Propulsion system for a ship

Abstract

The invention relates to a propulsion system for a ship, comprising at least one suction sail (3) comprising a suction system (10) and a drive unit (8) for driving the at least one suction sail (3) in rotation wherein the at least one suction sail (3) further comprises a plurality of sensors (12, 13, 14, 15) connected to a control unit (9), the control unit determines the operation of the suction system (10) and the drive unit (8). A propulsion system for a vessel is provided that allows the use of a suction sail to optimize the performance of the vessel.

Description

Technical Field

[0001] The present invention relates to a propulsion system for a ship, and more particularly to a propulsion system for a ship including one or more suction sails. Background Art

[0002] The use of propulsion systems for ships known as Wind Assisted Propulsion Systems (WAPS) is known, and their performance is related to the aerodynamic forces (lift) they can generate.

[0003] These forces are directly related to the aerodynamic characteristics of the system (such as its aerodynamic coefficients), the surface of the system, and the wind speed present.

[0004] The lift coefficient depends on two main variables: the geometry of the aerodynamic profile (asymmetric versus symmetric) and the angle of attack (defined as the angle between the chord of the profile and the direction of the air flow).

[0005] The first variable is the shape of the aerodynamic profile. A symmetric profile has an axis of symmetry collinear with the chord of the profile itself. When the angle of attack is zero, this type of profile has a zero lift coefficient because it does not create any asymmetry in the air flow around it, and thus there is no pressure difference.

[0006] Increasing the asymmetry in the aerodynamic profile creates a pressure difference in the air flow around the profile, resulting in a higher lift coefficient. However, these asymmetries can hardly be applied to WAPS because they must be able to operate for any wind direction.

[0007] The main limitation in implementing an asymmetric profile to increase the lift coefficient lies in the high complexity of the mechanical system of WAPS, which leads to high costs and greater weight.

[0008] The second variable is the angle of attack, which behaves as follows: for an angle of attack equal to zero, the air flow passes around the aerodynamic profile with little turbulence, and thus the lift is almost zero.

[0009] As the angle of attack increases, the lift coefficient increases linearly. At the same time, turbulence appears starting from the trailing edge.

[0010] There is a maximum lift angle of attack, and the turbulence and its effects are related to this maximum lift angle of attack.

[0011] Finally, above the maximum supported angle of attack, an effect called stall occurs. This phenomenon is the sudden separation of the air flow attached to the profile, which leads to a sudden decrease in lift.

[0012] In this case, the limitation of the maximum lift coefficient is related to losses and the sudden separation of the flow boundary layer.

[0013] In a wind-assisted propulsion system (WAPS), the use of a rigid suction sail is known. The purpose of the rigid suction sail is to maximize the lift coefficient by controlling the effects caused by the above two variables.

[0014] Starting from the angle of attack, a higher lift coefficient can be obtained if the separation of the boundary layer around the profile can be delayed with respect to the angle of attack. This can be achieved by sucking the air flow from the top of the profile, ensuring that the air flow remains attached to the sail surface for high angles of attack. The process is described in detail below:

[0015] (In the absence of suction) When the initial angle of attack for maximum lift is reached, a portion of the airflow over the camber is sucked in.

[0016] Suction adheres the boundary layer to the profile and delays stall, even though suction increases the angle of attack, which means an increase in the lift coefficient.

[0017] Due to the suction of the flow, the separation point remains approximately constant as the angle of attack (and thus the angle of incidence) increases. Therefore, after this flow release point, the structure and shape of the profile are not necessary and can be eliminated, thereby reducing the size of the profile.

[0018] Finally, since separation is controlled by suction, the shape of the profile can be modified by introducing significant asymmetry. The best solution to achieve this effect is through a "movable trailing edge" called a flap. This flap can be positioned in two different locations (one on each side of the chord of the aerodynamic profile), thereby creating asymmetry towards one side or the other to accommodate any wind direction.

[0019] The rigid suction sail has significant improvements over the rigid passive sail: the rigid suction sail increases the lift coefficient of the sail, which improves the efficiency of the rigid sail in terms of thrust per unit area of the sail. These improvements have many advantages:

[0020] The higher the lift coefficient, the smaller the size of the rigid sail required to provide the same thrust and thus the same fuel economy.

[0021] The reduced size means less cost of structural materials and shorter production time per unit, which translates into lower production costs.

[0022] The reduction in size and the materials used also reduces the weight per unit, which has a positive effect on the stability and storage capacity of the ship. It can be reduced by up to 50% in weight.

[0023] For the same available deck space, a smaller system allows for the installation of more units, thereby increasing the maximum potential reduction in fuel consumption for a single ship.

[0024] Smaller systems also mean less impact on visibility requirements.

[0025] On the other hand, the rigid suction sail also presents certain limitations, most of which are related to the suction system itself. The main limitations are:

[0026] Suction requires an active pump or fan that continuously inhales air. This results in a constant power consumption to keep the system in operation. It is important to note that this power consumption is a very small fraction of the thrust provided by the sail.

[0027] The area of the rigid sail surface that should perform boundary layer suction has a specific critical position, and it is very important to ensure that the rest of the rigid sail surface is sealed.

[0028] The performance of the rigid suction sail for upwind is low because in this operating scenario, the aerodynamic drag is highly correlated with the thrust.

[0029] Therefore, the rigid suction sail is suitable for ships with the following characteristics:

[0030] Ships with limited deck space.

[0031] Ships with reduced stability.

[0032] Ships with limited visibility.

[0033] Ships without support limitations because the ship does not require a folding system.

[0034] Fishing vessels fully meet these characteristics.

[0035] Therefore, an object of the present invention is to provide a propulsion system for a ship, which allows the ship to use a suction sail to optimize its performance. Summary of the Invention

[0036] With the propulsion system of the present invention, the above-mentioned disadvantages are solved, and other advantages to be described below are presented.

[0037] The propulsion system for a ship according to the present invention includes at least one suction sail, which includes the suction sail, a suction system, and a drive unit for driving the at least one suction sail to rotate. Wherein, the at least one suction sail further includes a plurality of sensors connected to a control unit, and the control unit determines the operation of the suction system and the drive unit.

[0038] This operation can be autonomous or semi-autonomous, that is, having very little interaction with the crew.

[0039] Advantageously, such a plurality of sensors includes at least one wind sensor, at least one sensor for the rotation of the suction sail, at least one sensor for the position of the flap of the suction sail, and / or at least one suction sensor.

[0040] Furthermore, the control unit preferably includes a user interface for the user to interact with the control unit.

[0041] If necessary, the propulsion system may also include a manual control unit, which is connected to the suction system and the drive unit for the manual control of the propulsion system.

[0042] Advantageously, the suction sail includes a rigid or flexible outer coating and a suction area provided with a plurality of holes.

[0043] Preferably, the drive unit is located at the lower end of the suction sail, and the drive unit is an electric or hydraulic drive unit driven by a power unit.

[0044] The suction sail further includes a support structure at its lower end to support the weight of the suction sail and limit the lateral movement of the suction sail.

[0045] According to a possible embodiment, the lower part of the suction sail includes an inclined support member, which allows the suction sail to be inclined relative to the vertical direction, that is, the suction sail is inclined relative to a substantially horizontal axis.

[0046] With the propulsion system for a ship according to the present invention, the operation of the suction sail can be automatically optimized based on the data collected by the sensors.

[0047] When the suction system is a single fan or multiple fans, the suction can be adjusted along the suction area to adapt to each area.

[0048] [[ID=2,7]]Multiple suction areas can also be formed, which generate a pressure gradient (and thus suction) to control the absorbed flow.

[0049] It allows the movement / positioning of the flap (by means of a motor and gears, through a cable) to be active or passive, so as to be mechanically positioned on one side or the other according to the (vertical) rotation of the suction sail. Description of the Drawings

[0050] To better understand the disclosed content, some drawings are included, in which the actual situation of the embodiments is schematically shown and only as a non-limiting example.

[0051] Figure 1 is a side view of a ship incorporating a propulsion system according to the present invention;

[0052] Figure 2 is a side view of a suction sail used in a propulsion system according to the present invention;

[0053] Figure 3 is a perspective view observed from below of a suction sail used in a propulsion system according to the present invention;

[0054] Figure 4 is a top view of a suction sail used in a propulsion system according to the present invention, showing the suction system therein;

[0055] Figure 5 is a cross-sectional view of a suction sail used in a propulsion system according to the present invention, showing the drive unit and the power unit therein;

[0056] Figure 6 is a view of the bottom of a suction sail used in a propulsion system according to an alternative embodiment of the present invention, wherein the suction sail is inclined with respect to a substantially horizontal axis;

[0057] Figure 7 is a block diagram of components forming a propulsion system according to the present invention; and

[0058] Figures 8 to 13 is a diagram showing different control methods of a propulsion system according to the present invention. Detailed Description of the Invention

[0059] Figure 1 shows a ship 2 including a propulsion system according to the present invention.

[0060] The propulsion system includes at least one suction sail 3, and at least one suction sail 3 includes an external coating 4, which can be rigid or flexible, and the suction sail 3 can rotate about its longitudinal axis 5.

[0061] The suction sail 3 further includes at least one flap 6 capable of rotating between different positions and at least two suction areas 7 provided with a plurality of holes.

[0062] The suction sail 3 further includes a suction system 10 and at least one drive unit 8, the suction system 10 can be of a fan type or equivalent to suck a part of the air flow from the leeward part of the profile, and the at least one drive unit 8 can be electric or hydraulic to rotate the suction sail 3, and the suction sail 3 is provided with an electric or hydraulic power unit 18, and the electric or hydraulic power unit 18 drives the drive unit 8.

[0063] In addition, the suction sail 3 is connected to the deck of the ship 2 by a support structure 17, and the support structure 17 can include a gear mechanism or a structure with bearings, wherein the support structure 17 can support the total weight and limit the lateral movement of the suction sail 3.

[0064] In Figure 6Alternative embodiments are shown, in which the lower part of the suction sail 3 comprises an inclined support 19 which, by means of a drive motor 20, allows the suction sail to be inclined relative to the vertical direction, i.e. the suction sail is inclined relative to a substantially horizontal axis.

[0065] As can be seen from Figure 7 the block diagram in, the propulsion system according to the invention also comprises a control unit 9 for autonomously controlling the drive unit 8 and the suction system 10 on the basis of information received from a plurality of sensors 12, 13, 14, 15, or manually controlled by means of a manual control unit 16 as described below.

[0066] To this end, the user can use the control unit 9 to adjust the autonomous or manual mode of effective propulsion provided by the suction sail 3.

[0067] As indicated, the propulsion system according to the invention comprises a plurality of sensors selected from the following:

[0068] - a wind sensor 12 for measuring the wind speed and direction, such as an anemometer for measuring the speed and a wind vane for measuring the direction, and / or an inertial sensor / tilt meter for measuring the inclination of the ship;

[0069] - a rotation sensor 13 for knowing in real time the angular position of the suction sail 3 relative to the longitudinal axis 5 of the ship 2;

[0070] - a position sensor 14 for knowing the position of the flap 6 between its possible operating positions; and

[0071] - a suction sensor 15 which detects the power and / or pressure to know the suction power provided by the suction system 10 by suction through the holes in the suction area 7, thus creating a corresponding pressure difference between the inner and outer areas of the suction sail 3.

[0072] The control unit also comprises:

[0073] a data collection system;

[0074] a processor;

[0075] autonomous control logic;

[0076] a drive system which sends drive signals to the power unit and the suction system;

[0077] a control / supervision human-machine interface, i.e. a control communication system for introducing autonomous control and monitoring the results obtained;

[0078] a human-machine interface for manual piloting.

[0079] The data collection system formed by these sensors 12, 13, 14, 15 allows the monitoring of environmental variables (such as wind, air pressure, temperature and humidity), operating variables (rotation speed, internal pressure, flow direction).

[0080] The control unit also allows the monitoring of variables of the reference system (ship), such as the characteristics of the propulsion unit (revolutions, flow rate, torque and propulsion force), speed, position and inertial unit.

[0081] The control unit 9 is also responsible for generating system health indicators for predictive maintenance, in which all data is received and processed to obtain an optimal control solution.

[0082] An example of the use of the propulsion system disclosed in this document is described below.

[0083] The suction sail is able to generate a high lift coefficient (aerodynamic force) by sucking a certain amount of air from the boundary layer (the air zone near the surface of the sail) of the camber (the top / front side of the sail), which prevents the separation of the air flow and prevents profile stall (the situation where no more lift is generated). This suction is carried out through one or more suction areas, generating a low-pressure zone inside the sail, which absorbs air from the outside.

[0084] The size of the boundary layer, and thus the amount of air to be inhaled, is a function of the Reynolds number (Re):

[0085]

[0086] The Reynolds number depends on:

[0087] - The air velocity (V).

[0088] - The density of the air (ρ), which in turn depends on the air pressure (P ∞ ) and the air temperature (T).

[0089] - The dynamic viscosity of the air (μ), which in turn depends on the air temperature (T).

[0090] If less of the required boundary layer is inhaled, this will lead to the separation of the boundary layer. If more of the boundary layer is inhaled, it will lead to excessive inhalation and thus consume unnecessary inhalation power.

[0091] In order to be able to operate the suction sail effectively and optimally, avoiding unwanted separation and excessive power consumption, the amount of air in the boundary layer to be sucked must be precisely controlled, as we have observed, this amount of air is variable with the speed, temperature and air pressure at each moment.

[0092] To this end, the control variable is the so-called Suction Pressure Coefficient (SPC), which is defined as

[0093]

[0094] Where:

[0095] P ∞ - is the external ambient pressure;

[0096] P a - is the suction pressure or the internal pressure of the sail;

[0097] The principle of the control logic is to control the vacuum motor to achieve the necessary P a in order to obtain the desired C pa (design) for all operating conditions.

[0098] Control option 1:

[0099] Figure 8 This first autonomous control option, as shown in, is based on the use of the following two sets of sensors:

[0100] - Sensors for measuring the wind, in particular for measuring the wind speed (V) and the wind direction (β) relative to the bow of the ship.

[0101] - Sensors for measuring the environmental / atmospheric conditions, in particular the temperature (T) and the pressure (P ∞ ).

[0102] To control the rotation of the sail and the position of the flap, the control system follows these steps:

[0103] - Obtain a wind direction reading (β).

[0104] - This wind direction (β) has an associated angle of attack (AoA) and a desired / target flap position for the desired / target sail. This relationship β - AoA is predefined (e.g., in a list) in the system according to the sail design and the control logic.

[0105] - The control system will act on the actuator to rotate the sail and position the flap by reading different rotation and position sensors to bring it to the new desired position.

[0106] For the suction control, the control system follows these steps:

[0107] - The control system obtains readings of the wind speed (V), the temperature (T) and the pressure (P ∞ ).

[0108] - Calculate the density (ρ), the dynamic pressure (P D ) and the Reynolds number (Re).

[0109] - This Reynolds number (Re) is associated with the desired / target suction pressure coefficient (C pa ). According to the sail design and control logic, this Re-C pa ratio is predefined (e.g., in a list) in the system.

[0110] - Calculate the desired pressure increment (ΔP). The operating curve of the suction system defines the operating conditions (e.g., revolutions per minute, power,...) that provide a certain ΔP.

[0111] - The control system will act on the suction actuator to operate the suction actuator under conditions that produce the desired ΔP (e.g., revolutions per minute, power,...). According to the sail design and control logic, the ΔP - suction (revolutions per minute, power,...) ratio is predefined (e.g., in a list) in the system.

[0112] Control Option 2:

[0113] Figure 9 This second autonomous control option as shown in

[0114] - Sensors for measuring the wind, particularly for measuring the wind speed (V) and wind direction (β) relative to the bow of the ship.

[0115] - Sensors for measuring environmental / atmospheric conditions, particularly temperature (T) and pressure (P ∞ ).

[0116] - A pitot tube equipped with pressure sensors. One of these pressure sensors measures the dynamic pressure (P d ). Other sensors measure the pressure difference between the suction pressure (P a ) and the static pressure (P ∞ ) to obtain the pressure increment (ΔP) between the inside and outside of the ship. The presence of one or more pressure sensors allows the measurement range to be divided into smaller sub-ranges and each sensor to be adjusted to that sub-range, thus improving the measurement accuracy.

[0117] To control the rotation of the sail and the position of the flap, the control system follows these steps:

[0118] - Obtain a wind direction reading (β).

[0119] - The wind direction (β) has an associated angle of attack (AoA) and desired / target flap position for the desired / target sail. According to the sail design and control logic, this relationship β - AoA is predefined (e.g., in a list) in the system.

[0120] - The control system will act on the actuator to rotate the sail and position the flap by reading different rotation and position sensors to bring it to a new desired position.

[0121] For suction control, the control system follows these steps:

[0122] - The control system obtains readings of wind speed (V), temperature (T), and pressure (P ∞ ).

[0123] - Calculate the density (ρ) and Reynolds number (Re).

[0124] - This Reynolds number (Re) is associated with the desired / target suction pressure coefficient (C pa ). According to the sail design and control logic, this Re-C pa ratio is predefined (e.g., in a list) in the system.

[0125] - Obtain the dynamic pressure (P d ) and pressure increment readings (ΔP) measured by the pitot tube and pressure sensor assembly.

[0126] - Calculate the actual suction pressure coefficient (C pa ).

[0127] - The control system will act on the suction actuator (e.g., revolutions per minute, power...) to adjust the actual C pa to the desired / target C pa .

[0128] Control option 3:

[0129] Figure 10 This third autonomous control option shown in

[0130] - Sensors for measuring the wind, particularly the wind speed (V) and wind direction (β) relative to the bow of the ship.

[0131] - Sensors for measuring environmental / atmospheric conditions, particularly temperature (T) and pressure (P ∞ ).

[0132] - Various pressure sensors measure the suction pressure (P a ). The presence of one or more pressure sensors allows the measurement range to be divided into smaller sub - ranges and each sensor to be adjusted to that sub - range, thus improving the measurement accuracy.

[0133] To control the rotation of the sail and the position of the flap, the control system follows these steps:

[0134] - Obtain the wind direction reading (β).

[0135] - The wind direction (β) has an associated angle of attack (AoA) and a desired / target wing position of the sail. This relationship β - AoA is predefined (e.g., in a list) in the system according to the sail design and control logic.

[0136] - The control system will act on the actuators to rotate the sail and position the flaps by reading different rotation and position sensors to bring it to the new desired position.

[0137] For suction control, the control system follows these steps:

[0138] - The control system obtains readings of the wind speed (V), temperature (T), and pressure (P ∞ ).

[0139] - Calculate the density (ρ) and the Reynolds number (Re).

[0140] - This Reynolds number (Re) is associated with the desired / target suction pressure coefficient (C pa ). This Re - C pa ratio is predefined (e.g., in a list) in the system according to the sail design and control logic.

[0141] - Obtain the pressure readings (P ∞ ), the suction pressure (P a ), the wind speed (V), and the calculated density (ρ).

[0142] - Calculate the actual suction pressure coefficient (C pa ).

[0143] - The control system will act on the suction actuator (e.g., revolutions per minute, power...) to adjust the actual C pa to the desired / target C pa .

[0144] Simplified control options:

[0145] Figure 11 The simplified options of the control method shown in ∞ apply to the above 3 options and include eliminating the measurement of the atmospheric conditions of temperature (T) and pressure (P

[0146] and obtaining predefined constant values of temperature (T) and density (ρ). This simplifies the system architecture as well as data collection and processing. In return, (depending on the control option applied) an error is introduced in determining the desired / target suction coefficient (C pa ), the desired / target pressure increment (ΔP), and / or the actual suction coefficient (C pa ), which leads to an error in the suction accuracy and results in sub - optimal operation.

[0147] The intermediate option can also be to use the ISA (International Standard Atmosphere) equations, which allow the environmental variables of temperature, pressure, and density to be related. Thus, by measuring only one of the three variables with a sensor, the other two can be calculated.

[0148] As an example, according to Option 1, the steps for suction control performed by the control system are described in detail:

[0149] - Pre-define temperature (T) and density (ρ) values.

[0150] - Obtain a wind speed reading (V).

[0151] - Calculate the dynamic pressure (P D ) and the Reynolds number (Re), where the dynamic pressure (P D ) and the Reynolds number (Re) now depend only on / change with the wind speed reading.

[0152] - The Reynolds number (Re) is associated with the desired / target suction pressure coefficient (C pa ). This Re-C pa ratio is pre-defined (e.g., in a list) in the system according to the sail design and control logic.

[0153] - Calculate the desired pressure increment (ΔP). The operating curve of the suction system defines the operating conditions (e.g., revolutions per minute, power...) that provide a certain ΔP.

[0154] - The control system will act on the suction actuator to operate the suction actuator under the conditions that produce the desired ΔP (e.g., revolutions per minute, power...). The ΔP - suction (revolutions per minute, power...) ratio is pre-defined (e.g., in a list) in the system according to the sail design and control logic.

[0155] Control Option 4

[0156] Figure 13 In the alternative control method shown in Option 4, the theoretical basis and principles of the control logic for sail rotation and flap position are the same as those detailed in the other 3 control methods.

[0157] Any aerodynamic profile exposed to the airflow generates a pressure distribution (P skin ) along its surface. The difference between the pressure distributions on both sides of the profile is the cause of the profile aerodynamic forces (i.e., lift and drag).

[0158] If the surface pressure (P skin ) is determined, then this surface pressure (P skin ) is converted into a pressure coefficient (C P ), where the pressure coefficient is defined as:

[0159]

[0160] This distribution (its shape and values) becomes dependent only on the angle of attack (AoA). At the same time, the lift coefficient (C L ) also depends only on the angle of attack (AoA), so that the surface pressure coefficient (C P ) of a point can be clearly associated with the lift coefficient (C L ) giving the profile.

[0161] By extrapolating it to the suction sail, for a given known AoA, we know what the surface pressure coefficient (C P ) should be at a given point if the suction is sufficient. If it is lower than the surface pressure coefficient (C P ) at that given point, it indicates a stall of the profile due to insufficient suction. This difference in C P occurs at any point along the profile chord, although it is preferred to select a point where the pressure change is more significant to simplify detection, which is close to the leading edge of the profile. This variation in the surface pressure coefficient (C Figure 12 ) for various angles of attack (AoA) can be seen in P .

[0162] The principle of the control logic is to control the vacuum motor to achieve that the measured C P is equal to the desired (design) C P under all operating conditions.

[0163] Figure 13 This autonomous control option shown in

[0164] is based on the use of the following three sets of sensors:

[0165] - Sensors for measuring the wind, in particular for measuring the wind speed (V) and the wind direction (β) relative to the bow of the ship. ∞ - Sensors for measuring the environmental / atmospheric conditions, in particular the temperature (T) and the pressure (P

[0166] - Various pressure sensors for measuring the surface pressure (P skin ) at one or more relevant points on the sail surface. The presence of one or more pressure sensors allows the measurement range to be divided into smaller sub - ranges and each sensor to be adjusted to that sub - range, thus improving the measurement accuracy.

[0167] To control the rotation of the sail and the position of the flap, the control system follows the following steps:

[0168] - Obtain a wind direction reading (β).

[0169] - This wind direction (β) is associated with the desired / target angle of attack (AoA) of the sail and the desired / target flap position predefined in the system according to the sail design.

[0170] - The control system will act on the actuator to rotate the wing and position the flap by reading different rotation and position sensors, thereby bringing it to the new desired position.

[0171] For suction control, the control system follows these steps:

[0172] - Obtain the temperature (T) and pressure readings (P ∞ )

[0173] - Calculate the density (ρ).

[0174] - Obtain the readings of wind speed (V), pressure (P ∞ ) and surface pressure (P skin ), as well as the calculated density (ρ).

[0175] - Calculate the surface pressure coefficient (C Pskin )

[0176] - Obtain the wind direction reading (β).

[0177] - This wind direction (β) is associated with the desired / target angle of attack (AoA) of the sail and the desired / target flap position predefined in the system according to the sail design.

[0178] - The angle of attack (AoA) is associated with the desired target surface pressure coefficient (C Pskin )

[0179] - The control system will act on the suction actuator (e.g., revolutions per minute, power...) to adjust the actual C Pskin to the desired / target C Pskin .

[0180] Although specific embodiments of the present invention have been referenced, it will be apparent to those skilled in the art that the described propulsion system is susceptible to various variations and modifications without departing from the scope of protection defined by the appended claims, and all of the recited details may be replaced by other technically equivalent details.

Claims

1. A propulsion system for a ship, comprising at least one suction sail (3), said at least one suction sail (3) including a suction sail (3), a suction system (10) and a drive unit (8) for driving the rotation of said at least one suction sail (3). It is characterized in that Said at least one suction sail (3) further includes a plurality of sensors (12, 13, 14, 15) connected to a control unit (9), and said control unit determines the operation of said suction system (10) and said drive unit (8).

2. The propulsion system for a ship according to claim 1, wherein, Said plurality of sensors includes at least one wind sensor (12).

3. The propulsion system for a ship according to claim 1 or 2, wherein, Said plurality of sensors includes at least one rotation sensor (13) of said suction sail (3).

4. The propulsion system for a ship according to any one of the preceding claims, wherein, Said plurality of sensors includes at least one position sensor (14) of a flap (6) of said suction sail (3).

5. A propulsion system for a ship according to any one of the preceding claims, wherein, Said plurality of sensors includes at least one suction sensor (15).

6. The propulsion system for a ship according to claim 1, wherein, Said control unit (9) includes a user interface (11).

7. The propulsion system for a ship according to claim 1, wherein, Said propulsion system further includes a manual control unit (16) connected to said suction system (10) and said drive unit (8).

8. The propulsion system for a ship according to claim 1, wherein, Said suction sail (3) includes a rigid or flexible outer coating (4).

9. The propulsion system for a ship according to claim 1, wherein, Said suction sail (3) includes two or more suction zones (7), and said two or more suction zones (7) are provided with a plurality of holes.

10. The propulsion system for a ship according to claim 1, wherein, Said drive unit (8) is located at the lower end of said suction sail (3).

11. The propulsion system for a ship according to claim 1 or 10, wherein, Said transmission unit (8) is an electric or hydraulic drive unit powered by a power unit (18).

12. The propulsion system for a ship according to claim 1, wherein, Said suction sail (3) includes a support structure (17) at the lower end of said suction sail (3).

13. The propulsion system for a ship according to claim 1, wherein, The lower part of said suction sail (3) includes an inclined support (19), and said inclined support (19) inclines said suction sail (3) about a substantially horizontal axis.

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