work ship 2 again in the reverse manner. First, the work ship 2 on the water 4 discontinued. Subsequently, the fixation of the anchorage 26 on the support leg 12 solved and the support leg 12 raised until anchoring 26 of the lifting arm 10 in the lead of the supporting leg 12 has reached the original position and the support leg 12 by means of the lifting arm 10 can be lifted out of the water.

For recovering or clearing one on the riverbed 24 located object, the work vessel has a working tube 20 on.

4 shows a schematic representation for explaining the application of the working tube 20 in which the working ship 2 out of the water 4 is lifted and safe on the support organs 8th stands. The working tube 20 has a diameter of 10 to 30 cm, but preferably 20 to 25 cm and is with the aboard the work vessel 2 located hydraulic excavator 16 via a quick-release coupling 18 connected. Preferably, the working tube has 20 via an underwater camera, an underwater probe as well as suction and rinsing devices and is carried out by means of the excavator 16 into the water 4 lowered. In order to minimize the resistance load of the water flow on the excavator, this is preferably designed as a lattice boom.

Furthermore, the excavator points 16 its own GPS system to work with 20 to work in coordination. This makes it possible to use the underwater probe to relocalize a given suspicion point to an object in GPS coordinates.

The suction and flushing device allows a flushing of the working tube 20 into the river bottom 24 to probe the object to determine the exact depth of the object. Furthermore, the suction and flushing device is used to expose the object in order to identify the object.

About the underwater camera and an associated cable connection from the working tube 20 to the work ship 2 can the procedure of the working tube 20 acoustically and visually by an operator on the work ship 2 be followed, and if necessary the object can be identified.

If an identification of the object, for example due to poor visibility, by means of the underwater camera is not possible, the identification is carried out directly by the use of a diver on the river bottom 24 , To protect the diver on the river bottom 24 According to the invention flow protection technology is used, which is a work on the river bottom 24 safe and without influence of the flow in the water 4 allows.

In 5 is a schematic representation of the use of a flow protection tube 22 shown. The flow protection tube 22 is preferably formed substantially circular cylindrical with a height of 3 to 5 m, but preferably 4 m, and a diameter of 2 to 3 m, but preferably 2.5 m.

For a work assignment, the working tube 20 disconnected from the excavator arm and the quick release 18 the flow protection tube 22 to the excavator 16 coupled. The flow protection tube 22 is then to the curb of the work ship 2 lifted, leaving a diver an interior pedestal in the flow protection tube 22 can enter.

By means of the excavator 16 becomes the flow protection tube 22 with the diver in the middle above the object at the bottom of the river 24 switched off. The precise control of the movement also takes place here by means of the GPS system of the excavator 16 ,

Is the flow protection tube 22 firmly on the riverbed 24 , the diver can use a ladder gear from the inner podium to the bottom of the water 24 Descend and perform the identification of the object visually and / or by careful scanning or the exposure of the object by careful digging or rinsing. This process can be advantageous via a camera on the diving helmet by an operator on board the work vessel 2 monitor.

The use of flow protection technology, such as a flow protection tube described above 22 , Advantageously also allows diving on the riverbed 24 at a flow velocity of the water 4 of more than 0.6 m per second.

If the object is a weapon or warfare agent, the object is placed in a container or directly on the flow protection tube 22 attached to safely lift the object, or possibly blasted directly in place.

On the other hand, if the object is not a weapon or a warfare agent but one at the bottom of the river 24 lying obstacle, a salvage can also be done via a clamshell grab, which by means of quick-release coupling 18 on the excavator 16 is attached. For this purpose, the object is grasped with the clamshell grab and aboard the working ship 2 lifted, where it can be safely stored. The movement of the clamshell bucket can be done using the GPS system of the hydraulic dredger 16 to be controlled.

After the salvage or evacuation of an object, a probing of the river bottom occurs 24 by the diver or by means of the working tube 20 ,

Is the salvage or evacuation a suspected point on the river bottom 24 completed, all work equipment on board the work ship 2 secured, stored and the working ship 2 by means of the supporting organs again on the water surface 6 discontinued. After lifting the support legs 12 these are fixed in a transport position. The work ship 2 can now go to the next suspicion point and the process starts again.

The device according to the invention or the method according to the invention advantageously increases the productivity of diving work on the river bed 24 , The computer-aided, hydraulically operated, spider-leg support organs 8th Advantageously increase the independence of weather conditions, in particular the height of the waves. The lowering of the support legs 12 side of the work vessel 2 provides more stability and possibly allows the use of a narrower work vessel 2 as the state of the art provides.

The use of a working tube according to the invention 20 and a flow protection tube according to the invention 22 In addition, it increases the independence from the tidal current. As a result, the work and process productivity and thus the efficiency of the labor input are advantageously increased.

Claims (14)

Floating work platform with a lifting system for lifting the working platform (2) out of the water (4) or lowering the working platform (2) onto the water (4), wherein the lifting system has at least four hydraulically operated support members (8), characterized in that the support members (8) each have a hydraulically operated lift arm (10) and a respective support leg (12), the lift arm (10) being attached at one end to the work platform (2) and at the other end to the support leg (12) the working platform (2) has an excavator (16) and a working tube (20) with an underwater probe, a suction device and a flushing device, wherein the working tube (20) with the excavator (16) is connectable and thus by means of the excavator (16) into the water (4) can be lowered. Floatable work platform behind Claim 1 characterized by an embodiment of the support legs (12) as a telescopic construction with a Tragbeingrundkörper and at least one mounted in the base telescopic stage. Floatable work platform behind Claim 1 or 2 characterized by in each case a foot plate (14) on the support leg (12) for planar placement of the support member (8) on the body of water (24), wherein the foot plates (14) have sensors for detecting the exact position of the foot plates (14) and / or air nozzles and irrigation nozzles and / or have a joint between foot plate (14) and support leg (12) to compensate for uneven floors. Floatable work platform according to one of the preceding claims, characterized by a computer control unit which is designed to control the movements of the support members (8) during settling and lifting. Floating work platform according to one of the preceding claims, characterized by a mechanical locking device of the support members (8) for fixing the support members (8) after completion of the positioning of the working platform (2) and for fixing the support members (8) for producing a transport position. Floating work platform according to one of the preceding claims, characterized in that the excavator (16) has a quick coupling closure (18) on the excavator, for fast coupling and uncoupling of work equipment. Floatable work platform according to one of the preceding claims, characterized by an embodiment of the excavator (16) with a GPS system. Floating work platform according to one of the preceding claims, characterized by a flow protection tube (22) which can be lowered into the water (4), wherein the flow protection tube (22) has a plurality of water passage openings in the lateral surface of the flow protection tube (22). Floating work platform according to one of the preceding claims, characterized by an acoustically operating locating device, which is designed in such a way to create a soil profile of the body of water (24). Method for performing underwater work with a buoyant work platform (2) according to any one of Claims 1 - 9 , wherein the working platform (2) has a lifting system with at least four hydraulically operated support members (8), characterized in that the support members (8) each have a lifting arm (10) and a support leg (12), the support leg (12) by means of hydraulically operated lifting arm (10) side of the working platform (2) in the water (4) is introduced or removed, the working platform (2) by means of hydraulically operated lifting arms (10) at a fixed state of the support legs (12) from the water (4 ) is lifted or is placed on the water (4), a working tube (20) with an underwater probe, a suction device and a flushing device by means of an excavator (16) from the elevated work platform (2) is lowered into the water (4) to work under water by means of the working tube (20). Method according to Claim 10 , characterized in that for lifting the working platform (2) the support legs (12) by means of the lifting arms (10) are lowered to a predetermined height above the water bottom (24) and at least one in a Tragbeingrundkörper the support leg (12) mounted telescopic stage the support legs (12) is lowered, for lowering the working platform (2) on the water (4) each at least one in a Tragbeingrundkörper the support leg (12) mounted telescopic stage of the support legs (12) is retracted and the support legs (12) by means of the lifting arms (10) are lifted out of the water (4). Method according to one of Claims 10 to 11 , characterized in that the movements of the support members (8) during settling and lifting of the support members (8) are controlled by a computer control unit and monitored by a plurality of sensors on the support members (8). Method according to one of Claims 10 to 12 , characterized in that the support members (8) after lifting the working platform (2) and after reaching a transport position of the support legs (12) are mechanically locked to fix the support members (8). Method according to one of Claims 10 to 13 , in each case a foot plate (14) with air nozzles and rinsing nozzles is arranged on the support legs (12) and by means of the air nozzles and rinsing nozzles the penetration of the support legs (12) into the body of water (24) is minimized and the release of the support legs ( 12) from the body of water (24) is facilitated.

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