Vessel

Abstract

A submersible dredging vessel having a hydrodynamic body optimized 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

P 138249NL00 Title: Vessel TECHNICAL FIELD Various aspects and examples thereof relate to the eld ofdepth control of a vessel. Other aspects and examples thereof relate to the eld of propulsion and direction control of a vessel. Further aspects and examples thereof relate to the field of localisation of a vessel in a body ofwater. Some aspects and examples thereofrelate to the field of a failsafe system of a vessel. BACKGROUND Dredging is done to remove sediment, debris and other materials from a bottom of a body ofwater, for example rivers, lakes, ports and harbours. Dredgingmay be done to maintain or increase waterway depth for navigation, to prevent ooding, support construction projects or restore ecosystems. Generally, dredging arrangements used for dredging are typically relatively large andcumbersome systems, making it complicated to dredge smaller bodies ofwater. SUMMARY 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 ofwater. This applies in particular to a vessel for injection dredging and water injection dredgingmore in particular. Injection dredging is a process in which one or more jets ofwater are direct to sediment at a bottom of a body ofwater. By virtue ofthe jets, sediment is stirred up from the bottom and caught in turbulence ofwater. This allows a current in the body ofwater to carry the sediment away from the location at which it has been stirred up. Theow ofwatermay be a result ofow ofa river, tidal ows, other, or a combination oftwo or more thereof. A first aspect provides a submersible dredging vessel comprising a body and a dredging module provided in said body. The dredging module comprises a dredgingpump for pumping a uid and a uid outlet manifold comprising uid outlet openings being arranged to provide directional jets of the uid. The submersible dredging vessel has a negative buoyancy during use. The uid outlet openings are arranged to provide the uid jets in a downward direction, relative to the vehicle. The dredgingpump is arranged to operate in a sink mode, wherein a sum ofthe upward force ofthe uid 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 ofthe upward force providedby the uid 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 ofthe upward force provided by the uid jets and the upward force acting on the submersible vehicle is larger than the downward force acting on the submersible dredging vessel. In order to dredge, using the submersible dredging vessel, the vehicle comprises a dredgingpump. The dredgingpump canpump a uid, e.g. water in which the vessel is submerged, from an inlet through a uid outlet manifold comprising uid outlet openings being arranged to provide directional jets ofuid. Jets ofuid are, in the context ofthe invention, jets ofwater that have locally a higher, directed, velocity than the rest ofthe body ofwater. In a specic example, jets ofuid are aimed in a downward direction relative to the vehicle such that they are aimed at the bottom ofa body ofwater. Due to the relatively high velocity ofthe jets, aimed at the bottom, sludge and other debris on the bottom ofthe body ofwater is ejected and transported away due to the current. Thus, it is possible to locally dredge a body of water using a dredgingpump arranged to eject uid jets via the uid outlet manifold. The submersible dredging vessel has a negative buoyancy during use, e.g. it sinks when provided in a body ofwater, which causes a downward movement ofthe vessel in a vertical direction in the body of water. The dredgingpump may be used to increase the buoyancy ofthe vessel, such that even a positive buoyancymay be achieved in which the vessel rises in the body ofwater, i.e. having an upwardmovement in the vertical direction. This may be achievedby sufciently powering the dredgingpump. When the dredgingpump 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 ofthe submersible dredging vessel in a body of water using the dredgingpump. 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 designmay be provided. In an implementation ofthe submersible dredging vessel, the upward force provided by the uid jets scales with the power provided to the dredgingpump. By providing the dredgingpump such that the uid jets scale with the power provided to said dredgingpump, e.g. by ejecting uid jets at a higher velocity by the dredgingpump, it is possible to accurately control the upward force and with that the behaviour ofthe vessel in vertical direction. Next to the three modes, itmay be possible to additionally power the dredgingpump such that it rises faster or it may be possible to reduce power provided to the dredgingpump such that the vessel sinks faster. In another implementation ofthe submersible dredging vessel, the uid jets are distributed over a width ofthe submersible dredging vessel. Providing the uid jets over a width ofthe submersible dredging vessel, itmay be facilitated that the upward force generated by the uid jets are evenly distributed over the width. As a result, stability around the longitudinal axis ofthe vesselmay be facilitated. In a further implementation ofthe submersible dredging vessel, the uid jets are distributed along a line perpendicular to a longitudinal axis ofthe submersible dredging vessel. This may allow for both evenly distributing the jets over the width and for providing the uid jets relatively close to each other, such that the jets may be focussed more efficiently. This may on this turn facilitate dredging, as multiple uid jets may hit a relatively small surface ofthe bottom ofthe body ofwater. In again another implementation ofthe 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 rst distance from a midpoint ofthe 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 ofthe vessel along the longitudinal axis, e.g. the front side or rear side ofthe vessel, is aimed at the surface ofthe body ofwater. This may allow, in case the dredgingpump is inoperable, to move the vessel vertically in an upward or downward direction by propelling the vessel in a direction ofmovement parallel to the longitudinal axis. This may be advantageous in case ofan emergency, and wherein the dredgingpump isnt 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. In yet a further implementation ofthe submersible dredging vessel, at least a one uid 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 ofthe rst distance. Once the dredgingpump is powered, the vessel is tilted towards the opposite direction, around the midpoint, such that the vessel is relatively horizontal in the body ofwater, e.g. in the stable mode. In the rise mode, the vessel is tilted such that the front side ofthe vessel is lower than the rear side ofthe vessel. This may allow for more convenient control and navigation ofthe vessel during operation, e.g. normal operation such as dredging. In yet a further implementation ofthe submersible dredging vessel, the submersible dredging vessel has a centre ofbuoyancy. During use, the centre of gravity and the centre ofbuoyancy are aligned in a vertical direction along the longitudinal axis. Once the centre of gravity and centre ofbuoyancy 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 equipmentmay be needed to prevent overturning ofthe vessel thereby allowing for a more compact design ofthe vessel. During rising or sinking ofthe vessel, the centre ofbuoyancymay 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 ofbuoyancymay be providedmore towards the rear ofthe vessel along the longitudinal axis, compared to sink or stable mode. As a result, the upward force ofthe uid jets providedby the dredgingpump may have a component parallel to the longitudinal direction ofthe vessel. In yet a further implementation ofthe submersible dredging vessel, the submersible dredging vessel further comprises a vertical position detection arrangement for detecting the current vertical position ofthe submersible vehicle in a body ofwater and a controller operably connected to the dredgingpump and the vertical position detection arrangement. The controller is arranged to control the vertical position of the submersible vehicle in the body ofwater by operating the dredgingpump in at least one ofthe sink mode, stable mode and rise mode, based on the current vertical position. By providing a vertical detection arrangement, itmay be possible for the vessel to determine its distance towards the bottom ofthe body of water. This data on its turn may be usedby the controller to control the vessel using the dredgingpump, e.g. in order to maintain a set distance from the bottom ofthe body ofwater. This may be in particular advantageous in case the bottom ofthe body ofwater comprises an uneven terrain, e.g. having protrusions and gaps. A second aspect provides for a method ofcontrolling the buoyancy of a submersible vehicle, preferably the submersible vehicle according to any ofthe preceding claims. The submersible vehicle has a negative buoyancy and comprises a dredgingpump. The method comprises providing the submersible vehicle in a body ofwater, powering the dredgingpump in a first range, second or third range, said range defining a percentage ofthe maximum operatingpower ofthe dredgingpump, such that the uid jets provide an upward force on the body ofthe submersible vessel. The sum of the upward force provided by the dredgingpump and the buoyancy is negative, zero or positive respectively. The second aspect allows for vertical control of a submersible dredging vessel, using a dredgingpump. Thus, it may be possible to control the vertical movement ofthe vessel and dredging a body ofwater using the same component, i.e. the dredgingpump. As a result, a compact designmay be provided that allows for dredging relatively small bodies ofwater. In an implementation, an upper limit ofthe first range is smaller than a lower limit ofthe second range, and an upper limit ofthe second range is smaller than a lower limit ofthe 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 ofthe vessel, whichmay cause damage. In another implementation, the second range is between 80% and 95% ofthe maximum operating power ofthe dredgingpump, or between 85% and 90% ofthe maximum operating power. Providing the stable range towards the higher end ofthe power that may be provided to the dredging pump, it may be facilitated that the dredgingpump provided relatively fast uid jets while preventing the vessel from sinking or rising. Relatively fast uid jets may be advantageous for dredging, as relatively fast uid jets have a higher impact on the bottom ofthe body ofwater, making it possible to remove sludge and / or debris from the bottom that is not possible with weaker jets. 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 ofwater, preferably without rudders. This applies in particular to a vessel for injection dredging. Injection dredging is a process in which one or more jets ofwater are direct to sediment at a bottom ofa body ofwater. By virtue ofthe jets, sediment is stirred up from the bottom and caught in turbulence ofwater. This allows a current in the body ofwater to carry the sediment away from the location at which it has been stirred up. Theow of watermay be a result ofow ofa river, tidal ows, other, or a combination oftwo or more thereof. A third aspect provides a submersible dredging vessel having a body and a direction oftravel. The submersible dredging vessel comprises a plurality ofprimary propulsion units distributed around a contour ofthe body ofthe submersible dredging vessel. Each primary prolusion unit ofthe plurality ofprimary 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 ofthe submersible dredging vessel. At least one primary propulsion unit ofthe plurality ofpropulsion units comprises a pump. By providing a plurality ofprimary propulsion units, each propulsion unit capable ofproviding a propelling force having a component parallel to the longitudinal axis ofthe submersible dredging vessel, the vesselmay be propelled in a direction along the longitudinal axis. Distributing the primary propulsion units around a contour ofthe body of the vessel facilitate distribution ofthe propelling force over the body of vessel, spreading the forces applied to the body ofthe vessel more evenly and allowing for a more lightweight and compact design ofthe submersible dredging vessel. At least one ofthe primary propulsion unit, preferably all primary propulsion units, comprise a pump. Pumps are commonly known and well developed in all shapes and sizes, whichmay allow for a specialized yet reliable primary propulsion unit. Additionally, by scaling the power provided to the pump, thepump can provide more propelling force. In other words, the propelling force providedby thepump may scale with the power provided to saidpump. 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, andmay give themud stream already an initial velocity in the direction needed. An implementation ofthe submersible dredging vessel, the contour ofthe body comprises four corners in a horizontal plane ofthe submersible dredging vessel. At least one primary propulsion unit ofthe plurality ofprimary propulsion units is provided in each corner. The direction oftravel and the longitudinal axis ofthe vesselmay be provided parallel to the horizontal plane. Providing at least primary propulsion unit in each corner ofthe 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 / backwardmovement of the vesselmay thus be provided, wherein the forward / backward movement denes the direction of travel, is parallel to the longitudinal axis ofthe 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 / backwardmovement may be facilitated. In another implementation ofthe submersible dredging vessel, two primary propulsion units ofthe plurality ofprimary propulsion units are provided adjacent to each other such that each primary propulsion unit ofthe two primary propulsion units has a component parallel to a direction towards the other primary propulsion unit ofthe two primary propulsion units. Thus, next to a component parallel to the longitudinal axis ofthe vessel, a component having an angle relative to the longitudinal axis has been provided. This additional component, i.e. the component ofa primary propulsion unit relative to an adjacent primary propulsion unit, allows for providing a propelling force that is not parallel to the longitudinal direction ofthe vessel and therefore may facilitate steering ofthe vessel in a direction parallel to the component ofthe propelling force. In a further implementation ofthe submersible dredging vessel, the propelling force ofeach primary propulsion unit ofthe plurality of propulsion units is provided in a horizontal plane ofthe submersible dredging vessel. As a result, all components ofthe 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 ofthe vessel in the horizontal plane, i.e. a forward / backwardmovement and a starboard / port movement, without affecting the vertical position ofthe vessel in the body ofwater. In yet a further implementation ofthe submersible dredging vessel, the longitudinal body has a front side provided at a rst distal end of the longitudinal body and a rear side provided at a second distal end ofthe longitudinal body, opposite the rst distal end. At least two primary propulsion units ofthe plurality ofprimary propulsion units are provided towards the front side and at least two primary propulsion units ofthe plurality ofprimary propulsion units are provided towards the rear. Providing primary propulsion units towards the distal ends ofthe vessel, at the front side and the back side ofthe vessel, may allow for efcient application ofthe propelling force, in particular a component ofthe propelling force not being parallel to the longitudinal axis ofthe vessel, to the body ofthe vessel. Since such components would be provided to the body ofthe vessel relatively far from the centre of gravity ofthe vessel, a relatively large arm exists, i.e. the distance between the location ofthe component and the centre of gravity, such that a relatively small propelling force is needed to turn the vessel. In again another implementation ofthe submersible dredging vessel, thepump comprises an inlet provided towards a side ofthe dredging vessel. An opening ofthe inlet is provided at an angle relative to the longitudinal axis ofthe vessel. By having the inlet at a side ofthe dredging vessel, with an opening provided at an angle relative to the longitudinal axis ofthe vessel, the opening is also provided at an angle relative to the outlet ofthe 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 ofthe body ofwater, may be minimized at the inlet ofthe pump. In other words, the inlet pressure ofthe liquid remains largely unaffected by the pressure ofthe propelling force. Thus, negative effects ofa uctuating inlet pressure may be mitigated, such as damage to thepump due to cavitation. In yet a further implementation ofthe submersible dredging vessel, thepump comprises a filter arranged to protect thepump from debris during use.A lter may advantageously be used to protect the pump, e.g. the impeller ofthe pump, against debris. Thus the lifespan ofthepump and / or components ofthepump may be increased. In again another implementation ofthe submersible dredging vessel, thepump is a centrifugal pump. Centrifugalpumps may provide a constant pressure at the outlet ofthe pump, resulting in a constant propelling force ofthe corresponding primary propulsion unit. Additionally, l l a centrifugalpump may provide a propelling force that is scalable by the power provided to the centrifugal pump. More power provided to the centrifugalpump may result in a larger propelling force at the corresponding primary propulsion unit. In yet a further implementation ofthe 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 ofthe 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. 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 ofthe secondary propulsion system has components in the same direction as the propelling force ofthe corresponding primary propulsion unit, thereby facilitating that the auxiliary propelling force and the corresponding propelling force are complementary to each other andhave no components that work in opposite direction and thus cancelling each other. In yet a further implementation, the secondary propulsion system comprises a propeller arranged to provide the auxiliary propelling force. A fourth aspect provides for a method ofrudderless navigating of a submersible dredging vessel as described above. The method comprises determining a movement direction, powering the at least one primary propulsion unit ofthe plurality ofpropulsion units such that the sum of components ofthe propelling forces ofeach ofthe correspondingprimary propulsion units ofthe plurality ofprimary propulsion units is positive in a direction having a component in the movement direction. Using the plurality ofprimary propulsion units, each providing a corresponding propelling force in a direction, allows for the control ofthe vessel, for example when submerged or when moving at the surface of a body ofwater. The resulting movement direction is a sum ofthe propelling forces ofeach of the primary propulsion units. Controlling the various propelling forces allows for steering the vessel, i.e. by providing such that the sum ofthe propelling forces is in a different direction than earlier. For example, ifthe sum ofthe propelling forces resulted in a propelling force parallel to the longitudinal direction of the vessel, the vessel would move forward. Ifnow the primary propulsion units provide a different amount ofpropelling force, e.g. by decreasing or increasing power provided to at least one primary propulsion unit, the resulting sum ofpropelling forces changes. As a result, the vessel can navigate in a body ofwater without the use ofrudders. Rudders may be a relatively unreliable and high maintenance component to allow for reliable steering, compared to the proposed method ofrudderless 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 ofprimary propulsion units, this effect may be greatly improved. In an implementation ofthe method, the sum ofcomponents of the propelling forces is positive in a direction parallel to the determined movement direction. By providing sufcient primary propulsion units around the contour ofthe vessel, the sum ofthe components ofthe 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 ofmovement. Not having any drift may allow for effective navigation ofthe vessel. In another implementation ofthe method, the method further comprises the step of: - powering the secondary propulsion system such that the sum of components ofthe 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. 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 ofwater are direct to sediment at a bottom of a body ofwater. 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 ofwater to carry the sediment away from the location at which it has been stirred up. The ow ofwatermay be a result ofow of a river, tidal ows, other, or a combination oftwo or more thereof. A fifth aspect provides a vessel, e.g. a submersible dredging vessel, for cooperating with a oating 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 ofthe oating object relative to the submersible dredging arrangement. The submersible dredging vessel further comprises a receiver operably connected to the controller and arranged to receive rst geographical coordinates ofthe oating object. The controller is arranged to determine second geographical coordinates ofthe submersible dredging vessel based on the first geographical coordinates ofthe oating object and the position ofthe oating 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, itmay be advantageous to provide for a triangulation system operably connected to the controller and arranged to determine the position of a oating object relative to the vessel. When submerged, itmay be difficult to determine the position ofthe vessel using conventional methods such as GPS as the body ofwatermay interference with such conventional methods. Conventionally, the oating object comprising the triangulation system may be used to estimate the position ofthe vessel relative to the oating object. However, this poses the challenge ofsending over this position ofthe vessel relative to the oating object takes a relative long time using conventional triangulation systems. By inverting the setup, i.e. by providing the triangulation system on the vessel such that it can determine the position ofthe oating object relative to the vessel, allows for this data to be analysed locally, i.e. onboard the vessel. Since the oating 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 ofthe vessel. Therefore, the position ofthe vessel in second geographical coordinates may be relatively quick, accurate, and frequently be determined. 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 ofthe vessel, e.g. a submersible dredging vessel,, the vessel further comprising a velocity measurement system operably connected to the controller and wherein the determining ofthe second geographical coordinates ofthe vessel is further based on the velocity ofthe vessel. Since the position ofthe vessel is locally determined, i.e. onboard ofthe vessel by the controller, itmay be possible to include more data to more accurately determine the position ofthe vessel relative to the oating object, e.g. the velocity ofthe vessel. The velocity of the vesselmay be an absolute velocity, i.e. the speed ofthe vehicle to a xed point such as a geographical coordinate such as the second geographical coordinate, or a relative velocity, i.e. the speed ofthe vehicle relative to the oating object and / or the body ofwater. Velocity measurements may be used to improve the accuracy of the data provided by the triangulation system, e.g. using a Kalman lter. 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. Iffor example it is known or determined that the vessel is at second geographical coordinates at a rst 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 ofthe triangulation system. In another implementation ofthe vessel, the velocity measurement system comprises an acoustic doppler current proler system aimed at a surface for determining the velocity ofthe vessel relative to the surface during use. Using an acoustic doppler current profiler, an accurate velocity measurement ofthe vessel relative to the surface may be provided. In a further implementation ofthe vessel, the surface is a water surface of a body ofwater or a bottom ofthe body ofwater. When using an acoustic doppler current proler system aimed at the surface ofthe body of water, the velocity ofthe 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 ofthe vessel. In case the water on the surface moves relatively quick, no longer the absolute speed ofthe vesselmay be determined directly. The oating object may move in the same direction with the same speed as the current, the speed relative to the oating object may be determined. From this, possibly with a time trace ofthe rst geographical coordinates, e.g. the speed of movement ofthe water surface, the absolute velocitymay still be determined. Additionally, itmay be advantageous to measure the speed of the surface ofthe body ofwater, as measuring the speed relative to the bottom ofthe body ofwatermay be complicatedwhen dredging, as the produced sludge sediment may interfere with the acoustic signal. In again another implementation ofthe vessel, the acoustic doppler current proler system is aimed at a first surface and a second surface for determining the velocity ofthe vessel and wherein the first surface is a surface ofthe body ofwater and the second surface is a bottom ofthe body ofwater. Combiningmore sensors, it may be possible to even more accurately determine the velocity ofthe vessel. For example, by measuring the surface ofthe body ofwater and the bottom, before or after dredging, itmay be possible to measure the speed ofthe water due to the current. This datamy on its turn be used to more accurately determine the velocity ofthe vessel during dredging, as the absolute velocity ofthe vessel may be determinedfrom the sum ofthe velocity ofthe vessel relative to the body ofwater and the velocity ofthe body ofwater relative to the bottom of the body ofwater, i.e. the earth. In again another implementation ofthe vessel, the vessel further comprises a rst depth meter operably connected to the controller and arranged to determine the distance between the vessel and a bottom of a body ofwater. By determining the distance between the vessel and the bottom surface, itmay be possible to determine ifthe vessel is at the correct height for operation, e.g. dredging or moving, without coming too close or too far away from the bottom ofthe vessel. In yet a further implementation ofthe 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 ofthe body ofwater 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 ofthe bottom, e.g. using a sonar measurement at different frequencies, material characteristics ofthe bottom ofthe body of watermay be determined. For example, ifthe first depth meter operates at a first frequency, able to penetrate the top soil ofthe bottom ofthe 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 ofthe top soil may be determined. Additionally, using frequencies closer to each other, it may be possible to determine the composition ofthe bottom ofthe body of water. This may be advantageous to determine if dredging is possible, e.g. by ensuring the bottom ofthe body ofwater is made of a material thatmay be dredged. In again another implementation ofthe vessel, the controller is arranged to determine the depth ofthe water body based on the second geographical coordinates ofthe vessel and the distance between the vessel and the bottom ofthe body ofwater. By combining the second geographical coordinates and the distance between the vessel and bottom surface ofthe body ofwater, it may be possible to determine the depth ofthe body of water. By using the depth, or height, component ofthe second geographical coordinates, it is possible to determine the distance between the vessel and the surface ofthe body ofwater. Information relating to the depth ofthe body ofwater 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 sufciently deep body ofwater. In yet a further implementation ofthe vessel, the vessel further comprises a pressure gauge as a specic 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 ofthe body ofwater based on the pressure acting upon the vessel.A pressure gauge may provide additional information regardinghow deep the vessel is submerged in the body ofwater, as the pressure scales with the vertical distance to the surface ofthe body ofwater. The data providedby the pressure gauge may be combined with the second geographical coordinates, in particular the vertical component ofthe second geographical coordinates, to more accurately determine the distance between the surface ofthe body ofwater and the vessel. In again another implementation ofthe vessel, the controller is arranged to map the depth ofthe body ofwater based on the distance between the vessel and the surface ofthe body ofwater, on the distance between the vessel and the bottom ofthe body ofwater and the second geographical coordinates. In the context ofthe 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 depthmap and / or bathymetricmap may be used to keep track ofthe dredging process, to determine of dredging has been completed and to provide current information about the depth ofthe body of water as well as determining local heights on the bottom ofthe body of water. A sixth aspect provides a oating object arranged to oat during use. The oating object comprises a location detection system for determining rst geographical coordinates ofthe oating object and a transmitter arranged to send the coordinates ofthe oating object to a receiver of a vessel. Since the oating object is not submerged, it is possible to use conventional position detection methods thatmay be transmitted as first geographical coordinates to the vessel. In an implementation, the location detection system is arranged to determine the location ofthe oating 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. In another implementation, the oating object comprises at least one ofa buoy or a ship.Abuoy or a ship are commonly used, and reliable oating objects.Abuoymay be used in case ofa relatively quiet surface of the body ofwater, 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 itmay act as a staging platform for the dredging operation while the a buoymay be more useful on smaller bodies ofwater, e.g. a small river or a lake. A seventh aspect provides a dredging arrangement comprising a vessel, e.g. a submersible dredging vessel, as previously described and a oating object as previously described. The vessel is physically connected to the oating object. The physical connectionmay be established using a cable, e.g. a stainless steel cable. The physical connection may allow for transference ofdata andmay facilitate that the vessel and oating object remain within a certain range from each other. An eighth aspect provides a method ofdetermining 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 oating object on a body of water, said oating, object comprising a location detection system for determining the coordinates ofthe oating object, determining the coordinates ofthe oating object using the location detection system, preferably using the location detection system and a global navigation satellite system, transmitting the coordinates ofthe oating object to the vessel, determining the position ofthe oating object relative to vessel using the triangulation system, determining the coordinates ofthe vessel based on the coordinates ofthe oating object and the position ofthe vessel relative to the oating object. Performing the above describedmethod allows for determination ofthe position ofthe vessel in a body ofwater in second geographical coordinates, based on the distance of a oating object to said vessel and first geographical coordinates ofthe oating object. By determining the position ofthe oating object relative to the submersible dredging vessel using the triangulation system provided on the vessel, instead ofdetermining the position ofthe vessel relative to the oating object using a triangulation system provided on a oating object, it is possible to relatively quick and therefore frequently determine the second geographical coordinates ofthe vessel. A ninth aspect provides a method ofmapping a bottom ofa body ofwater using a dredging arrangement, preferably the dredging arrangement as previously disclosed. The method comprises determining the coordinates ofa submersed vessel, e.g. a submersible dredging vessel, as previously disclosed, determining the distance between the vessel and the surface ofthe body ofwater based on the position ofthe vessel relative to the oating object, determining the distance between the vessel and the bottom ofthe body ofwater using a first depth meter provided on the vessel, mapping the bottom ofa body ofwater based on the distance between the vessel and the surface ofthe body ofwater, based on the distance between the vessel and the bottom ofthe body ofwater andbased on the coordinates ofthe submersed vessel. By performing the described method, an accurate map ofthe situation before, during and after dredgingmay be provided using the dredging arrangement. In an implementation ofthe method ofmapping ofa body of water, the first depth meter is a first echo sounding arrangement operating at a rst frequency. The method further comprises wherein the first depth meter is a rst echo sounding arrangement operating at a first frequency, determining the distance between the vessel and the bottom ofthe 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 ofthe bottom ofthe body ofwater using the distance between the vessel ofthe 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. In another implementation ofthe method ofmapping of a body of water, the characteristics ofthe bottom ofthe body ofwater has data comprising information about the sediment layers ofthe bottom. This may allow for adding even further detail when mapping such as for example the contents ofthe sediment layers, e.g. the top soil. From this it may be determined ifthere are products in the sediment layer whichmay not be possible to dredge, such as a naval wreckage. Furthermore, it is preferred to provide for a submersible vessel, for example for dredging and water injection dredging in particular, that is capable offailsafe 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 ofwater are direct to sediment at a bottom ofa body ofwater. By virtue ofthe jets, sediment is stirred up from the bottom and caught in turbulence ofwater. This allows a current in the body ofwater to carry the sediment away from the location at which it has been stirred up. The ow ofwater may be a result ofow ofa river, tidal ows, other, or a combination oftwo or more thereof. 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 ofthe electrical power system and the propulsion arrangement. The electrical power system comprises a rst power supply and a secondpower supply. The rst power supply and the secondpower supply are individually provided in a corresponding rst liquid-tight container and a corresponding second liquid- tight container respectively. 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 ofthe rst power supply and the secondpower 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 ofthe first power supply and the primary propulsion unit. By providing power supplies in an liquid-tight container itmay be facilitated that in case of a leakage in the body ofthe vessel, e.g. a hole in the body ofthe vessel, that no water reaches the power supplies and damage to the power supplies may be prevented. When the power supplies are damaged, theymay no longer be arranged to provide power to the components ofthe 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 ofthe 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. Furthermore, by providing a primary propulsion unit and secondary propulsion system, each connected to at least one ofthe first power supply and the secondpower supply, itmay be facilitated that in case one ofthe 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 ofthe 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 secondpower supply for powering. For example, the primary propulsion unit may be directly connected to the first power supply, and the secondary propulsion unitmay be directly connected to the second power supply. Additionally, the rst power supplymay actively charge the secondpower supply, thus indirectly powering the secondary propulsion unit. This may also facilitate that the secondpower supply remains charged such that the when the second power supply is needed, e.g. in case of distress, the secondpower supplymay be used to its fullest extent. 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 ofwater as soon quickly as possible. Specically, when the diagnostic system detects an operational failure, the secondpower supply powers the secondary propulsion system such that the vessel moves more quickly, e.g. towards a surface. 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 ofthe 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. In an implementation ofthe 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 rst set of electrically powered components is connected to the rst power supply and the secondpower supply. The second set of electrically powered components is connected to the first power supply. The secondpower supply is arranged to power the first set of electrically powered components based on detected operational failure in the rst 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 ofthe vessel in a body ofwater and a control system arranged to process the data for use by an actuator, e.g. apump to affect the vertical position ofthe vessel in the body ofwater, to maintain a predetermined vertical position can be part ofthe control and sensing system. 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 rst set of electrically powered components and are connected to both the rst power supply and the secondpower 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 offailure ofthe first power supply, the critical components are still poweredby the second power supply. Since less components are poweredby the secondpower supply than by the rst power supply, during conventional operation ofthe vessel, less power needs to be provided to the components. As a result, they secondpower supplymay 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 oftime before the secondpower supply is depleted, compared to the first power supply. In another implementation, at least a part ofthe 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 ofthe control and sensing system. By providing at least a part ofthe control and sensing system, e.g. the controller, in a liquid-tight container, it may be facilitated that in case ofa leakage ofthe vessel, the part ofthe control and sensing system provided in the container is not exposed to the liquid. Exposing components ofthe control and sensing system to liquidmay cause damage. In a further implementation, the vessel further comprises an air chamber and a compressed air supply system in uid 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 ll the air chamber with air from the container. During use, a container comprising compressed airmay be provided in the air supply system. In case ofan emergency, e.g. faulty components detected by the diagnostic system, the compressed air ofthe containermay be provided to the air chamber. This increases the buoyancy ofthe 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 ofthe body of water, in case ofan emergency, may facilitate retrieving the vessel so it can be salvaged or repaired for future use. In again another implementation, the compressed air supply comprises an electrically powered fail-open valve connected to the first power supply for controllably lling 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 lls the air chamber. This may be advantageous, as this allows the vessel to reach the surface of a body ofwater even in case ofa power failure on board ofthe vessel, for example ifthe rst power supply is no longer are able to provide power. Additionally or alternatively, a capacitor feed signal fail-safe servo may be used instead. In yet a further implementation, the compressed air supply is operatively connected to the diagnostic arrangement and arranged to controllably ll the air chamber with air based on detected operational failure in the secondpower supply. The diagnostic arrangement can detect operational failure ofcomponents ofthe vessel, e.g. the first and second power supply, and based on an operational failure open the valve such that the compressed air ofthe container enters the air chamber. Thismay be advantageous in case there are operational failures thatmay 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. 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 secondpower 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 secondpower supply, itmay 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 rst power supply, e.g. the first power supply becoming abnormally hot, the components ofthe safety system may be activated accordingly. 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 ofthe 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 ofthe first power supply and the secondpower supply. An optical distress signal and a GPS beacon may be used to detect the vessel, once it has reached the surface ofthe body ofwater, when the vessel is in distress. In case of operational failure ofthe rst 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 ofwater having a strong current wherein the vesselmay be carried away by the current once it has reached to surface ofthe body ofwater. This allows for the fast retrieval ofthe vessel in case of distress. In yet a further implementation, the control and sensing system comprises a plurality of controllers, each ofthe plurality ofcontrollers is arranged to individually control the vessel through the control and sensing system. When a plurality ofcontrollers is provided, each controller being capable ofcontrolling 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 difcult to retrieve once a controller is damaged, e.g. due to a leakage. In yet a further implementation, the plurality ofcontrollers are arranged to operate in parallel with each other. Thus, the controllers may operate next to each other, such that abnormal behavior in a controllermay be detected, e.g. when a single controller behaves differently from the other controllers, andmay allow for instantaneous taking control ofthe vessel by a further controller in case a rst 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 savedwhen a controller fails and a further controller can take over its duty such that control ofthe vesselmay be ensured at all times. 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 rst set of electrically powered components comprises ofa primary subset of electrically powered components, said thirdpower supply arranged to power the primary subset of electrically powered components based on detected operational failure in the secondpower supply. Providing a thirdpower supplymay be used to power an even more critical set of electrical equipment in case of distress, e.g. ifthe first and secondpower supply are no longer able to power the rst and second electrically powered components. By powering a primary subset ofthe first set of electrically powered components, even less powermay be needed such that the thirdpower supplymay be provided with less capacity than the rst and second power supply and thus saving space. Additionally or alternatively, by only powering the primary subset, less power is needed and thus the thirdpower supply is able to power the subset of first electrical power components for an even longer period oftime. In yet a further implementation, the thirdpower supply is arranged to power the primary subset of electrically powered components based on detected operational failure in the secondpower supply. This may facilitate that the thirdpower supply remains charged as it only powers the primary subset of electrically powered components when the secondpower supply, and therefore the rst 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. 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 ofthe power system, when components ofthe charging system are exposed, intentionally or unintentionally, safety ofpersonal charging the vesselmay be facilitated. 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 releasedfrom 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 ofsaid 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 offailure ofthe control systems ofthe vessel, e.g. the controllers, the vesselmay still be manually controlledfrom a distance. The remote control arrangement may be provided on a oating object, e.g. a ship, ormay be provided on the shore. This may facilitate the retrieval ofthe vessel in case ofdamage. 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: - 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 rst power supply and a secondpower supply arranged to power the primary propulsion unit and secondary propulsion system respectively; activating the secondpower supply when the rst power supply has an operational failure, powering the secondary propulsion system using the secondpower supply. By providing a second power supply arranged to power the secondary propulsion system in case ofan operational failure ofthe rst power supply, itmay 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 ofthe first power supply, activating the secondary propulsion system may speed to movement ofthe vessel such that itmay 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 supplymay be provided smaller, i.e. having reduced dimensions, compared to the rst power supply. 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 thirdpower supply. The safety system comprising a GPS system, and optionally at least one ofan acousticmodem or USBL, and at least one ofan optical alarm and or audible alarm. The method further comprises the steps of activating the third power supply when the secondpower supply has an operational failure, andpowering the GPS system and the at least one ofan optical alarm and audible alarm. In case the first and secondpower supply are no longer able to power the vessel, the thirdpower supplymay be used to make it more convenient to locate the vessel such that itmay be retrieved, specifically by activating a GPS system such that the its locationmay be broadcasted to a receiver andby providing an optical alarm and / or an audible alarm such that nearby people may be alerted and guided to the location ofthe vessel. Optionally, at least one ofan acousticmodem orUSBL 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 ofthe body ofwater or below the surface ofthe body ofwater may be facilitated. A thirteenth aspect provides a method ofcommunication ofa dredging arrangement in distress. The dredging arrangement comprises a vessel, e.g. a submersible dredging vessel, and a oating object. The vessel and oating object are in communication via a primary communication arrangement, preferably aUSBL arrangement. The method comprises the steps ofoperating a submerged vessel in a body ofwater, ascending the vessel to the surface ofthe body ofwater ifthe primary communication between the vessel and the oating object is lost, and start communication with the oating object through a secondary communication arrangement. The secondary communication arrangement is preferably a GPS arrangement. In case a primary communication arrangement is no longer functional to provide information about the location ofthe vessel, a backup communication system may be used. In the specic 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 ofthe vessel to the oating object. By broadcasting the location of the distressed vessel, the vesselmay be locatedmore easily. In an aspect, the method ofcommunication of a dredging arrangement in distress further comprises the step of: - start communication with the oating object through a tertiary communication arrangement ifcommunication through the secondary communication arrangement is unsuccessful. The tertiary communication arrangement is preferably a WiFi-arrangement. Ifthe GPS system, i.e. the secondary communication arrangement, is not working, a further backup system using a different methodmay be used to determine and broadcast the location ofthe vessel to the oating object. In a further aspect, the method ofcommunication ofa dredging arrangement in distress further comprises the step of start communication with a cellular network through a cellular network arrangement if communication through one ofthe secondary and tertiary communication arrangement is unsuccessful. When the tertiary communication arrangement is also not able to determine and broadcast the location ofthe vessel to the oating 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. In an even further aspect, the method ofcommunication ofa dredging arrangement in distress according further comprises the step of start communication with a satellite transponder ifcommunication through one ofthe secondary communication arrangement, the tertiary communication arrangement and cellular network arrangement is unsuccessful. When the cellular network arrangement is also not able to determine and broadcast the location ofthe vessel to the oating object, a satellite transpondermay be used for communication. The satellite transponder, which optionallymay house a local embeddedGPS receiver, may be used to determine the location ofthe vessel and broadcast it to the oating object, or to different location in case the oating object is also not operable. It will be clear to the skilled person that while a submersible dredging vessel is used as an example, certain aspects ofthe invention may be used for common submersible vessels, or regular vessels. BRIEF DESCRIPTIONOFTHE DRAWINGS The various aspects and examples thereof will now be discussed in conjunction with drawings. In the drawings: Figure 1: shows an isometric view of a submersible dredging vessel; Figure 2A: shows a top view ofthe submersible dredging vessel; Figure 2B: shows a side view ofthe submersible dredging vessel; Figure 2C: shows a bottom view ofthe submersible dredging vessel; Figure 3: shows an isometric view ofthe submersible dredging vessel having its outer body removed from a rst angle; Figure 4: shows an isometric view ofthe submersible dredging vessel having its outer body removed from a second angle; and Figure 5: shows a schematic example of a dredging arrangement comprising a oating object and a dredging vessel. DETAILED DESCRIPTION Figure 1 shows a submersible dredging vessel 100 having a body 102 and a direction oftravel D. In the example, the body 102 is an outer shell ofthe vessel 100, defining the outer contour ofthe 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 ofwater. For example, a longitudinal shape, in which the length ofthe body 102 exceeds the width and height ofthe 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 ofthe body 102, thus increasing energy consumption ofthe vessel 100. The vessel 100 has a horizontal plane H, specifically a virtual horizontal plane H, that is being spanned by a longitudinal axis L ofthe vessel 100 and a transversal axis T, said transversal axis T being parallel to the width direction ofthe 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. The longitudinal body 102 has a front side 110 provided at a rst distal end ofthe longitudinal body 102 and a rear side 112 at a second distal end ofthe longitudinal body 102, opposite the first distal end. In the example, two corners 108 are provided towards a front side ofthe vessel 100 and two corners 108 are provided towards a rear side ofthe vessel 100. In the example, the two corners 108 provided towards the front side 110 and rear side 112 ofthe vessel 100 respectively are connected to each other such as to form a half circle 108. Turning to Figs. 2A-2C, an example ofthe submersible dredging vessel 100 has been depicted, showing a top view, side view andbottom 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 apump 126. Specifically, the pump 104 is in this example a centrifugal pump, e.g. a single-stage centrifugalpump having a single impeller, a multi-stage centrifugalpump having a plurality ofimpellers, a jetpump, a submersible pump, i.e. apump designed to be fully submerged during operation without damaging the motor ofthe submersible pump, or aow pump, butmay 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, dirtpumps or rotary pumps, such as gear pumps. It will be clear to the skilled person that the variouspump designs each have advantages, that will make them more suitable for some situations, butmay be all suitable for use as apump 126 for a primary propulsion unit 104. The propelling force providedby the primary propulsion unit 104may be improvedby providing a nozzle 128 at the outlet of a correspondingpump 126. The shape ofthe nozzle 128 may be used to increase or reduce the speed at which the liquid exits the primary propulsion unit 104, ejected by thepump 126. For example, by having a nozzle 128 ofwhich the opening surface ofthe outlet is reduced relative to the surface ofthe outlet ofthe correspondingpump 126, speed ofthe ejected liquid is increased. Additionally, the nozzle 128 may be used to aim the direction ofthe propelling force ofa correspondingpump 126, by having the outlet ofthe nozzle 128 aimed in a preferred direction. The direction in which the outlet ofthe nozzle 128 is aimedhas a component parallel to the direction ofthe propelling force. As can be seen in Figs. 2A and 2C, the plurality ofpropulsion units 104 are distributed around the contour 106 ofthe body 102 ofthe submersible dredging vessel 100 for distributing the propelling force provided by each corresponding primary propulsion unit 104. Each primary propulsion unit 104 ofthe plurality ofpropulsion units 104 is arranged to provide said propelling force. By distributing the propulsion units around the contour 106 ofthe body 102, the propelling force may be provided at different locations on the vessel 100. In the shown example, four primary propulsion units 104 ofthe plurality ofprimary 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 ofthe 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 providedby the propulsion units 104 on the starboard side ofthe 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. In the example, each propelling force ofa 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 ofmovement D. In the example, the primary propulsion units 104 are provided adjacent to each other such that each primary propulsion unit 104 ofthe two primary propulsion units 104 has a component towards the other primary propulsion units 104. In other words, the outlets ofthe primary propulsion units 104 andmore precisely, the direction ofjets of water that the primary propulsion units 104 are arranged to provide, have a component angled relative to the direction ofmovementD and, in the example, the longitudinal direction L ofthe vessel 100. 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 ofthe 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 ofthe propulsion units 104 are provided such that direction ofjets ofwater that the primary propulsion units 104 are parallel to the longitudinal direction L ofthe vessel 100 from a side view ofthe vessel or parallel to the virtual horizontal planeH ofthe vessel 100. This allows for rotating ofthe vessel 100, e.g. rotating the vessel in a starboard or port direction, without having to turn the outlet ofthe primary propulsion units 104, e.g. the nozzle 128. In the shown example, the propelling force ofeach primary propulsion unit 104 is provided in a horizontal planeH ofthe submersible dredging vessel 100, specifically, both the component parallel to the direction oftravelD and the component towards the other adjacent primary propulsion unit 104 are provided in a horizontal planeH or parallel to the transversal axis T. Thus, the primary propulsion units 104may be used to control the movement ofthe 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. In the example, two primary propulsion units 104 are provided adjacent to each other such that each primary propulsion unit 104 ofthe pair has a component towards the other primary propulsion units 104 or parallel to the transversal axis T, at the front 110 ofthe vessel 100 and towards the rear 112 ofthe vessel 100. Since the pair ofprimary 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 ofthe vessel 100. In an example, ifthe two primary propulsion units 104 provides at the rear side 1 12 ofthe vessel 100 are powered, each providing the same amount ofpropelling force, each propulsion unit 104 ofthe pair has a component towards the other ofthe pair ofpropulsion units 104. When the pair ofpropulsion 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 directionD remains. Generally, the resulting propelling force ofeach propelling force of a corresponding primary propulsion unit 104may be determined using vector-mathematics. From this it follows that the vessel 100 can be navigated, actuated, and controlled, in a body ofwater by adjusting the power provided to the propulsion units 104. In the shown example, specifically in the example shown in Fig. 2B, thepump 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 ofthe pump 104. When debris above a certain size enters thepump 104, thepump may be damaged 104. Also an inlet ofthe dredgingpump 120 may be provided with a filter. 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 ofthe example comprises a thruster with an electromotor arranged to drive a propellor ofthe thruster. Additionally or alternatively, the secondary propulsion system 116 may be provided using different propulsion devices, such as the previously describedpumps. In the example, the secondary propulsion system comprises two thrusters, provided at the rear end ofthe vessel 1 12; one for a port side and one for a starboard side. Optionally, a third thrustermay be provided between the two thrusters provided at port and starboard side ofthe stern. It will however be clear to the skilled person that the secondary propulsion system 116 may comprise a different number ofpropulsion devices, or a mix ofpropulsion devices. Comparable to the primary propulsion units 104, the secondary propulsion system 116 produces an auxiliary propelling force based on individual auxiliary propelling forces providedby 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. In one example, the thrusters ofthe 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 ofa port thruster clockwise and a propeller of a starboard thruster counterclockwise - or the other way around. Turning to Figs 2C, 8 and 4, it can be seen that the submersible dredging vessel 100 comprises a dredging module 118. The dredging module 118 comprises a dredgingpump 120 for pumping a uid and a uid outlet manifold 124 comprising a uid outlet openings 122 being arranged to provide direction jets ofthe uid. Referring to Fig. 2C specically, the uid outlet openings 122 are arranged to provide the uid jets in a downward direction, relative to the vessel 100, in the example such that the uid jets are aimed towards the bottom ofa body ofwater. The direction ofthe uid 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 ofthe body ofwater, in use. Additionally or alternatively, the uid outlet openings 122 may be arranged to provide the water jets diverging from a vertical axis ofthe vessel 100, such that the water jets are directly outwardly, under an angle, seen from bow sight or stern sight. The uid 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, ormay have openings ofvarious 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 ofthe vessel 100, such that the uid exists at a lower velocity than towards the counter ofthe dredging vessel 100. Alternatively, the openings may be larger away from the centre, to allow for substantially equal ows ofwater through all openings. By providing jets aimed at the bottom ofa body ofwater, for example a seabed, a port bottom, or a river bedding, the material making up the bottom ofthe body ofwatermay come loose, thus that the sedimentmay be uidised in the water. The loose material thus uidised may than be carried away by the current ofthe body ofwater, such that locally the bottom ofthe body ofwater has been adjusted. The carrying awaymay occur under inuence ofenvironmental parameters, like tidal ows, river ows, force of gravity - as a density current -, other or a combination oftwo or more thereof. Thus, by using direction jets it is possible to dredge a bottom of a body ofwater, without providingmeans to transport the loosened material and instead making use ofthe existing current ofthe body ofwater. The dredgingpump 120 may be apump ofthe same type as the primary propulsion units 104. Specifically, the dredgingpump 120 in the example is a centrifugal pump, e.g. a single-stage centrifugalpump having a single impeller, a multi-stage centrifugalpump having a plurality ofimpellers, a submersible pump or a ow pump. Alternatively, the dredgingpump 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 uid jets scales with the power provided to the dredgingpump 120. In other words, the more power provided towards the dredgingpump 120, the more upward force is provided to the vessel by the uid jets. As depicted in the example of Fig. 2C, the uid jets 122 are distributed over a widthW ofthe submersible dredging vessel 100. For example, the uid jets 122 may be distributed over the widthW in clusters, with a subset ofuid jets 122 being relatively close to each other, or evenly spaced over the width W, such that all uid jets 122 are at a same distance from neighbouring uid jets 122. Additionally or alternatively, the uid jets 122 may be provided in multiple rows in longitudinal direction L, e.g. in two rows, while the uid jets 122 in each row are distributed over the width W. In the example, the uid jets are distributed along a line L2 perpendicular to the longitudinal axis L ofthe submersible dredging vessel 100, specifically evenly spaced along the line L2. The submersible dredging vessel 100 comprises a centre of gravity G provided along the longitudinal axis L at a first distance d1 from a midpointM ofthe longitudinal axis L. In the example, at least one uid outlet opening 122 is arranged to provide a uid 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 ofthe rst distance d1. This means that the second distance d2 is larger than the rst distance d1. In another example, the second distance d2 is smaller than the first distance d1. In again another example, the second distance d2 is substantially equal to the rst distance d1. 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 ofthe body ofwater. When the dredgingpump 120 is powered, it can operate in different operating modes, each mode affecting the buoyancy ofthe vessel 100 differently. In the example, the dredgingpump 120 is arranged to operate three modes. In the first mode, a sink mode, a sum ofthe upward force of the uid 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 providedby the mass ofthe submersible dredging vessel 100. For example, ifthe dredgingpump 120 ofthe vessel is turned off, or powered at a relatively low level e.g. less than 85% such as 80% ofthe maximum operating power ofthe dredgingpump 120, the sum ofthe upward force of the uid jets and the upwardbuoyancy force acting on the submersible dredging vessel 100 is not sufcient to overcome the downward force, causing the vessel 100 to sink. The larger the difference between the downward force and the sum ofupward forces, the more quickly the vessel 100 will sink. In a second mode, a stable mode or equilibrium mode, the sum ofthe upward force provided by the uid 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 ofwater, preventing rising or falling ofthe vessel 100. More power is provided to the dredgingpump 120 than in the sink mode, balancing the downward force and the sum ofthe upward forces acting on the body. For example the dredgingpump 120 operates between 80% and 95% ofits maximum operating power, such as between 85% and 90% In a third mode, a rise mode, the sum ofthe upward force providedby the uid 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. In the rise mode, the dredgingpump 120 is powered more than in the stable mode, e.g. more than 90% e.g., 95% ofthe maximum operating power ofthe dredgingpump 120, such that the sum ofupward forces is positive compared to the downward acting force. The larger the difference between the sum ofthe upward forces and the downward acting force, the faster the vessel 100 will rise to the surface. As depicted in Fig. 2B, the submersible dredging vessel 100 comprises a centre ofbuoyancy B and wherein, during use, the centre of gravityG and the centre ofbuoyancyB are aligned in a vertical direction, for example in at least one ofthe 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 ofbuoyancyB is provided above the centre of gravity G, but it will be clear to the skilled person that the opposite, i.e. the centre ofbuoyancyB provide below the centre of gravity G, is also possible. Turning to Fig. 5, shows a schematic example ofa dredging arrangement 200. The dredging arrangement 200 comprises the submersible dredging vessel 100 and a buoy 400 arranged to oat during use ofthe dredging arrangement 200. Preferably, this is achieved passively, without powering the buoy 400, such that the buoy 400 can remain aoat without requiring energy. In the example, this is achievedby providing a hollow space in the buoy 400, lled with a product having a density lower than that ofwater, e.g. air at atmospheric pressure. Additionally or alternatively, the buoy 400 is provided as an inatable buoy 400. In order to determine, and control, the vertical position ofthe vessel 100 in a body ofwater, a vertical detection arrangement is provided. The submersible dredging vessel 100 comprises the vertical detection arrangement 302, for detecting the current vertical position ofthe submersible vessel 100 in a body ofwater, and a controller 304. The controller 304 is operatively connected to the dredgingpump 120 and the vertical position detection arrangement 302. The controller 304 is arranged to control the vertical position ofthe submersible vessel 100 in the body of water by operating the dredgingpump 120 in at least one ofthe sink mode, stable mode and rise mode, based on the current vertical position. In the example ofFig. 5, the submersible dredging vessel 100 further comprises a triangulation system 306 operatively connected to the controller 304. This controller 304may be the same controller used to control the vertical position ofthe submersible vessel 100 in the body of water, ormay be provided as a separate controller. The triangulation system 306 is arranged to determine the position ofa buoy, as an example of a oating object 400, relative to the submersible dredging vessel 100. In the example, the triangulation system 306 comprises a Ultra Short Base Line (USBL) 320 acoustic triangulation system. Such aUSBL system 320 may be arranged to determine relative coordinates ofthe buoy 400 with respect to the vessel 100. In the shown example, theUSBL system 320 comprises aUSBL sensory device 322 attached to the vessel 100 and a beacon 324 attached to the buoy 400 on the other end. 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 ofthe buoy 400 relative to the vessel 100 may be determined. The buoy 400 comprises a location detection system 326 for determining rst geographical coordinates ofthe buoy 400 and a transmitter 328 arranged to send the coordinates ofthe buoy 400 to a receiver 330 ofthe submersible dredging vessel 100. In the example, the location detection system 326 is arranged to determine the location ofthe 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 earths magnetic eld, e.g. magnetic anomaly navigation or INS systems, whether or not GNSS based. Additionally or alternatively, the buoy 400 may comprise aUSBL system arranged to cooperate with theUSBL system 320 provided on the vessel 100. In such an example, the USBL provided on the buoymay 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 ofthe measurements. Nevertheless, the twoUSBL systems may cooperate to more accurately determine the position ofthe vessel relative to the buoy, and vice versa, e.g. usingKalman ltering. The vessel 100 further comprises a receiver 330 operatively connected to the controller 304 and arranged to receive rst geographical coordinates ofthe 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 ofthe submersible dredging vessel 100 based on the first geographical coordinates ofthe buoy 400 and the position ofthe buoy 400 relative to the submersible dredging vessel 100 in Cartesian or polar coordinates. Once a location ofthe buoy 400 is known in first geographical coordinates, and transmitted to the vessel 100, it is possible to combine this data with position ofthe buoy 400 relative to the vessel 100 and determine the position ofthe vessel 100 in second geographical coordinates. Once the second geographical coordinates ofthe 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. In another example, the buoy 400 determines a position ofthe vessel 100 relative to the buoy 400. Subsequently, based on the determined relative position and absolute position data ofthe buoy 400 based on satnav information receivedby the buoy 400, the buoy 400 determines an absolute geographical position ofthe 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. In the example, the second geographical coordinates are more accurately determinedby enhancing the data comprising the rst geographical coordinates and the position ofthe buoy 400 relative to the vessel with data about the velocity ofthe vessel 100. When the vessel 100 is moving, e.g. due to being propelledby 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 ofthe originally determined second geographical coordinates, as determining the rst geographical coordinates and the position ofthe buoy 400 relative to the vessel, and thus the determination ofthe second geographical coordinates, may happen at fixed intervals, e.g. every few seconds. Therefore, the vessel 100 ofthe example further comprises a velocity measurement system 308 operatively connected to the controller 304, allowing determining ofthe second geographical coordinates ofthe submersible dredging vessel 100 to be further based on the velocity ofthe 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 ofthe vessel may be provided as part ofthe velocity measurement system 808. The velocity measurement system 808 comprises an acoustic doppler current proler system 810 aimed at a surface, in the example the water surface, for determining the velocity ofthe submersible dredging vessel 100 relative to the water surface or the bottom ofthe body ofwater during use. Alternatively or additionally, the doppler current profiler - or a second doppler current profiler - is aimed at the bottom ofthe body ofwater for determining a velocity ofthe submersible dredging vessel 100 relative to the bottom ofthe body ofwater. Additionally or alternatively, at least one doppler current proler may be provided that is inclined relative to the horizontal plane H, such that the doppler current proler may be used to measure the distance ofthe vessel 100 to a nearby object provided in the body ofwater, e.g. a quay wall. The velocity measurement system 808 may be implemented in other ways. For example, a vane or a propeller coupled to a motion sensor or rotation sensormay be used. Additionally or alternatively, an electromagnetic log can be used to determine the speed ofwaterow past the vessel 100 may, making use of a sensor providing an electromagnetic field. When the vessel 100 moves through the body ofwater, the water and electromagnetic field induce a voltage that is proportional to the speed ofthe water relative to the vessel 100. In a further example, at least one ofan 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 ofthe vessel 100 over time. The INS, electromagnetic log and doppler current proler system 310 may be used in combination with each other, or individually. When the systems are used in combination, the velocity ofthe vessel 100 may be more accurately determined, as data between systems may be compared and used to account for errors such as drift. In the example, the doppler current proler system 310 comprises a Doppler Velocity Log 312, or DVL, that uses four acoustic transducers in a Janus conguration 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 ofthe body ofwater at equal angles relative to the surface in pairs pointing in opposite directions. This setup allows theDVL 312 to measure Doppler shifts along each axis, enabling determination ofthe velocity ofthe vessel 100 in three- dimensional space (in the direction oftravel D, perpendicular in the direction oftravelD in the horizontal plane H, and perpendicular to the direction oftravelD perpendicular to the horizontal plane H; surge, sway and heave). By aiming theDVL 312 towards the surface ofthe body ofwater, the velocity ofthe vessel 100 relative to the body ofwater can be determined. Preferably, theDVL 312 is provided above a possible density gravity sediment or sludge current that may be produced during dredging due to the jet ofthe dredgingpump 120, in order to prevent the sediment or sludge interfering the signals ofthe acoustic transducers. Alternatively, the acoustic doppler current proler system 310 is aimed at the water surface and the bottom ofthe body ofwater for determining the velocity ofthe 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. The submersible dredging vessel 100 may be used to map the bottom ofthe body ofwater. This may be needed in order to determine if dredging has been successful, or iflocally more dredging is needed to have a sufciently deep body ofwater. Therefore, the submersible dredging vessel 100 ofthe example further comprises a rst echo sounder, as an example of a first depth meter (or altitude meter) 814, operatively connected to the controller 804 and arranged to determine the distance between the submersible dredging vessel 100 and a bottom ofa body ofwater. Combining the depth information provided by the rst echo sounder 814 with the second geographical coordinates, it is possible to provide data indicative ofhow deep the body ofwater is at a specific geographical coordinate, e.g. a map. Thus, the vessel 100 ofthe example is arranged to map the bottom ofthe body ofwater, based on the second geographical coordinates ofthe submersible dredging vessel 100, the depth ofthe vessel 100 below the surface ofthe water, for example measure by means ofthe pressure gauge, and the distance between the submersible dredging vessel 100 and the bottom ofthe body ofwater. The vessel 100 further comprises a second echo sounder, as an example ofa 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 ofthe body ofwater. The controller 304 is arranged to determine material characteristics based on the distance determined between the submersible dredging vessel 100 by the rst echo sounder as a rst depth meter and the second echo sounder as a second depth meter. Specifically, the rst and second echo sounder operate at different frequencies. For example a rst echo soundermay 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 ofthe bottom ofthe body ofwater differently, i.e. to different depths, before being reected back to corresponding echo sounder. As a result, the acoustic pulses have a different travel time from which the depth of a specific layer ofthe bottom ofthe body ofwatermay be determined. Operating the first echo sounder and second echo sounder at different frequencies, both over a corresponding range offrequencies, may thus be used to determine characteristics ofthe material that comprises the bottom ofthe body ofwater. 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 ofthe body ofwater based on the pressure acting upon the submersible dredging vessel 100. Additionally or alternatively, the triangulation system 306 may be used to determine the depth ofthe 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 oats on the surface ofthe body ofwater, the vertical component ofthe distance between the buoy 400 and the vessel 100 is indicative for the depth ofthe vessel 100. Once the distance between the vessel 100 and the surface ofthe body ofwater is known, the controller 804 in the example is arranged to determine the depth ofthe body ofwater based on the distance between the submersible dredging vessel 100 and the surface ofthe body ofwater and based on the distance between the submersible dredging vessel 100 and the bottom ofthe body ofwater. The submersible dredging vessel 100 comprises an electrical power system 884 connected to a propulsion arrangement 882, for providing power to the propulsion arrangement 882, and a diagnostic system 840 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 ofthe electrical power system 334 and the propulsion arrangement 332. Operational failure may be detected by measuring properties ofthe propulsion arrangement 332 and / or the electrical power system 884. Optionally, operational failure may be detected in other components ofthe vessel 100, e.g. the diagnostic arrangement 840, the safety system 852 etc., or the dredging arrangement 200. For example, the resistance over the propulsion arrangement 882 may be measured and wherein a relatively low or high resistance may be indicative of operational failure. Additionally or alternatively, temperature ofthe electrical power system 884, humidity in the electrical power system 884 as well as voltages and currents at various locations through the electrical power system 884 and / or the propulsion arrangement 882 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 884 and the propulsion arrangement 882. When operational failure is detected, the vessel 100 ofthe depicted example is arranged to return to the surface ofthe body ofwater 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 884 comprises a rst and secondpower supply 886, 888. In the shown example, the rst power supply 336 is a larger power supply than the secondpower supply 338. Larger meaning in this context that more powermay be provided and that more powermay be storedwhen fully charged. The first and second power supply 336, 338 are individually provided in a corresponding rst 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 ofan external impact, e.g. ifthe vessel 100 collides with a foreign object. The liquid-tight containers, may be provided such that theymay be opened such that the power supply 886, 888 provided in the liquid-tight containers may be serviced and / or repaired. The propulsion arrangement 882 comprises a primary propulsion unit 104 and a secondary propulsion system 1 16. The primary propulsion unit 104 and the secondary propulsion system 116 are each connected to the first power supply 886 and the secondpower supply 888. In the shown example, a plurality ofprimary propulsion units 104 is provided, each primary propulsion unit 104 being a pump. The secondpower 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 ofthe 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 ofoperational failure ofthe 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. Since the secondary propulsion system 116 consumes less power than the primary propulsion units 104, the secondpower supply 338 is sufcient for operation even if it is provided as a smaller power supply compared to the rst 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 ofthe primary propulsion system, e.g. a variable frequency drive, is provided in a liquid- tight container and / or at least part ofthe secondary propulsion system is provided in the second liquid-tight container. The submersible dredging vessel 100 comprises a control and sensing system 842 having first set of electrically powered components 844 and a second set of electrically powered components 846. The rst set of electrically powered components 844 is connected to the first power supply 886 and the second power supply 888, each for powering the rst set of electrically powered components 844 individually. In other words, the rst set of electrically powered components 344 can be powered both by the rst power supply 336 and the second power supply 338 in case one ofthe power supplies is not operative. 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 secondpower 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. The first set of electrically powered components 344 ofthe 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 ofthe vessel 100. 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 ofthe body ofwater. Thus, in case of power failure ofthe first power supply 336, all equipment not needed to return the vessel 100 to the surface does not consume any power stored in the secondpower supply 338, facilitating that sufcient power is available for the rst set of electrical components 844. In the example, the electrical power system 334 further comprises a thirdpower supply 348 operatively connected to the control and sensing system 342 and the diagnostic arrangement 340. The rst set of electrically powered components 344 comprises a primary subset of electrically powered components. The thirdpower 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. Thus, in case ofeven bigger distress, in which both the rst power supply 336 and the secondpower supply 338 are not able ofproviding 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 lled with air to increase buoyancy ofthe vessel 100 such that it rises to the surface. To protect the at least a part ofthe control and sensing system 342 from external impact, said part ofthe control and sensing system 342 is provided in a liquid-tight container. In the shown example, part ofthe control and sensing system 342 is provided in a dedicated liquid-tight container. The liquid-tight container is comparable to the liquid-tight containers, ofthe first and secondpower supply 886, 338.In the scenario in which the vessel 100 may be in distress, e.g. by having a leakage, the liquid- tight containermay act as a barrier against water entering the vessel 100. This may prevent the control and sensing system 842 from becoming damaged, and allow operation during distress such that the vessel 100 may be safely returned to the surface ofthe body ofwater. In an example, the liquid-tight container for the control and sensing system 842 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 ofthe rst power supply and the secondpower supply 336, 338 and the liquid-tight compartment in which part ofthe primary propulsion system 104, e.g. the variable frequency drive ofthe pumps, is be provided. In the example, the vessel 100 further comprises one or more air chambers and a compressed air supply system 350 in uid connection with the air chamber. Specifically, in the example the air chamber is a hollow space in the vessel 100 having sufcient volume to store a gas, e.g. air, at pressure conditions for a certain depth in the body ofwater or atmospheric at the surface ofthe body ofwater, such that the vessel 100 rises to the surface by increasing the buoyancy ofthe vessel 100. The air supply system 850 comprises a connector for connecting to a container comprising compressed air and an air supply control valve arranged to controllably ll the air chamber with air from the container. The containermay 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 850 such that the contents ofthe containermay be provided to the air supply system 850 without leakage. Thus when the air supply control valve is in an open position, the pressurized air from the container enters the lower pressure air chamber, thereby increasing the buoyancy ofthe vessel. The compressed air supply system 850 ofthe example further comprises an electrically powered fail-open valve, next to the air supply control valve, connected to the rst power supply 886 and secondpower supply 888 for controllably filling the air chamber with air. Thus, ifthe first power supply 886 and second power supply 888 are no longer able to provide power to the air supply system 850, the fail-open valve, opens. As an example, the fail-open valve may comprise a servo that, once unpowered by the first power supply 886 and the secondpower supply 888 opens the valve. 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 ofthem may be provided instead. Additionally, in the example the compressed air supply 850 is operatively connected to the diagnostic arrangement 840 and arranged to controllably fill the air chamber with air based on operational failure detected by the diagnostic arrangement 840 in the secondpower supply 888. In the example, the vessel 100 further comprises a safety system 352 connected to the secondpower supply 338 and the diagnostic arrangement 340. The secondpower supply 338 is arranged to power the safety system 352 based on operational failure detectedby the diagnostic arrangement 340 in the first power supply 336. The safety system 352 ofthe example comprises a navigation light 354 arranged to provide an optical distress signal and a GPS beacon 356 arranged to determine a geographical position ofthe submersible dredging vessel 100, e.g. second geographical coordinates, and transmit said geographical position to a receiver. Such a receivermay be a receiver provided on the buoy or provided shore-side. The navigation light 354 is arranged to be powered by at least one ofthe first power supply 336, the secondpower 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 ofthe body ofwater. The navigation light 354may be provided as a single light source or as a plurality oflights. The optical distress signalmay 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 354may comprise a plurality oflight sources, e.g. a plurality of optical distress signals. Additionally or alternatively, the safety system 352 may comprise a at least one ofa combined satellite modem, a GPS beacon, a USBL system and an acoustic beacon. In the shown example, the control and sensing system 342 comprises a plurality ofcontrollers 304. Each ofthe plurality ofcontrollers 304 is arranged to individually control the submersible dredging vessel 100 through the control and sensing system 342. The plurality ofcontrollers 304 in the example are arranged to operate in parallel with each other. Each controllers 304 is individually capable ofcontrolling 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 ofthe dredging vessel 100 such that the vessel 100 may still be retrieved. Optionally, the vessel 100 may be congured such that, when all controllers 304 ofthe vessel 100 are no longer operative, e.g. due to faulty behavior or damage, the safety system 352 may automatically become activatedby a hardwired connection. For example, emergency lights and / or the GPS system may be activated. Additionally or alternatively, the dredgingpump ofthe vessel 100 may be activated, andpowered such that the vessel 100 rises to the surface, e.g. by powering the dredgingpump to its maximum pumping capacity. 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 controlledfrom a distance in case parts ofthe control and sensing system 842 are no longer capable ofsufciently controlling the vessel 100. For example, ifthe controllers 804 are damaged, a usermay manually intervene using the remote control arrangement using a remote controller. Additionally or alternatively, the remote control arrangement may be used to control the vessel 100 remotely once one ofthe 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 arrangementmay be used for special operations ofthe vessel 100, e.g. docking purposes. The controller 304 ofthe submersible dredging vessel 100 is arranged to receive the control signals for controlling the submersible dredging vessel 100. In the example, each ofthe 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 switchmay be a digital switch, operatedby a controller. This may allow for different operating modes ofthe vessel 100, e.g. when docking. In such a scenario, certain parts ofthe vessel 100 may be shut-off. Additionally or alternatively, the vessel 100 may comprise a main switch arranged to control a starting sequence ofthe various electrically powered components ofthe 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 offdue 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 xed interval, e.g. every few seconds, using for example a relay. In an example, when at least one controller is activated, the main switch and the relaymay no longer be needed to start the rest ofthe components, e.g. the other controllers 304, as the at least one activated controller is arranged to provide this capability. 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 thatmay need to be inserted in a keyhole in the vessel 100, and which an operatormay 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 ofthe vessel 100 may be provided with multiple fail-safe mechanisms to ensure safe operation, such as the reed switch and the electrical bridging element. Additionally or alternatively, a digital key or an electronic key may be provided, e.g. a digital signal thatmay 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 operatingmode when the electrical bridging element is connected, and wherein the charging arrangement is in chargingmode when the electrical bridge element is released from the charging arrangement. The electrical bridging element be provided as a handle, comprising an electrical wire. Both ends ofthe handle may be electrically connected to a corresponding plus and min pole ofthe electrical power system 884, 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 operatormay not accidentally come in to contact with them. In an embodiment, the plus and minus poles comprise four poles each, e.g. four plus poles and four minus poles. When charging, three ofthe four poles are connected to the charging system, thereby charging the electrical power system 334. The fourth pole plus andminus pole are connected to a corresponding plus and minus pole ofthe electrical power system 334, in a fashion similar to that ofthe 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 andminus pole are connectedby the handle, while the other three plus poles and three minus poles are not connected. The closed loop ofthe fourth plus andminus pole may be detected by the electrical power system 334, said signalmay be used to allow powering ofthe submersible dredging vessel 100. An interrupted loop between the fourth plus andminus 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 ofthe vessel 100 may be provided. For example, physical access to the charging system may be gainedby opening a door or hatch from the vessel 100. Said door or hatch may be connected to a switch, e.g. a Reed-switch, such that when the door or hatch is opened, the vessel 100 is depowered at least locally such that the charging system is depowered andmay 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 ofthe vessel 100. Variations are understood to be comprised within the scope ofthe invention as defined in the appended claims. For example, it will be clear to the skilled person that the vesselmay be used for other purposes than injection dredging. For example, the vesselmay be used as an intelligent semi-stationarypump unit aiding other devices performing a dredging process, by connecting hoses or pipelines to the dredgingpump and propulsionpumps respectively, pumping up sediment towards a predetermined location, or it can be used in a process ofmass excavation or bed levelling dredging. In summary, the various aspects and implementations thereof relate to the following examples: A1. 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 uid and a uid outlet manifold comprisinguid outlet openings being arranged to provide directional jets ofthe uid; - wherein the submersible dredging vessel has a negative buoyancy during use; - wherein the uid outlet openings are arranged to provide the uid jets in a downward direction, relative to the vehicle; and - wherein the dredgingpump is arranged to operate in: - a sink mode, wherein a sum ofthe upward force ofthe uid 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 ofthe upward force provided by the uid 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 ofthe upward force provided by the uid jets and the upward force acting on the submersible vehicle is larger than the downward force acting on the submersible dredging vessel. A2. Submersible dredging vessel according to example A1, wherein the upward force provided by the uid jets scales with the power provided to the dredgingpump. A3. Submersible dredging vessel according to example A1 or A2, wherein the uid jets are distributed over a width ofthe submersible dredging vessel. A4. Submersible dredging vessel according to example A3, wherein the uid jets are distributed along a line perpendicular to a longitudinal axis ofthe submersible dredging vessel. A5. Submersible dredging vessel according to any ofthe examples A1 - A4, further comprising a centre gravity and a longitudinal axis, wherein said centre of gravity is provided along said longitudinal axis at a rst distance from a midpoint ofthe longitudinal axis. A6. Submersible dredging vessel according to example A5, wherein at least a one uid 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 ofthe rst distance. A7. Submersible dredging vessel according to example A5 or A6, having a centre ofbuoyancy and wherein, during use, the centre of gravity and the centre ofbuoyancy are aligned in a vertical direction. A8. Submersible dredging vessel according to any ofthe examples A1 - A7, further comprising: - a vertical position detection arrangement for detecting the current vertical position ofthe submersible vehicle in a body ofwater; - a controller operably connected to the dredgingpump and the vertical position detection arrangement and wherein the controller is arranged to control the vertical position of the submersible vehicle in the body ofwater by operating the dredgingpump in at least one ofthe sink mode, stable mode and rise mode, based on the current vertical position. A9. Method ofcontrolling the buoyancy ofa submersible vehicle, preferably the submersible vehicle according to any ofthe examples A1 - A8, wherein the submersible vehicle has a negative buoyancy and comprises a dredgingpump, wherein the method comprises the steps of: - providing the submersible vehicle in a body ofwater; - powering the dredgingpump in a rst range, second or third range, said range defining a percentage ofthe maximum operating power of the dredgingpump, such that the uid jets provide an upward force on the body ofthe submersible vessel, and wherein the sum ofthe upward force provided by the dredgingpump and the buoyancy is negative, zero or positive respectively. A10. Method according to example A9, wherein an upper limit ofthe first range is smaller than a lower limit ofthe second range, and an upper limit ofthe second range is smaller than a lower limit ofthe third range. A1 1. Method according to example A9 or A10, wherein the second range is between 80% and90% ofthe maximum operating power ofthe dredgingpump, for example 85% and95% ofthe maximum operating power. B1. A submersible dredging vessel having a body and a direction of travel, said submersible dredging vessel comprising: - a plurality ofprimary propulsion units distributed around a contour ofthe body ofthe submersible dredging vessel, wherein each primary propulsion unit ofthe plurality ofprimary 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 ofthe submersible dredging vessel; and - wherein at least one primary propulsion unit ofthe plurality of propulsion units comprises a pump. B2. Submersible dredging vessel according to example Bl, wherein the contour ofthe body comprises four corners in a horizontal plane ofthe submersible dredging vessel and wherein at least one primary propulsion unit ofthe plurality ofprimary propulsion units is provided in each corner. B3. Submersible dredging vessel according to example B2, wherein two primary propulsion units ofthe plurality ofprimary propulsion units are provided adjacent to each other such that each primary propulsion ofthe two primary propulsion units has a component parallel to a direction towards the other primary propulsion unit ofthe two primary propulsion units. B4. Submersible dredging vessel according to any ofthe examples Bl - B3, wherein the propelling force ofeach primary propulsion unit ofthe plurality ofprimary propulsion units is provided in a horizontal plane ofthe submersible dredging vessel. B5. Submersible dredging vessel according to any ofthe examples Bl - B4, wherein the longitudinal body has a front side provided at a rst distal end ofthe longitudinal body and a rear side provided at a second distal end ofthe longitudinal body, opposite the first distal end, and wherein at least two primary propulsion units ofthe plurality ofthe primary propulsion units are provided towards the front side and at least two primary propulsion units ofthe plurality ofthe primary propulsion units are provided towards the rear side. B6. Submersible dredging vessel according to any ofthe examples Bl - B5, wherein thepump comprises an inlet provided towards a side ofthe dredging vessel and wherein an opening ofthe inlet is provided at an angle relative to a longitudinal axis ofthe vessel. B7. Submersible dredging vessel according to any ofthe examples Bl - B6, wherein thepump comprises a filter arranged to protect thepump from debris during use. B8. Submersible dredging vessel according to any ofthe examples Bl - B7, wherein thepump is a centrifugal pump. B9. Submersible dredging vessel according to any ofthe examples Bl - B8, 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. B10. Submersible dredging vessel according to example B9, wherein the auxiliary propelling force is parallel to the propelling force of at least one primary propulsion unit. Bl l. Submersible dredging vessel according to example B9 or B10, wherein the secondary propulsion system comprises a propeller arranged to provide the auxiliary propelling force. B12. Method ofrudderless navigating of a submersible dredging vessel according to any ofthe examples Bl - Bl 1, comprising the steps of: - determining a movement direction; - powering the at least one primary propulsion unit ofthe plurality ofpropulsion units such that the sum ofthe components ofthe propelling forces ofeach ofthe corresponding primary propulsion units of the plurality ofprimary propulsion units is positive in a direction having a component in the movement direction. B13. Method ofrudderless navigating of a submersible dredging vessel according to example B12, wherein the sum ofthe components ofthe propelling forces is positive in a direction parallel to the determined movement direction. B14. Method ofrudderless navigating of a submersible dredging vessel according to example B12 or B13, further comprising the step of: - powering the secondary propulsion system such that the sum of components ofthe propelling forces and the auxiliary propelling force is positive in a direction having a component in the determined movement direction. C 1. A vessel for cooperation with a oating object comprising: - a controller; - a triangulation system operably connected to the controller and arranged to determine the position ofthe oating object relative to the vessel; - a receiver operably connected to the controller and arranged to receive first geographical coordinates ofthe oating object; and - wherein the controller is arranged to determine second geographical coordinates ofthe vessel based on the first geographical coordinates ofthe oating object and the position ofthe oating object relative to the vessel. C2. Vessel according to example C1, further comprising a velocity measurement system arranged to determine the velocity ofthe vessel, the velocity measurement system being operably connected to the controller and wherein the determining ofthe second geographical coordinates ofthe vessel is further based on the velocity ofthe vessel. C3. Vessel according to example C2, wherein the velocity measurement system comprises an acoustic doppler current proler system arranged to be aimed, in use, at a surface for determining the velocity ofthe vessel relative to the surface during use. C4. Vessel according to example C3, wherein the surface is a water surface of a body ofwater or a bottom ofthe body ofwater. C5. Vessel according to example C3, wherein the acoustic doppler current profiler system is aimed at a rst surface and a second surface for determining the velocity ofthe vessel andwherein the first surface is a surface ofthe body ofwater and the second surface is a bottom ofthe body of water. C6. Vessel according to any ofthe examples C1 - C5, 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 ofwater. C7. Vessel according to example C6, further comprising a second depth meter operably connected to the controller and arranged to determine the distance between the vessel and the bottom ofthe body ofwater and wherein the controller is arranged to determine material characteristics of the bottom ofthe body ofwater based on the distance determined between the vessel by the rst depth meter and the second depth meter. C8. Vessel according to example C6 or C7, wherein the controller is arranged to determine the depth ofthe body ofwater based on the second geographical coordinates ofthe vessel and the distance between the vessel and the bottom ofthe body ofwater. C9. Vessel according to any ofthe examples C6-C8, 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 ofthe body ofwater based on the pressure acting upon the vessel. C10. Vessel according to any ofthe examples C6- C9, wherein the controller is arranged to map the bottom ofthe body ofwater based on a first distance between the vessel and the surface ofthe body ofwater, on a second distance between the vessel and the bottom ofthe body ofwater, and on the second geographical coordinates. C1 1. A oating object arranged to oat during use, wherein the oating object comprises: - a location detection system for determining rst geographical coordinates ofthe oating object; and - a transmitter arranged to send the coordinates ofthe oating object to a receiver ofa vessel. C12. Floating object according to example C11, wherein the location detection system is arranged to determine the location ofthe oating object using a satellite navigation system. C13. Floating object according to example C11 or C12, wherein the oating object comprises at least one of a buoy or a ship. C14. Dredging arrangement comprising: - a vessel according to any ofthe examples C1 to C10; - a oating object according to any ofthe examples C1 1 to C13, and wherein the vessel is physically connected to the oating object. C15. Method ofdetermining the coordinates ofa submersed vessel using a dredging arrangement, preferably the dredging arrangement according to example C14, comprising: providing a oating object on a body ofwater, said oating object comprising a location detection system for determining the coordinates ofthe oating object; determining the coordinates ofthe oating object using the location detection system, preferably using the location detection system and a global navigation satellite system; transmitting the coordinates ofthe oating object to the vessel; determining the position ofthe oating object relative to vessel using the triangulation system; and determining the coordinates ofthe vessel based on the coordinates of the oating object and the position ofthe vessel relative to the oating object. C16. Method ofmapping a bottom ofa body ofwater using a dredging arrangement, preferably the dredging arrangement according to example C14, comprising the steps of: determining the coordinates of a submersed vessel according to example C15; determining the distance between the vessel and the surface ofthe body ofwater based on the position ofthe vessel relative to the oating object; determining the distance between the vessel and the bottom ofthe body ofwater using a rst depth meter provided on the vessel; mapping the bottom ofa body ofwater based on the distance between the vessel and the surface ofthe body ofwater, based on the distance between the vessel and the bottom ofthe body ofwater and based on the coordinates ofthe submersed vessel. C17. Method ofmapping of a body ofwater according to example C16, wherein the first depth meter is a rst echo sounding arrangement operating at a rst frequency; the method further comprising the steps of: determining the distance between the vessel and the bottom ofthe body ofwater using a second echo sounding arrangement operating at a second frequency providing on the vessel, wherein the rst frequency and the second frequency are different; determining the characteristics ofthe bottom ofthe body ofwater using the distance between the vessel ofthe first depth meter and the second depth meter. C18. Method ofmapping of a body ofwater according to example C17, wherein the characteristics ofthe bottom ofthe body ofwater has data comprising information about the sediment layers ofthe bottom. D1. 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 ofthe electrical power system and the propulsion arrangement; wherein: the electrical power system comprises a first power supply and a secondpower supply, wherein the rst power supply and the secondpower supply are individually provided in a corresponding rst 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 secondpower supply; and the secondpower supply is arranged to power the secondary propulsion system, based on detected operational failure by the diagnostic arrangement in at least one ofthe first power supply and the primary propulsion unit. D2. The vessel according to example D1, 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 rst set of electrically powered components is connected to the first power supply and the secondpower supply, each for powering the rst set of electrically powered components individually; the second set of electrically powered components is connected to the first power supply; and the secondpower supply is arranged to power the first set of electrically powered components based on detected operational failure in the first power supply. D3. The vessel according to example D2, wherein at least a part ofthe control and sensing system is provided in an liquid-tight container, preferably a dedicated liquid-tight container. D4. The vessel according to any ofthe examples D1 - D3, further comprising an air chamber and a compressed air supply system in uid 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 ll the air chamber with air from the container. D5. The vessel according to example D4, 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. D6. The vessel according to example D4 or D5, 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 secondpower supply. D7. The vessel according to any ofthe examples D1 - D6, further comprising a safety system connected to at least the secondpower 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 rst power supply. D8. The vessel according to example D7, 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 ofthe vessel and transmit the geographical position to a receiver, wherein the navigation light is arranged to be poweredby at least one ofthe first power supply and the secondpower supply. D9. The vessel according to any ofthe examples D1 - D8, wherein the control and sensing system comprises a plurality ofcontrollers, each ofthe plurality ofcontroller arranged to individually control the vessel through the control and sensing system. D10. The vessel according to example D9, wherein the plurality of controllers are arranged to operate in parallel with each other. D1 1. The vessel according to any ofthe examples D2-D 10, 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 rst set of electrically 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. D12 The vessel according to any ofthe examples D2-D1 1, 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. D13. The vessel according to example D12, 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 releasedfrom the charging arrangement. D14. A dredging arrangement comprising a vessel according to any of the examples D1 -D13 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. D 15. Amethod of activating a safety mechanism ofa vessel, preferably the vessel according to any ofthe examples D1 - D13, 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 rst power supply and a second power supply arranged to power the primary propulsion unit and secondary propulsion system respectively; activating the secondpower supply when the first power supply has an operational failure; powering the secondary propulsion system using the secondpower supply. D16. The method of activating safety mechanism ofa vessel according to example D15, wherein the vessel further comprises a third power supply and a safety system arranged to be powered by the thirdpower supply, said safety system comprising a GPS system and at least one ofan optical alarm and audible alarm; wherein the method further comprises the steps of: activating the thirdpower supply when the secondpower supply has an operational failure; powering the GPS system and the at least one ofan optical alarm and audible alarm. D17. Amethod ofcommunication ofa dredging arrangement in distress, wherein the dredging arrangement comprises a vessel and a oating object, said vessel and oating object in communication via a primary communication arrangement, preferably aUSBL arrangement, wherein the method comprises the steps of: operating a submerged vessel in a body ofwater; ascending the vessel to the surface ofthe body ofwater ifthe primary communication between the vessel and the oating object is lost; start communication with the oating object through a secondary communication arrangement, wherein the secondary communication arrangement is preferably GPS arrangement. D18. The method ofcommunication of a dredging arrangement in distress according to example D17, further comprising the step of: start communication with the oating object through a tertiary communication arrangement ifcommunication through the secondary communication arrangement is unsuccessful, wherein the tertiary communication arrangement is preferably a WiFi-arrangement. D19. The method ofcommunication of a dredging arrangement in distress according to examples D17 or D18, further comprising the step of: start communication with a cellular network through a cellular network arrangement ifcommunication through one ofthe secondary and tertiary communication arrangement is unsuccessful. D20. The method ofcommunication of a dredging arrangement in distress according to any ofthe examples D17-D 19, further comprising the step of: start communication with a satellite transponder if communication through one ofthe secondary communication arrangement, the tertiary communication arrangement and cellular network arrangement is unsuccessful.

Claims

1. An underwater dredging vessel comprising a body and a dredging module provided for in the said body, whereby the dredging module A dredging pump comprises a for pumping liquids fluid outlet manifold that includes fluid outlet openings that are designed to supply targeted jets of the fluid; where the underwater dredging vessel has negative buoyancy during usage; where the liquid outlet openings are designed to direct the liquid jets into a to provide a downward direction, relative to the vessel; and where the dredging pump is configured to operate in: a sink mode, where a sum of the upward force of the liquid jets and an upward force acting on the underwater dredging vessel operates smaller than a downward force acting on the underwater dredging vessel works; a stable mode, where the sum of the upward force is provided due to the liquid jets and the upward force acting on the underwater vessel operates, is substantially equal to the downward force acting on the underwater dredging vessel works; and an upward mode, where the sum of the upward force provided by the liquid jets and the upward force acting on the underwater vessel operates larger than the downward force acting on the underwater dredging vessel.

2. Underwater dredging vessel within the meaning of claim 1, where the upward force delivered by the liquid jets scales with the power delivered to the dredging pump.

3. Underwater dredging vessel within the meaning of claim 1 or 2, where the Liquid jets are distributed across the width of the underwater dredging vessel.

4. Underwater dredging vessel within the meaning of claim 3, whereby the liquid jets are distributed along a line perpendicular to a longitudinal axis of the underwater dredging vessel.

5. Underwater dredging vessel according to one of claims 1 - 4, furthermore comprising a center of gravity and a longitudinal axis, where named The center of gravity is provided along the said longitudinal axis on a first distance from a center of the longitudinal axis.

6. Underwater dredging vessel within the meaning of claim 5, whereby at least a liquid jet is provided along a line perpendicular to the longitudinal axis, where said line intersects the longitudinal axis at a second distance from the center, and where the second distance lies in an extension of the first distance.

7. Underwater dredging vessel within the meaning of claim 5 or 6, with a buoyancy point and where, during use, the center of gravity and the buoyancy are aligned in a vertical direction.

8. Underwater dredging vessel according to one of claims 1 - 7, furthermore comprising: a vertical position detection device for detecting the current vertical position of the underwater vessel in a body of water; a controller that is operationally connected to the dredging pump and the vertical position detection device and where the controller is configured to the vertical position of the underwater vessel in the body of water regulate by operating the dredging pump in at least one of the sink mode, steady mode and rise mode, based on the current vertical position.

9. Method for regulating the buoyancy of an underwater vessel, preferably the underwater vessel according to one of the conclusions 1 - 8, where the underwater vessel a negative has buoyancy and includes a dredging pump, whereby the method of operation includes: equipped with the underwater vessel in a body of water; driving the dredging pump in a first, second, or third range, where said range is a percentage of the maximum operating capital of the dredging pump denies, such that the liquid jets an upward force on the body of the supply underwater vessel, and where the sum of the upward power supplied by the dredging pump and buoyancy is respectively negative, zero, or positive.

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

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

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