vessel

Abstract

A submersible dredging vessel having a hydrodynamic body optimised for energy-efficient underwater movement. The vessel comprises four primary propulsion units, each incorporating a pump. The vessel has negative buoyancy, causing it to sink when not powered. The vessel comprises a dredging pump arranged to dredge and to control the vertical location in a body of water. The dredging pump can operate in three modes: sink, stable, and rise. In sink mode, the downward force exceeds upward forces, causing descent. Stable mode balances forces, maintaining a constant depth, while rise mode increases upward force to ascend.

Description

[0001] P138249PC00

[0002] Title: Vessel

[0003] TECHNICAL FIELD

[0004] Various aspects and examples thereof relate to the field of depth control of a vessel.

[0005] Other aspects and examples thereof relate to the field of propulsion and direction control of a vessel.

[0006] Further aspects and examples thereof relate to the field of localisation of a vessel in a body of water.

[0007] Some aspects and examples thereof relate to the field of a failsafe system of a vessel.

[0008] BACKGROUND

[0009] Dredging is done to remove sediment, debris and other materials from a bottom of a body of water, for example rivers, lakes, ports and harbours. Dredging may be done to maintain or increase waterway depth for navigation, to prevent flooding, support construction projects or restore ecosystems.

[0010] Generally, dredging arrangements used for dredging are typically relatively large and cumbersome systems, making it complicated to dredge smaller bodies of water.

[0011] SUMMARY

[0012] It is preferred to provide for a device for dredging that is compact while still being able to be accurately navigated in vertical direction in a body of water. This applies in particular to a vessel for injection dredging and water injection dredging more in particular. Injection dredging is a process in which one or more jets of water are direct to sediment at a bottom of a body of water. By virtue of the jets, sediment is stirred up from the bottom and caught in turbulence of water. This allows a current in the body of water to carry the sediment away from the location at which it has been stirred up. The flow of water may be a result of flow of a river, tidal flows, other, or a combination of two or more thereof.

[0013] A first aspect provides a submersible dredging vessel comprising a body and a dredging module provided in said body. The dredging module comprises a dredging pump for pumping a fluid and a fluid outlet manifold comprising fluid outlet openings being arranged to provide directional jets of the fluid. The submersible dredging vessel has a negative buoyancy during use. The fluid outlet openings are arranged to provide the fluid jets in a downward direction, relative to the vehicle. The dredging pump is arranged to operate in a sink mode, wherein a sum of the upward force of the fluid jets and an upward force acting on the submersible dredging vessel is smaller than a downward force acting on the submersible dredging vessel, a stable mode, wherein the sum of the upward force provided by the fluid jets and the upward force acting on the submersible vehicle is substantially equal to the downward force acting on the submersible dredging vessel, and a rise mode, wherein the sum of the upward force provided by the fluid jets and the upward force acting on the submersible vehicle is larger than the downward force acting on the submersible dredging vessel.

[0014] In order to dredge, using the submersible dredging vessel, the vehicle comprises a dredging pump. The dredging pump can pump a fluid, e.g. water in which the vessel is submerged, from an inlet through a fluid outlet manifold comprising fluid outlet openings being arranged to provide directional jets of fluid. Jets of fluid are, in the context of the invention, jets of water that have locally a higher, directed, velocity than the rest of the body of water. In a specific example, jets of fluid are aimed in a downward direction relative to the vehicle such that they are aimed at the bottom of a body of water. Due to the relatively high velocity of the jets, aimed at the bottom, sludge and other debris on the bottom of the body of water is ejected and transported away due to the current. Thus, it is possible to locally dredge a body of water using a dredging pump arranged to eject fluid jets via the fluid outlet manifold.

[0015] The submersible dredging vessel has a negative buoyancy during use, e.g. it sinks when provided in a body of water, which causes a downward movement of the vessel in a vertical direction in the body of water. The dredging pump may be used to increase the buoyancy of the vessel, such that even a positive buoyancy may be achieved in which the vessel rises in the body of water, i.e. having an upward movement in the vertical direction. This may be achieved by sufficiently powering the dredging pump. When the dredging pump is powered less than in the rise mode, but more than in the sink mode, it is possible to have a neutral buoyancy in which the vessel does not rise or sink. Thus, it is possible to control the vertical direction of the submersible dredging vessel in a body of water using the dredging pump. Since no other equipment is needed, e.g. propulsion units, to move control the vessel in the vertical direction, space is saved in the vessel and a relatively compact design may be provided.

[0016] In an implementation of the submersible dredging vessel, the upward force provided by the fluid jets scales with the power provided to the dredging pump. By providing the dredging pump such that the fluid jets scale with the power provided to said dredging pump, e.g. by ejecting fluid jets at a higher velocity by the dredging pump, it is possible to accurately control the upward force and with that the behaviour of the vessel in vertical direction. Next to the three modes, it may be possible to additionally power the dredging pump such that it rises faster or it may be possible to reduce power provided to the dredging pump such that the vessel sinks faster. In another implementation of the submersible dredging vessel, the fluid jets are distributed over a width of the submersible dredging vessel. Providing the fluid jets over a width of the submersible dredging vessel, it may be facilitated that the upward force generated by the fluid jets are evenly distributed over the width. As a result, stability around the longitudinal axis of the vessel may be facilitated.

[0017] In a further implementation of the submersible dredging vessel, the fluid jets are distributed along a line perpendicular to a longitudinal axis of the submersible dredging vessel. This may allow for both evenly distributing the jets over the width and for providing the fluid jets relatively close to each other, such that the jets may be focussed more efficiently. This may on this turn facilitate dredging, as multiple fluid jets may hit a relatively small surface of the bottom of the body of water.

[0018] In again another implementation of the submersible dredging vessel, the vehicle further comprises a centre gravity and a longitudinal axis. The centre of gravity is provided along said longitudinal axis at a first distance from a midpoint of the longitudinal axis. This may allow for the vessel to be tilted in case no other forces are applied to the vessel, such that one side of the vessel along the longitudinal axis, e.g. the front side or rear side of the vessel, is aimed at the surface of the body of water. This may allow, in case the dredging pump is inoperable, to move the vessel vertically in an upward or downward direction by propelling the vessel in a direction of movement parallel to the longitudinal axis. This may be advantageous in case of an emergency, and wherein the dredging pump isn’t available to let the vessel rise. In such a scenario, primary propulsion units and / or the secondary propulsion system may be used to let the submerged vessel resurface, optionally in combination with auxiliary systems such as a compressed air system.

[0019] In yet a further implementation of the submersible dredging vessel, at least a one fluid jet is provided along a line perpendicular to the longitudinal axis, wherein said line intersects the longitudinal axis at a second distance from the midpoint, and wherein the second distance is in an extension of the first distance. Once the dredging pump is powered, the vessel is tilted towards the opposite direction, around the midpoint, such that the vessel is relatively horizontal in the body of water, e.g. in the stable mode. In the rise mode, the vessel is tilted such that the front side of the vessel is lower than the rear side of the vessel. This may allow for more convenient control and navigation of the vessel during operation, e.g. normal operation such as dredging.

[0020] In yet a further implementation of the submersible dredging vessel, the submersible dredging vessel has a centre of buoyancy. During use, the centre of gravity and the centre of buoyancy are aligned in a vertical direction along the longitudinal axis. Once the centre of gravity and centre of buoyancy are vertically aligned, the vessel is stable around the longitudinal direction such that it does not overturn when not powered. As a result, no control system and equipment may be needed to prevent overturning of the vessel thereby allowing for a more compact design of the vessel. During rising or sinking of the vessel, the centre of buoyancy may still be vertically aligned with the centre of gravity along the longitudinal axis, however it may shift relative to said longitudinal axis. For example, when rising, the centre of buoyancy may be provided more towards the rear of the vessel along the longitudinal axis, compared to sink or stable mode. As a result, the upward force of the fluid jets provided by the dredging pump may have a component parallel to the longitudinal direction of the vessel.

[0021] In yet a further implementation of the submersible dredging vessel, the submersible dredging vessel further comprises a vertical position detection arrangement for detecting the current vertical position of the submersible vehicle in a body of water and a controller operably connected to the dredging pump and the vertical position detection arrangement. The controller is arranged to control the vertical position of the submersible vehicle in the body of water by operating the dredging pump in at least one of the sink mode, stable mode and rise mode, based on the current vertical position. By providing a vertical detection arrangement, it may be possible for the vessel to determine its distance towards the bottom of the body of water. This data on its turn may be used by the controller to control the vessel using the dredging pump, e.g. in order to maintain a set distance from the bottom of the body of water. This may be in particular advantageous in case the bottom of the body of water comprises an uneven terrain, e.g. having protrusions and gaps.

[0022] A second aspect provides for a method of controlling the buoyancy of a submersible vehicle, preferably the submersible vehicle according to any of the preceding claims. The submersible vehicle has a negative buoyancy and comprises a dredging pump. The method comprises providing the submersible vehicle in a body of water, powering the dredging pump in a first range, second or third range, said range defining a percentage of the maximum operating power of the dredging pump, such that the fluid jets provide an upward force on the body of the submersible vessel. The sum of the upward force provided by the dredging pump and the buoyancy is negative, zero or positive respectively. The second aspect allows for vertical control of a submersible dredging vessel, using a dredging pump. Thus, it may be possible to control the vertical movement of the vessel and dredging a body of water using the same component, i.e. the dredging pump. As a result, a compact design may be provided that allows for dredging relatively small bodies of water.

[0023] In an implementation, an upper limit of the first range is smaller than a lower limit of the second range, and an upper limit of the second range is smaller than a lower limit of the third range. By providing three subsequent ranges, corresponding to sink mode, stable mode and rise mode respectively, it is possible to smoothly transition from one mode to another. This may prevent sudden forces applied to the body of the vessel, which may cause damage.

[0024] In another implementation, the second range is between 80% and 95% of the maximum operating power of the dredging pump, or between 85% and 90% of the maximum operating power. Providing the stable range towards the higher end of the power that may be provided to the dredging pump, it may be facilitated that the dredging pump provided relatively fast fluid jets while preventing the vessel from sinking or rising. Relatively fast fluid jets may be advantageous for dredging, as relatively fast fluid jets have a higher impact on the bottom of the body of water, making it possible to remove sludge and / or debris from the bottom that is not possible with weaker jets.

[0025] Furthermore, it is preferred to provide a dredging device that is relatively compact and capable of driving and steering a dredging device in a body of water, preferably without rudders. This applies in particular to a vessel for injection dredging. Injection dredging is a process in which one or more jets of water are direct to sediment at a bottom of a body of water. By virtue of the jets, sediment is stirred up from the bottom and caught in turbulence of water. This allows a current in the body of water to carry the sediment away from the location at which it has been stirred up. The flow of water may be a result of flow of a river, tidal flows, other, or a combination of two or more thereof.

[0026] A third aspect provides a submersible dredging vessel having a body and a direction of travel. The submersible dredging vessel comprises a plurality of primary propulsion units distributed around a contour of the body of the submersible dredging vessel. Each primary prolusion unit of the plurality of primary propulsion units is arranged to provide a propelling force. Each propelling force of a corresponding primary propulsion unit has a component parallel to the longitudinal axis of the submersible dredging vessel. At least one primary propulsion unit of the plurality of propulsion units comprises a pump.

[0027] By providing a plurality of primary propulsion units, each propulsion unit capable of providing a propelling force having a component parallel to the longitudinal axis of the submersible dredging vessel, the vessel may be propelled in a direction along the longitudinal axis. Distributing the primary propulsion units around a contour of the body of the vessel facilitate distribution of the propelling force over the body of vessel, spreading the forces applied to the body of the vessel more evenly and allowing for a more lightweight and compact design of the submersible dredging vessel. At least one of the primary propulsion unit, preferably all primary propulsion units, comprise a pump. Pumps are commonly known and well developed in all shapes and sizes, which may allow for a specialised yet reliable primary propulsion unit. Additionally, by scaling the power provided to the pump, the pump can provide more propelling force. In other words, the propelling force provided by the pump may scale with the power provided to said pump.

[0028] Water injection dredging is commonly done in an upstream fashion, for example starting from the mouth of a harbor sailing inlands against tidal, river currents, or from deep to shallow waters. Thus, using a propulsion system such as the primary propulsion units during dredging, the primary propulsion units may also aid the water injection process by providing initial downstream thrust to the material to be dredged, e.g. a mud stream, and may give the mud stream already an initial velocity in the direction needed. An implementation of the submersible dredging vessel, the contour of the body comprises four corners in a horizontal plane of the submersible dredging vessel. At least one primary propulsion unit of the plurality of primary propulsion units is provided in each corner. The direction of travel and the longitudinal axis of the vessel may be provided parallel to the horizontal plane. Providing at least primary propulsion unit in each corner of the contour, the primary propulsion units can be provided to provide a propelling force in the horizontal plane, allowing for movement relative to said plane. More specifically, a forward / backward movement of the vessel may thus be provided, wherein the forward / backward movement defines the direction of travel, is parallel to the longitudinal axis of the vessel and is parallel to the horizontal plane. Thus, by spreading the primary propulsion units such that at least one primary propulsion unit is provided in each corner, a forward / backward movement may be facilitated.

[0029] In another implementation of the submersible dredging vessel, two primary propulsion units of the plurality of primary propulsion units are provided adjacent to each other such that each primary propulsion unit of the two primary propulsion units has a component parallel to a direction towards the other primary propulsion unit of the two primary propulsion units. Thus, next to a component parallel to the longitudinal axis of the vessel, a component having an angle relative to the longitudinal axis has been provided. This additional component, i.e. the component of a primary propulsion unit relative to an adjacent primary propulsion unit, allows for providing a propelling force that is not parallel to the longitudinal direction of the vessel and therefore may facilitate steering of the vessel in a direction parallel to the component of the propelling force.

[0030] In a further implementation of the submersible dredging vessel, the propelling force of each primary propulsion unit of the plurality of propulsion units is provided in a horizontal plane of the submersible dredging vessel. As a result, all components of the propelling force may be provided in, or at least parallel to, the horizontal plane. Thus, the primary propulsion units can be used for controlling the movement of the vessel in the horizontal plane, i.e. a forward / backward movement and a starboard / port movement, without affecting the vertical position of the vessel in the body of water.

[0031] In yet a further implementation of the submersible dredging vessel, the longitudinal body has a front side provided at a first distal end of the longitudinal body and a rear side provided at a second distal end of the longitudinal body, opposite the first distal end. At least two primary propulsion units of the plurality of primary propulsion units are provided towards the front side and at least two primary propulsion units of the plurality of primary propulsion units are provided towards the rear. Providing primary propulsion units towards the distal ends of the vessel, at the front side and the back side of the vessel, may allow for efficient application of the propelling force, in particular a component of the propelling force not being parallel to the longitudinal axis of the vessel, to the body of the vessel. Since such components would be provided to the body of the vessel relatively far from the centre of gravity of the vessel, a relatively large arm exists, i.e. the distance between the location of the component and the centre of gravity, such that a relatively small propelling force is needed to turn the vessel.

[0032] In again another implementation of the submersible dredging vessel, the pump comprises an inlet provided towards a side of the dredging vessel. An opening of the inlet is provided at an angle relative to the longitudinal axis of the vessel. By having the inlet at a side of the dredging vessel, with an opening provided at an angle relative to the longitudinal axis of the vessel, the opening is also provided at an angle relative to the outlet of the pump, i.e. at an angle relative to the propelling force. As a result, the effects that the propelling force may have locally on the pressure of the body of water, may be minimised at the inlet of the pump. In other words, the inlet pressure of the liquid remains largely unaffected by the pressure of the propelling force. Thus, negative effects of a fluctuating inlet pressure may be mitigated, such as damage to the pump due to cavitation.

[0033] In yet a further implementation of the submersible dredging vessel, the pump comprises a filter arranged to protect the pump from debris during use. A filter may advantageously be used to protect the pump, e.g. the impeller of the pump, against debris. Thus the lifespan of the pump and / or components of the pump may be increased.

[0034] In again another implementation of the submersible dredging vessel, the pump is a centrifugal pump. Centrifugal pumps may provide a constant pressure at the outlet of the pump, resulting in a constant propelling force of the corresponding primary propulsion unit. Additionally, a centrifugal pump may provide a propelling force that is scalable by the power provided to the centrifugal pump. More power provided to the centrifugal pump may result in a larger propelling force at the corresponding primary propulsion unit. In yet a further implementation of the submersible dredging vessel, the vessel further comprises a secondary propulsion system. The secondary propulsion system is arranged to provide an auxiliary propelling force. The auxiliary propelling force has a component parallel to the propelling force of at least one primary propulsion unit. The secondary propulsion system may provide an additional propelling force supplementary to, or instead of, the primary propelling force of the corresponding primary propulsion unit. As a result, this auxiliary propelling force may be used to propel the vessel at a greater speed than only the primary propulsion units may be capable of.

[0035] In yet a further implementation, the auxiliary propelling force is parallel to the propelling force of at least one primary propulsion unit. As a result, the auxiliary propelling force of the secondary propulsion system has components in the same direction as the propelling force of the corresponding primary propulsion unit, thereby facilitating that the auxiliary propelling force and the corresponding propelling force are complementary to each other and have no components that work in opposite direction and thus cancelling each other.

[0036] In yet a further implementation, the secondary propulsion system comprises a propeller arranged to provide the auxiliary propelling force.

[0037] A fourth aspect provides for a method of rudderless navigating of a submersible dredging vessel as described above. The method comprises determining a movement direction, powering the at least one primary propulsion unit of the plurality of propulsion units such that the sum of components of the propelhng forces of each of the corresponding primary propulsion units of the plurality of primary propulsion units is positive in a direction having a component in the movement direction. Using the plurality of primary propulsion units, each providing a corresponding propelling force in a direction, allows for the control of the vessel, for example when submerged or when moving at the surface of a body of water. The resulting movement direction is a sum of the propelling forces of each of the primary propulsion units.

[0038] Controlling the various propelling forces allows for steering the vessel, i.e. by providing such that the sum of the propelling forces is in a different direction than earlier. For example, if the sum of the propelling forces resulted in a propelling force parallel to the longitudinal direction of the vessel, the vessel would move forward. If now the primary propulsion units provide a different amount of propelling force, e.g. by decreasing or increasing power provided to at least one primary propulsion unit, the resulting sum of propelling forces changes. As a result, the vessel can navigate in a body of water without the use of rudders. Rudders may be a relatively unreliable and high maintenance component to allow for reliable steering, compared to the proposed method of rudderless navigating. Additionally, compared to the proposed method, navigating using rudders is relatively slow, meaning that there is a relatively long response time before a vessel steers in a certain direction once a rudder is turned. Using the plurality of primary propulsion units, this effect may be greatly improved.

[0039] In an implementation of the method, the sum of components of the propelling forces is positive in a direction parallel to the determined movement direction. By providing sufficient primary propulsion units around the contour of the vessel, the sum of the components of the propelling forces can be provided such, by powering and depowering the primary propulsion units, such that the vessel can be steered such that it does not drift, i.e. has a component in a direction not being in the determined direction of movement. Not having any drift may allow for effective navigation of the vessel.

[0040] In another implementation of the method, the method further comprises the step of:

[0041] - powering the secondary propulsion system such that the sum of components of the propelling forces and the auxiliary propelling force is positive in a direction having a component in the determined movement direction. The secondary propulsion system may support the primary propulsion units, increasing the speed at which the vessel in the determined movement direction.

[0042] Furthermore, it is preferred to provide a vessel, e.g. a submersible vessel, for example for dredging, that can be accurately located and tracked during use while being submerged. This applies in particular to a vessel for injection dredging. Injection dredging is a process in which one or more jets of water are direct to sediment at a bottom of a body of water. By virtue of the jets, sediment is stirred up from the bottom and caught in turbulence of water. This allows a current in the body of water to carry the sediment away from the location at which it has been stirred up. The flow of water may be a result of flow of a river, tidal flows, other, or a combination of two or more thereof.

[0043] A fifth aspect provides a vessel, e.g. a submersible dredging vessel, for cooperating with a floating object. The submersible dredging vessel comprises a controller and a triangulation system operably connected to the controller. The triangulation system is arranged to determine the position of the floating object relative to the submersible dredging arrangement. The submersible dredging vessel further comprises a receiver operably connected to the controller and arranged to receive first geographical coordinates of the floating object. The controller is arranged to determine second geographical coordinates of the submersible dredging vessel based on the first geographical coordinates of the floating object and the position of the floating object relative to the submersible dredging vessel. In order to be able to track the vessel, in particular when the vessel is a submersible vessel that is submerged, it may be advantageous to provide for a triangulation system operably connected to the controller and arranged to determine the position of a floating object relative to the vessel. When submerged, it may be difficult to determine the position of the vessel using conventional methods such as GPS as the body of water may interference with such conventional methods. Conventionally, the floating object comprising the triangulation system may be used to estimate the position of the vessel relative to the floating object. However, this poses the challenge of sending over this position of the vessel relative to the floating object takes a relative long time using conventional triangulation systems.

[0044] By inverting the setup, i.e. by providing the triangulation system on the vessel such that it can determine the position of the floating object relative to the vessel, allows for this data to be analysed locally, i.e. onboard the vessel. Since the floating object may be stationary, or removes relatively slow and predictable compared to the vessel, first geographical coordinates need to be transferred less frequent to the vessel to obtain accurate second geographical coordinates. As a result, the limitations relating to data transference are reduced, as most data is generated and processed locally, i.e. onboard of the vessel. Therefore, the position of the vessel in second geographical coordinates may be relatively quick, accurate, and frequently be determined.

[0045] It will be clear that the vessel is suitable for various water-based applications such as, but not limited to, submerged applications, in particular submerged dredging. In an implementation of the vessel, e.g. a submersible dredging vessel,, the vessel further comprising a velocity measurement system operably connected to the controller and wherein the determining of the second geographical coordinates of the vessel is further based on the velocity of the vessel. Since the position of the vessel is locally determined, i.e. onboard of the vessel by the controller, it may be possible to include more data to more accurately determine the position of the vessel relative to the floating object, e.g. the velocity of the vessel. The velocity of the vessel may be an absolute velocity, i.e. the speed of the vehicle to a fixed point such as a geographical coordinate such as the second geographical coordinate, or a relative velocity, i.e. the speed of the vehicle relative to the floating object and / or the body of water.

[0046] Velocity measurements may be used to improve the accuracy of the data provided by the triangulation system, e.g. using a Kalman filter. Additionally, the velocity measurements may be done at a smaller time interval than the measurements performed by the triangulation system such that the second geographical coordinates may still be determined in between measurements by the triangulation system. If for example it is known or determined that the vessel is at second geographical coordinates at a first time, while moving with a constant speed in a fixed direction, it can be accurately determined where the vessel is after a certain time has passed at a second time without the measurement data of the triangulation system.

[0047] In another implementation of the vessel, the velocity measurement system comprises an acoustic doppler current profiler system aimed at a surface for determining the velocity of the vessel relative to the surface during use. Using an acoustic doppler current profiler, an accurate velocity measurement of the vessel relative to the surface may be provided.

[0048] In a further implementation of the vessel, the surface is a water surface of a body of water or a bottom of the body of water. When using an acoustic doppler current profiler system aimed at the surface of the body of water, the velocity of the vessel relative to the surface may be determined. If the water at the surface stands still or has a relatively low speed, e.g. due to a weak current, the velocity determined by the acoustic doppler current profiler system may be, or approach respectively, the absolute speed of the vessel. In case the water on the surface moves relatively quick, no longer the absolute speed of the vessel may be determined directly. The floating object may move in the same direction with the same speed as the current, the speed relative to the floating object may be determined. From this, possibly with a time trace of the first geographical coordinates, e.g. the speed of movement of the water surface, the absolute velocity may still be determined. Additionally, it may be advantageous to measure the speed of the surface of the body of water, as measuring the speed relative to the bottom of the body of water may be complicated when dredging, as the produced sludge sediment may interfere with the acoustic signal.

[0049] In again another implementation of the vessel, the acoustic doppler current profiler system is aimed at a first surface and a second surface for determining the velocity of the vessel and wherein the first surface is a surface of the body of water and the second surface is a bottom of the body of water. Combining more sensors, it may be possible to even more accurately determine the velocity of the vessel. For example, by measuring the surface of the body of water and the bottom, before or after dredging, it may be possible to measure the speed of the water due to the current. This data my on its turn be used to more accurately determine the velocity of the vessel during dredging, as the absolute velocity of the vessel may be determined from the sum of the velocity of the vessel relative to the body of water and the velocity of the body of water relative to the bottom of the body of water, i.e. the earth.

[0050] In again another implementation of the vessel, the vessel further comprises a first depth meter operably connected to the controller and arranged to determine the distance between the vessel and a bottom of a body of water. By determining the distance between the vessel and the bottom surface, it may be possible to determine if the vessel is at the correct height for operation, e.g. dredging or moving, without coming too close or too far away from the bottom of the vessel.

[0051] In yet a further implementation of the vessel, the vessel further comprises a second depth meter operably connected to the controller and arranged to determine the distance between the vessel and the bottom of the body of water and wherein the controller is arranged to determine material characteristics based on the distance determined between the vessel by the first depth meter and the second depth meter. When both depth meters measure different layers of the bottom, e.g. using a sonar measurement at different frequencies, material characteristics of the bottom of the body of water may be determined. For example, if the first depth meter operates at a first frequency, able to penetrate the top soil of the bottom of the body of water but not a subsequent layer while the second depth meter operates at a second frequency, not able to penetrate the top soil, the height of the top soil may be determined. Additionally, using frequencies closer to each other, it may be possible to determine the composition of the bottom of the body of water. This may be advantageous to determine if dredging is possible, e.g. by ensuring the bottom of the body of water is made of a material that may be dredged.

[0052] In again another implementation of the vessel, the controller is arranged to determine the depth of the water body based on the second geographical coordinates of the vessel and the distance between the vessel and the bottom of the body of water. By combining the second geographical coordinates and the distance between the vessel and bottom surface of the body of water, it may be possible to determine the depth of the body of water. By using the depth, or height, component of the second geographical coordinates, it is possible to determine the distance between the vessel and the surface of the body of water. Information relating to the depth of the body of water may, in particular in combination with the second geographical coordinates, be used to determine if dredging needs to be performed at a second location and / or if dredging needs to be performed to provide for a sufficiently deep body of water.

[0053] In yet a further implementation of the vessel, the vessel further comprises a pressure gauge as a specific example of a depth meter. The pressure gauge is operably connected to the controller and arranged to determine the pressure acting upon the vessel, wherein the controller is arranged to determine the distance between the vessel and a surface of the body of water based on the pressure acting upon the vessel. A pressure gauge may provide additional information regarding how deep the vessel is submerged in the body of water, as the pressure scales with the vertical distance to the surface of the body of water. The data provided by the pressure gauge may be combined with the second geographical coordinates, in particular the vertical component of the second geographical coordinates, to more accurately determine the distance between the surface of the body of water and the vessel.

[0054] In again another implementation of the vessel, the controller is arranged to map the depth of the body of water based on the distance between the vessel and the surface of the body of water, on the distance between the vessel and the bottom of the body of water and the second geographical coordinates. In the context of the invention, mapping should be understood as logging depth values with geographical coordinates, e.g. second geographical coordinates, for forming a depth map and / or a bathymetric map. Such a depth map and / or bathymetric map may be used to keep track of the dredging process, to determine of dredging has been completed and to provide current information about the depth of the body of water as well as determining local heights on the bottom of the body of water.

[0055] A sixth aspect provides a floating object arranged to float during use. The floating object comprises a location detection system for determining first geographical coordinates of the floating object and a transmitter arranged to send the coordinates of the floating object to a receiver of a vessel. Since the floating object is not submerged, it is possible to use conventional position detection methods that may be transmitted as first geographical coordinates to the vessel.

[0056] In an implementation, the location detection system is arranged to determine the location of the floating object using a satellite navigation system. A satellite navigation system is a commonly used, relatively cheap and reliable method of determining the first geographical coordinates, such that they can be transmitted to the vessel, for determining the second geographical coordinates.

[0057] In another implementation, the floating object comprises at least one of a buoy or a ship. A buoy or a ship are commonly used, and reliable floating objects. A buoy may be used in case of a relatively quiet surface of the body of water, e.g. not having high waves and / or wind speeds, while a ship may be used for other situations. Additionally, a ship may be preferred in case of off-shore applications, e.g. on the ocean, as it may act as a staging platform for the dredging operation while the a buoy may be more useful on smaller bodies of water, e.g. a small river or a lake.

[0058] A seventh aspect provides a dredging arrangement comprising a vessel, e.g. a submersible dredging vessel, as previously described and a floating object as previously described. The vessel is physically connected to the floating object. The physical connection may be established using a cable, e.g. a stainless steel cable. The physical connection may allow for transference of data and may facilitate that the vessel and floating object remain within a certain range from each other. An eighth aspect provides a method of determining the coordinates of a submersed vessel, e.g. a submersible dredging vessel, using a dredging arrangement, preferably the dredging arrangement as previously disclosed. The method comprises providing a floating object on a body of water, said floating, object comprising a location detection system for determining the coordinates of the floating object, determining the coordinates of the floating object using the location detection system, preferably using the location detection system and a global navigation satellite system, transmitting the coordinates of the floating object to the vessel, determining the position of the floating object relative to vessel using the triangulation system, determining the coordinates of the vessel based on the coordinates of the floating object and the position of the vessel relative to the floating object.

[0059] Performing the above described method allows for determination of the position of the vessel in a body of water in second geographical coordinates, based on the distance of a floating object to said vessel and first geographical coordinates of the floating object. By determining the position of the floating object relative to the submersible dredging vessel using the triangulation system provided on the vessel, instead of determining the position of the vessel relative to the floating object using a triangulation system provided on a floating object, it is possible to relatively quick and therefore frequently determine the second geographical coordinates of the vessel.

[0060] A ninth aspect provides a method of mapping a bottom of a body of water using a dredging arrangement, preferably the dredging arrangement as previously disclosed. The method comprises determining the coordinates of a submersed vessel, e.g. a submersible dredging vessel, as previously disclosed, determining the distance between the vessel and the surface of the body of water based on the position of the vessel relative to the floating object, determining the distance between the vessel and the bottom of the body of water using a first depth meter provided on the vessel, mapping the bottom of a body of water based on the distance between the vessel and the surface of the body of water, based on the distance between the vessel and the bottom of the body of water and based on the coordinates of the submersed vessel.

[0061] By performing the described method, an accurate map of the situation before, during and after dredging may be provided using the dredging arrangement.

[0062] In an implementation of the method of mapping of a body of water, the first depth meter is a first echo sounding arrangement operating at a first frequency. The method further comprises wherein the first depth meter is a first echo sounding arrangement operating at a first frequency, determining the distance between the vessel and the bottom of the body of water using a second echo sounding arrangement operating at a second frequency providing on the vessel, wherein the first frequency and the second frequency are different; and determining the characteristics of the bottom of the body of water using the distance between the vessel of the first depth meter and the second depth meter. This may allow for adding further detail to the map such as for example the height, or depth, of various layers such as the top soil.

[0063] In another implementation of the method of mapping of a body of water, the characteristics of the bottom of the body of water has data comprising information about the sediment layers of the bottom. This may allow for adding even further detail when mapping such as for example the contents of the sediment layers, e.g. the top soil. From this it may be determined if there are products in the sediment layer which may not be possible to dredge, such as a naval wreckage.

[0064] Furthermore, it is preferred to provide for a submersible vessel, for example for dredging and water injection dredging in particular, that is capable of failsafe operation and is able to be easily retrievable and recoverable during submerged operation in case of distress, such as damage to the dredging device. Injection dredging is a process in which one or more jets of water are direct to sediment at a bottom of a body of water. By virtue of the jets, sediment is stirred up from the bottom and caught in turbulence of water. This allows a current in the body of water to carry the sediment away from the location at which it has been stirred up. The flow of water may be a result of flow of a river, tidal flows, other, or a combination of two or more thereof.

[0065] A tenth aspect provides a vessel, e.g. a submersible dredging vessel, comprising an electrical power system connected to a propulsion arrangement for providing power to the propulsion arrangement and a diagnostic arrangement operatively connected to the propulsion arrangement and the electrical power system. The diagnostic arrangement is arranged to detect operational failure of at least one of the electrical power system and the propulsion arrangement. The electrical power system comprises a first power supply and a second power supply. The first power supply and the second power supply are individually provided in a corresponding first liquid-tight container and a corresponding second liquid- tight container respectively.

[0066] The propulsion arrangement comprises a primary propulsion unit and a secondary propulsion system. The primary propulsion unit and the secondary propulsion system are each connected to at least one of the first power supply and the second power supply. The second power supply is arranged to power the secondary propulsion system, based on detected operational failure by the diagnostic arrangement in at least one of the first power supply and the primary propulsion unit. By providing power supplies in an liquid-tight container it may be facilitated that in case of a leakage in the body of the vessel, e.g. a hole in the body of the vessel, that no water reaches the power supplies and damage to the power supplies may be prevented. When the power supplies are damaged, they may no longer be arranged to provide power to the components of the vessel, such as the primary propulsion unit. By providing at least two power supplies, each in a corresponding liquid-tight container, a further barrier against a leakage may be provided. In case one of the liquid-tight containers is also damaged, e.g. the liquid-tight container housing the first power supply, and liquid is able to enter the damaged liquid-tight container, a backup power supply remains protected against the liquid entering the vessel and entering the damaged liquid-tight container.

[0067] Furthermore, by providing a primary propulsion unit and secondary propulsion system, each connected to at least one of the first power supply and the second power supply, it may be facilitated that in case one of the power supplies is no longer operative, i.e. no longer able to provide power to the primary propulsion unit and / or the secondary propulsion unit, the other power supply is able to power the first propulsion unit and the secondary propulsion system such that the movement of the vessel still can be controlled. The primary propulsion unit and the second propulsion system may be directly or indirectly be connected to the first power supply and the second power supply for powering. For example, the primary propulsion unit may be directly connected to the first power supply, and the secondary propulsion unit may be directly connected to the second power supply. Additionally, the first power supply may actively charge the second power supply, thus indirectly powering the secondary propulsion unit. This may also facilitate that the second power supply remains charged such that the when the second power supply is needed, e.g. in case of distress, the second power supply may be used to its fullest extent.

[0068] By now providing a diagnostic arrangement arranged to detect operational failure in one of at least the electrical power system and the propulsion arrangement, it is possible to ensure that the vessel is returned to the surface of a body of water as soon quickly as possible. Specifically, when the diagnostic system detects an operational failure, the second power supply powers the secondary propulsion system such that the vessel moves more quickly, e.g. towards a surface.

[0069] Using the described features above, a vessel has been provided that allows for fail safe operation, but providing additional protective barriers of critical equipment such as the power supplies, by providing redundancy, e.g. by providing multiple power supplies and by automatically provide extra propelling force via the secondary propulsion system for retrieving the vessel before it no longer can be controlled, e.g. by having too much damaged equipment and / or by having too much water on the inside of the vessel. It will be clear that the vessel is suitable for various water-based applications such as, but not limited to, submerged applications, in particular submerged dredging.

[0070] In an implementation of the vessel, the vessel further comprising a control and sensing system having a first set of electrically powered components and a second set of electrically powered components. The first set of electrically powered components is connected to the first power supply and the second power supply. The second set of electrically powered components is connected to the first power supply. The second power supply is arranged to power the first set of electrically powered components based on detected operational failure in the first power supply. In the context of the invention, the control and sensing system should be understood as the sensors and control systems needed to operate the vessel during use. For example, a depth measurement system for measuring the depth of the vessel in a body of water and a control system arranged to process the data for use by an actuator, e.g. a pump to affect the vertical position of the vessel in the body of water, to maintain a predetermined vertical position can be part of the control and sensing system.

[0071] The various components making up the control and sensing system can be separated into at least two categories: critical and less-critical. The critical components correspond to the first set of electrically powered components and are connected to both the first power supply and the second power supply. The less-critical components correspond to the second set of electrically powered components and are connected only to the first power supply. In case of failure of the first power supply, the critical components are still powered by the second power supply. Since less components are powered by the second power supply than by the first power supply, during conventional operation of the vessel, less power needs to be provided to the components. As a result, they second power supply may be provided smaller than the primary power supply, thereby saving space and allowing for a smaller vessel and / or the critical components may be powered for a longer amount of time before the second power supply is depleted, compared to the first power supply.

[0072] In another implementation, at least a part of the control and sensing system is provided in an liquid-tight container. Preferably the liquid-tight container is a dedicated liquid-tight container for storing the part of the control and sensing system. By providing at least a part of the control and sensing system, e.g. the controller, in a liquid-tight container, it may be facilitated that in case of a leakage of the vessel, the part of the control and sensing system provided in the container is not exposed to the liquid. Exposing components of the control and sensing system to liquid may cause damage.

[0073] In a further implementation, the vessel further comprises an air chamber and a compressed air supply system in fluid connection with the air chamber. The air supply system comprises a connector for connecting to a container comprising compressed air and an air supply control valve arranged to controllably fill the air chamber with air from the container. During use, a container comprising compressed air may be provided in the air supply system. In case of an emergency, e.g. faulty components detected by the diagnostic system, the compressed air of the container may be provided to the air chamber. This increases the buoyancy of the vessel such that less power is required to bring the vessel to the surface of a body of water. Alternatively, sufficiently compressed air is provided that the vessel has a positive buoyancy such that no power needs to be provided to bring the vessel to the surface. Bringing the vessel to the surface of the body of water, in case of an emergency, may facilitate retrieving the vessel so it can be salvaged or repaired for future use.

[0074] In again another implementation, the compressed air supply comprises an electrically powered fail-open valve connected to the first power supply for controllably filling the air chamber with air. For example, a servo may be provided that, when powered, ensures the compressed air remains in the container. In case the servo is no longer powered the valve opens, since the valve is a fail-open valve, and the compressed air fills the air chamber. This may be advantageous, as this allows the vessel to reach the surface of a body of water even in case of a power failure on board of the vessel, for example if the first power supply is no longer are able to provide power. Additionally or alternatively, a capacitor feed signal fail-safe servo may be used instead.

[0075] In yet a further implementation, the compressed air supply is operatively connected to the diagnostic arrangement and arranged to controllably fill the air chamber with air based on detected operational failure in the second power supply. The diagnostic arrangement can detect operational failure of components of the vessel, e.g. the first and second power supply, and based on an operational failure open the valve such that the compressed air of the container enters the air chamber. This may be advantageous in case there are operational failures that may be critical to the vessel, e.g. a leakage, that may not be detected early for which their consequences need to be mitigated by other means such as a fail-open valve.

[0076] In yet a further implementation, the vessel further comprises a safety system connected to at least the second power supply, preferably also the first power supply, and the diagnostic arrangement. The second power supply is arranged to power the safety system based on detected operational failure in the first power supply. By connecting the safety system to the second power supply, it may be facilitated that in an emergency situation, in which the first power supply is no longer able to power the vessel, the safety system may still be powered. Operationally connecting the diagnostic arrangement to the safety system may allow for the use of diagnostic arrangement to detect faulty components and indicate this to the safety system such that corrective measurements may be taken. For example, when the diagnostic arrangement detects operational failure in the first power supply, e.g. the first power supply becoming abnormally hot, the components of the safety system may be activated accordingly.

[0077] In yet a further implementation, the safety system comprises a navigation light arranged to provide an optical distress signal and a GPS beacon arranged to determine a geographical position of the vessel and transmit the geographical position to a receiver. The navigation light and the GPS beacon are provided on the vessel and arranged to be powered by at least one of the first power supply and the second power supply. An optical distress signal and a GPS beacon may be used to detect the vessel, once it has reached the surface of the body of water, when the vessel is in distress. In case of operational failure of the first power supply, the safety system may be activated such that the vessel is more conveniently detected, in particular when there is poor visibility, e.g. in darkness or when there is fog, or when operating in a large body of water having a strong current wherein the vessel may be carried away by the current once it has reached to surface of the body of water. This allows for the fast retrieval of the vessel in case of distress.

[0078] In yet a further implementation, the control and sensing system comprises a plurality of controllers, each of the plurality of controllers is arranged to individually control the vessel through the control and sensing system. When a plurality of controllers is provided, each controller being capable of controlhng the vessel via the control and sensing system, it is ensured that if a single controller no longer is able to perform normally, e.g. due to damage, a further controller is provided to control the vessel. This may prevent the dredging vessel from becoming uncontrollable and difficult to retrieve once a controller is damaged, e.g. due to a leakage.

[0079] In yet a further implementation, the plurality of controllers are arranged to operate in parallel with each other. Thus, the controllers may operate next to each other, such that abnormal behavior in a controller may be detected, e.g. when a single controller behaves differently from the other controllers, and may allow for instantaneous taking control of the vessel by a further controller in case a first controller fails. When the controllers run in parallel, there is no need to start booting the software on the controller when another controller fails. Advantageously, time is saved when a controller fails and a further controller can take over its duty such that control of the vessel may be ensured at all times.

[0080] In yet a further implementation, the electrical power system further comprises a third power supply operatively connected to the control and sensing system and wherein the first set of electrically powered components comprises of a primary subset of electrically powered components, said third power supply arranged to power the primary subset of electrically powered components based on detected operational failure in the second power supply. Providing a third power supply may be used to power an even more critical set of electrical equipment in case of distress, e.g. if the first and second power supply are no longer able to power the first and second electrically powered components. By powering a primary subset of the first set of electrically powered components, even less power may be needed such that the third power supply may be provided with less capacity than the first and second power supply and thus saving space. Additionally or alternatively, by only powering the primary subset, less power is needed and thus the third power supply is able to power the subset of first electrical power components for an even longer period of time.

[0081] In yet a further implementation, the third power supply is arranged to power the primary subset of electrically powered components based on detected operational failure in the second power supply. This may facilitate that the third power supply remains charged as it only powers the primary subset of electrically powered components when the second power supply, and therefore the first power supply, no longer are able to power the vessel. Thus, the third power supply remains charged for when needed, e.g. in case of distress.

[0082] In yet a further implementation, the electrical power system further comprises a charging arrangement for forming a connection with a charging system for charging the electrical power system, wherein the charging arrangement is arranged to have an operating mode, in which the electrical power system is arranged to power the vessel and prevents forming the connection with the charging system, and a charging mode, in which the electrical power system is arranged allow forming the connection with the charging system. Preferably at least the charging arrangement is depowered in the charging mode. By preventing the power system from powering the at least the charging arrangement, and optionally from stopping charging of the power system, when components of the charging system are exposed, intentionally or unintentionally, safety of personal charging the vessel may be facilitated.

[0083] In yet a further implementation, the charging arrangement comprises an electrical bridging element arranged to be releasably connected to the charging arrangement, wherein the charging arrangement is in the operating mode when the electrical bridging element is connected, and wherein the charging arrangement is in charging mode when the electrical bridge element is released from the charging arrangement. An electrical bridging element may be provided as a physical component that is intuitive and easy to easy by personal charging the vessel, further improving safety of said personal when charging the vessel, specifically when coupling the vessel to the charging system and uncoupling the vessel from the charging system. A eleventh aspect provides a dredging arrangement comprising a vessel as previously described and a remote control arrangement comprising a remote controller arranged to send control signals to the vessel. The vessel comprises a controller arranged to receive the control signals for controlling the vessel, and wherein the controller is connected to the second power supply. By providing a remote control arrangement to control the vessel, it may be possible that in case of failure of the control systems of the vessel, e.g. the controllers, the vessel may still be manually controlled from a distance. The remote control arrangement may be provided on a floating object, e.g. a ship, or may be provided on the shore. This may facilitate the retrieval of the vessel in case of damage.

[0084] A twelfth aspect provides a method of activating a safety mechanism of a vessel, e.g. a submersible dredging vessel, preferably the submersible dredging vessel as previously described, comprising the steps of:

[0085] - providing a vessel comprising an electrical power system and a propulsion arrangement. The propulsion arrangement comprises a primary propulsion unit and a secondary propulsion system. The electrical power system comprises a first power supply and a second power supply arranged to power the primary propulsion unit and secondary propulsion system respectively; activating the second power supply when the first power supply has an operational failure, powering the secondary propulsion system using the second power supply.

[0086] By providing a second power supply arranged to power the secondary propulsion system in case of an operational failure of the first power supply, it may be ensured that the vessel remains controllable when submerged and / or surfaced. In case the primary propulsion unit remains operable in case of operational failure of the first power supply, activating the secondary propulsion system may speed to movement of the vessel such that it may be retrieved sooner. Alternatively, in case the primary propulsion unit is no longer operational, the secondary propulsion system may propel the vessel. This may be particular advantageous in case that the secondary propulsion system requires less power, such that the second power supply may be provided smaller, i.e. having reduced dimensions, compared to the first power supply.

[0087] In an implementation the method of activating a safety mechanism of a vessel, the vessel further comprises a third power supply and a safety system arranged to be powered by the third power supply. The safety system comprising a GPS system, and optionally at least one of an acoustic modem or USBL, and at least one of an optical alarm and or audible alarm. The method further comprises the steps of activating the third power supply when the second power supply has an operational failure, and powering the GPS system and the at least one of an optical alarm and audible alarm. In case the first and second power supply are no longer able to power the vessel, the third power supply may be used to make it more convenient to locate the vessel such that it may be retrieved, specifically by activating a GPS system such that the its location may be broadcasted to a receiver and by providing an optical alarm and / or an audible alarm such that nearby people may be alerted and guided to the location of the vessel. Optionally, at least one of an acoustic modem or USBL is provided, which may be in particular advantageous when the vessel fails to reach the surface and remains submerged. As a result, retrieving the vessel when present on the surface of the body of water or below the surface of the body of water may be facilitated.

[0088] A thirteenth aspect provides a method of communication of a dredging arrangement in distress. The dredging arrangement comprises a vessel, e.g. a submersible dredging vessel, and a floating object. The vessel and floating object are in communication via a primary communication arrangement, preferably a USBL arrangement. The method comprises the steps of operating a submerged vessel in a body of water, ascending the vessel to the surface of the body of water if the primary communication between the vessel and the floating object is lost, and start communication with the floating object through a secondary communication arrangement. The secondary communication arrangement is preferably a GPS arrangement.

[0089] In case a primary communication arrangement is no longer functional to provide information about the location of the vessel, a backup communication system may be used. In the specific example the backup communication system, i.e. the secondary communication arrangement, is a GPS arrangement, for example a GPS beacon, arranged to broadcast the location of the vessel to the floating object. By broadcasting the location of the distressed vessel, the vessel may be located more easily.

[0090] In an aspect, the method of communication of a dredging arrangement in distress further comprises the step of:

[0091] - start communication with the floating object through a tertiary communication arrangement if communication through the secondary communication arrangement is unsuccessful. The tertiary communication arrangement is preferably a WiFi-arrangement.

[0092] If the GPS system, i.e. the secondary communication arrangement, is not working, a further backup system using a different method may be used to determine and broadcast the location of the vessel to the floating object.

[0093] In a further aspect, the method of communication of a dredging arrangement in distress further comprises the step of start communication with a cellular network through a cellular network arrangement if communication through one of the secondary and tertiary communication arrangement is unsuccessful. When the tertiary communication arrangement is also not able to determine and broadcast the location of the vessel to the floating object, a cellular network arrangement, and additionally or alternatively a back-up GPS receiver, may be used instead. Thus, a further alternative backup system is provided.

[0094] In an even further aspect, the method of communication of a dredging arrangement in distress according further comprises the step of start communication with a satellite transponder if communication through one of the secondary communication arrangement, the tertiary communication arrangement and cellular network arrangement is unsuccessful.

[0095] When the cellular network arrangement is also not able to determine and broadcast the location of the vessel to the floating object, a satellite transponder may be used for communication. The satellite transponder, which optionally may house a local embedded GPS receiver, may be used to determine the location of the vessel and broadcast it to the floating object, or to different location in case the floating object is also not operable.

[0096] A fourteenth aspect provides a set of modular submersible vessel modules. The set of module submersible vessel modules comprises a central system module, a first propulsion arrangement arranged to cooperate with the central system module to form a first submersible vessel and a second propulsion arrangement arranged to cooperate with the central system module to form a second submersible vessel. The central system module and the first propulsion arrangement are configured to provide a first submersible vessel having a negative buoyancy. The central system module and the second propulsion arrangement are configured to provide a second submersible vessel having a positive buoyancy. Advantageously, a modular submersible vessel concept is provided, wherein a single central system module can be combined with different propulsion arrangements to form submersible vessels having different buoyancy characteristics. In an example, all control systems, control logic and battery systems are provided in the central system module, such that this module does not need to be replaced when configuring the vessel for a different operation.

[0097] By cooperating the central system module with a first propulsion arrangement, a first submersible vessel having a negative buoyancy may be provided, for example for dredging operations, for example in accordance with the first aspect, while cooperation with a second propulsion arrangement provides a second submersible vessel having a positive buoyancy, for example for hydrographic operations, offshore operations or transport of payload. Thus, depending on the application, a favourable buoyancy of the submersible vessel may be picked such that the energy use for depth control of the vessel may be minimised. The first propulsion arrangement and the second propulsion arrangement may each comprise any number of submodules, allowing the propulsion and buoyancy characteristics of the vessel to be adapted to the intended application, while maintaining the same central system module.

[0098] In an implementation of the set of modular submersible vessel modules, the first submersible vessel is a submersible dredging vessel and wherein the first propulsion arrangement comprises a dredging pump. Advantageously, by configuring the first submersible vessel as a submersible dredging vessel and by providing the first propulsion arrangement with a dredging pump, the dredging pump can be used both for dredging and for controlling the vertical position of the vessel. The submersible dredging vessel has a negative buoyancy during use, while the dredging pump is arranged to provide downwardly directed fluid jets that generate an upward force on the vessel. By operating the dredging pump in a sink mode, a stable mode or a rise mode, the upward force generated by the fluid jets can be smaller than, substantially equal to, or larger than the downward force acting on the vessel, thereby allowing controlled sinking, maintaining a desired depth, or rising of the vessel. This allows vertical control of the submersible dredging vessel using the dredging pump itself, without requiring additional buoyancy control systems, while maintaining a compact and modular vessel configuration.

[0099] In an implementation of the set of modular submersible vessel modules, the second propulsion arrangement comprises a depth control arrangement, wherein the depth control arrangement comprises at least one of a thruster and a rudder. By providing the second propulsion arrangement with a depth control arrangement comprising at least one of a thruster and a rudder, the depth and buoyancy behaviour of the submersible vessel can be actively controlled during use. As the vessel may be configured to be net positive buoyant, e.g. by forming a vessel comprising the central system module and the second propulsion arrangement, the depth control arrangement may be arranged to generate a controllable downward force, for example by means of one or more vertical thrusters and optionally cooperating rudders or control fins. Vertical thrusters may be implemented as thrusters having a centre axis being placed on the vessel at an angle relative to a length axis of the vessel and relative to a transverse axis of the vessel. Preferably, the angle is ninety degrees. By selectively actuating the depth control arrangement, the downward force can overcome the positive buoyancy of the vessel, such that the vessel can be brought to and maintained at a desired depth, or be made negative buoyant when required. Advantageously, if the vessel has a small positive buoyancy a relatively small and energy efficient depth control arrangement may be provided.

[0100] In an implementation of the set of modular submersible vessel modules, at least one of the first propulsion arrangement and the second propulsion arrangement comprises a plurality of primary propulsion units distributed around a contour of the corresponding propulsion arrangement. An advantage of this implementation is that a modular and exchangeable propulsion concept may be facilitated. Distributing the primary propulsion units around the contour allows propulsion functionality to be realised as a self-contained arrangement that can cooperate with a central system module without requiring changes to the control systems or power systems housed therein. Such a propulsion arrangement may be built up from multiple submodules, each comprising one or more primary propulsion units, allowing propulsion capacity, directionality and functionality to be adapted to a specific application by replacing or reconfiguring modules. This may facilitate modularity, may reduce the need for multiple dedicated vessels, and may allow rapid reconfiguration of the submersible vessel for different operational scenarios.

[0101] In an implementation of the set of modular submersible vessel modules, at least one of the first propulsion arrangement and the second propulsion arrangement comprises a secondary propulsion system. Advantageously, providing the secondary propulsion system as part of a propulsion arrangement allows the central system module, comprising the control systems and battery systems, to remain unchanged when configuring the vessel for different applications. This facilitates a modular vessel architecture in which propulsion capacity, redundancy and operational behaviour may be adapted by exchanging propulsion arrangements, thereby reducing system complexity and enabling rapid reconfiguration for different operational scenarios.

[0102] In an implementation of the set of modular submersible vessel modules, the central system module comprises an air chamber arrangement comprising an air control system configured to control the amount of air present in the air chamber arrangement. Advantageously, the buoyancy of the vessel can be actively and controllably adjusted during use. Selectively adding air to or removing air from the air chamber arrangement changes the buoyant force acting on the vessel, allowing the vessel to be configured as negative buoyant, substantially neutral buoyant or positive buoyant depending on the operational requirements. This may enable controlled vertical behaviour of the vessel, for example to accommodate different payloads, operating depths or applications, while maintaining the modular vessel concept in which the central system module, including control systems and battery systems, remains unchanged and cooperates with different propulsion arrangements.

[0103] In an implementation of the set of modular submersible vessel modules, at least one of the first propulsion arrangement and the second propulsion arrangements comprises a front module, arranged to be provided towards the front of the central system module, and a back module, arranged to be provided towards the back of the central system module. Front and back of the central system module may be understood as front and back in context of the direction of travel of the vessel during use.

[0104] A fifteenth aspect provides for a submersibles vessel comprising a central system module and a second propulsion arrangement according to the fourteenth aspect.

[0105] A sixteenth aspect provides for a submersible dredging vessel comprising a central system module and a first propulsion arrangement according to the fourteenth aspect.

[0106] It will be clear to the skilled person that while a submersible dredging vessel is used as an example, certain aspects of the invention may be used for common submersible vessels, or regular vessels.

[0107] BRIEF DESCRIPTION OF THE DRAWINGS

[0108] The various aspects and examples thereof will now be discussed in conjunction with drawings. In the drawings:

[0109] Figure 1: shows an isometric view of a submersible dredging vessel;

[0110] Figure 2A: shows a top view of the submersible dredging vessel;

[0111] Figure 2B: shows a side view of the submersible dredging vessel;

[0112] Figure 2C: shows a bottom view of the submersible dredging vessel;

[0113] Figure 3: shows an isometric view of the submersible dredging vessel having it’s outer body removed from a first angle;

[0114] Figure 4: shows an isometric view of the submersible dredging vessel having it’s outer body removed from a second angle; and

[0115] Figure 5: shows a schematic example of a dredging arrangement comprising a floating object and a dredging vessel.

[0116] Figure 6: shows an isometric view of an example of a set of modular submersible vessel modules;

[0117] Figure 7A: shows an isometric view of an example of a first submersible vessel formed by the set of modular submersible vessel modules; and

[0118] Figure 7B: shows an isometric view of an example of a second submersible vessel formed by the set of submersible vessel modules.

[0119] DETAILED DESCRIPTION

[0120] Figure 1 shows a submersible dredging vessel 100 having a body 102 and a direction of travel D. In the example, the body 102 is an outer shell of the vessel 100, defining the outer contour of the vessel 100. Preferably, the body 102 is shaped as a hydrodynamic body 102, in order to facilitate the relatively energy efficient movement through a body of water. For example, a longitudinal shape, in which the length of the body 102 exceeds the width and height of the body 102, may be considered a hydrodynamic shape. As shown in the depicted example, the body 102 has a longitudinal shape and no acute angles, as acute angles may negatively affect the hydrodynamic properties of the body 102, thus increasing energy consumption of the vessel 100.

[0121] The vessel 100 has a horizontal plane H, specifically a virtual horizontal plane H, that is being spanned by a longitudinal axis L of the vessel 100 and a transversal axis T, said transversal axis T being parallel to the width direction of the vessel 100. The body 102 has a contour 106 in the horizontal plane H, said contour 106 having four corners 108. The corners 108 have no acute angles or, in other words, are rounded preferably with a relatively large radius.

[0122] The longitudinal body 102 has a front side 110 provided at a first distal end of the longitudinal body 102 and a rear side 112 at a second distal end of the longitudinal body 102, opposite the first distal end. In the example, two corners 108 are provided towards a front side of the vessel 100 and two corners 108 are provided towards a rear side of the vessel 100. In the example, the two corners 108 provided towards the front side 110 and rear side 112 of the vessel 100 respectively are connected to each other such as to form a half circle 108’.

[0123] Turning to Figs. 2A-2C, an example of the submersible dredging vessel 100 has been depicted, showing a top view, side view and bottom view respectively. The submersible dredging vessel 100 comprises a plurality of, in the shown example four, primary propulsions units 104. In the example, each primary propulsion unit 104 comprises a pump 126. Specifically, the pump 104 is in this example a centrifugal pump, e.g. a single-stage centrifugal pump having a single impeller, a multi-stage centrifugal pump having a plurality of impellers, a jet pump, a submersible pump, i.e. a pump designed to be fully submerged during operation without damaging the motor of the submersible pump, or a flow pump, but may also be implemented as a positive displacement pump, such as reciprocating pumps, e.g. piston or plunger pumps, electrical wastewater pumps, submersible pumps, immersion pumps, sewage pumps, dirt pumps or rotary pumps, such as gear pumps.

[0124] It will be clear to the skilled person that the various pump designs each have advantages, that will make them more suitable for some situations, but may be all suitable for use as a pump 126 for a primary propulsion unit 104. The propelling force provided by the primary propulsion unit 104 may be improved by providing a nozzle 128 at the outlet of a corresponding pump 126. The shape of the nozzle 128 may be used to increase or reduce the speed at which the liquid exits the primary propulsion unit 104, ejected by the pump 126. For example, by having a nozzle 128 of which the opening surface of the outlet is reduced relative to the surface of the outlet of the corresponding pump 126, speed of the ejected liquid is increased. Additionally, the nozzle 128 may be used to aim the direction of the propelling force of a corresponding pump 126, by having the outlet of the nozzle 128 aimed in a preferred direction. The direction in which the outlet of the nozzle 128 is aimed has a component parallel to the direction of the propelling force.

[0125] As can be seen in Figs. 2A and 2C, the plurality of propulsion units 104 are distributed around the contour 106 of the body 102 of the submersible dredging vessel 100 for distributing the propelling force provided by each corresponding primary propulsion unit 104. Each primary propulsion unit 104 of the plurality of propulsion units 104 is arranged to provide said propelling force. By distributing the propulsion units around the contour 106 of the body 102, the propelling force may be provided at different locations on the vessel 100.

[0126] In the shown example, four primary propulsion units 104 of the plurality of primary propulsion units 104 are each provided in a corresponding corner 108, which corners form the semi-circle 108’. As an example, as the vessel 100 needs to make a forward starboard turn, the rear propulsion units 104 on the port side of the vessel 100 need to provide more propelling force than the rear propulsion units 104 on the starboard side of the vessel 100. This may be achieved by lowering power provided by the propulsion units 104 on the starboard side of the vessel 100, for example by turning them off. Alternatively or additionally, the front starboard propulsion units 104 provide a force more than the front port propulsion units 104.

[0127] In the example, each propelling force of a corresponding primary propulsion unit 104 has a component parallel to the longitudinal axis L of the submersible dredging vessel 100, facilitating movement parallel to the direction of movement D. In the example, the primary propulsion units 104 are provided adjacent to each other such that each primary propulsion unit 104 of the two primary propulsion units 104 has a component towards the other primary propulsion units 104. In other words, the outlets of the primary propulsion units 104 and more precisely, the direction of jets of water that the primary propulsion units 104 are arranged to provide, have a component angled relative to the direction of movement D and, in the example, the longitudinal direction L of the vessel 100.

[0128] The angle relative to the movement direction is be between 5 and 30 degrees, e.g. 10 and 25 degrees, more specifically between 15 and 20 degrees. Alternatively, the primary propulsion units 104 are provided adjacent to each other such that each primary propulsion unit 104 of the two primary propulsion units 104 has a component away from the other primary propulsion units 104. The angle relative to the longitudinal direction L is for the propulsion units 104 at the front 110 larger than for the propulsion units 104 at the rear 112. At the bow, this may be 20°, plus or minus 20% and at the stern, this may be 10°, plus or minus 20%. Preferably, the outlets of the propulsion units 104 are provided such that direction of jets of water that the primary propulsion units 104 are parallel to the longitudinal direction L of the vessel 100 from a side view of the vessel or parallel to the virtual horizontal plane H of the vessel 100. This allows for rotating of the vessel 100, e.g. rotating the vessel in a starboard or port direction, without having to turn the outlet of the primary propulsion units 104, e.g. the nozzle 128.

[0129] In the shown example, the propelling force of each primary propulsion unit 104 is provided in a horizontal plane H of the submersible dredging vessel 100, specifically, both the component parallel to the direction of travel D and the component towards the other adjacent primary propulsion unit 104 are provided in a horizontal plane H or parallel to the transversal axis T. Thus, the primary propulsion units 104 may be used to control the movement of the vessel in the horizontal plane H, e.g. a forward, backward, starboard and port movement or combination thereof, by activating the primary propulsion units 104 accordingly.

[0130] In the example, two primary propulsion units 104 are provided adjacent to each other such that each primary propulsion unit 104 of the pair has a component towards the other primary propulsion units 104 or parallel to the transversal axis T, at the front 110 of the vessel 100 and towards the rear 112 of the vessel 100. Since the pair of primary propulsion units 104 have a same component, except in opposite direction, towards each other, they cancel each other out and allowing movement parallel to the longitudinal axis L of the vessel 100.

[0131] In an example, if the two primary propulsion units 104 provides at the rear side 112 of the vessel 100 are powered, each providing the same amount of propelling force, each propulsion unit 104 of the pair has a component towards the other of the pair of propulsion units 104. When the pair of propulsion units 104 now both provide the same propelling force, the components towards each other - or away from one another - cancel each other out and only the component parallel to the movement direction D remains.

[0132] Generally, the resulting propelling force of each propelling force of a corresponding primary propulsion unit 104 may be determined using vector-mathematics. From this it follows that the vessel 100 can be navigated, actuated, and controlled, in a body of water by adjusting the power provided to the propulsion units 104.

[0133] In the shown example, specifically in the example shown in Fig. 2B, the pump 104 comprises a filter 114 arranged to protect the pump 104 from debris during use. A filter can consist of a grating, or raster, preventing debris above a certain size from entering the inlet of the pump 104. When debris above a certain size enters the pump 104, the pump may be damaged 104. Also an inlet of the dredging pump 120 may be provided with a filter.

[0134] In the example, depicted in Figs. 3 and 4, the submersible dredging vessel 100 further comprises a secondary propulsion system 116 arranged to provide an auxiliary propelling force. The secondary propulsion system 116 of the example comprises a thruster with an electromotor arranged to drive a propellor of the thruster. Additionally or alternatively, the secondary propulsion system 116 may be provided using different propulsion devices, such as the previously described pumps.

[0135] In the example, the secondary propulsion system comprises two thrusters, provided at the rear end of the vessel 112; one for a port side and one for a starboard side. Optionally, a third thruster may be provided between the two thrusters provided at port and starboard side of the stern. It will however be clear to the skilled person that the secondary propulsion system 116 may comprise a different number of propulsion devices, or a mix of propulsion devices.

[0136] Comparable to the primary propulsion units 104, the secondary propulsion system 116 produces an auxiliary propelling force based on individual auxiliary propelling forces provided by each thruster. The auxiliary propelling force has a component parallel to the propelling force, for example an auxiliary propelling force parallel to the propelling force, such that the auxiliary propelling force may be used to support the propelling force, e.g. providing extra propelling force moving forward.

[0137] In one example, the thrusters of the secondary propulsion system 116 are bidirectional in the sense the propellers can rotate clockwise and counterclockwise. This may be used for steering the vessel 100, for example by rotating a propeller of a port thruster clockwise and a propeller of a starboard thruster counterclockwise - or the other way around.

[0138] Turning to Figs 2C, 3 and 4, it can be seen that the submersible dredging vessel 100 comprises a dredging module 118. The dredging module 118 comprises a dredging pump 120 for pumping a fluid and a fluid outlet manifold 124 comprising a fluid outlet openings 122 being arranged to provide direction jets of the fluid. Referring to Fig. 2C specifically, the fluid outlet openings 122 are arranged to provide the fluid jets in a downward direction, relative to the vessel 100, in the example such that the fluid jets are aimed towards the bottom of a body of water.

[0139] The direction of the fluid jets may, in use be vertically oriented relative to the water surface, or alternatively, be provided under an angle relative to the water surface, though in the latter example with a large component vertically relative to the surface of the body of water, in use.

[0140] Additionally or alternatively, the fluid outlet openings 122 may be arranged to provide the water jets diverging from a vertical axis of the vessel 100, such that the water jets are directly outwardly, under an angle, seen from bow sight or stern sight.

[0141] The fluid outlet openings 122 may be provided such that they all have a the same opening size, e.g. a constant diameter forming a circular opening, or may have openings of various sizes, e.g. wherein the diameter of the circular opening varies between outlet openings 122. For example, larger openings 122 may be provided towards the centre of the vessel 100, such that the fluid exists at a lower velocity than towards the counter of the dredging vessel 100. Alternatively, the openings may be larger away from the centre, to allow for substantially equal flows of water through all openings.

[0142] By providing jets aimed at the bottom of a body of water, for example a seabed, a port bottom, or a river bedding, the material making up the bottom of the body of water may come loose, thus that the sediment may be fluidised in the water. The loose material thus fluidised may than be carried away by the current of the body of water, such that locally the bottom of the body of water has been adjusted. The carrying away may occur under influence of environmental parameters, like tidal flows, river flows, force of gravity - as a density current -, other or a combination of two or more thereof.

[0143] Thus, by using direction jets it is possible to dredge a bottom of a body of water, without providing means to transport the loosened material and instead making use of the existing current of the body of water. The dredging pump 120 may be a pump of the same type as the primary propulsion units 104. Specifically, the dredging pump 120 in the example is a centrifugal pump, e.g. a single-stage centrifugal pump having a single impeller, a multi-stage centrifugal pump having a plurality of impellers, a submersible pump or a flow pump.

[0144] Alternatively, the dredging pump 120 may also be implemented as a positive displacement pump, such as reciprocating pumps, e.g. piston or plunger pumps, or rotary pumps, such as gear pumps. Generally, the upward force provided by the fluid jets scales with the power provided to the dredging pump 120. In other words, the more power provided towards the dredging pump 120, the more upward force is provided to the vessel by the fluid jets.

[0145] As depicted in the example of Fig. 2C, the fluid jets 122 are distributed over a width W of the submersible dredging vessel 100. For example, the fluid jets 122 may be distributed over the width W in clusters, with a subset of fluid jets 122 being relatively close to each other, or evenly spaced over the width W, such that all fluid jets 122 are at a same distance from neighbouring fluid jets 122.

[0146] Additionally or alternatively, the fluid jets 122 may be provided in multiple rows in longitudinal direction L, e.g. in two rows, while the fluid jets 122 in each row are distributed over the width W. In the example, the fluid jets are distributed along a line L2 perpendicular to the longitudinal axis L of the submersible dredging vessel 100, specifically evenly spaced along the line L2.

[0147] The submersible dredging vessel 100 comprises a centre of gravity G provided along the longitudinal axis L at a first distance dl from a midpoint M of the longitudinal axis L. In the example, at least one fluid outlet opening 122 is arranged to provide a fluid jet along a line L2 perpendicular to the longitudinal axis L. The line L2 intersects the longitudinal axis L at a second distance d2 from the midpoint M. The second distance d2 is an extension of the first distance dl. This means that the second distance d2 is larger than the first distance dl. In another example, the second distance d2 is smaller than the first distance dl. In again another example, the second distance d2 is substantially equal to the first distance dl.

[0148] The submersible dredging vessel 100 has a negative buoyancy, of itself. In other words, when the submersible dredging vessel 100 is not being powered or driven, the dredging vessel 100 will sink to the bottom of the body of water. When the dredging pump 120 is powered, it can operate in different operating modes, each mode affecting the buoyancy of the vessel 100 differently.

[0149] In the example, the dredging pump 120 is arranged to operate three modes. In the first mode, a sink mode, a sum of the upward force of the fluid jets and an upward force acting on the submersible dredging vessel 100 is smaller than a downward force acting on the submersible dredging vessel 100 provided by the mass of the submersible dredging vessel 100. For example, if the dredging pump 120 of the vessel is turned off, or powered at a relatively low level e.g. less than 85% such as 80% of the maximum operating power of the dredging pump 120, the sum of the upward force of the fluid jets and the upward buoyancy force acting on the submersible dredging vessel 100 is not sufficient to overcome the downward force, causing the vessel 100 to sink.

[0150] The larger the difference between the downward force and the sum of upward forces, the more quickly the vessel 100 will sink. In a second mode, a stable mode or equilibrium mode, the sum of the upward force provided by the fluid jets and the upward force acting on the submersible vessel 100 is substantially equal to the downward force acting on the submersible dredging vessel. In this mode, the vessel 100 is maintained at a constant level in the body of water, preventing rising or falling of the vessel 100. More power is provided to the dredging pump 120 than in the sink mode, balancing the downward force and the sum of the upward forces acting on the body. For example the dredging pump 120 operates between 80% and 95% of its maximum operating power, such as between 85% and 90% In a third mode, a rise mode, the sum of the upward force provided by the fluid jets and the upward force acting on the submersible dredging vessel 100 is larger than the downward force acting on the submersible dredging vessel 100.

[0151] In the rise mode, the dredging pump 120 is powered more than in the stable mode, e.g. more than 90% e.g., 95% of the maximum operating power of the dredging pump 120, such that the sum of upward forces is positive compared to the downward acting force. The larger the difference between the sum of the upward forces and the downward acting force, the faster the vessel 100 will rise to the surface.

[0152] As depicted in Fig. 2B, the submersible dredging vessel 100 comprises a centre of buoyancy B and wherein, during use, the centre of gravity G and the centre of buoyancy B are aligned in a vertical direction, for example in at least one of the sink mode, stable mode and rise mode. As a result, the vessel 100 does not rotate around the longitudinal axis L during use. In the depicted example, the centre of buoyancy B is provided above the centre of gravity G, but it will be clear to the skilled person that the opposite, i.e. the centre of buoyancy B provide below the centre of gravity G, is also possible.

[0153] Turning to Fig. 5, shows a schematic example of a dredging arrangement 200. The dredging arrangement 200 comprises the submersible dredging vessel 100 and a buoy 400 arranged to float during use of the dredging arrangement 200. Preferably, this is achieved passively, without powering the buoy 400, such that the buoy 400 can remain afloat without requiring energy. In the example, this is achieved by providing a hollow space in the buoy 400, filled with a product having a density lower than that of water, e.g. air at atmospheric pressure. Additionally or alternatively, the buoy 400 is provided as an inflatable buoy 400.

[0154] In order to determine, and control, the vertical position of the vessel 100 in a body of water, a vertical detection arrangement is provided. The submersible dredging vessel 100 comprises the vertical detection arrangement 302, for detecting the current vertical position of the submersible vessel 100 in a body of water, and a controller 304. The controller 304 is operatively connected to the dredging pump 120 and the vertical position detection arrangement 302. The controller 304 is arranged to control the vertical position of the submersible vessel 100 in the body of water by operating the dredging pump 120 in at least one of the sink mode, stable mode and rise mode, based on the current vertical position.

[0155] In the example of Fig. 5, the submersible dredging vessel 100 further comprises a triangulation system 306 operatively connected to the controller 304. This controller 304 may be the same controller used to control the vertical position of the submersible vessel 100 in the body of water, or may be provided as a separate controller. The triangulation system 306 is arranged to determine the position of a buoy, as an example of a floating object 400, relative to the submersible dredging vessel 100.

[0156] In the example, the triangulation system 306 comprises a Ultra Short Base Line (USBL) 320 acoustic triangulation system. Such a USBL system 320 may be arranged to determine relative coordinates of the buoy 400 with respect to the vessel 100. In the shown example, the USBL system 320 comprises a USBL sensory device 322 attached to the vessel 100 and a beacon 324 attached to the buoy 400 on the other end.

[0157] The beacon 324 is arranged to receive and transmit signals to the USBL sensory device 322. Alternatively, the triangulation system 306 can comprise a Short Base Line (SBL) or Long Base Line (LBL) acoustic system. If a SBL system is used instead, an array of acoustic transducers may be provided on the vessel 100, and a beacon to the buoy 400. By measuring the signal emitted by the beacon attached to the buoy 400, the location of the buoy 400 relative to the vessel 100 may be determined.

[0158] The buoy 400 comprises a location detection system 326 for determining first geographical coordinates of the buoy 400 and a transmitter 328 arranged to send the coordinates of the buoy 400 to a receiver 330 of the submersible dredging vessel 100. In the example, the location detection system 326 is arranged to determine the location of the buoy 400 using a satellite navigation system, e.g. GPS, Galileo, GLONASS, BeiDou. Additionally or alternatively, the location detection system 326 may be based on terrestrial radio navigation, e.g. LORAN or eLORAN, and / or based on the earth’s magnetic field, e.g. magnetic anomaly navigation or INS systems, whether or not GNSS based.

[0159] Additionally or alternatively, the buoy 400 may comprise a USBL system arranged to cooperate with the USBL system 320 provided on the vessel 100. In such an example, the USBL provided on the buoy may be provided at larger time intervals, e.g. by delaying the interval, to the vessel 100, than the data relating to the second geographical coordinates to the buoy 400 due to data limitations, e.g. due to the intrinsic nature of the measurements. Nevertheless, the two USBL systems may cooperate to more accurately determine the position of the vessel relative to the buoy, and vice versa, e.g. using Kalman filtering.

[0160] The vessel 100 further comprises a receiver 330 operatively connected to the controller 304 and arranged to receive first geographical coordinates of the buoy 400, in the example determined using a GPS system 326, from a transmitter 328 comprised by the buoy 400. The controller 304 is arranged to determine second coordinates of the submersible dredging vessel 100 based on the first geographical coordinates of the buoy 400 and the position of the buoy 400 relative to the submersible dredging vessel 100 in Cartesian or polar coordinates.

[0161] Once a location of the buoy 400 is known in first geographical coordinates, and transmitted to the vessel 100, it is possible to combine this data with position of the buoy 400 relative to the vessel 100 and determine the position of the vessel 100 in second geographical coordinates. Once the second geographical coordinates of the vessel 100 have been determined, they can be send to the buoy 400. This may allow for the buoy 400 to broadcast the second geographical coordinates to, for example, a ship or a control station located on the shore.

[0162] In another example, the buoy 400 determines a position of the vessel 100 relative to the buoy 400. Subsequently, based on the determined relative position and absolute position data of the buoy 400 based on satnav information received by the buoy 400, the buoy 400 determines an absolute geographical position of the vessel 100 and sends the determined absolute geographical coordinates to the vessel 100 and / or to another data station, either on shore, in the air or on a vessel.

[0163] In the example, the second geographical coordinates are more accurately determined by enhancing the data comprising the first geographical coordinates and the position of the buoy 400 relative to the vessel with data about the velocity of the vessel 100. When the vessel 100 is moving, e.g. due to being propelled by the primary propulsion units 104 and / or the secondary propulsion system and / or by the current in the body of water, the vessel 100 may no longer be at the position of the originally determined second geographical coordinates, as determining the first geographical coordinates and the position of the buoy 400 relative to the vessel, and thus the determination of the second geographical coordinates, may happen at fixed intervals, e.g. every few seconds.

[0164] Therefore, the vessel 100 of the example further comprises a velocity measurement system 308 operatively connected to the controller 304, allowing determining of the second geographical coordinates of the submersible dredging vessel 100 to be further based on the velocity of the submersible dredging vessel 100. As an example, the velocity measurement system 308 may further comprise equipment arranged to measure sound speed, e.g. obtained through water salinity, pressure and / or temperature from a CTD working with the controller 304, temperature, and / or an north keeping inertial navigation system. It will be clear to the skilled person that additional or alternative equipment for measuring the velocity of the vessel may be provided as part of the velocity measurement system 308.

[0165] The velocity measurement system 308 comprises an acoustic doppler current profiler system 310 aimed at a surface, in the example the water surface, for determining the velocity of the submersible dredging vessel 100 relative to the water surface or the bottom of the body of water during use. Alternatively or additionally, the doppler current profiler - or a second doppler current profiler - is aimed at the bottom of the body of water for determining a velocity of the submersible dredging vessel 100 relative to the bottom of the body of water.

[0166] Additionally or alternatively, at least one doppler current profiler may be provided that is inclined relative to the horizontal plane H, such that the doppler current profiler may be used to measure the distance of the vessel 100 to a nearby object provided in the body of water, e.g. a quay wall. The velocity measurement system 308 may be implemented in other ways. For example, a vane or a propeller coupled to a motion sensor or rotation sensor may be used.

[0167] Additionally or alternatively, an electromagnetic log can be used to determine the speed of water flow past the vessel 100 may, making use of a sensor providing an electromagnetic field. When the vessel 100 moves through the body of water, the water and electromagnetic field induce a voltage that is proportional to the speed of the water relative to the vessel 100. In a further example, at least one of an inertial navigation system (INS) and inertial measurement unit (IMU) may be used, said INS and / o r IMU comprise at least one accelerometer and one gyroscope, arranged to estimate changes in velocity and rotation respectively. From this, it is possible to estimate the velocity and orientation of the vessel 100 over time.

[0168] The INS, electromagnetic log and doppler current profiler system 310 may be used in combination with each other, or individually. When the systems are used in combination, the velocity of the vessel 100 may be more accurately determined, as data between systems may be compared and used to account for errors such as drift.

[0169] In the example, the doppler current profiler system 310 comprises a Doppler Velocity Log 312, or DVL, that uses four acoustic transducers in a Janus configuration and wherein each acoustic transducer pings a signal towards the water surface. In said Janus configuration, the four acoustic transducers are angled outward towards the surface of the body of water at equal angles relative to the surface in pairs pointing in opposite directions.

[0170] This setup allows the DVL 312 to measure Doppler shifts along each axis, enabling determination of the velocity of the vessel 100 in three-dimensional space (in the direction of travel D, perpendicular in the direction of travel D in the horizontal plane H, and perpendicular to the direction of travel D perpendicular to the horizontal plane H; surge, sway and heave).

[0171] By aiming the DVL 312 towards the surface of the body of water, the velocity of the vessel 100 relative to the body of water can be determined. Preferably, the DVL 312 is provided above a possible density gravity sediment or sludge current that may be produced during dredging due to the jet of the dredging pump 120, in order to prevent the sediment or sludge interfering the signals of the acoustic transducers. Alternatively, the acoustic doppler current profiler system 310 is aimed at the water surface and the bottom of the body of water for determining the velocity of the submersible dredging vessel 100; so the acoustic doppler current profile 310 may be arranged such that during operation, it is aimed upwards, downwards or sidewards.

[0172] The submersible dredging vessel 100 may be used to map the bottom of the body of water. This may be needed in order to determine if dredging has been successful, or if locally more dredging is needed to have a sufficiently deep body of water. Therefore, the submersible dredging vessel 100 of the example further comprises a first echo sounder, as an example of a first depth meter (or altitude meter) 314, operatively connected to the controller 304 and arranged to determine the distance between the submersible dredging vessel 100 and a bottom of a body of water.

[0173] Combining the depth information provided by the first echo sounder 314 with the second geographical coordinates, it is possible to provide data indicative of how deep the body of water is at a specific geographical coordinate, e.g. a map. Thus, the vessel 100 of the example is arranged to map the bottom of the body of water, based on the second geographical coordinates of the submersible dredging vessel 100, the depth of the vessel 100 below the surface of the water, for example measure by means of the pressure gauge, and the distance between the submersible dredging vessel 100 and the bottom of the body of water.

[0174] The vessel 100 further comprises a second echo sounder, as an example of a second depth meter 316, operatively connected to the controller 304 and arranged to determine the distance between the submersible dredging vessel 100 and the bottom of the body of water. The controller 304 is arranged to determine material characteristics based on the distance determined between the submersible dredging vessel 100 by the first echo sounder as a first depth meter and the second echo sounder as a second depth meter.

[0175] Specifically, the first and second echo sounder operate at different frequencies. For example a first echo sounder may be operated in a range between 100kHz and 300 kHz, e.g. 200 kHz, while the second echo sounder may be operated in a range between 10 kHz and 50 kHz, e.g. 33 kHz. For each frequency, the acoustic pulse emitted by the corresponding echo sounder, penetrates at least part of the bottom of the body of water differently, i.e. to different depths, before being reflected back to corresponding echo sounder.

[0176] As a result, the acoustic pulses have a different travel time from which the depth of a specific layer of the bottom of the body of water may be determined. Operating the first echo sounder and second echo sounder at different frequencies, both over a corresponding range of frequencies, may thus be used to determine characteristics of the material that comprises the bottom of the body of water.

[0177] The vessel 100 further comprises a pressure gauge 318 as a depth sensor operatively connected to the controller 304 and arranged to determine the pressure acting upon the submersible dredging vessel 100. The controller 304 is arranged to determine the distance between the submersible dredging vessel 100 and a surface of the body of water based on the pressure acting upon the submersible dredging vessel 100.

[0178] Additionally or alternatively, the triangulation system 306 may be used to determine the depth of the vessel 100, by determining the distance between buoy 400 and the vessel 100 in a three-dimensional, or spherical, coordinate system. Since the buoy 400 floats on the surface of the body of water, the vertical component of the distance between the buoy 400 and the vessel 100 is indicative for the depth of the vessel 100.

[0179] Once the distance between the vessel 100 and the surface of the body of water is known, the controller 304 in the example is arranged to determine the depth of the body of water based on the distance between the submersible dredging vessel 100 and the surface of the body of water and based on the distance between the submersible dredging vessel 100 and the bottom of the body of water.

[0180] The submersible dredging vessel 100 comprises an electrical power system 334 connected to a propulsion arrangement 332, for providing power to the propulsion arrangement 332, and a diagnostic system 340 operatively connected to the propulsion arrangement 332 and the electrical power system 334. The diagnostic system 340 is arranged to detect operational failure of at least one of the electrical power system 334 and the propulsion arrangement 332. Operational failure may be detected by measuring properties of the propulsion arrangement 332 and / or the electrical power system 334. Optionally, operational failure may be detected in other components of the vessel 100, e.g. the diagnostic arrangement 340, the safety system 352 etc., or the dredging arrangement 200.

[0181] For example, the resistance over the propulsion arrangement 332 may be measured and wherein a relatively low or high resistance may be indicative of operational failure. Additionally or alternatively, temperature of the electrical power system 334, humidity in the electrical power system 334 as well as voltages and currents at various locations through the electrical power system 334 and / or the propulsion arrangement 332 may be measured. These may, for example, be measured using sensors and equipment such as relays, contactors, convertors, fuses, etc. Operational failure in the examples may be indicative for damage to the vessel 100, in particular the to the electrical power system 334 and the propulsion arrangement 332. When operational failure is detected, the vessel 100 of the depicted example is arranged to return to the surface of the body of water it was operating in, such that the vessel 100 can be retrieved before further damage may occur and the vessel 100 may not be recoverable. The electrical power system 334 comprises a first and second power supply 336, 338. In the shown example, the first power supply 336 is a larger power supply than the second power supply 338. Larger meaning in this context that more power may be provided and that more power may be stored when fully charged.

[0182] The first and second power supply 336, 338 are individually provided in a corresponding first liquid-tight container and a corresponding second liquid-tight container respectively. In the shown example, the liquid-tight containers are provided as containers made from a durable material, e.g. stainless steel. This may allow the containers to remain liquid-tight in case of an external impact, e.g. if the vessel 100 collides with a foreign object. The liquid-tight containers, may be provided such that they may be opened such that the power supply 336, 338 provided in the liquid-tight containers may be serviced and / or repaired.

[0183] The propulsion arrangement 332 comprises a primary propulsion unit 104 and a secondary propulsion system 116. The primary propulsion unit 104 and the secondary propulsion system 116 are each connected to the first power supply 336 and the second power supply 338. In the shown example, a plurality of primary propulsion units 104 is provided, each primary propulsion unit 104 being a pump.

[0184] The second power supply 338 in the example used to power an impeller, e.g. a propeller, based system using less power, when fully powered, than the primary propulsion units 104. As such, the second power supply 338 is arranged to power the secondary propulsion system 116 based on detected operational failure by the diagnostic arrangement 340 in at least one of the first power supply 336 and the primary propulsion unit 104. This allows for the vessel 100 to run both the primary propulsion units 104 and the secondary propulsion system 116 in order to reach the surface relatively quickly and, in case of operational failure of the primary propulsion units 104, to power the secondary propulsion system 116 acting as an emergency system in order to bring the vessel 100 towards the surface and optionally propel the vessel 100 ashore or towards a certain predetermined safe location.

[0185] Since the secondary propulsion system 116 consumes less power than the primary propulsion units 104, the second power supply 338 is sufficient for operation even if it is provided as a smaller power supply compared to the first power supply 336. Providing a smaller power supply may be advantageous to make sure the vessel 100 remains relatively compact and lightweight. As an example, at least a part of the primary propulsion system, e.g. a variable frequency drive, is provided in a liquid-tight container and / or at least part of the secondary propulsion system is provided in the second liquid-tight container.

[0186] The submersible dredging vessel 100 comprises a control and sensing system 342 having first set of electrically powered components 344 and a second set of electrically powered components 346. The first set of electrically powered components 344 is connected to the first power supply 336 and the second power supply 338, each for powering the first set of electrically powered components 344 individually. In other words, the first set of electrically powered components 344 can be powered both by the first power supply 336 and the second power supply 338 in case one of the power supplies is not operative.

[0187] The second set of electrically powered components 346 is connected to the first power supply 336 for powering the second set of electrically powered components 346. The second power supply 338 is arranged to power the first set of electrically powered components 344 based on operational failure detected by the diagnostic arrangement 340 in the first power supply 336.

[0188] The first set of electrically powered components 344 of the example are critical components for ensuring that the vessel 100 may be returned to the surface, next to the propelling system, such as equipment needed to determine the position of the vessel 100.

[0189] The second set of electrically powered components 346 may comprise equipment that may be advantageous during regular operation, but is not necessary for returning the vessel 100 to the surface, such as equipment for mapping the bottom of the body of water. Thus, in case of power failure of the first power supply 336, all equipment not needed to return the vessel 100 to the surface does not consume any power stored in the second power supply 338, facilitating that sufficient power is available for the first set of electrical components 344.

[0190] In the example, the electrical power system 334 further comprises a third power supply 348 operatively connected to the control and sensing system 342 and the diagnostic arrangement 340. The first set of electrically powered components 344 comprises a primary subset of electrically powered components. The third power supply 348 is arranged to power the primary subset of electrically powered components based on operational failure detected by the diagnostic arrangement 340 in the second power supply 336.

[0191] Thus, in case of even bigger distress, in which both the first power supply 336 and the second power supply 338 are not able of providing power only core equipment, i.e. the primary subset of electrically powered components may still be powered. For example, no propulsion systems may be powered, but instead one or more air chambers may be filled with air to increase buoyancy of the vessel 100 such that it rises to the surface. To protect the at least a part of the control and sensing system 342 from external impact, said part of the control and sensing system 342 is provided in a liquid-tight container. In the shown example, part of the control and sensing system 342 is provided in a dedicated liquid-tight container. The liquid-tight container is comparable to the liquid- tight containers, of the first and second power supply 336, 338. In the scenario in which the vessel 100 may be in distress, e.g. by having a leakage, the liquid-tight container may act as a barrier against water entering the vessel 100.

[0192] This may prevent the control and sensing system 342 from becoming damaged, and allow operation during distress such that the vessel 100 may be safely returned to the surface of the body of water. In an example, the liquid-tight container for the control and sensing system 342 is provided in the first liquid-tight container. Preferably all connections to and from the liquid-tight containers and components are liquid-tight, including, but not limited to, the connections between the containers of the first power supply and the second power supply 336, 338 and the liquid-tight compartment in which part of the primary propulsion system 104, e.g. the variable frequency drive of the pumps, is be provided.

[0193] In the example, the vessel 100 further comprises one or more air chambers and a compressed air supply system 350 in fluid connection with the air chamber. Specifically, in the example the air chamber is a hollow space in the vessel 100 having sufficient volume to store a gas, e.g. air, at pressure conditions for a certain depth in the body of water or atmospheric at the surface of the body of water, such that the vessel 100 rises to the surface by increasing the buoyancy of the vessel 100.

[0194] The air supply system 350 comprises a connector for connecting to a container comprising compressed air and an air supply control valve arranged to controllably fill the air chamber with air from the container. The container may be a conventionally compressed air container, e.g. having a screw connection to connect the container to the connect. The connecter is arranged to releasably connect a container to the air supply system 350 such that the contents of the container may be provided to the air supply system 350 without leakage. Thus when the air supply control valve is in an open position, the pressurised air from the container enters the lower pressure air chamber, thereby increasing the buoyancy of the vessel.

[0195] The compressed air supply system 350 of the example further comprises an electrically powered fail-open valve, next to the air supply control valve, connected to the first power supply 336 and second power supply 338 for controllably filling the air chamber with air. Thus, if the first power supply 336 and second power supply 338 are no longer able to provide power to the air supply system 350, the fail-open valve, opens. As an example, the fail-open valve may comprise a servo that, once unpowered by the first power supply 336 and the second power supply 338 opens the valve.

[0196] In case the first power supply 336 no longer is able to provide power to the air supply system 350, the air supply control valve may remain closed, unless activated by a controller to open. It will be clear to the skilled person that, besides providing the fail-open valve together with the air supply control valve, only one of them may be provided instead. Additionally, in the example the compressed air supply 350 is operatively connected to the diagnostic arrangement 340 and arranged to controllably fill the air chamber with air based on operational failure detected by the diagnostic arrangement 340 in the second power supply 338.

[0197] In the example, the vessel 100 further comprises a safety system 352 connected to the second power supply 338 and the diagnostic arrangement 340. The second power supply 338 is arranged to power the safety system 352 based on operational failure detected by the diagnostic arrangement 340 in the first power supply 336.

[0198] The safety system 352 of the example comprises a navigation light 354 arranged to provide an optical distress signal and a GPS beacon 356 arranged to determine a geographical position of the submersible dredging vessel 100, e.g. second geographical coordinates, and transmit said geographical position to a receiver. Such a receiver may be a receiver provided on the buoy or provided shore-side.

[0199] The navigation light 354 is arranged to be powered by at least one of the first power supply 336, the second power supply 338 and the third power supply 348 and the GPS beacon 356 is arranged to be powered by the third power supply 348. The navigation light 354 and the GPS beacon 356 may facilitate retrieving the vessel 100 once the vessel 100 reaches the surface of the body of water.

[0200] The navigation light 354 may be provided as a single light source or as a plurality of lights. The optical distress signal may be a constant single light source, an intermittent light source or a light source broadcasting a message, e.g. a message in Morse-code. The navigation light 354 may comprise a plurality of light sources, e.g. a plurality of optical distress signals. Additionally or alternatively, the safety system 352 may comprise a at least one of a combined satellite modem, a GPS beacon, a USBL system and an acoustic beacon.

[0201] In the shown example, the control and sensing system 342 comprises a plurality of controllers 304. Each of the plurality of controllers 304 is arranged to individually control the submersible dredging vessel 100 through the control and sensing system 342. The plurality of controllers 304 in the example are arranged to operate in parallel with each other. Each controllers 304 is individually capable of controlling the vessel 100. Thus, a redundancy has been introduced in the vessel 100, allowing the controllers 304 to correct or replace a faulty controllers 304 during operation. As a result, damage to the controllers 304, may not directly result in loss of control of the dredging vessel 100 such that the vessel 100 may still be retrieved.

[0202] Optionally, the vessel 100 may be configured such that, when all controllers 304 of the vessel 100 are no longer operative, e.g. due to faulty behavior or damage, the safety system 352 may automatically become activated by a hardwired connection. For example, emergency lights and / or the GPS system may be activated. Additionally or alternatively, the dredging pump of the vessel 100 may be activated, and powered such that the vessel 100 rises to the surface, e.g. by powering the dredging pump to its maximum pumping capacity.

[0203] The dredging arrangement 200 comprises a remote control arrangement comprising a remote controller arranged to send control signals to the submersible dredging vessel 100. This may allow the vessel 100 to be controlled from a distance in case parts of the control and sensing system 342 are no longer capable of sufficiently controlling the vessel 100. For example, if the controllers 304 are damaged, a user may manually intervene using the remote control arrangement using a remote controller.

[0204] Additionally or alternatively, the remote control arrangement may be used to control the vessel 100 remotely once one of the primary propulsion system, secondary propulsion system, the primary power supply and secondary power supply are no longer functional, e.g. broken. Alternatively, the remote control arrangement may be used for special operations of the vessel 100, e.g. docking purposes. The controller 304 of the submersible dredging vessel 100 is arranged to receive the control signals for controlling the submersible dredging vessel 100.

[0205] In the example, each of the control and sensing system 342, the primary propulsion 104, the secondary propulsion 116, the diagnostic system 340 and the safety system 352 may be individually switched on / off using a switch, such as to account for specific situations. Additionally or alternatively, the switch may be a digital switch, operated by a controller. This may allow for different operating modes of the vessel 100, e.g. when docking. In such a scenario, certain parts of the vessel 100 may be shut-off.

[0206] Additionally or alternatively, the vessel 100 may comprise a main switch arranged to control a starting sequence of the various electrically powered components of the vessel 100. If said main switch is in an ‘on -position, the vessel 100 will attempt to turn on its various components, even if said components have been turned off during use, e.g. when faulty behavior is detected such as high voltage peaks. For example, in the scenario in which at least two controllers 304 have been provided, and both controllers 304 have been turned off due to safety measures or when the vessel 100 has been stored, turning the main switch to its ‘on -position, the controllers 304 will attempt to boot at a fixed interval, e.g. every few seconds, using for example a relay.

[0207] In an example, when at least one controller is activated, the main switch and the relay may no longer be needed to start the rest of the components, e.g. the other controllers 304, as the at least one activated controller is arranged to provide this capability.

[0208] In the shown example, the electrical power system 334 further comprises a charging arrangement for forming a connection with a charging system for charging the electrical power system 334, The charging arrangement is arranged to have an operating mode, in which the electrical power system 334 is arranged to power the submersible dredging vessel 100 and prevents forming the connection with the charging system, and a charging mode, in which the electrical power system 334 is arranged to allow forming the connection with the charging system. This may, for example, be a physical key that may need to be inserted in a keyhole in the vessel 100, and which an operator may switch between the operating mode and the charging mode. When the vessel 100 is being charged, the vehicle may still be active. The charging arrangement of the vessel 100 may be provided with multiple fail-safe mechanisms to ensure safe operation, such as the reed switch and the electrical bridging element.

[0209] Additionally or alternatively, a digital key or an electronic key may be provided, e.g. a digital signal that may be provided remotely such as from a remote control centre or locally using an ID-badge having a magnetic strip arranged to cooperate with a digital card reader provided on the vessel 100. As an example, the charging arrangement comprises an electrical bridging element arranged to be releasably connected to the charging arrangement, wherein the charging arrangement is in the operating mode when the electrical bridging element is connected, and wherein the charging arrangement is in charging mode when the electrical bridge element is released from the charging arrangement.

[0210] The electrical bridging element be provided as a handle, comprising an electrical wire. Both ends of the handle may be electrically connected to a corresponding plus and min pole of the electrical power system 334, thus forming a closed loop system when present. Such a closed loop system is indicative that the handle is present, and that the poles are covered such that an operator may not accidentally come in to contact with them.

[0211] In an embodiment, the plus and minus poles comprise four poles each, e.g. four plus poles and four minus poles. When charging, three of the four poles are connected to the charging system, thereby charging the electrical power system 334. The fourth pole plus and minus pole are connected to a corresponding plus and minus pole of the electrical power system 334, in a fashion similar to that of the aforementioned electrical bridging element, i.e. the handle. Thus a closed loop is formed and the electrical power system may be prevented from going into an emergency shut-down mode. When the handle is present, the situation is reversed, i.e. the fourth plus and minus pole are connected by the handle, while the other three plus poles and three minus poles are not connected.

[0212] The closed loop of the fourth plus and minus pole may be detected by the electrical power system 334, said signal may be used to allow powering of the submersible dredging vessel 100. An interrupted loop between the fourth plus and minus pole may also be detected by the system, e.g. when charging, such that the vessel 100 may be prevented from receiving power from the electrical power system 334. Additional or alternative safety measures relating to charging of the vessel 100 may be provided.

[0213] For example, physical access to the charging system may be gained by opening a door or hatch from the vessel 100. Said door or hatch may be connected to a switch, e.g. a Reedswitch, such that when the door or hatch is opened, the vessel 100 is depowered at least locally such that the charging system is depowered and may not be powered by the electrical power system 334. Additionally or alternatively, opening the door or hatch may also stop charging the electrical power system 334 of the vessel 100.

[0214] Fig. 6 depicts an example of a set of modular submersible vessel modules 500. The set of modular submersible vessel modules 500 comprises a central system module 502, a first propulsion arrangement 504 arranged to cooperate with the central system module 502 to form a first submersible vessel 510, and a second propulsion arrangement 506 arranged to cooperate with the central system module 502 to form a second submersible vessel 512. The central system module 502 and the first propulsion arrangement 504 are configured to provide a first submersible vessel 510 having a negative buoyancy, while the central system module 502 and the second propulsion arrangement 506 are configured to provide a second submersible vessel 512 having a positive buoyancy.

[0215] The central system module 502 of the example comprises two submodules, a top part 502’ and a bottom part 502 ”.In the shown example, the top part 502’ is a buoyancy foam module arranged to affect the buoyancy of the central system module 502. The buoyancy foam module 502’ may increase the buoyancy of the central system module 502. In the shown example, the bottom part 502” of the central system module 502 accommodates the control systems, control logic and power systems of the vessel.

[0216] Each of the first propulsion arrangement 504 and the second propulsion arrangement 506 likewise comprises multiple submodules that are arranged to cooperate with the central system module 502. The first propulsion arrangement 504 comprises a first front module 504’, a first back module 504” and a dredging pump 120, which together form a propulsion arrangement suitable for a submersible dredging vessel. It will be clear to the skilled person that a dredging pump 120 may also be provided as a payload, i.e. not being part of the first propulsion arrangement 504. For example, a dredging pump 120 may be provided on the second submersible vessel 512. The dredging pump 120 may than be transported, or be used in short pulses to clean the seabed, without being used to control the depth of the vessel, as is the case in the first submersible vessel 510.

[0217] The second propulsion arrangement 506 comprises a second front module 506’ and a second back module 506 ”, which together form a propulsion arrangement suitable for operations requiring a positive buoyancy. This modular configuration allows propulsion and buoyancy characteristics of the vessel to be adapted by exchanging propulsion arrangements, while the central system module 502 remains unchanged.

[0218] The central system module 502 is arranged to cooperate with the first propulsion arrangement 504 and the second propulsion arrangement 506 by means of connections elements. The connection elements are arranged to securely and preferably rigidly connect either the first propulsion arrangement 504 or the second propulsion arrangement 506 to the central system module 502. More in particular, propulsion arrangement connection elements are provided on the first front module 504’, the first back module 504 ”, the dredging pump 120, the second front module 506’ and the second back module 506” that are arranged to cooperate with central system connection elements provided on the central system module 502, at the front and the rear of the central system module 502.

[0219] The connection elements may be implemented as pairing holes and protrusions, provided with securing elements like, for example, a hole transversely provided in the protrusion, in which hole a securing pin may be provided, which securing pin also protrudes through a wall of the pairing hole and the part of the vessel 100 in which the pairing hole is provided. This implementation is merely an example of connecting parts, other implementation for connecting parts known to the skilled person may be implemented for providing a releasable connection between the central system module 502 on the one hand and any of the first propulsion arrangement 504 and the second propulsion arrangement 506 on the other hand.

[0220] The first submersible vessel 510 of the example is configured as a submersible dredging vessel 100, wherein the first propulsion arrangement 504 comprises a dredging pump 120. The dredging pump 120 is arranged to pump a fluid and to provide directional fluid jets, preferably directed downwardly relative to the vessel 510, for performing dredging of a bottom of a body of water. During use, the dredging pump 120 may further be operated to influence the buoyancy and vertical position of the vessel by generating an upward force, such that the vessel can be selectively operated in a sink mode, a stable mode or a rise mode, thereby allowing controlled vertical positioning of the submersible dredging vessel while maintaining the modular vessel configuration.

[0221] The second propulsion arrangement 506 of the depicted example comprises a depth control arrangement 514, the depth control arrangement 514 comprising four thrusters 514 as well as two pairs of fins 514, one pair of fins 514 provided towards the front of the vessel 512 and one pair of fins 514 provided towards the rear of the vessel 512. The depth control arrangement 514 is arranged to generate a controllable force having a vertical component for controlling the depth of the vessel 512 during use. The four vertical thrusters 514 of the example each have a centre axis arranged at an angle relative to a longitudinal axis of the vessel 512, in the shown example substantially ninety degrees, such that the generated thrust has a predominantly vertical direction.

[0222] In addition to controlling depth, the thrusters 514 are arranged to counteract pitching and roll moments by selectively controlling the power supplied to the thrusters provided towards the front and rear of the vessel 512 and / or towards port and starboard sides of the vessel 512. Alternatively or additionally, control surfaces or rudders may be provided to cooperate with a flow of water along the vessel body, wherein such control surfaces or rudders may be actuated to affect pitch, roll and / or depth of the vessel 510, 512 during use. This allows different implementations of depth and attitude control while remaining consistent with the modular vessel concept described herein.

[0223] The thrusters 514 may be fixed relative to the vessel body or may be movably mounted, for example pivotable, to allow the direction of the generated thrust to be adjusted. The pivoting action may be provided by a driver, for example a servo motor. In a fixed configuration, the thrusters provide a force primarily for vertical movement, while in a movable configuration the thrusters may additionally provide a horizontal force component to assist in manoeuvring. Additionally or alternatively, the depth control arrangement 514 comprises one or more control surfaces or rudders arranged to cooperate with a flow of water along the vessel body, such that vertical movement is induced during forward motion of the vessel. Said control surfaces or rudders may move such as to affect the pitch of the vessel 510, 512.

[0224] In the shown example of the set of modular submersible vessel modules 500, the first propulsion arrangement 504 and the second propulsion arrangement 506 each comprises a plurality of primary propulsion units 104 distributed around a contour of the corresponding propulsion arrangement. The primary propulsion units 104 may comprise pumps, such as centrifugal pumps arranged to eject fluid jets, and / or thrusters arranged to generate directed thrust in a body of water. By distributing the primary propulsion units 104 around the contour, propelling forces can be applied at multiple locations of the vessel, allowing the resulting propelling forces to be combined for controlled movement in a body of water. This configuration further allows the propulsion arrangement 504 to be realised as a modular assembly that can cooperate with the central system module 502 without modification thereof, thereby facilitating exchangeability of propulsion arrangements 504 and adaptation of the vessel to different operational applications within the modular vessel concept.

[0225] The first propulsion arrangement 504 of the shown example comprises a secondary propulsion system 116. The secondary propulsion system 116 may comprise one or more thrusters or propellers arranged to provide an auxiliary propelling force that supplements or replaces the propelling force generated by the primary propulsion units 104. The secondary propulsion system 116 is arranged to provide an auxiliary propelling force that supplements or replaces a propelling force provided by primary propulsion units 104 during use.

[0226] By providing the secondary propulsion system 116 as part of a propulsion arrangement that cooperates with the central system module 502, propulsion functionality can be adapted to different operational requirements without modification of the central system module 502, thereby supporting the modular configuration of the submersible vessel and facilitating exchangeability of propulsion arrangements for different applications. The second propulsion arrangement 506 does comprise thrusters, however in the example they are used for depth control and not for providing an auxiliary propulsion.

[0227] In the example, the central system module 502 comprises an air chamber arrangement 516 comprising an air control system configured to control the amount of air present in the air chamber arrangement 516. The air control system comprises at least one air chamber, a connection to a compressed air supply, and one or more controllable valves for supplying air to the air chamber arrangement 516 and for releasing air therefrom. During use, air can be introduced into the air chamber arrangement 516 to increase buoyancy or can be vented to reduce buoyancy, thereby allowing the buoyancy of the vessel to be adjusted in response to operational requirements such as payload, operating depth or water pressure.

[0228] The air control system may further be arranged to compensate for compression and expansion of air at different depths by selectively adding or releasing air, such that a desired buoyancy condition is maintained over a range of water depths. The air chamber arrangement 516 may cooperate with depth control arrangement 514, such as thrusters and / or fins, wherein the vessel 512 is configured to be slightly positive buoyant and the air control system is used to set a base buoyancy level while the thrusters provide fine depth control. The air chamber arrangement 516 may be used in combination with passive buoyancy elements, such as buoyancy foam, or may replace such elements entirely, thereby providing a dynamically adjustable buoyancy system within the modular vessel configuration.

[0229] During use, pitching moments may occur during operation, for example due to small inaccuracies or delays in controlling the dredging pump 120 and / or due to water flow around the vessel 510, 512. To counteract such pitching moments, additional pitch control may be provided. In an implementation, at least one forward-oriented propulsion pump is provided with a nozzle having a vertical force component, wherein the nozzle is controlled by a pitch controller to generate a compensating moment. In an alternative implementation, the dredging pump and associated outlet manifold are positioned along the longitudinal axis at a location forward of the centre of gravity, rather than rearward thereof, such that forces generated by the dredging pump inherently counteract pitching tendencies during operation.

[0230] Fig. 7 A depicts an example of a submersible dredging vessel formed by cooperation of a central system module 502 and a first propulsion arrangement 504. In this configuration, the first propulsion arrangement 504 comprises a dredging pump 120 and is configured to provide a vessel having a negative buoyancy, suitable for dredging operations in a body of water. The dredging pump 120 is arranged to provide directional fluid jets for dredging and may further be operated to influence the buoyancy and vertical position of the vessel during use.

[0231] Fig. 7B depicts an example of a submersible vessel formed by cooperation of the same central system module 502 and a second propulsion arrangement 506. In this configuration, the second propulsion arrangement 506 is configured to provide a vessel having a positive buoyancy and is suitable for operations other than dredging, for example offshore operations or transport of payload. The second propulsion arrangement 506 may comprise depth control elements, such as thrusters or control surfaces, for actively controlling the depth of the vessel during use. In both examples, the central system module 502 remains unchanged, thereby illustrating the modular vessel concept.

[0232] Variations are understood to be comprised within the scope of the invention as defined in the appended claims. For example, it will be clear to the skilled person that the vessel may be used for other purposes than injection dredging. For example, the vessel may be used as an intelligent semi- stationary pump unit aiding other devices performing a dredging process, by connecting hoses or pipelines to the dredging pump and propulsion pumps respectively, pumping up sediment towards a predetermined location, or it can be used in a process of mass excavation or bed levelling dredging.

Claims

Claims1. A submersible dredging vessel comprising a body and a dredging module provided in said body, the dredging module comprising a dredging pump for pumping a fluid and a fluid outlet manifold comprising fluid outlet openings being arranged to provide directional jets of the fluid; wherein the submersible dredging vessel has a negative buoyancy during use; wherein the fluid outlet openings are arranged to provide the fluid jets in a downward direction, relative to the vehicle; and wherein the dredging pump is arranged to operate in: a sink mode, wherein a sum of the upward force of the fluid jets and an upward force acting on the submersible dredging vessel is smaller than a downward force acting on the submersible dredging vessel; a stable mode, wherein the sum of the upward force provided by the fluid jets and the upward force acting on the submersible vehicle is substantially equal to the downward force acting on the submersible dredging vessel; and a rise mode, wherein the sum of the upward force provided by the fluid jets and the upward force acting on the submersible vehicle is larger than the downward force acting on the submersible dredging vessel.

2. Submersible dredging vessel according to claim 1, wherein the upward force provided by the fluid jets scales with the power provided to the dredging pump.

3. Submersible dredging vessel according to claim 1 or 2, wherein the fluid jets are distributed over a width of the submersible dredging vessel.

4. Submersible dredging vessel according to claim 3, wherein the fluid jets are distributed along a line perpendicular to a longitudinal axis of the submersible dredging vessel.

5. Submersible dredging vessel according to any of the claims 1 - 4, further comprising a centre gravity and a longitudinal axis, wherein said centre of gravity is provided along said longitudinal axis at a first distance from a midpoint of the longitudinal axis.

6. Submersible dredging vessel according to claim 5, wherein at least a one fluid jet is provided along a line perpendicular to the longitudinal axis, wherein said line intersects the longitudinal axis at a second distance from the midpoint, and wherein the second distance is in an extension of the first distance.

7. Submersible dredging vessel according to claim 5 or 6, having a centre of buoyancy and wherein, during use, the centre of gravity and the centre of buoyancy are aligned in a vertical direction.

8. Submersible dredging vessel according to any of the claims 1 - 7, further comprising:- a vertical position detection arrangement for detecting the current vertical position of the submersible vehicle in a body of water;- a controller operably connected to the dredging pump and the vertical position detection arrangement and wherein the controller is arranged to control the vertical position of the submersible vehicle in the body of water by operating the dredging pump in at least one of the sink mode, stable mode and rise mode, based on the current vertical position.

9. Method of controlling the buoyancy of a submersible vehicle, preferably the submersible vehicle according to any of the claims 1 - 8, wherein the submersible vehicle has a negative buoyancy and comprises a dredging pump, wherein the method comprises the steps of: providing the submersible vehicle in a body of water; powering the dredging pump in a first range, second or third range, said range defining a percentage of the maximum operating power of the dredging pump, such that the fluid jets provide an upward force on the body of the submersible vessel, and wherein the sum of the upward force provided by the dredging pump and the buoyancy is negative, zero or positive respectively.

10. Method according to claim 9, wherein an upper limit of the first range is smaller than a lower limit of the second range, and an upper limit of the second range is smaller than a lower limit of the third range.

11. Method according to claim 9 or 10, wherein the second range is between 80% and 90% of the maximum operating power of the dredging pump, for example 85% and 95% of the maximum operating power.

12. A submersible dredging vessel having a body and a direction of travel, said submersible dredging vessel comprising: a plurality of primary propulsion units distributed around a contour of the body of the submersible dredging vessel, wherein each primary propulsion unit of the plurality of primary propulsion units is arranged to provide a propelling force; wherein each propelling force of a corresponding primary propulsion unit has a component parallel to longitudinal axis of the submersible dredging vessel; and wherein at least one primary propulsion unit of the plurality of propulsion units comprises a pump.

13. Submersible dredging vessel according to claim 12, wherein the contour of the body comprises four corners in a horizontal plane of the submersible dredging vessel and wherein at least one primary propulsion unit of the plurality of primary propulsion units is provided in each corner.

14. Submersible dredging vessel according to claim 13, wherein two primary propulsion units of the plurality of primary propulsion units are provided adjacent to each other such that each primary propulsion of the two primary propulsion units has acomponent parallel to a direction towards the other primary propulsion unit of the two primary propulsion units.

15. Submersible dredging vessel according to any of the claims 12 - 14, wherein the propelling force of each primary propulsion unit of the plurality of primary propulsion units is provided in a horizontal plane of the submersible dredging vessel.

16. Submersible dredging vessel according to any of the claims 12 - 15, wherein the longitudinal body has a front side provided at a first distal end of the longitudinal body and a rear side provided at a second distal end of the longitudinal body, opposite the first distal end, and wherein at least two primary propulsion units of the plurality of the primary propulsion units are provided towards the front side and at least two primary propulsion units of the plurality of the primary propulsion units are provided towards the rear side.

17. Submersible dredging vessel according to any of the claims 12 - 16, wherein the pump comprises an inlet provided towards a side of the dredging vessel and wherein an opening of the inlet is provided at an angle relative to a longitudinal axis of the vessel.

18. Submersible dredging vessel according to any of the claims 12 - 17, wherein the pump comprises a filter arranged to protect the pump from debris during use.

19. Submersible dredging vessel according to any of the claims 12 - 18, wherein the pump is a centrifugal pump.

20. Submersible dredging vessel according to any of the claims 12 - 19, further comprising a secondary propulsion system arranged to provide an auxiliary propelling force, said auxiliary propelling force has a component parallel to the propelling force of at least one primary propulsion unit.

21. Submersible dredging vessel according to claim 20, wherein the auxiliary propelling force is parallel to the propelling force of at least one primary propulsion unit.

22. Submersible dredging vessel according to claim 20 or 21, wherein the secondary propulsion system comprises a propeller arranged to provide the auxiliary propelling force.

23. Method of rudderless navigating of a submersible dredging vessel according to any of the claims 12 - 22, comprising the steps of: determining a movement direction; powering the at least one primary propulsion unit of the plurality of propulsion units such that the sum of the components of the propelling forces of each of the corresponding primary propulsion units of the plurality of primary propulsion units is positive in a direction having a component in the movement direction.

24. Method of rudderless navigating of a submersible dredging vessel according to claim 23, wherein the sum of the components of the propelling forces is positive in a direction parallel to the determined movement direction.

25. Method of rudderless navigating of a submersible dredging vessel according to claim 23 or 24, further comprising the step of powering the secondary propulsion system such that the sum of components of the propelling forces and the auxiliary propelling force is positive in a direction having a component in the determined movement direction.

26. A vessel for cooperation with a floating object comprising: a controller; a triangulation system operably connected to the controller and arranged to determine the position of the floating object relative to the vessel; a receiver operably connected to the controller and arranged to receive first geographical coordinates of the floating object; and wherein the controller is arranged to determine second geographical coordinates of the vessel based on the first geographical coordinates of the floating object and the position of the floating object relative to the vessel.

27. Vessel according to claim 26, further comprising a velocity measurement system arranged to determine the velocity of the vessel, the velocity measurement system being operably connected to the controller and wherein the determining of the second geographical coordinates of the vessel is further based on the velocity of the vessel.

28. Vessel according to claim 27, wherein the velocity measurement system comprises an acoustic doppler current profiler system arranged to be aimed, in use, at a surface for determining the velocity of the vessel relative to the surface during use.

29. Vessel according to claim 28, wherein the surface is a water surface of a body of water or a bottom of the body of water.

30. Vessel according to claim 28, wherein the acoustic doppler current profiler system is aimed at a first surface and a second surface for determining the velocity of the vessel and wherein the first surface is a surface of the body of water and the second surface is a bottom of the body of water.

31. Vessel according to any of the claims 26 - 30, further comprising a first depth meter operably connected to the controller and arranged to determine the distance between the vessel and a bottom of a body of water.

32. Vessel according to claim 31, further comprising a second depth meter operably connected to the controller and arranged to determine the distance between the vessel and the bottom of the body of water and wherein the controller is arranged to determine material characteristics of the bottom of the body of water based on the distance determined between the vessel by the first depth meter and the second depth meter.

33. Vessel according to claim 31 or 32, wherein the controller is arranged to determine the depth of the body of water based on the second geographical coordinates of the vessel and the distance between the vessel and the bottom of the body of water.

34. Vessel according to any of the claims 31-33, wherein the vessel further comprises a pressure gauge operably connected to the controller and arranged to determine the pressure acting upon the vessel, wherein the controller is arranged to determine the distance between the vessel and a surface of the body of water based on the pressure acting upon the vessel.

35. Vessel according to any of the claims 31- 34, wherein the controller is arranged to map the bottom of the body of water based on a first distance between the vessel and the surface of the body of water, on a second distance between the vessel and the bottom of the body of water, and on the second geographical coordinates.

36. A floating object arranged to float during use, wherein the floating object comprises: a location detection system for determining first geographical coordinates of the floating object; and a transmitter arranged to send the coordinates of the floating object to a receiver of a vessel.

37. Floating object according to claim 36, wherein the location detection system is arranged to determine the location of the floating object using a satellite navigation system.

38. Floating object according to claim 36 or 37, wherein the floating object comprises at least one of a buoy or a ship.

39. Dredging arrangement comprising: a vessel according to any of the claims 26 to 35; a floating object according to any of the claims 36 to 38, and wherein the vessel is physically connected to the floating object.

40. Method of determining the coordinates of a submersed vessel using a dredging arrangement, preferably the dredging arrangement according to claim 39, comprising: providing a floating object on a body of water, said floating object comprising a location detection system for determining the coordinates of the floating object; determining the coordinates of the floating object using the location detection system, preferably using the location detection system and a global navigation satellite system; transmitting the coordinates of the floating object to the vessel; determining the position of the floating object relative to vessel using the triangulation system; and determining the coordinates of the vessel based on the coordinates of the floating object and the position of the vessel relative to the floating object.

41. Method of mapping a bottom of a body of water using a dredging arrangement, preferably the dredging arrangement according to claim 39, comprising the steps of: determining the coordinates of a submersed vessel according to claim 40;determining the distance between the vessel and the surface of the body of water based on the position of the vessel relative to the floating object; determining the distance between the vessel and the bottom of the body of water using a first depth meter provided on the vessel; mapping the bottom of a body of water based on the distance between the vessel and the surface of the body of water, based on the distance between the vessel and the bottom of the body of water and based on the coordinates of the submersed vessel.

42. Method of mapping of a body of water according to claim 41, wherein the first depth meter is a first echo sounding arrangement operating at a first frequency; the method further comprising the steps of: determining the distance between the vessel and the bottom of the body of water using a second echo sounding arrangement operating at a second frequency providing on the vessel, wherein the first frequency and the second frequency are different; determining the characteristics of the bottom of the body of water using the distance between the vessel of the first depth meter and the second depth meter.

43. Method of mapping of a body of water according to claim 42, wherein the characteristics of the bottom of the body of water has data comprising information about the sediment layers of the bottom.

44. A vessel comprising an electrical power system connected to a propulsion arrangement for providing power to the propulsion arrangement and a diagnostic arrangement operatively connected to the propulsion arrangement and the electrical power system, the diagnostic arrangement being arranged to detect operational failure of at least one of the electrical power system and the propulsion arrangement; wherein: the electrical power system comprises a first power supply and a second power supply, wherein the first power supply and the second power supply are individually provided in a corresponding first liquid-tight container and a corresponding second liquid-tight container respectively; the propulsion arrangement comprises a primary propulsion unit and a secondary propulsion system, wherein the primary propulsion unit and the secondary propulsion system are each connected to at least one of the first power supply and the second power supply; and the second power supply is arranged to power the secondary propulsion system, based on detected operational failure by the diagnostic arrangement in at least one of the first power supply and the primary propulsion unit.

45. The vessel according to claim 44, further comprising a control and sensing system having a first set of electrically powered components and a second set of electrically powered components, wherein:the first set of electrically powered components is connected to the first power supply and the second power supply, each for powering the first set of electrically powered components individually; the second set of electrically powered components is connected to the first power supply; and the second power supply is arranged to power the first set of electrically powered components based on detected operational failure in the first power supply.

46. The vessel according to claim 45, wherein at least a part of the control and sensing system is provided in an liquid-tight container, preferably a dedicated liquid-tight container.

47. The vessel according to any of the claims 44 - 46, further comprising an air chamber and a compressed air supply system in fluid connection with the air chamber, wherein the air supply system comprises a connector for connecting to a container comprising compressed air and an air supply control valve arranged to controllably fill the air chamber with air from the container.

48. The vessel according to claim 47, wherein the compressed air supply system comprises an electrically powered fail-open valve connected to the first power supply for controllably filling the air chamber with air.

49. The vessel according to claim 47 or 48, wherein the compressed air supply is operatively connected to the diagnostic arrangement and arranged to controllably fill the air chamber with air based on operational failure detected by the diagnostic arrangement in the second power supply.

50. The vessel according to any of the claims 44 - 49, further comprising a safety system connected to at least the second power supply and the diagnostic arrangement and wherein the second power supply is arranged to power the safety system based on operational failure detected by the diagnostic arrangement in the first power supply.

51. The vessel according to claim 50, wherein the safety system comprises a navigation light arranged to provide an optical distress signal and a GPS beacon arranged to determine a geographical position of the vessel and transmit the geographical position to a receiver, wherein the navigation light is arranged to be powered by at least one of the first power supply and the second power supply.

52. The vessel according to any of the claims 44 - 51, wherein the control and sensing system comprises a plurality of controllers, each of the plurality of controller arranged to individually control the vessel through the control and sensing system.

53. The vessel according to claim 52, wherein the plurality of controllers are arranged to operate in parallel with each other.

54. The vessel according to any of the claims 45-53, wherein the electrical power system further comprises a third power supply operatively connected to the control and sensing system and the diagnostic arrangement, and wherein the first set ofelectrically powered components comprises a primary subset of electrically powered components, said third power supply arranged to power the primary subset of electrically powered components based on detected operational failure in the second power supply.

55. The vessel according to any of the claims 45-54, wherein the electrical power system further comprises a charging arrangement for forming a connection with a charging system for charging the electrical power system, wherein the charging arrangement is arranged to have an operating mode, in which the electrical power system is arranged to power the vessel and prevents forming the connection with the charging system, and a charging mode, in which the electrical power system is arranged to allow forming the connection with the charging system.

56. The vessel according to claim 55, wherein the charging arrangement comprises an electrical bridging element arranged to be releasably connected to the charging arrangement, wherein the charging arrangement is in the operating mode when the electrical bridging element is connected, and wherein the charging arrangement is in charging mode when the electrical bridge element is released from the charging arrangement.

57. A dredging arrangement comprising a vessel according to any of the claims 44 - 56 and a remote control arrangement comprising a remote controller arranged to send control signals to the vessel and wherein the vessel comprises a controller arranged to receive the control signals for controlling the vessel, and wherein the controller is connected to the third power supply.

58. A method of activating a safety mechanism of a vessel, preferably the vessel according to any of the claims 44 - 56, comprising the steps of: providing a vessel comprising an electrical power system and a propulsion arrangement, wherein the propulsion arrangement comprises a primary propulsion unit and a secondary propulsion system and wherein the electrical power system comprising a first power supply and a second power supply arranged to power the primary propulsion unit and secondary propulsion system respectively; activating the second power supply when the first power supply has an operational failure; powering the secondary propulsion system using the second power supply.

59. The method of activating safety mechanism of a vessel according to claim 58, wherein the vessel further comprises a third power supply and a safety system arranged to be powered by the third power supply, said safety system comprising a GPS system and at least one of an optical alarm and audible alarm; wherein the method further comprises the steps of: activating the third power supply when the second power supply has an operational failure; powering the GPS system and the at least one of an optical alarm and audible alarm.

60. A method of communication of a dredging arrangement in distress, wherein the dredging arrangement comprises a vessel and a floating object, said vessel and floating object in communication via a primary communication arrangement, preferably a USBL arrangement, wherein the method comprises the steps of: operating a submerged vessel in a body of water; ascending the vessel to the surface of the body of water if the primary communication between the vessel and the floating object is lost; start communication with the floating object through a secondary communication arrangement, wherein the secondary communication arrangement is preferably GPS arrangement.

61. The method of communication of a dredging arrangement in distress according to claim 60, further comprising the step of: start communication with the floating object through a tertiary communication arrangement if communication through the secondary communication arrangement is unsuccessful, wherein the tertiary communication arrangement is preferably a WiFi- arrangement.

62. The method of communication of a dredging arrangement in distress according to claims 60 or 61, further comprising the step of: start communication with a cellular network through a cellular network arrangement if communication through one of the secondary and tertiary communication arrangement is unsuccessful.

63. The method of communication of a dredging arrangement in distress according to any of the claims 60-62, further comprising the step of: start communication with a satellite transponder if communication through one of the secondary communication arrangement, the tertiary communication arrangement and cellular network arrangement is unsuccessful.

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