Integrated Propulsion and Steering System

Abstract

An electrically driven propulsion system for a watercraft comprises an electric motor, a pulse inverter, a thrust bearing, and a transmission is presented. The pulse inverter can be electrically coupled to the electric motor and adapted to provide an electrical supply power of at least 50 kW to the electric motor. The electrically driven propulsion system further comprises a common waterproof housing. An external section of the transmission can be arranged outside of the common waterproof housing. The transmission can be adapted to rotationally couple the external section of the transmission to the electric motor. The thrust bearing can be mechanically coupled to the rotary shaft of said transmission and to the common waterproof housing. The thrust bearing can be adapted to transfer a force applied to the transmission along an axial direction of said rotary shaft of the transmission to the common waterproof housing.

Claims

1. An electrically driven propulsion system for a watercraft, the electrically driven propulsion system comprising: an electric motor adapted to provide a mechanical power of at least 50 kW; a transmission comprising a rotary shaft; a pulse inverter electrically coupled to the electric motor and adapted to provide an electrical supply power of at least 50 kW to the electric motor; a thrust bearing; and a common waterproof housing; wherein the electric motor, the pulse inverter and an enclosed section of the transmission are arranged inside the common waterproof housing; wherein an external section of the transmission is arranged outside of the common waterproof housing; wherein the transmission is adapted to rotationally couple the external section of the transmission to the electric motor; and wherein the thrust bearing is mechanically coupled to the rotary shaft of said transmission and to the common waterproof housing and adapted to transfer a force applied to the transmission along an axial direction of said rotary shaft to the common waterproof housing.

2. The electrically driven propulsion system according to claim 1, wherein the external section of the transmission comprises a propeller coupling adapted for mounting a propeller thereto.

3. The electrically driven propulsion system according to claim 2, wherein the watercraft comprises a hull with an opening; and wherein the electrically driven propulsion system is adapted to be connected as a whole to the hull with the opening, such that at least a section of the electric motor is arranged on a first side of the opening and the propeller coupling and at least a portion of the common waterproof housing are arranged on a second side of the opening opposite to the first side, and such that a waterproof connection forms between the common waterproof housing and the hull.

4. The electrically driven propulsion system according to claim 1, wherein the electric motor is an axial flux motor.

5. The electrically driven propulsion system according to claim 1, wherein the common waterproof housing is adapted to provide a motor upgrade space for a motor power upgrade component, and wherein the pulse inverter is adapted to provide an electrical output power of at least two times the mechanical power that the electric motor is adapted to provide.

6. The electrically driven propulsion system according to claim 1, which further comprises a sensor disposed within the common waterproof housing and adapted to detect a change in a sound or vibrational level of the electrically driven propulsion system.

7. The electrically driven propulsion system according to claim 3, wherein the common waterproof housing comprises a motor section in which the electric motor is arranged; and wherein a width of the portion of the common waterproof housing adapted to be arranged on the second side of the opening exceeds a width of the motor section.

8. The electrically driven propulsion system according to claim 3, wherein the common waterproof housing comprises a ring-shaped seal face adapted to encircle the opening of the hull to provide the waterproof connection.

9. The electrically driven propulsion system according to claim 2, wherein the transmission comprises a shaft comprising the propeller coupling and an axis, and wherein an orientation of the axis of the shaft is static.

10. The electrically driven propulsion system according to claim 3, further comprising a heat exchanger disposed within the common waterproof housing, wherein a primary side of the heat exchanger comprises at least one primary coolant opening adapted to be arranged on the second side of the opening, and wherein a secondary side of the heat exchanger comprises at least one secondary coolant opening adapted to be disposed proximate the first side of the opening.

11. The electrically driven propulsion system according to claim 1, which further comprises a rudder actuator, wherein at least a section of the rudder actuator is disposed within the common waterproof housing.

12. A connecting frame for connecting a propulsion system to a hull with an opening, wherein the connecting frame comprises: a first ring-shaped element comprising a first opening, first connecting elements, and through holes; a second ring-shaped element comprising a second opening; second connecting elements, wherein the first connecting elements and the second connecting elements comprise a first common arrangement; and detachable connection elements adapted to couple to fixing means of the propulsion system; a first sealing face arranged on the first ring-shaped element and encircling the first opening; and a second sealing face arranged on the first ring-shaped element opposite to the first sealing face and encircling the first opening; wherein the first ring-shaped element and second ring-shaped element are adapted to be connected using the first connecting elements and the second connecting elements and with a relative orientation defined by the first common arrangement; and wherein, according to the relative orientation: the first opening overlaps with the second opening to form an opening of the connecting frame; the through holes coincide with the detachable connection elements; and the first sealing face is arranged between the connected first ring-shaped element and second ring-shaped element and adapted to provide a waterproof connection between the connecting frame and the hull with the opening.

13. A connecting system, comprising: a connecting frame configured to couple a propulsion system to a hull with an opening, wherein the connecting frame comprises: a first ring-shaped element comprising a first opening, first connecting elements, and through holes; a second ring-shaped element comprising a second opening; second connecting elements, wherein the first connecting elements and the second connecting elements comprise a first common arrangement; and detachable connection elements adapted to couple to fixing means of the propulsion system; a first sealing face arranged on the first ring-shaped element and encircling the first opening; and a second sealing face arranged on the first ring-shaped element opposite to the first sealing face and encircling the first opening; wherein the first ring-shaped element and second ring-shaped element are adapted to be connected using the first connecting elements and the second connecting elements and with a relative orientation defined by the first common arrangement; and a support element adapted to mechanically support the propulsion system via a support arm.

14. The connecting system according to claim 13, wherein the support element is adapted to be coupled to the connecting frame such that the support arm extends away from the connecting frame.

15. The connecting system according to claim 13, wherein, according to the relative orientation: the first opening overlaps with the second opening to form an opening of the connecting frame; the through holes coincide with the detachable connection elements; and the first sealing face is arranged between the connected first ring-shaped element and second ring-shaped element and adapted to provide a waterproof connection between the connecting frame and the hull with the opening.

16. A method for connecting an electrically driven propulsion system as a whole to a hull with an opening, wherein the electrically driven propulsion system comprises: an electric motor adapted to provide a mechanical power; a transmission functionally coupled to the electric motor, the transmission comprising a propeller coupling adapted for mounting a propeller; and a common waterproof housing, wherein the electric motor and an enclosed section of the transmission are arranged inside the common waterproof housing, wherein the propeller coupling is arranged outside the common waterproof housing, wherein the transmission is adapted to rotationally couple the propeller coupling to the electric motor, and wherein the common waterproof housing comprises a motor section in which the electric motor is arranged; the method comprising: providing the electrically driven propulsion system as a whole on a second side of the opening of the hull; moving at least a section of the motor section through the opening to a first side of the opening opposite to the second side, such that at least a portion of the common waterproof housing remains on the second side; and fixing the electrically driven propulsion system to the hull with the opening; and forming a waterproof connection between the hull with the opening and the common waterproof housing.

17. The method according to claim 16, wherein the fixing the electrically driven propulsion system to the hull with the opening comprises fixing the electrically driven propulsion system as a surface drive to the hull with the opening.

18. The method according to claim 16, wherein the electric motor provides a mechanical power of at least 50 kW.

19. The method according to claim 16, wherein the at least a section of the motor section is moved through the opening while keeping the electrically driven propulsion system assembled as a whole and while keeping the propeller coupling on the second side.

20. The method according to claim 16, wherein the at least a section of the motor section is moved through the opening while keeping the propeller coupling on the second side.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0235] The techniques of the present disclosure and the advantages associated therewith will be apparent from a description of exemplary embodiments in accordance with the accompanying drawings, in which:

[0236] FIG. 1a shows an electrically driven propulsion system according to an embodiment;

[0237] FIG. 1b shows an application example of the electrically driven propulsion system;

[0238] FIG. 1c shows another application example of the electrically driven propulsion system;

[0239] FIG. 1d shows another application example of the electrically driven propulsion system;

[0240] FIG. 2 shows an electrically driven propulsion system according to another embodiment;

[0241] FIG. 3 shows an electrically driven propulsion system according to another embodiment;

[0242] FIG. 4 shows an electrically driven propulsion system according to another embodiment;

[0243] FIG. 5a shows an electrically driven propulsion system with a connecting from according to an embodiment;

[0244] FIG. 5b shows an electrically driven propulsion system with a connecting from according to another embodiment;

[0245] FIG. 6 shows an electrically driven propulsion system according to another embodiment;

[0246] FIG. 7a shows an electrically driven propulsion system according to another embodiment;

[0247] FIG. 7b shows the electrically driven propulsion system according to the embodiment of FIG. 7a;

[0248] FIG. 7c shows the electrically driven propulsion system according to the embodiment of FIG. 7a, FIG. 7b;

[0249] FIG. 7d shows a propeller for surface drive;

[0250] FIG. 7e shows an electrically driven propulsion system according to another embodiment;

[0251] FIG. 8a shows an electrically driven propulsion system according to another embodiment;

[0252] FIG. 8b shows the electrically driven propulsion system according to the embodiment of FIG. 8a;

[0253] FIG. 8c shows an electric motor according to an embodiment;

[0254] FIG. 8d shows an electric motor according to a different embodiment;

[0255] FIG. 9a shows a method for connecting an electrically driven propulsion system to a hull according to an embodiment;

[0256] FIG. 9b shows a method for connecting an electrically driven propulsion system to a hull according to another embodiment;

[0257] FIG. 9c shows a method for connecting an electrically driven propulsion system to a hull according to another embodiment;

[0258] FIG. 10a shows a side view of a connecting frame;

[0259] FIG. 10b shows a front view of the connecting frame; and

[0260] FIG. 11 shows a hull prepared for connecting the electrically driven propulsion system as a surface drive.

DETAILED DESCRIPTION

[0261] FIG. 1a shows an electrically driven propulsion system 100 according to an embodiment. The propulsion system 100 forms a monolithic unit comprising the electric motor 102 and a transmission 106 coupled to the electric motor 102, as well as a pulse inverter 118 providing an electrical supply power to the electric motor 102. A corresponding electrically driven propulsion system 100 is also referred to as an integrated propulsion system 100.

[0262] The transmission 106 comprises an encased section 106e inside the housing 108, as well as an external section 106x outside of the waterproof housing 108 at its far end from the motor 102. The transmission 106 rotationally couples the external section 106x to the electric motor 102 via the encase section 106e, hence transferring a rotational movement of the electric motor 102 out of the housing 108. It comprises any component required for this purpose. According to the example depicted in FIG. 1a, this is a (rotary) shaft 106.

[0263] The electrically driven propulsion system 100 further comprises a thrust bearing 164. When the electric motor 102 is driven with electric output power from the pulse inverter 118 to rotate a rotary shaft 106 of the transmission, this movement causes a propeller of the watercraft to rotate. The propeller is coupled to the rotary shaft 106 directly or via a drive provided by the watercraft.

[0264] The rotation of the propeller results in a forward force 166, or a propulsion 166, respectively, of the rotary shaft 106 along its axial direction 168. The thrust bearing 164 transfers this force 166 onto the housing, thereby generating a propulsion 166′ of the housing and ultimately of the watercraft. Therefore, the thrust bearing 164 is connected to the rotary shaft 106 and to the housing to couple the two rotationally, i. e. its inner ring is rigidly connected to the rotary shaft 106 and its outer ring of the bearing is rigidly connected to the housing 108.

[0265] The monolithic design of the electrically driven propulsion system 100 allows for equipping a watercraft with the electrically driven propulsion system 100 in a few simple steps. The components of the system 100, i. e. the electric motor 102, the inverter 118, the transmission 106, and the thrust bearing 164 are fully optimized with respect to each other. Therefore, by equipping his or her watercraft with the electrically driven propulsion system 100, a user installs a high-power, high-efficiency system for an optimized range of the watercraft. No further selection of additional components and no corresponding expert knowledge is required, and the risk of losing efficiency or range is eliminated.

[0266] Moreover, the integrated (monolithic) design allows for replacing it as a whole quickly and easily in case of a failure of one of the components, i. e. with all essential components mounted in their respective locations for operation. The defective component may be diagnosed and replaced later, for example in a dedicated facility, as the watercraft with the replaced propulsion system is already back in operation. The monolithic unit 100 may be mechanically sealed or locked to prevent a user from opening it and to permit access only in a controlled environment, such as a maintenance and repair facility.

[0267] Any need to disassemble or assemble any component of the electrically driven propulsion system 100 at the location of the watercraft is avoided. The installation or replacement may reliably be performed by a person without specialized skills and knowledge of any of the components of the electrically driven propulsion system 100.

[0268] In a preferred embodiment, the electric motor 102 is an axial flux motor. Axial flux motors are particularly light-weight and compact, for example compared to radial flux motors. Therefore, the use of an axial flux motor renders the installation and exchange of the integrated propulsion system 100 as a hole way more manageable and secure. The axial flux motors 102 operate at relatively low revolution speeds of 1500 to 3500 rounds per minute, similar to the optimal revolution speed of the propeller, for example for a surface drive. Consequently, the integrated propulsion system 100 may in principle be formed without any gearing mechanism or ratio between the electric motor 102 and its external section 106x.

[0269] Depending on the embodiment, it provides a mechanical power of 100 kW or 200 kW. The axial flux motor 102 adapted to provide the mechanical power of 100 kW has a weight of 25 kg, and the axial flux motor 102 adapted to provide the mechanical power of 200 kW has a weight of 50 kg.

[0270] The common waterproof housing 108 protects the components it surrounds from external influences, such as seawater or weather conditions, in particular on the watercraft. On the other hand, the housing 108 protects a user from electrical hazards related to the electric motor 102, in particular on the inside 216 of the hull 202. For this purpose, the housing 108 comprises a layer of insulating material or a layer of grounded, conductive material.

[0271] Moreover, the common waterproof housing 108 provides an acoustic shielding for the motor and the enclosed section 106e of the transmission, and reduces noise on board emerging from those components.

[0272] The integrated propulsion system 100 is compatible with various boat layouts, and optimized embodiments for a number of layouts will be presented throughout this description. FIG. 1b, FIG. 1c, and FIG. 1d illustrate application examples.

[0273] According to FIG. 1b, the integrated propulsion system 100 is installed in a watercraft with a fixed shaft. The transmission 106 of the integrated propulsion system 100 connects directly to the fixed shaft, and is optimized for this purpose with a planetary gearing 106b providing a gear ratio optimized for the watercraft. The system comes as a kit with a support structure 128 to adjust the integrated propulsion system 100 to the inclination angle of the fixed shaft.

[0274] According to FIG. 1c, the integrated propulsion system 100 is installed as a component of a sail drive for a sailing boat. The shaft 106 of the propulsion system 100 connects to an input gear of a spur gear of the sail drive. There, the electrically driven propulsion system 100 may replace a combustion engine to reduce the noise level on board and improve the sustainability of the sailing boat.

[0275] According to FIG. 1d, the integrated propulsion system 100 is installed at the transom 202 of the watercraft, preferably as a surface drive. The propulsion system 100 pierces through the transom 202 and is arranged part inside, part outside of the watercraft.

[0276] The external section 106e of the transmission comprises a propeller coupling 106c for mounting a propeller. The system 100 therefore includes any mechanical component required to couple the propeller shaft 106e, or the propeller coupling 106c, respectively (and ultimately a propeller mounted to the coupling 106c) rotationally to the electric motor 102. In the following, such a system 100 is referred to a fully mechanically integrated.

[0277] This option is particularly favorable for high-speed watercraft, for example with a cruising speed of 20 to 50 kn. The system comes as a kit with a support structure 128 to adjust the integrated propulsion system 100 to the optimum inclination angle of the surface drive.

[0278] FIG. 2 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 2 is similar to the one of FIG. 1a. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 2 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0279] The integrated propulsion system comprises two noise/vibration sensors 152, which detect a sound level or a sound pattern of the system 100, generate a corresponding electronic signal, and send it through a signal line 154 out of the system and to a signal processor 156 of the system.

[0280] The signal processor 156 or an external processor connected to the signal line 154 detects changes in the sound level or sound pattern of the system 100.

[0281] When a permanent change is detected, it may be an indication for an upcoming failure, for example you to an increased friction between elements of the system 100. The processor 156 generates an electronic report message, indicating that the integrated propulsion system 100 may need to be replaced.

[0282] When a sudden change in the sound level or the sound pattern of the system 100 is detected and exceeds a critical level, this may be an indication of a contact or a collision of the watercraft with an obstacle. The processor 156 generates an electronic warning message, which may for example trigger an alarm or a transmission of an emergency message, for example via a long-distance network.

[0283] The signal line 154 is shown only for one of the sensors 152, but is equally formed for the second one.

[0284] Two signal lines 154 are shown, one leading to the processor 156 and one leading out of the housing 108, but according to different embodiments, only one of the two is formed.

[0285] One of the noise/vibration sensors 152 is arranged in direct contact with the electric motor 102, to specifically monitor changes in the sound level or sound pattern of the electric motor. The other noise/vibration sensor 152 is arranged at a far end of the housing 108 from the motor 102 in direct contact with the housing. In embodiments, wherein the far end of the housing 108 is in contact with a surrounding body of water, such as the embodiment of FIG. 1d, this noise/vibration sensor 152 monitors body sound transferred by the water. Additional noise/vibration sensors 152 may be provided, for example in the vicinity or in direct contact with individual components of the transmission 106, or only one of the noise/vibration sensors 152 may be present.

[0286] FIG. 3 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 3 is similar to the one of FIG. 1a and FIG. 2. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 3 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0287] The transmission 106 of the electrically driven propulsion system 100 of FIG. 3 comprises a planetary gearing 106b to implement a gear ratio between a second (rotary) shaft 106c and a first (rotary) shaft 106a of the transmission. The first shaft 106 a is coupled to the electric motor 102 and forms a motor shaft 106a. The second shaft 106c may carry a propeller 104 or propeller coupling 106c like in the example of FIG. 1d or be connected to an external transmission like in the embodiments of FIG. 1b, FIG. 1c.

[0288] The transmission serves to match the highest-efficiency rotation speed of the second shaft 106c to the highest-efficiency rotation speed of the propeller 104 or the external transmission. The highest efficiency rotation speed of the second shaft 106c refers to the rotation speed of the second shaft 106c, at which the overall electrical power to mechanical power conversion efficiency of the integrated propulsion system 100 is maximum. Mechanical power refers to the mechanical power generated at the second shaft 106c due to its rotational movement. The electrical power refers to an input power provided to the pulse inverter 118 via a power inlet of the pulse inverter from an external current source, such as a battery.

[0289] The electrically driven propulsion system 100 of FIG. 3 further comprises a heat exchanger 122.

[0290] The heat exchanger 122 is thermally coupled via its secondary side 126 to any component of the system 100 requiring cooling, in particular the electric motor 102, but also to the pulse inverter 118, the transmission 106 or a thrust bearing (not shown) as required. The secondary side 126 of the heat exchanger comprises cooling channels 126c filled with a coolant and connecting the heat exchanger 122 to the respective components. The coolant has an optimized composition comprises a sufficient amount of glycol to prevent freezing in any relevant situation. The heat exchanger further comprises a coolant pump (not shown) to generate a flow of the coolant in the channels 126c of its secondary side 126.

[0291] The secondary side 126 of the heat exchanger 122 further provides two openings 1260, namely an outlet and an inlet for coolant to an external device, such as a battery or a cabin. If not required, the openings 1260 are bridged.

[0292] A primary side 124 of the heat exchanger 122 connects to openings 1240 outside the housing 108. In operation, the openings 1240 are either directly exposed to a body of water surrounding the watercraft and take up water as a coolant therefrom. Alternatively, the openings 1240 are connected to the surrounding body of water using additional external tubing, for example through a feedthrough in the hull of the watercraft. A coolant pump (not shown) ensures a sufficient flow of water at the primary side 124 of the heat exchanger 122.

[0293] FIG. 4 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 4 is similar to the one of FIG. 1a, FIG. 2, and FIG. 3. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 4 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0294] According to the embodiment of FIG. 4, the housing 108 of the electrically driven propulsion system 100 comprises a fore (motor) section 108a wherein the motor is arranged and an aft (transmission) section 108b wherein the encased section 106e of the transmission 106 is arranged.

[0295] The transmission section 108b has a larger width w1 than the motor section w2. The widths w1, w2 refer to widths of the respective cross sections of the housing 108, for example in the planes 160, 162 perpendicular to the longitudinal direction 158 of the system 100 intersecting the housing 108 at different positions along the longitudinal direction 158.

[0296] The embodiment of FIG. 4 is preferably mounted to a transom 202 of a watercraft. The fore (motor) section 108a is located directly fore of the aft (transmission) section 108b and its cross section is completely comprised in a fore projection of the aft (transmission) section 108b.

[0297] Therefore, when the integrated propulsion system 100 is inserted into the transom 202 through an opening 204, the motor section 108a is taken up completely by the watercraft, whereas the transmission section 108b serves as a stopper to define the depth to which the integrated propulsion system 100 is introduced. A portion of the transmission section 108b remains outside of the watercraft.

[0298] A seal (not shown) between the housing 108 and the hull 202 ensures a waterproof connection.

[0299] Thus, an ideal geometry is realized for a surface drive, with the propeller coupling 106c aft of the transom 202 and the entire hull. The surface drive is particularly energy efficient for high speeds exceeding 20 kn, making the integrated propulsion system 100 attractive for high-speed, electrically driven watercraft. The high efficiency of the surface drive helps to make best possible use of the charge capacity of the battery and to improve the range of the high-speed, electrically driven watercraft.

[0300] To further optimize the integrated propulsion system 100 of FIG. 4 for this purpose, it is designed with a linear arrangement along its longitudinal direction 158, which pierces through the opening 204 of the hull 202. In other words, the electric motor 102, the shaft 106 and the propeller coupling 106p are all intersected by a single line extending along the longitudinal direction 158. In this embodiment, the longitudinal direction of the integrated propulsion system coincides with the axis of the shaft 106 coupled to the motor 102, and with a horizontal axis x perpendicular to a vertical axis z and a second horizontal axis y.

[0301] FIG. 5a shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 5a is similar to the one of FIG. 1a, FIG. 2, FIG. 3, and FIG. 4.

[0302] Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 5a is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0303] While the integrated propulsion system 100 of the embodiment of FIG. 4 is shown as mounted directly to the hull 202, a connecting frame 302 is provided between the integrated propulsion system 100 of FIG. 5a and the hull 202. The integrated propulsion system 100 is mounted to the connecting frame 302.

[0304] The connecting frame 302 comprises a first ring-shaped element 308 on the inside 216 of the hull 202 and second ring-shaped element 308 on the outside 210 of the hull 202.

[0305] Threaded holes 318 of the second ring-shaped element 308 and slightly larger through holes 316 of the first ring-shaped element 306 facilitate a connection between the two. Through holes similar to the ones 316 of the first ring-shaped element 306 are formed in the hull 202. Connecting the ring-shaped elements 306, 308 with bolts 322 clamps them to the hull 202, and sealing rings (not shown) between the ring-shaped elements 306, 308 and the hull 202 establish a waterproof connection between the connecting frame 302, 306, 308 and the hull 202.

[0306] The integrated propulsion system 100 of FIG. 5a comprises through holes 110a formed on a ring-shaped sealing face 110.

[0307] The ring-shaped elements 306, 308 further comprise through holes 320a and threaded holes 320b, which serve to establish a detachable connection. The arrangements of both the through holes 320a and the threaded holes 320b correspond to the arrangement of the through holes 110a of the ring-shaped sealing face 110. Therefore, inserting bolts 222 through the through holes 110a and the trough holes 320a and tightening them to the threaded holes 320b connects the integrated propulsion system 100 to the hull 202. A sealing ring (not shown) between the sealing face 110 and the second ring-shaped elements 306 ensures a waterproof connection between the two.

[0308] A corresponding connection using a connecting frame 302 is optionally and preferably also applied in any of the other embodiments. It ensures a reliably detachable connection between the electrically driven propulsion system 100 and the watercraft, without any risk of touching or damaging the watercraft, in particular its hull 204, in the process of attach or detaching the electrically driven propulsion system 100 from or to the watercraft.

[0309] The connecting frame 302 permits to install and remove the integrated propulsion system 100 from outside of the watercraft using a detachable connection, thus avoiding any need to work inside the typically narrow inside space of the watercraft, or its hull, respectively.

[0310] According to the embodiment of FIG. 5a, the thrust bearing 164 provides a waterproof connection between the housing 108 and the rotary shaft 106, and therefore forms a section of the common waterproof housing. In other words, a section of the thrust bearing 164 is arranged in a wall of the waterproof housing 108.

[0311] FIG. 5b shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 5b is similar to the one of FIG. 1a, FIG. 2, FIG. 3, FIG. 4, and FIG. 5a. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 5b is designed with a series of modifications.

[0312] According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0313] According to the embodiment of FIG. 5b, a connecting system is established by combining the connecting frame 302 with a support element 128 connected to the frame 128.

[0314] The support element 128 comprises a support arm 128a which is connected to and extends away from the connecting frame 302. It further comprises a support column 128b, which is connected to and extends away from the support arm 128 in the vertical direction z. The support column is adapted to support the integrated propulsion system 100 at its housing 108.

[0315] The support element 128 reduces vibrations of the housing 108, of the integrated propulsion system 100, and in particular of the electric motor 102. This reduces undesired noise emerging from the unit and improves its reliability and lifetime. Moreover, the length of the support arm 128a is preselected according to the length of the portion of the integrated propulsion system 100 to be inserted into the hull 202, such that the support arm 128a helps to define a mounting depth of the integrated propulsion system 100 in the hull 202. The support element 128 therefore renders the mounting of the electrically driven propulsion system 100 more simple and reliable.

[0316] The support arm 128a extend away from the connecting frame 302, more specifically from the lower edge of the opening 304 of the connecting frame 302. Therefore, when the propulsion system 100 is inserted into the watercraft through the transom 202 with the opening 204 along the direction x, the support arm 128a serves to guide the movement of the propulsion system 100 and restrains it along both the vertical direction z and a horizontal sidewards direction y. Therefore, the system 100 may be inserted into the watercraft with a minimum of force, in particular with much less force than would be required to stabilize the position of the system 100 without the guiding arm 128 (e. g. along the vertical direction z). Moreover, the support arm 128a may guide the movement of the system 100 along a straight trajectory x and avoid unwanted movements along the sidewards direction y.

[0317] The integrated propulsion system 100 according to the embodiment of FIG. 5b further comprises anti-mechanical-shock elements (not shown) to mechanically insulate the electric motor 102 from the housing 108. The anti-mechanical-shock elements are arranged inside the housing 108 and between the housing 108 and the motor 102. The comprise support elements made from a material with a high internal friction, for example comprising viton. They further improve the noise level, reliability, and lifetime of the electric motor 102. Corresponding anti-mechanical-shock elements are optionally and preferably applied in any of the other embodiments.

[0318] FIG. 6 shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 6 is similar to the one of FIG. 1a, FIG. 2, FIG. 3, FIG. 4, FIG. 5a and FIG. 5b. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 6 is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0319] The electrically driven propulsion system 100 of FIG. 6 comprises a gearing mechanism 106b similar to the one described in the context of the embodiment of FIG. 3. However, as opposed to the gearing mechanism 106b of FIG. 3, which provides a coupling between the first shaft and the second shaft along a continuous line, the gearing mechanism 106b of FIG. 6 provides an offset 130, or a displacement 130, respectively, between the first shaft and the second shaft along a direction perpendicular to their respective axes.

[0320] The offset 130 in the embodiment of FIG. 6 is implemented by using a spur gear in the gearing mechanism 106b, alone or in combination with the planetary gear described above.

[0321] The offset 130 improves the design flexibility of the system 100. In particular, it helps to lower the propeller coupling 106c to the water line of the watercraft.

[0322] The electrically driven propulsion system 100 of FIG. 6 further comprises a noise/vibration sensor 152 arranged outside 210 of the watercraft and below the propeller shaft 106c and the propeller coupling 106p, and therefore below the water line of the watercraft. As described above, this arrangement of the noise/vibration sensor 152 allows for capturing body sound from a body of water surrounding the watercraft.

[0323] FIG. 7a, FIG. 7b, and FIG. 7c show an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 7a, FIG. 7b, and FIG. 7c is similar to the one of FIG. 1a, FIG. 2, FIG. 3, FIG. 4, FIG. 5a, FIG. 5b and FIG. 6. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 7a, FIG. 7b, and FIG. 7c is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0324] The embodiment of FIG. 7a, FIG. 7b, and FIG. 7c uses two axial flux motors 102. An electric supply power is provided to the axial flux motors 102 by the pulse inverter 118. The pulse inverter 118 receives its input power from a power inlet 120 fed through the waterproof housing 108 in a waterproof manner to connect a battery outside of the housing 108. When the electrically driven propulsion system 100 is mounted to the watercraft, the power inlet 120 is located inside the watercraft and accessible there.

[0325] A watercraft battery providing a DC voltage may be connected to the power inlet 120. The pulse inverter 118 generates the AC electrical supply current for the electric motors 102 from the DC voltage. The pulse inverter 118 is also coupled to a data line 116 to receive control commands and software updates, such as updates of parameters related to the operation of the pulse inverter 118.

[0326] Axial flux motors may be constructed with higher power densities than conventional engines and electric motors, such as radial flux motors. As the revolution speed of the axial flux motors 102 is similar to the optimal revolution speed of the propeller 104, the gearbox 106b may have a small gear ratio, such as a gear ratio of 1.18, and thus a higher efficiency than a gearbox with a high gear ratio typically applied in combination with an engine or an electric motor with a higher revolution speed.

[0327] The common waterproof housing 108 provides a motor section 108a for the electric motor on a first side 216 of a sealing face 110, and a transmission section 108b on the opposite, second side 210 of the sealing face 110. Threaded holes 110a are formed on the sealing face 110. The transmission section 108b contains a section of the propeller shaft 106c and a section of the gearbox 106b. Other parts of the transmission 106, namely the motor shaft 106a and most of the gearbox 106b, are placed inside the motor section 108b.

[0328] Consequently, when the electrically driven propulsion system 100 is connected with its sealing face 110 to a hull 202, the electric motors 102 are located inside of the hull 202 where they are protected from environmental influences and acoustically shielded to minimize a noise level on board and on deck.

[0329] The electrically driven propulsion system 100 also comprises an electromechanical rudder actuator 112 arranged in the common waterproof housing 108. The electromechanical rudder actuator 112 actuates rudders 114b, 114s arranged portside and starboard of the propeller 104. Therefore, the electromechanical rudder actuator 112 receives an electrical signal from a data line 116. The data line 116 ends in a data input connector 116c.

[0330] The data input connector 116c is arranged on the common waterproof housing 108 to provide access from outside of the common waterproof housing 108. The data input connector 116c is sealed against the common waterproof housing 108 in a waterproof way. The data line 116 is also used for software update, such as updates of parameters related to the operation of the electromechanical rudder actuator 112.

[0331] The electrically driven propulsion system according to the embodiment of FIG. 7a, FIG. 7b, and FIG. 7c further comprises a propeller 104 optimized for a surface drive.

[0332] FIG. 7c and FIG. 7d illustrate the design of the propeller 104 designed for the surface drive.

[0333] Referring to FIG. 7c, which shows a stern projection of the integrated propulsion system 100, the propeller 100 comprises a radial sections 144 extending away from the center of the propeller 104, which is mounted to the propeller coupling 106p.

[0334] An essentially flat section 146 extends away from the radial section 144 along the azimuthal direction of the propeller 104 with an angle β of essentially 90° between the radial section 144 and an outer edge of the essentially flat section 146e.

[0335] Referring to FIG. 7d, which shows a side view of the integrated propulsion system 100, the essentially flat section 146, or its outer edge 146e, respectively, are formed at an angle γ with respect to the longitudinal direction of the propeller 104. The angle γ is defined by the pitch 150 and the diameter 148 of the propeller 104. In particular, the tangent of the angle γ is the diameter 148 over half the pitch 150.

[0336] FIG. 7e shows an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 7e is similar to the one of FIG. 7a, FIG. 7b, and FIG. 7c. Similar elements are indicated by same reference numerals and will not be described again.

[0337] As compared to the embodiment of FIG. 7a, FIG. 7b, and FIG. 7c, the embodiment of FIG. 7e comprises a single electric motor of 102 instead of two electric motors. Instead of the second electric motor, the embodiment of FIG. 7e comprises a motor upgrade space 138 to receive an additional electric motor if required.

[0338] Such an embodiment improves the design flexibility of the integrated propulsion system 100, making use of the applied axial flux motor 102. The geometry of the axial flux motor 102 beneficially permits to add or remove an electric motor and thus improves the design flexibility and the modularity of the electrically driven propulsion system 100.

[0339] All other components, in particular the pulse inverter 118 and the transmission 106, are provided for with specification in terms of electrical and mechanical power corresponding to the integrated propulsion system 100 with the maximum number of electric motors 102.

[0340] According to the embodiment depicted in FIG. 7e, the motor section 108a has space for two electric motors. It comprises one electric motor 102 and an upgrade space 138 for one additional electric motor. However, according to alternative embodiments, the motor section 108a provides space for two, four or more electric motors 102. The motor section 108a may comprise a single electric motor 102, and additional electric motors may be added in a modular way as needed to increase the overall maximum power of the electrically driven propulsion system 100. For maximum flexibility, any of the electric motors is preferably exchangeable with any other of the electric motors 102, i. e. the electric motors and the additional electric motors have similar physical dimensions and electrical characteristics.

[0341] FIG. 8a and FIG. 8b show an integrated propulsion system 100 according to another embodiment. The integrated propulsion system 100 of FIG. 8a and FIG. 8b is similar to the one of FIG. 7a, FIG. 7b, and FIG. 7c. Similar elements are indicated by same reference numerals and will not be described again. The integrated propulsion system 100 of FIG. 8a and FIG. 8b is designed with a series of modifications. According to different embodiments, the electrically driven propulsion system 100 is formed with any single one or any combination of the described modifications.

[0342] The embodiment of FIG. 8a and FIG. 8b further comprises an electromechanical rudder actuator 112, which receives signals from the data input connector 116c. The rudder actuator 112 actuates a central tiller arm 134 in response to the received signals. The movement of the central tiller arm 134 actuates a starboard tiller arm 134s and a portside tiller arm (not shown), thereby actuating a starboard rudder 114s and a portside rudder (not shown).

[0343] According to a corresponding embodiment, the electrically driven propulsion system 100 does not only integrate the propulsion as such, but also the steering of the watercraft. The entire unit is provided as a monolithic and fully optimized system. Thus, it renders installing the electrically driven propulsion system 100 as easy as possible, for example as a surface drive.

[0344] As compared to the embodiment of FIG. 7a, FIG. 7b, and FIG. 7c, the embodiment of FIG. 8a and FIG. 8b comprises a single electric motor 102, i. e. an electric motor 102 with a single housing. Nevertheless, a motor upgrade is possible, namely making use of an upgrade space in the housing of the electric motor 102.

[0345] FIG. 8c and FIG. 8d are detailed views of embodiments of electric motors 102 corresponding to the one of FIG. 8a and FIG. 8b.

[0346] The electric motor 102 of FIG. 8c comprises a stator 140 with windings of electric lines to drive the currents with windings and generate an electric field at the stator 140. The electric motor 102 further comprises rotors 142 with permanent magnets, arranged rotatably on an axis (not shown).

[0347] The electric motor 102 of FIG. 8d is similar to the electric motor of FIG. 8c. However, the electric motor of FIG. 8d comprises only one rotor 142 and a motor upgrade space 138 instead of the second motor. The rotor upgrade space 142 and hence the electric motor 102 may be upgraded with the second rotor 142.

[0348] According to the embodiments of FIG. 8c and FIG. 8d, the electric motor 102 provides space for two rotors 102, and two or one rotor(s) is (are) provided. However, according to alternative embodiments, the electric motor 102 is designed for three, four, five, six seven eight, or more rotors 142. It may initially comprise one, two, three, four, or more rotors 142.

[0349] According to a different embodiment (not shown), the electrically driven propulsion system comprises a motor space 108a for a plurality of motors 102, such as in FIG. 7a, FIG. 7e. Each single motor may have a modular design with a plurality of motors, as described in the context of FIG. 8c, FIG. 8d.

[0350] FIG. 9a and FIG. 9b illustrate a method 200 for connecting the electrically driven propulsion system 100 to a hull 202 with an opening 204, more specifically to the transom 202 of the hull. The electrically driven propulsion system 100 may be connected directly to the transom 202 with the opening 204. Optionally, a connecting frame 302 with an opening 304 matched to the opening 204 in the transom 202 may be mounted to the transom 202 prior to connecting the electrically driven propulsion system 100.

[0351] The connecting frame 302 allows for a quick, reliable and safe exchange of the electrically driven propulsion system 100 as a whole. In particular, the risk of damaging the hull 202 is reduced, as any physical contact between moving components and the hull 202 is prevented.

[0352] The connecting frame 302 according to the embodiment of FIG. 9a and FIG. 9b comprises a first ring-shaped element 306 mounted to the outside 210 of the watercraft, a second ring-shaped element 308 mounted to the inside 216 of the watercraft, and a seal 312 between a sealing face 310 of the first ring-shaped element 306 on the one side and the second ring-shaped element 308 as well as the transom 202 on the other.

[0353] In a first step, the electrically driven propulsion system 100 is placed on the outside 210 of the watercraft. A seal 212 is provided between the sealing face 110 and the hull 202.

[0354] In a second step 214, the motor section 108a of the electrically driven propulsion system 100 with the electric motors 102 is moved 214 through the opening 204 in the transom 202, and, if installed, through the opening 304 of the connecting frame 302, to the inside 216 of the watercraft. The propeller coupling 106p and the propeller 104 remain on the outside 210 of the watercraft.

[0355] In a third step 218a, 218b, the electrically driven propulsion system 100 is fixed 218 to the transom 202 and, if installed, to the connecting frame 302. To this end, through holes 110a, 220, 320a may be provided in the (sealing face 100 of the) propulsion system 100, transom 202 and the connecting frame 302. Via these through holes, bolts 222 are inserted 218a and screwed 218b into the threaded holes 320b in the (second ring-shaped element 308 of the) connecting frame 302 to implement the fixing 218. In embodiments without a connecting frame 302 (not shown), nuts on the inside 216 of the watercraft provide the threaded holes 320b.

[0356] In a fourth step, a waterproof connection is formed between the common waterproof housing 108 of the electrically driven propulsion system 100 and the transom 202 or, if installed, the connecting frame 302. Therefore, the bolts 222 are screwed 218b into the threaded holes 320a with a defined torque and with the seal 212 between the sealing face 110 and the transom 202 or the connecting frame 302, respectively.

[0357] Thus, the electrically driven propulsion system 100 may be connected to a watercraft in a few quick and simple steps. The electrically driven propulsion system 100 may be disconnected from the watercraft just as easily and quickly by performing the reverse of each step and in a reversed order of the steps. In case of a failure of the electrically driven propulsion system 100, for example related to the failure of one of the electric motors 102 or of the transmission 106, the electrically driven propulsion system 100 may be changed as a whole by disconnecting the defective electrically driven propulsion system 100 and connecting a corresponding replacement part. The modular design of the electrically driven propulsion system 100 allows for providing the replacement part more quickly and efficiently.

[0358] For example, multiple electrically driven propulsion systems 100 may be kept in a central storage facility. In case of a failure of an electrically driven propulsion system 100 installed on a boat somewhere in the world, one of the multiple electrically driven propulsion systems 100 may be just slightly modified in the central storage facility for the use as a replacement part for the defective system, for example by installing a suitable number of electric motors 102.

[0359] Subsequently, the replacement part may be shipped to a location of the boat and replace the electrically driven propulsion system 100 with the failure. The overall duration of the process from learning of the failure at the central storage facility to finishing the replacement of the electrically driven propulsion systems 100 on the boat may be short, for example less than 36 hours.

[0360] FIG. 9c summarizes the most important steps of the method 200.

[0361] In step 230, the electrically driven propulsion system 100 is provided as a whole on a second side 210 of the opening 204 of the hull 202.

[0362] In step 214, at least a section of the motor section 108a is moved, while keeping the electrically driven propulsion system 100 assembled as a whole and while keeping the propeller coupling 106p on the second side 210, through the opening 204 to a first side 216 of the opening 204 opposite to the second side 210.

[0363] In step 218, the electrically driven propulsion system 100 is fixed 218a, 218b to the hull 202 with the opening 204.

[0364] In step 232, a waterproof connection is formed between the hull 202 and the common waterproof housing 108.

[0365] FIG. 10a and FIG. 10b depict a connecting frame 302 according to an embodiment. Similar to the embodiment depicted in FIG. 9a and FIG. 9b, the connecting frame 302 comprises the first ring-shaped element 306 and the second ring-shaped element 308 with essentially identical shapes in a plane perpendicular to the longitudinal direction. The first ring-shaped element 306 and the second ring-shaped element 308 each comprise an opening 304a, 304b with an essentially identical shape. Threaded holes 316 in the first ring-shaped element 306 and through holes 318 in the second ring-shaped element 308 with identical arrangements serve as connecting means to connect the first ring-shaped element 306 and the second ring-shaped element 308 to each other using bolts 322. The first ring-shaped element 306 further comprises through holes 320a with a predefined arrangement, and the second ring-shaped element 308 comprises threaded holes 320b with the same arrangement.

[0366] When the first ring-shaped element 306 and the second ring-shaped element 308 are connected to each other using the through holes 318, the threaded holes 316, and the bolts 322, the openings 304a, 304b overlap to form an opening 304 of the connecting frame 302. For mounting the connecting frame 302 to the transom 202, the opening 204 of the transom 202 is formed to match the shape of the openings 304, 304a, 304b.

[0367] A first sealing face 310 is formed on the first ring-shaped element 306 to form a waterproof connection between the connecting frame 302 and the hull. Therefore, the first ring-shaped element 306 and the second ring-shaped element 308 are connected to each other with the hull 202 between them and the seal 312 between the hull 202 and the first sealing face 310.

[0368] When the first ring-shaped element 306 and the second ring-shaped element 308 are connected using the connecting means 316, 318, the through holes 320a and the threaded holes 320b overlap due to their identical arrangements. This allows for connecting the electrically driven propulsion system 100 to the connecting frame 302 by pushing 218a the bolts 222 through the (through holes 110a of the sealing face 110 of the electrically driven propulsion system 100 and the) through holes 320a and screwing 218b them into the threaded holes 320b. The first ring-shaped element 306 further comprises a second sealing face 320 on a face pointing away from the first sealing face 310. When the electrically driven propulsion system 100 is connected to the connecting frame 302 with the seal 212 between the sealing face 110 of the electrically driven propulsion system 100 and the second sealing face 320 of the first ring-shaped element, a waterproof connection may be formed by screwing the bolts 222 into the threaded holes 320b with a defined torque.

[0369] FIG. 11 illustrates a transom 202 of a hull 404 prepared for connecting the electrically driven propulsion system 100 as a surface drive. Therefore, an opening 204 is generated in the hull 404, typically in the transom 202 in the lower region of the transom 202.

[0370] An upper edge 402 of the opening is formed in a proximity of a static water line 400 of the hull 404, or of a watercraft comprising the hull 404, respectively. The static water line 400 refers to the water line when the hull or watercraft is not moving.

[0371] Watercraft with a surface drive typically has a high cruising speed and a hull adapted for planing. When the watercraft moves at/above its planning speed, the transom 202 lifts up, resulting in a lower water line 400′. The opening 204 is formed with its lower edge at the level of this lower, planing-speed water line 400′.

[0372] Through holes 220 are formed around the opening 204 in an arrangement matching the arrangement of the through holes 110a on the sealing face 100 of the electrically driven propulsion system 100, or of the through holes 320a or the threaded holes 320b of the connecting frame 302, respectively. The electrically driven propulsion system 100 may be connected to the hull 202 by pushing 218a bolts 222 through the through holes 110a and 220 (and the through holes 320a of a connecting frame 302, if installed) and screwing 218a them into the threaded holes 320b as described in the context of FIG. 9a, FIG. 9b, and FIG. 9c.

[0373] When the electrically driven propulsion system 100 is connected to the hull 404 according to this embodiment, the propeller coupling 106c, or the propeller 104, respectively, is arranged in the proximity of the planing-speed water line 400′. When a propeller 104 is installed, part of the propeller 104 is below the planing-speed water line 400′, whereas the remaining part of the propeller 104 is above the planing-speed water line 400′, as is characteristic of a surface drive. However, with respect to the resting watercraft, propeller coupling 106c and propeller 104 are in a vicinity of the static water line 400 below the static water line 400, typically up to 10 or 20 cm below the static water line 400.

[0374] A surface drive may provide a high efficiency, i. e. a strong forward propulsion per electric power supplied by the propulsion system, for example through the power inlet. This may improve the efficiency of an electric watercraft comprising the electrically driven propulsion system. In particular, a propeller coupling 106p, a propeller shaft 106c or a propeller 104 of a surface drive has an optimum revolution speed similar to a revolution speed of an electric motor 102 such as an axial flux motor 102. Installing the electrically driven propulsion system 100 as a surface drive therefore supports the use of a transmission 106 with a small gear ratio, which improves the energy efficiency and thus the range further.

[0375] The foregoing description should not be read as implying that any particular element, step, or function can be an essential or critical element that must be included in the claim scope. Also, none of the claims can be intended to invoke 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,” “module,” “device,” “unit,” “component,” “element,” “member,” “apparatus,” “machine,” “system,” “processor,” “processing device,” or “controller” within a claim can be understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and can be not intended to invoke 35 U.S.C. § 112(f). Even under the broadest reasonable interpretation, in light of this paragraph of this specification, the claims are not intended to invoke 35 U.S.C. § 112(f) absent the specific language described above.

[0376] The present disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, each of the new structures described herein, may be modified to suit particular local variations or requirements while retaining their basic configurations or structural relationships with each other or while performing the same or similar functions described herein. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive. Accordingly, the scope of the inventions can be established by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Further, the individual elements of the claims are not well-understood, routine, or conventional. Instead, the claims are directed to the unconventional inventive concept described in the specification.

LIST OF REFERENCE SIGNS

[0377] 100 electrically driven propulsion system [0378] 102 electric motors [0379] 104 propeller [0380] 106 transmission [0381] 106a motor shaft [0382] 106b gearbox [0383] 106c propeller shaft [0384] 106e encased section of transmission [0385] 106p propeller coupling [0386] 106x external section of transmission [0387] 108 common waterproof housing [0388] 108a motor section [0389] 108b transmission section [0390] 110 sealing face of the electrically driven propulsion system [0391] 110a through holes on the sealing face of the electrically driven propulsion system [0392] 112 rudder actuator [0393] 114b buckboard rudder [0394] 114s starboard rudder [0395] 116 data line [0396] 116c data input connector [0397] 118 pulse inverter [0398] 120 power inlet [0399] 122 heat exchanger [0400] 124 primary side of the heat exchanger [0401] 124c primary coolant channel [0402] 1240 primary coolant opening [0403] 126 secondary side of the heat exchanger [0404] 126c secondary coolant channel [0405] 1260 secondary coolant opening [0406] 128 support element [0407] 128a support arm [0408] 128b support column [0409] 130 offset along the vertical direction [0410] 132 thrust bearing [0411] 134 common tiller arm [0412] 134s starboard tiller arm [0413] 136 portion of the encased section of the transmission outside the watercraft [0414] 138 motor upgrade space [0415] 140 stator [0416] 142 rotor [0417] 144 radial section of propeller [0418] 146 essentially flat section of propeller [0419] 146e outer edge of flat section of propeller [0420] β Angle between outer edge and radial direction [0421] γ Angle between outer edge and center line [0422] 148 diameter of propeller [0423] 150 pitch of propeller [0424] 152 noise/vibration sensor [0425] 154 signal line of noise/vibration sensor [0426] 156 processor for analyzing signal of noise/vibration sensor [0427] 158 longitudinal direction [0428] 160 plane perpendicular to longitudinal direction [0429] 162 second plane perpendicular to longitudinal direction [0430] 164 thrust bearing [0431] 166 force/propulsion along axial direction [0432] 166′ transferred force/propulsion [0433] 168 axial direction [0434] 200 method for connecting the electrically driven propulsion system to a hull with an opening [0435] 202 hull, transom [0436] 204 opening of hull, transom [0437] 210 second side, outside [0438] 212 seal for the sealing face of the electrically driven propulsion system [0439] 214 moving the motor section through the opening [0440] 216 first side, inside [0441] 218 fixing the electrically driven propulsion system to the hull, transom [0442] 218a inserting bolts, pushing bolts through holes [0443] 218b screwing bolts into threaded holes [0444] 220 through holes of hull, transom [0445] 222 bolts for the threaded holes on the sealing face of the electrically driven propulsion system [0446] 230 providing the electrically driven propulsion system [0447] 232 forming a waterproof connection [0448] 302 connecting frame [0449] 304 opening of the connecting frame [0450] 304a opening of first ring-shaped element [0451] 304b opening of second ring-shaped element [0452] 306 first ring-shaped element [0453] 308 second ring-shaped element [0454] 310 first sealing face of the connecting frame [0455] 312 seal for the first sealing face of the connecting frame [0456] 316 threaded holes as first connecting means of the first ring-shaped element [0457] 318 through holes as a second connecting means of the second ring-shaped element [0458] 320a through holes of first ring-shaped element [0459] 320b threaded holes of second ring-shaped element [0460] 322 bolts for the threaded holes of the first ring-shaped element [0461] 400 static water line [0462] 400′ planing-speed water line [0463] 402 lower edge of opening of hull, transom [0464] 404 hull, watercraft for surface drive