WO2021140057A1

WO2021140057A1 - Alignment system and method for operating an alignment system

Info

Publication number: WO2021140057A1
Application number: PCT/EP2021/000001
Authority: WO
Inventors: Pascal Dorster
Original assignee: Pascal Dorster
Priority date: 2020-01-07
Filing date: 2021-01-06
Publication date: 2021-07-15
Also published as: EP4087777A1

Abstract

Alignment system (1) for a water vessel (100) comprising a fixture (2), an input unit (5), a control unit (4) and a propulsion element (3) wherein the fixture is arranged to provide a pivot point to which the water vessel is rotatably connected. The propulsion element is arranged to provide an alignment force (300) in two opposed transverse directions of the water vessel, wherein the alignment force results in a rotational movement of the water vessel around the fixture. The input unit is arranged to transduce inputs to input signals (500) and transmit the input signals to the control unit. The control unit is arranged to provide a control signal (400) for controlling the propulsion element, wherein the control signal depends on the input signals. The input unit comprises at least one distance sensor (50), wherein the distance sensor is arranged to receive a distance of objects in proximity to the water vessel as the input, and the input unit comprises a directional unit, wherein the directional unit is arranged to receive a directional information as the input.

Description

Alignment system and method for operating an alignment system

The disclosure concerns an alignment system arranged to adjust and/or maintain an alignment of a water vessel, in particular a boat or a ship. Here and in the following, the alignment comprises a direction in which the water vessel is aligned. In particular, alignment may comprise a relative position of the water vessel or an absolute position of the water vessel. The relative position may be defined with respect to objects in proximity to the water vessel. The absolute position may be defined by a GPS-coordinate and/or a position of a fixture.

Here and in the following the water vessel comprises a bow and a stern, wherein a longitudinal axis connects the stern and the bow. The water vessel comprises a starboard side and a port side, wherein a transverse axis connects the starboard side and the port side. The water vessel comprises a vertical axis, wherein the vertical axis extends perpendicular with respect to the longitudinal axis and the transverse axis. Here and in the following a movement of the water vessel may be a translative movement along an axis or a rotational movement around an axis. In particular, the movement of the water vessel may be one or a combination of:

A translative movement of the water vessel along the longitudinal axis (also known as 'surge'),

A translative movement of the water vessel along a transverse axis (also known as 'sway'),

A translative movement of the water vessel along a vertical axis (also known as 'heave'),

A rotational movement of the water vessel about the longitudinal axis (also known as 'rolling'),

A rotational movement of the water vessel about the transverse axis (also known as 'pitch'),

A rotational movement of the water vessel about the vertical axis (also known as 'yaw').

According to an embodiment, the alignment system comprises a fixture, an input unit, a control unit and a propulsion element. The fixture is arranged to provide a pivot point to which the water vessel is rotatably connected. The fixture is arranged to fixedly attach the water vessel to the seabed or to an object having a fixed position. In particular, the fixture provides a form-fitting connection to the object or the seabed. For example the fixture is an anchor or a moored buoy. A link may be arranged to mechanically connect the fixture and the water vessel. In particular the link may be a chain and/or a rope, wherein one end of the link is attached to the fixture and the other end of the link is attached to the water vessel, in particular the link is attached to the bow of the water vessel. The position of the pivot point may be at any position between the fixture and the water vessel. In particular, the pivot point may change over time. For example, the pivot point depends on multiple factors, like external force acting on the water vessel, weight of the link, length of the ling, depth of the water.

According to one embodiment the propulsion element is arranged to provide an alignment force in two opposed transverse directions of the water vessel, wherein the alignment force results in a rotational movement of the water vessel around the fixture. The propulsion element may comprise a propellor or a jet stream engine. In particular the propulsion element may be a thruster. In particular, the thruster is partially encapsulated to avoid injuries of people swimming nearby the boat. The alignment force acts at least partially along the transverse axis. In particular, the alignment force may be subdivided in a first portion acting along the transverse axis and a second portion acting along the longitudinal axis. The propulsion element may be partially integrated in the hull of the water vessel. In particular the propulsion unit is embedded in the keel of the water vessel, whereby the propulsion element does not protrude from the hull of the water vessel. Advantageously, the propulsion unit is free of moving parts outside the hull of the water vessel

The propulsion element may comprise at least one electrical motor, which is mounted at the stern of the water vessel. In particular, the propulsion element may comprise at least one electrical motor which is mounted at the bow of the water vessel. The electrical motor or motors may be arranged to receive a control signal from the control unit, to smoothly dynamically position the boat in order to face the average swell. The electrical motor or motors may be part of a main engine of the water vessel, which is arranged to enable propulsion of the water vessel along its longitudinal axis. For example, the main engine is a hybrid engine, which comprises at least one electrical motor and a combustion engine.

According to one embodiment, the input unit is arranged to transduce inputs to input signals and transmit the input signals to the control unit. The inputs may be information, which is entered manually or information which is received by means of a sensor.

According to one embodiment, the control unit is arranged to provide a control signal for controlling the propulsion element, wherein the control signal depends on the input signals. In particular, the control unit weights the input signals to determine a target alignment for the water vessel. Furthermore, the control unit is arranged to determine a difference between the target alignment and the actual alignment of the water vessel. The control unit may be arranged to control the propulsion unit such that the actual alignment of the water vessel becomes and/or remains essentially identical to the target alignment. Here and in the following, the alignment of the water vessel comprises an angle and a position of the water vessel. A position may be described by means of coordinates. An angle may be described by a cardinal direction in which the longitudinal axis of the water vessel is aligned or by an angle with respect to a reference, where the reference may be a direction of the swell.

According to one embodiment, the input unit comprises at least one distance sensor, wherein the distance sensor is arranged to receive a distance of objects in proximity to the water vessel as the input. In particular the distance sensor is arranged to determine a distance between the water vessel and objects.

The objects may be stones, further water vessels and/or other objects which may cause damage to the water vessel in case of a collision. In particular, the alignment system comprises at least two distance sensors arranged at the stern of the water vessel, where one of the distance sensors receives the distance of objects on the port side of the water vessel and one of the distance sensors receives the distance of objects on the starboard side of the water vessel. In particular a single distance sensor may be arranged on top of the water vessel, wherein the single distance sensor is arranged to detect objects in positions 360° around the water vessel.

According to one embodiment the input unit comprises a directional unit, wherein the directional unit is arranged to receive a directional information as the input. The directional information may be a cardinal direction or a relative angle. The relative angle may be measured with respect to the longitudinal axis of the water vessel. In particular, the directional unit may receive weather forecast or live weather information, wherein the directional unit extracts information about strength and direction of wind, swell and/or current. According to one embodiment, the alignment system for a water vessel comprises the fixture, the input unit, the control unit and the propulsion element. The fixture is arranged to provide a pivot point to which the water vessel is rotatably connected. The propulsion element is arranged to provide an alignment force in two opposed transverse directions of the water vessel. The alignment force may result in a rotational movement of the water vessel around the pivot point, in particular the fixture. The input unit is arranged to transduce inputs to input signals and transmit the input signals to the control unit. The control unit is arranged to provide a control signal for controlling the propulsion element, wherein the control signal depends on the input signals. The input unit comprises at least one distance sensor, wherein the distance sensor is arranged to receive a distance of objects in proximity to the water vessel as the input. The input unit comprises a directional unit, wherein the directional unit is arranged to receive a directional information as the input. The distance sensor may comprise a radar, a millimeter wave radar, an echo sounder, a computer vision system, in particular a laser scanner, a thermal sensor and/or LIDAR.

Components of the input unit, the control unit and the propulsion element may be arranged in a common housing, integrated in a common PCB or in a common integrated circuit. Thus, the distinction between input unit, control unit and propulsion element is based on the function and not on a spatial arrangement of the components of the alignment system.

The alignment system described here is based, among other things, on the following considerations. In general, the alignment of a water vessel which is attached by means of a fixture, in particular an anchor or a mooring buoy, is defined by current and wind. Typically, the fixture is attached to the bow of the water vessel, whereby the water vessel aligns such that the bow faces against the direction of the wind and/or current. In particular, the swell of the water surrounding the water vessel may approach the boat from a different direction than the wind and/or the current. Hence, the motion of the water vessel caused by the swell is not controlled, which may cause discomfort, and which may result in reduced safety or even in danger for people on the water vessel. In particular, the swell may cause rolling, which may be created by the natural swell of the sea, if the longitudinal axis is aligned obliquely with respect to the direction of the swell. In particular, the water vessel may enter resonant oscillation in the rolling motion, which may cause discomfort and sea sickness. Moreover, rolling may be created by swell coming from other water vessels, which pass by the water vessel.

Furthermore, multiple water vessels anchoring in a common area may align differently, because wind and current may be locally different and/or the water vessels may interact differently with the wind and the current. In particular, the multiple water vessels may align randomly, because neither wind nor current provides coherent force, which results in a lack of alignment of the multiple water vessels with respect to each other. Thus, it is important to maintain a minimum distance of water vessels to objects, in particular other water vessels, in proximity to the water vessel to avoid collisions.

In document EP1824730A1 is a system disclosed, which is arranged for stabilizing a water vessel, wherein the alignment is maintained by means of an electronic compass. However, said system does not maintain a minimum distance between the water vessel and objects in proximity to the water vessel.

The alignment system described here makes use of the idea, to control the alignment of the water vessel to be able to align the water vessel with respect to environmental conditions, like swell, wind or current, whilst maintaining a minimal distance between the water vessel and objects in proximity to the water distance.

Advantageously the alignment system reduces discomfort caused by uncontrolled motion of the water vessel and improves the safety of the water vessel, by maintaining a minimum distance between objects and the water vessel.

According to an embodiment, the propulsion element comprises a first thruster and a second thruster. The first thruster may be arranged in proximity to the bow and the second thruster may be arranged in proximity to the stern. For example, the first and the second thruster are arranged to apply alignment forces in opposite directions, whereby the water vessel may rotate around a rotational axis between the first and the second thruster. Thus, the propulsion element having a first thruster and a second thruster enable it to maneuver and align the water vessel in a particularly confined space.

According to an embodiment, the distance sensor is arranged to detect objects above the water surface and/or below the water surface and or to measure the depth of the water under the water vessel. For example, the distance sensor is arranged to determine the distance and a relative position of objects. The distance sensor may be arranged to generate a map of objects in proximity to the water vessel. In particular the distance sensor is arranged to detect moving objects, wherein the distance sensor is arranged to determine the relative velocity of the moving objects. For example, the distance sensor is arranged to predict the movement path of moving objects.

According to an embodiment, the distance sensor is arranged within an encapsulation, wherein the encapsulation is the hull of the water vessel or a housing. In particular, the distance sensor is completely surrounded by the hull of the water vessel. The hull of the water vessel forms outer surfaces of the water vessel, which are in direct contact with the water of the water vessel. In particular, the distance sensor is arranged to send and/or receive signals through the hull. Alternatively, the distance sensor is arranged within a housing, wherein the housing comprises a polymer layer, which is transparent for the input being detected by means of the distance sensor. In particular, the housing may be arranged next to a radar system and/or next to a top light. In particular, the housing may be arranged at a height of at least 3 meters, preferably at least 5 meters above water level, to recuse the impact of salt water on the distance sensor. Advantageously the encapsulation protects the distance sensor from environmental conditions like UV-light, moisture and salt.

According to an embodiment the directional unit comprises a steering element, wherein the steering element is arranged to receive a manually definable cardinal direction as the directional information. In particular the steering element comprises a joystick or a keypad to manually enter a cardinal direction. In particular, the steering element may be a mobile device which is not mechanically connected to the water vessel. The steering element may be a mobile phone, which is arranged to transfer the directional information to the control element. Alternatively, the steering element may comprise multiple joysticks to control multiple thrusters or a rotation knob to control multiple thrusters. In particular, the rotation knob is arranged to control the rotation of multiple thrusters. According to an embodiment, the directional unit comprises a swell detector, wherein the swell detector is arranged to receive a direction of swell as directional information. The swell detector is arranged to receive electromagnetic radiation as the input, and the swell detector is arranged to determine magnitude, speed and/or frequency of swell approaching the water vessel. The swell detector may be a vision system, or a set of vision systems arranged for detection of electromagnetic radiation in the wavelength range of visible light or other frequencies like NIR, IR. The swell detector sensor may collect natural light (sun, moon) reflection from the sea surface passively or may actively emit light using sea surface reflection from emitted light, in particular laser light. For example, the swell detector comprises a laser source for Lidar and/or a NIR light source for Time of Flight measurements and/or thermal detector for thermal vision.

The swell detector is arranged to determine the motion, in particular the amplitude, of the swell and the average direction of the swell from the detected electromagnetic radiation. The swell detector may be arranged to filter the received input and compute the average direction of the swell with respect to the position and angle of the water vessel. The swell detector is arranged to transfer a second input signal to the control unit, which eventually sends a control signal to the propulsion element. The propulsion element moves/rotates the water vessel to optimize the alignment of the water vessel, to reduce the impact of the swell on rotational motion of the boat. The water vessel is attached in a region of the bow by means of the fixture, whereby the control of the alignment of the water vessel is simplified.

According to one embodiment, the directional unit comprises an accelerometer, wherein the accelerometer is arranged to receive an acceleration of the water vessel as the input. For example, the accelerometer is arranged to detect acceleration of the water vessel in three spatial directions. In particular, the accelerometer is arranged to detect surge, sway, heave, rolling, pitch and/or yaw of the water vessel. The accelerometer may filter the frequency of the measured acceleration, such that specifically acceleration induced by swell is detected. The accelerometer may be arranged to average the measured acceleration over a time span of at least one minute, preferably at least five minutes, highly preferred at least 10 minutes. By averaging the measured acceleration, the average swell direction may be determined by means of the accelerometer. In particular, a reactance value of the alignment system is adjustable. The time span may depend on the reactance value. For high reactance values, the alignment system averages the measured acceleration over a shorter time span than for lower reactance values. Advantageously, a low reactance value results in smaller alignment forces. Thereby, less perceivable acceleration due to the alignment forces is caused by the alignment system, which increases the comfort on the water vessel.

According to one embodiment, the fixture is an anchor or a moored buoy. The fixture is coupled to the water vessel by means of a link, whereby the fixture creates a pivot point for movements of the water vessel.

According to one embodiment the water vessel comprises the stern and the bow, wherein the fixture is coupled to a region of the water vessel which is closer to the bow than to the stern and the alignment force acts on the water vessel at a region which is closer to the stern than to the bow. The alignment force acts perpendicular to a longitudinal axis of the water vessel, wherein the longitudinal axis connects the stern and the bow. The stem refers to the back or aft-most part of a water vessel, in particular a ship or boat, technically defined as the area built up over the stempost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow. The bow is the forward part of the hull of the water vessel, the point that is usually most forward when the vessel is underway. Here and in the following the term stern refers to the entire back of the water vessel.

According to one embodiment, the propulsion element is driven electrically. The alignment system may comprise batteries to power the input unit, the control unit and the propulsion unit. In particular, the alignment system may operate without a combustion engine, which advantageously reduces pollution, exposure to noise and odor. In particular, a generator is used to recharge the batteries. The batteries may be recharged during navigation by means of the alternator of the main engine. During the navigation, the water vessel is not attached to the seabed by means of the fixture. The batteries may be charged by means of a solar panel or by means of a power source in a marina.

A method for operating an alignment system is further disclosed. In particular, the method can be used to operate an alignment system described herein. This means that all features disclosed for the alignment system are also disclosed for the method and vice versa.

According to one embodiment, the method for operating an alignment system for a water vessel with a fixture, a propulsion element, a control unit and an input unit, wherein the input unit has a distance sensor and a directional unit comprises the steps of: a. generating a pivot point by attaching the water vessel by means of the fixture; b. transducing a distance information of objects in proximity to the water vessel by means of the distance sensor to a first input signal and transferring the first input signal to the control unit; c. transducing a directional information by means of the directional unit to a second input signal and transferring the second input signal to the control unit; d. generating a control signal by means of the control unit, wherein the control signal depends on the first input signal and the second input signal; e. transmitting the control signal to the propulsion element, wherein the propulsion element generates an alignment force in a transverse direction depending on the control signal; f. moving the water vessel by means or the propulsion element around the pivot point as defined by the control signal.

The pivot point generated in method step a. is a fix point to which the water vessel is coupled. The water vessel is movable with respect to the pivot point, wherein the range of motion depends on the link between the pivot point and the water vessel. In particular, the link may be a chain or a rope. The fixture may be an anchor or a mooring buoy.

In method step b. transducing the distance information of objects in proximity of the water vessel may include measuring the relative distance of the water vessel and the object and measuring the relative position of the water vessel and the object. Here and in the following, objects in proximity of the water vessel may include objects within a distance up to 10 meters, or up to 20 meters, preferably up to 100 meters or up to 300 meters. In method step c. the directional information, which is transduced, may be a relative direction with respect to the water vessel or a cardinal direction. Moreover, the directional information may comprise an average direction of swell approaching the water vessel, a manually defined cardinal direction, a cardinal direction of wind, current or swell provided by a weather forecast or live weather information.

In method step d. the control unit may filter input signals, weight input signals with respect to each other and match input signals to verify their plausibility. Depending on the input signals, the control unit determines a target alignment of the water vessel. Based on the difference between the target alignment and the current alignment the control signal is generated and continuously adjusted. In particular, the target alignment is selected autonomous and adaptive to the sea conditions and environment by means of the alignment system. A user is not required to continuously control the alignment of the water vessel.

In particular, the control signal depends on a definable reactance value. In particular, a user may define the reactance value manually. For high reactance values, the control unit generates the control signal such that the alignment system corrects minor deviations of the actual alignment of the water vessel from the target alignment and/or the control signal controls the propulsion unit to quickly move the water vessel to the target alignment and/or the refresh rate of the target alignment is high. For low reactance values, the control unit generates the control signal such that the alignment system corrects solely major deviations of the actual alignment of the water vessel from the target alignment and/or the control signal controls the propulsion unit to slowly move the water vessel to the target alignment and/or the refresh rate of the target alignment is low. Advantageously, the definable reactance value allows to adjust the behavior of the alignment system adequately to different situations. For example, a higher reactance is required for stronger winds, currents or swells to achieve a minimal rolling of the water vessel. A lower reactance may be required to save energy consumption of the alignment system. In particular, the reactance value may adjust automatically depending on environmental conditions measured by means of the input unit. For example, the reactance value is increased for increasing speed of wind, increasing speed of current or stronger swell.

In method step e. the control signal is transferred to the propulsion element, wherein the propulsion element generates an alignment force based on the control signal. The alignment force acts along the transverse axis, whereby the water vessel sways around the pivot point. Thus, the alignment system utilizes the fixture and the link to adjust the alignment of the water vessel, which is advantageously energy efficient.

According to one embodiment of the method, the water vessel comprises the longitudinal axis extending from the bow to the stern of the water vessel, wherein in method step d. the control unit weights the first input signal and the second input signal, the control unit defines a target alignment based on the first input signal and the second input signal, wherein at the target alignment the water vessel is aligned with respect to the direction of the swell, such that a rolling motion of the water vessel is minimized, and a definable minimal distance between objects and the water vessel is maintained. In particular, the target alignment comprises a target angle of the longitudinal axis with respect to the direction of the swell, in particular an average direction of the swell approaching the water vessel. For example, target alignment comprises a target angle in which the longitudinal axis of the water vessel extends essentially parallel with respect to the average swell direction, where in the average swell direction is the average direction in which the swell approaching the water vessel propagates. In particular the average swell direction may be based on an average of multiple swells having at least a first and a second swell direction, wherein the first swell direction and the second swell direction are weighted depending on the amplitude of the respective swell.

According to one embodiment, the distance sensor measures a depth of the water under the water vessel. The distance sensor is arranged to set the definable minimal distance to a value, wherein the value is the sum of at least three times the measured depth of the water and a length of the water vessel measured from the stem to the bow of the water vessel. In particular, the definable minimal distance may be the sum of at least four times the measured depth of the water and the length of the water vessel. The depth of the water under the water vessel may be determined by echoing, by measuring the length of the link during method step a., or by requesting depth information from a gps map.

According to one embodiment in method step c. the directional information is a manually entered cardinal direction, wherein the cardinal direction corresponds to the direction of the swell approaching the water vessel. In particular, the cardinal direction is entered by means of a steering element. In particular, the alignment system requests a manual input of an estimated average swell direction. The alignment system determines a target alignment based on the cardinal direction and the second input signal, which is provided by the distance sensor. In particular, the alignment system may comprise an accelerometer, which is arranged to measure and analyze the acceleration of the water vessel. Based on the measured acceleration, the target alignment may be adapted.

According to one embodiment the directional unit comprises a swell detector, wherein the swell detector receives a direction of swell as directional information, the swell detector receives the direction of swell by means of electromagnetic radiation as an input, and the swell detector determines direction, magnitude, speed and/or frequency of swell approaching the water vessel. In particular, the swell detector is arranged to detect a moving object, in particular a boat or a ship, passing by the water vessel. The swell detector is arranged to analyze the size, trajectory and speed in order to determine the direction of swell caused by the moving object. The swell detector may be arranged to compute a series of waves created by the moving object including their strength, direction, and timing to reach the water vessel in reference to the position and orientation of the moving object. The control unit may fuse input signals from vision sensors with other sensing information like radar in order to improve the performance In particular, the alignment system is arranged to optimize the alignment of the water vessel with respect to the direction of the swell caused by the moving object.

According to one embodiment the directional unit comprises an accelerometer, wherein the accelerometer detects motion of the water vessel induced by swell and the accelerometer transduces the detected motion in a directional information. In particular, the accelerometer detects translative movement of the water vessel, to determine changes in alignment of the water vessel. The control unit determines the effect of the propulsion element on the motion of the water vessel, based on the input signal provided by the accelerometer, wherein the propulsion element is controlled dynamically based on the input signal provided by the accelerometer. Moreover, the accelerometer is arranged to statistically analyze movement of the water vessel over a definable time span. In particular, the input unit may comprise at least two of an accelerometer, a swell detector and a steering element, wherein the control unit is arranged to calibrate the directional unit based on the multiple inputs. In particular, the directional unit comprises at least one of a motion sensor, a gyroscope, a wind detector, wherein the output is matched with further input signals provided by the directional unit in order to confirm or falsify the input signals.

According to one embodiment, the definable minimal distance depends on the intensity of the swell detected by means of the directional unit. In particular, the minimal distance depends on the current, the amplitude of the swell and/or the speed of wind. For example, the definable minimal distance increases with increasing amplitude of the swell, increasing current and/or increasing speed of wind.

According to one embodiment the swell detector detects simultaneous swells approaching the water vessel from different directions, and the control unit separately weights the simultaneous swells when generating the control signal, depending on the intensity and duration of the swells respectively. Here and in the following the intensity of a swell depends on the amplitude of said swell and the duration of a swell depends on the speed at which the swell is propagating and the number of waves of said swell. In particular the swell detector is arranged to detect swell having a first swell direction and swell having a second swell direction, wherein the the first swell direction and the second swell direction extend obliquely with respect to each other. In particular, the swell detector determines the intensity and the duration of the swells extending in different directions. The control unit may be arranged to weight the directional information of the first swell direction and the second swell direction based on their respective intensity and duration.

According to one embodiment, the distance sensor determines the depth of the water under the water vessel, the fixture is coupled to the water vessel by means of a link having a length, and the control unit receives a value of the length as a third input signal and a value of the depth of the water as a fourth input signal, wherein the control unit determines a range of motion of the water vessel with respect to the fixture, based on the third input value and the fourth input value. The range of motion may be a virtually defined area on the water surface, which corresponds to an area of possible positions of the water vessel. The range of motion may be limited by a maximum distance to the pivot point, which is defined by the link. In particular, the range of motion is essentially a circular area, wherein the fixture is essentially in the center of said circular area as seen in a top view onto the water surface.

The distance sensor determines the position of objects in the range of motion and in an edge region surrounding the range of motion, wherein a width of the edge region corresponds to the minimal definable distance, wherein the width is measured in a radial direction away from the range of motion. For example, the distance sensor continuously generates a map of objects and optional determines their trajectory. The control unit may be arranged to superimpose the measured position of objects with the range of motion.

The control unit determines a target alignment of the water vessel within the range of motion based on the first input signal, the second input signal, the third input signal and the fourth input signal. The target alignment may be selected from possible target positions along the perimeter of the range of motion, wherein the perimeter is adjacent to the edge region. The target alignment may be selected such that the link provides a mechanical stop. In other words, the target alignment is selected such that the chain or rope, by means of which the water vessel is connected to the fixture, is in a tensed state. Advantageously, the use of the fixture as a mechanical stop reduces required energy to maintain the target alignment and simplifies maintaining the target alignment.

The control unit generates the control signal, such that the water vessel is moved to the target alignment by means of the propulsion element. In particular, the target alignment is selected such that the target position is a failsafe position. Here and in the following, a failsafe position is a position, in which the environmental conditions, in particular external forces, cause an increase of the distance between the water vessel and an object detected by means of the distance sensor. For example, the external forces, in particular the current, the wind and the swell cause the water vessel to move away from the object and the alignment force causes the water vessel to move towards said object. Advantageously, in a failsafe position the distance between the water vessel and the said object does not fall below the definable minimal distance, i. By contrast, the environmental conditions increase the distance between the water vessel and the object, if the propulsion unit ceases to generate the alignment force in an unforeseen manner, for which reason the failsafe position is particularly safe.

According to one embodiment, the alignment system maintains a minimum angle between the longitudinal axis and the direction of the wind and/or the direction of the current acting on the water vessel. For water vessels without the alignment system, the water vessel continuously changes its position and alignment, due to the interaction of wind forces, current forces and forces provided by the fixation. For example, the wind forces and/or current forces push the water vessel away from the fixture, as long as the wind and/or current direction comes from the same side as the fixation is arranged with respect to the water vessel. When the fixation is arranged on a different side of the longitudinal axis than the direction of the wind and/or current, the wind and/or current push the water vessel towards the fixture. Typically, the mechanical stop of the fixture causes a rotation of the water vessel, which reduces the angle between the longitudinal axis and the direction of wind and or current. Consequently, the water vessel moves in a pendular movement, wherein the wind and/or current pushes the water vessel back and forth between the mechanical stops provided by the fixture.

The alignment system may be arranged to align the longitudinal axis such that the external forces push the water vessel away from the fixture, whereby the link continuously acts as a mechanical stop. In particular, the alignment force counteracts the rotational movement pulling the longitudinal axis towards a direction parallel to the current and or wind. In particular, the propulsion element solely provides a rotation of the water vessel with respect to the direction of the wind and/or current, whereby the wind and/or the current push the water vessel away from the fixture, whereby the fixture continuously acts as the mechanical stop for the alignment of the water vessel. Advantageously, such control of the alignment of the water vessel, enables a particularly reliable and energy efficient alignment of the water vessel.

Further advantages and advantageous embodiments and further embodiments of the alignment system and the method for operating the alignment system result from the following embodiment examples shown in connection with the figures.

Showing In figure 1 an exemplary embodiment of a water vessel without alignment system in a schematic top view;

In figure 2 an exemplary embodiment of a water vessel comprising an alignment system which generates an alignment force in a schematic top view;

In figure 3 an exemplary embodiment of a water vessel comprising an alignment system which aligns the water vessel with respect to a first swell direction in a schematic top view;

In figure 4 an exemplary embodiment of a water vessel comprising an alignment system which aligns the water vessel with respect to a second swell direction in a schematic top view;

In figure 5 an exemplary embodiment of a water vessel comprising an alignment system detecting an object in proximity to the water vessel in a schematic top view;

In figure 6 a schematic representation of a method for operating an alignment system;

In figure 7 an exemplary embodiment of an alignment system for a water vessel in a schematic top view, wherein the alignment system approximates a range of motion;

Figure 8 shows an exemplary embodiment of an alignment system for a water vessel, wherein the water vessel is shown in a schematic side view;

Figure 9 shows an exemplary embodiment of a water vessel comprising an alignment system in a schematic top view, wherein the water vessel is exposed to a first swell direction and a second swell direction and wherein an object is in proximity to the water vessel;

Figure 10 shows possible alignments of an exemplary embodiment of a water vessel comprising an alignment system in a schematic top view, wherein the alignment system utilizes external forces for alignment of the water vessel.

Elements that are the same, similar or have the same effect are given the same reference signs in the figures. The figures and the proportions of the elements shown in the figures with respect to one another are not to be regarded as to scale. Rather, individual elements may be shown exaggeratedly large for better representability and/or for better comprehensibility.

Figure 1 shows a water vessel 100 in a schematic top view. The water vessel 100 comprises a fixture 2 which is coupled to the water vessel 100 by means of a link 20. The fixture 2 is an anchor which provides a pivot point around which the water vessel 100 may move. The water vessel 100 has a longitudinal axis 104. Without an alignment system the alignment of the water vessel 100 depends on the environmental conditions like current, wind and swell. In general, the swell 600 has a first swell direction 601 to which the longitudinal axis 104 is not necessarily aligned. Thus, the swell causes random rotational movement (rolling) of the water vessel around its longitudinal axis 104. Which may cause discomfort of passengers and which may be dangerous. Figure 2 shows a water vessel 100 comprising an exemplary embodiment of the alignment system 1 in a schematic top view. The fixture 2 and the link 20 connects the water vessel 100 to a pivot point around which the water vessel 100 is rotatable. In the present embodiment, the fixture 2 is an anchor. Alternatively, the fixture 2 may be a moored buoy. The alignment system 1 for the water vessel 100 comprises an input unit 5, a control unit 4 and a propulsion element 3. The propulsion element 3 is arranged to provide an alignment force 300 in two opposed transverse directions of the water vessel 100, wherein the transverse directions are perpendicular with respect to the longitudinal axis 104. The alignment force 300 results in a rotational movement of the water vessel 100 around the fixture 2.

The input unit 5 is arranged to transduce inputs to input signals 500 and transmit the input signals 500 to the control unit 4. The control unit 4 is arranged to provide a control signal 400 for controlling the propulsion element 3, wherein the control signal 400 depends on the input signals 500. The input unit 5 comprises at least one distance sensor 50, wherein the distance sensor 50 is arranged to receive a distance of objects 55 in proximity to the water vessel 100 as the input. In this embodiment shown in figure 2, there is no object in proximity of the water vessel.

The input unit 5 comprises a directional unit 51, wherein the directional unit 51 is arranged to receive a directional information as the input. The directional unit 51 comprises a swell detector 511, which is arranged to receive the first swell direction 601 of the swell 600 as directional information. The swell detector 511 is arranged to receive electromagnetic radiation as the input, and the swell detector 511 is arranged to determine magnitude, speed and/or frequency of the swell 600 approaching the water vessel 100.

As an alternative to the swell detector 511 or additionally to the swell detector 511, the input unit 5 comprises an accelerometer 512, wherein the accelerometer 512 is arranged to receive an acceleration of the water vessel 100 as the input. The accelerometer 512 is arranged to measure acceleration forces in three spatial directions. In particular, the accelerometer 512 is arranged to derive the first swell direction 601 from the measured acceleration forces.

In particular, the unit 51 comprises a steering element 510, wherein the steering element 510 is arranged to receive a manually definable cardinal direction as the directional information For example, the steering element 510 is arranged to directly control the propulsion element 3. A user may estimate a reasonable alignment and bring the water vessel 100 in said alignment by means of the steering element 510. The alignment may be arranged to define the reasonable alignment as an initial target alignment 401. The alignment system 1 may be arranged to maintain said reasonable alignment. Alternatively, the alignment system may be arranged to continuously adjust the target alignment 401 based on the input signals provided by the input unit 5.

The control unit 4 is arranged to determine the target alignment 401, wherein at the target angle an angle between the longitudinal axis 104 and the first swell direction 601 is minimized in order to reduce rolling of the water vessel 100, while a minimal distance to objects 55 is maintained. In particular, the control unit 4 is arranged to generate a control signal 400, which controls the propulsion unit 3 to move the water vessel 100 in the target alignment 401 and maintain the water vessel 100 in the target alignment 401. In particular, the control unit 4 continuously controls and adjusts the current alignment of the water vessel 100 with respect to the target alignment 401.

Figure 3 shows an exemplary embodiment of the alignment system 1 for a water vessel 100 in a schematic top view. In the embodiment of figure 3, the alignment system 1 aligned the water vessel 100 with respect to the swell 600 having the first swell direction 601. Thus, an angle between the first swell direction 601 and the longitudinal axis 104 is minimized to reduce rolling motion of the water vessel 100.

A moving object, in particular a boat, passes by the water vessel 100, which causes the swell 600 having a second swell direction 602. The input unit 5 comprises the swell detector 511, which is arranged to detect swell 600 approaching the water vessel 100 from different directions simultaneously. The input unit 5 is arranged to identify the first swell direction 601 and the second swell direction 602. In particular, the input unit 5 is arranged to measure the intensity and duration of the swell in the second 602 and in the first swell direction 601. The control unit 4 separately weights the swell having the first swell direction 601 and the second swell direction 602 when generating the control signal 400. The weight of each directional information depends on the intensity and duration of the swell in each swell direction 601, 602 respectively.

Figure 4 shows the exemplary embodiment of the alignment system 1 for a water vessel 100 in a schematic top view. In the embodiment of figure 4, the alignment system 1 aligns the water vessel 100 with respect to the swell 600 having the first swell direction 601 and second swell direction 602. The control unit 4 determines a target alignment, which is based on the weighted consideration of the first swell direction 601 and the second swell direction 602. In this case the weight of the second swell direction 602 is higher than the weight of the first swell direction 601. The control unit 4 determines the target alignment of the water vessel 100 to be selected such that an angle between the longitudinal axis 104 and the second swell direction 602 is minimized. The control unit 4 transfers a control signal 300 to the propulsion unit 3, which generates the alignment force 300. The alignment force 300 moves the water vessel in the target alignment 401.

The alignment system 1 is arranged to continuously adjust the target alignment 401 based on the environmental conditions considered by the input signals 500. Thus, the target alignment 401 will return to the state shown in figure 3, after the swell 600 having the second swell direction 602, has passed by the water vessel 100.

Figure 9 shows an exemplary embodiment of a water vessel 100 comprising an alignment system 1 in a schematic top view, wherein the water vessel 100 is exposed to a first swell direction 601 and a second swell direction 602 and wherein an object 55 is in proximity to the water vessel 100. The input unit 5 is arranged to detect the object 55 by means of the distance sensor 50. In this case, the object 55 is on the starboard side 105 of the water vessel 100. The alignment system is arranged to maintain the minimal distance 91 between the object 55 and the water vessel 100. The swell detector 511 detects the first swell direction 601, which results from natural swell 600 and a second swell direction 602, which results from a moving object 55, in particular a boat. Even though the input unit 5 detects the second swell, the control unit may be arranged to weigh the input signals, such that the minimal distance 19 is maintained or even increased, to preempt the expected movement of the water vessel 100 in the second swell direction 602. In particular, the control unit 4 is arranged to weigh the input signals such that the minimal distance 91 is always maintained.

Figure 5 shows an exemplary embodiment of a water vessel 100 comprising an alignment system 1 detecting an object 55 in proximity to the water vessel 100 in a schematic top view. The input unit 5 measures the distance between the water vessel 100 and the object 55 and transduces the measured distance to the first input signal 501. Furthermore, the input unit transduces the first swell direction 601 to a second input signal 502. The control unit 4 defines a target alignment based on the first input signal and the second input signal. The target alignment 401 is selected such that the definable minimal distance 91 is not deceeded. In particular, the control unit controls the propulsion element 3 to generate an alignment force 300, which moves the water vessel 100 in a longitudinal direction away from the object 55, to maintain the definable minimal distance 91.

Figure 6 shows a schematic representation of a method for operating an alignment system 1. When operating the alignment system 1 for the water vessel 100 the following steps a. to f. are executed:

Method step a. comprises generating a pivot point by attaching the water vessel 100 by means of the fixture 2. In the present embodiment of figure 5, the water vessel is attached by means of an anchor 2 having a link 20 connecting the vessel to the pivot point.

Method step b. comprises transducing a distance information of objects 55 in proximity to the water vessel 100 by means of the distance sensor 50 to a first input signal 501 and transferring the first input signal 501 to the control unit 4. The input unit 5 is arranged to measure a distance between the water vessel 100 and the object 55. In particular, the input unit 5 is arranged to measure a distance to multiple objects 55 simultaneously.

Method step c. comprises transducing a directional information by means of the directional unit 51 to a second input signal 502 and transferring the second input signal 502 to the control unit 4. In the present embodiment, the directional information corresponds to the first swell direction 601 of the swell 600. The first swell direction 601 may be detected by means of an accelerometer 512 or a swell detector 511.

Method step d. comprises generating a control signal 400 by means of the control unit 4, wherein the control signal 400 depends on the first input signal 501 and the second input signal 502. In particular, the control unit 4 weights the first input signal 501 and the second input signal 502. The control unit 4 may be arranged to give the first input signal 501 a particularly high weight, if the definable minimal distance is deceeded.

Method step e. comprises transmitting the control signal 400 to the propulsion element 3, wherein the propulsion element 3 generates an alignment force 300 in a transverse direction depending on the control signal 400. When controlling the propulsion force 300 current, wind and/or swell detected by means of the input unit 5 may be considered. For example, moving the water vessel to the target alignment utilizing environmental conditions, in particular the external force 406, may advantageously reduce the energy consumption of the alignment system 1. Method step f. comprises moving the water vessel 100 by means or the propulsion element 3 around the pivot point as defined by the control signal 400. In particular, the control signal 400 may halt the propulsion unit for utilizing the environmental forces acting on the water vessel, to move the water vessel 100 towards the target alignment.

Figure 7 shows an exemplary embodiment of an alignment system 1 for a water vessel 100 which approximates a range of motion. The distance sensor 50 determines the depth of the water 90 below the water vessel 100. The fixture 2 is coupled to the water vessel 100 by means of the link 20 having a length and the control unit 4 receives a value of the length as a third input 503 and a value of the depth of the water as a fourth input 504. The control unit 4 determines a range of motion 403 of the water vessel 100 with respect to the fixture 2 based on the third and the fourth input 503, 504. The distance sensor 50 determines the position of objects 55 in the range of motion 403 and in an edge region 404 surrounding the range of motion 403, wherein a width of the edge region 404 corresponds to the minimal distance 91.

The control unit 4 determines a target alignment 401 of the water vessel 100 within the range of motion 403 based on the first input 501, the second input 502, the third input 503 and the fourth input 504. The control unit 4 generates the control signal 400, such that the water vessel 100 is moved to the target alignment 401 by means of the propulsion unit 3. In particular, the definable minimal distance 91 to different objects 55 may differ. For example, the environmental conditions like current, swell, and wind may be considered when defining the minimal distance 91 of the water vessel 100 to an object 55. The distance sensor 50 may be arranged to detect objects 55 above and below the water surface. In particular a user may manually define a minimal distance 91 for each object 55 detected.

The distance sensor 50 measures the depth 90 of the water under the water vessel 100, and the distance sensor 50 is arranged to set the definable minimal distance 401 to a value, wherein the value is at least the sum of three times the measured depth 90 of the water and a length of the water vessel 100 measured from stern 102 to bow 103 of the water vessel 100. The length may be saved in a memory unit of the alignment system 1.

Figure 8 shows an exemplary embodiment of an alignment system 1 for a water vessel 100, wherein the water vessel 100 is shown in a schematic side view. The water vessel 100 comprises a stem 102 and a bow 103, wherein the fixture 2 is coupled to a region of the water vessel 100 which is closer to the bow 103 than to the stem 103. The alignment force 300 acts on the water vessel 100 at a region which is closer to the stem 102 than to the bow 103, and the alignment force 300 acts perpendicular to the longitudinal axis 104 of the water vessel 100, wherein the longitudinal axis 104 connects the stern 102 and the bow 103. During operation of the alignment system, the water vessel 100 is attached to a pivot point by means of the fixture. Advantageously, the pivot point simplifies controlling the alignment of the water vessel 100. Moreover, the pivot point enables an energy efficient alignment of the water vessel, because major forces having impact on the water vessel 100 act on the link 20 and the fixture 2. This is particularly advantageous, if the propulsion element 3 is driven electrically and the power is provided by a battery.

By the description of the invention based on the embodiments the invention is not limited to these. Rather, the invention encompasses any new feature as well as any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or embodiments.

Figure 10 shows possible alignments of an exemplary embodiment of a water vessel 100 comprising an alignment system 1 in a schematic top view, wherein the alignment system 1 utilizes external forces 406 for alignment of the water vessel 100. The external force 406 corresponds to the sum of all environmental forces acting on the water vessel 100. The external forces may comprise forces caused by wind, current and swell. In particular, forces provided by the fixture 2 and the propulsion unit 3 are not part of the external force 406. The alignment system 1 is arranged to align the water vessel 100 at a target angle, wherein at the target angle the external force 406 and a retention force 201 act in opposite directions, wherein the retention force 201 is provided by the fixture 2. In particular, the fixture 2 is arranged on the side on which the external force 406 acts. In other words, the alignment system 1 maintains the water vessel in alignment, in which the external force 406 pushes the water vessel 100 away from the fixture 2, whereby the link 20 acts as a mechanical stop for the alignment of the water vessel 100.

The embodiment shown in figure 10 shows two possible target alignments of the water vessel 100. In a first alignment, the external force 406 acts on the starboard side 105 and the fixture is arranged on the starboard side 105 of the water vessel 100. The alignment force 300 pulls the stern towards the starboard side 105, to maintain a minimal angle 405 between the longitudinal axis 104 and the direction of the external force 406. Said minimal angle may be at least 5°, preferably at least 10°. In a second alignment, the external force 406 acts on the port side 106 and the fixture 2 is arranged in the port side 106 of the water vessel 100. The alignment force 300 pulls the stern towards the port side 106, to maintain the minimal angle 405 between the longitudinal axis 104 and the direction of the external force 406.

In particular, the input unit 5 may be arranged to detect the external force 406. In particular, the alignment system 1 may be arranged to select the target alignment of the water vessel such that at least one of the following conditions, preferably all of the following conditions, are fulfilled:

A minimal distance 91 of the water vessel 100 to objects 55 is maintained,

The external force 406 and the retention force 201 act essentially in opposite directions,

The external force 406 acts obliquely with respect to the longitudinal axis 104,

An angle between the average direction of the swell 600 and the longitudinal axis 104 is minimized.

In particular, the swell 600 may contribute to the external force 406.

This patent application claims the priority of the Hungarian patent application P2000006, the disclosure of which is hereby incorporated by reference. Reference signs

1 Alignment system

2 fixture

3 Propulsion element

4 Control unit

5 Input unit

20 Link

50 Distance sensor

51 Directional unit 55 object

90 depth

91 Minimal distance 100 Water vessel 101 encapsulation 102 stem

103 bow

104 Longitudinal axis

105 Starboard side

106 Portside 201 Retention force 300 Alignment force

400 Control signal

401 Target alignment

403 Range of motion

404 Edge region

405 tilt angle extemal force

Input signals Steering element Swell detector accelerometer First input signal Second input signal Third input signal Fourth input signal swell

Fist swell direction

Second swell direction

Claims

1. Alignment system (1) for a water vessel (100) comprising a fixture (2), an input unit (5), a control unit (4) and a propulsion element (3) wherein the fixture (2) is arranged to provide a pivot point to which the water vessel (100) is rotatably connected, the propulsion element (3) is arranged to provide an alignment force (300) in two opposed transverse directions of the water vessel (100), the input unit (5) is arranged to transduce inputs to input signals (500) and transmit the input signals (500) to the control unit (4), the control unit (4) is arranged to provide a control signal (400) for controlling the propulsion element (3), wherein the control signal (400) depends on the input signals (500), the input unit (5) comprises at least one distance sensor (50), wherein the distance sensor (50) is arranged to receive a distance of objects in proximity to the water vessel (100) as the input, and the input unit (5) comprises a directional unit (51), wherein the directional unit (51) is arranged to receive a directional information as the input.

2. Alignment system (1) according to claim 1, wherein the distance sensor (50) is arranged to detect objects (55) above the water surface and/or below the water surface and/or to measure the depth (90) of the water under the water vessel (100).

3. Alignment system (1) according to one of the preceding claims, wherein the distance sensor (50) is arranged within an encapsulation (101), wherein the encapsulation is the hull of the water vessel (100) or a housing.

4. Alignment system (1) according to one of the preceding claims, wherein the directional unit (51) comprises a steering element (510), wherein the steering element (510) is arranged to receive a manually definable cardinal direction as the directional information.

5. Alignment system (1) according to one of the preceding claims, wherein the directional unit (51) comprises a swell detector (511), wherein

- the swell detector (511) is arranged to receive a direction of swell as directional information,

- the swell detector (511 ) is arranged to receive electromagnetic radiation as the input, and

- the swell detector (511) is arranged to determine magnitude, speed and/or frequency of swell approaching the water vessel (100).

6. Alignment system (1) according to one of the preceding claims, wherein the directional unit (51) comprises an accelerometer (512), wherein the accelerometer (512) is arranged to receive an acceleration of the water vessel (100) as the input.

7. Alignment system (1) according to one of the preceding claims, wherein the fixture (2) is an anchor or a moored buoy. 8. Alignment system (1) according to one of the preceding claims, wherein the water vessel (100) comprises a stem (102) and a bow (103), wherein the fixture (2) is coupled to a region of the water vessel (100) which is closer to the bow (103) than to the stem (103), the alignment force (300) acts on the water vessel (100) at a region which is closer to the stern (102) than to the bow (103), and the alignment force (300) acts perpendicular to a longitudinal axis (104) of the water vessel (100), wherein the longitudinal axis (104) connects the stern (102) and the bow (103).

9. Alignment system (1) according to one of the preceding claims, wherein the propulsion element (3) is driven electrically.

10. Method for operating an alignment system (1) for a water vessel (100) with a fixture (2), a propulsion element (3), a control unit (4) and an input unit (5), wherein the input unit (5) has a distance sensor (50) and a directional unit (51) comprising the steps of: a. generating a pivot point by attaching the water vessel (100) by means of the fixture (2); b. transducing a distance information of objects (55) in proximity to the water vessel (100) by means of the distance sensor (50) to a first input signal and transferring the first input signal (501) to the control unit (4); c. transducing a directional information by means of the directional unit (51) to a second input signal (502) and transferring the second input signal to the control unit (4); d. generating a control signal (400) by means of the control unit (4), wherein the control signal (400) depends on the first input signal (501) and the second input signal (502); e. transmitting the control signal (400) to the propulsion element (3), wherein the propulsion element (3) generates an alignment force (300) in a transverse direction depending on the control signal (400); f. moving the water vessel (100) by means or the propulsion element (3) around the pivot point as defined by the control signal (400).

11. Method according to the preceding claims, wherein the water vessel (100) comprises a longitudinal axis (104) extending from a bow (103) to a stern (102) of the water vessel (100), and in method step d. the control unit (4) weights the first input signal (501) and the second input signal (502); the control unit (4) defines a target alignment (401) based on the first input signal (501) and the second input signal (502), wherein at the target alignment (401) the water vessel (100) is aligned with respect to the direction of the swell (601, 602), such that a rolling motion of the water vessel (100) is minimized, and a definable minimal distance (91) between objects (55) and the water vessel (100) is maintained.

12. Method according to the preceding claim, wherein the distance sensor (50) measures the depth (90) of the water under the water vessel (100), the distance sensor (50) is arranged to set the definable minimal distance (401) to a value, wherein the value is at least the sum of the depth (90) and a length of the water vessel (100) measured from stem (102) to bow (103) of the water vessel (100).

13. Method according to one of the preceding claims, wherein in method step c. the directional information is a manually entered cardinal direction, wherein the cardinal direction corresponds to the direction of the swell approaching the water vessel (100), and/or the directional unit (51) comprises a swell detector (511), wherein the swell detector (511) receives a direction of swell as directional information, the swell detector (511) receives the direction of swell by means of electromagnetic radiation as an input, and the swell detector (511) determines direction, magnitude, speed and/or frequency of swell approaching the water vessel (100), and/or the directional unit (51) comprises an accelerometer (512), wherein the accelerometer (512) detects motion of the water vessel (100) induced by swell and the accelerometer (512) transduces the detected motion in a directional information.

14. Method according to the preceding claim, wherein the definable minimal distance (91) depends on the intensity of the swell detected by means of the directional unit (51).

15. Method according to claim 13 or 14, wherein the swell detector (511) detects swell (600) approaching the water vessel (100) from different directions simultaneously, and the control unit (4) separately weights the swell (600) when generating the control signal (400), depending on the intensity and duration of the swell (600) in each direction respectively.

16. Method according to one of the preceding claims, wherein the distance sensor (50) determines the depth of the water (90) below the water vessel

(100), the fixture (2) is coupled to the water vessel (100) by means of a link (20) having a length, the control unit (4) receives a value of the length as a third input (503) and a value of the depth (90) of the water as a fourth input (504), the control unit (4) determines a range of motion (403) of the water vessel (100) with respect to the fixture (2) based on the third and the fourth input (503, 504), the distance sensor (50) determines the position of objects (55) in the range of motion (403) and in an edge region (404) surrounding the range of motion (403), wherein a width of the edge region (404) corresponds to the minimal distance (91), the control unit (4) determines a target alignment (401) of the water vessel (100) within the range of motion (403) based on the first input (501), the second input (502), the third input (503) and the fourth input (504), and the control unit (4) generates the control signal (400), such that the water vessel (100) is moved to the target alignment (401) by means of the propulsion unit (3).

17. Method according to one of the preceding claims, wherein the alignment system (1) maintains a minimum angle between the longitudinal axis (104) and the direction of the wind and/or the direction of the current acting on the water vessel (100).