ELECTRIC MOTORISED WATERCRAFT AND DRIVELINE SYSTEM

Abstract

In one aspect of the invention, there is provided a modular electrically motorized watercraft (10), the watercraft comprising a hull module (20) and a driveline system (60). The driveline system (60) comprises an electric power module (50) and a driveline module (30). The driveline module (30) is configured to be arranged at an underside of the hull module (20).

Claims

1. A modular electrically motorized watercraft comprising: a hull module; and a driveline system having an electric power module and a driveline module; wherein the driveline module is configured to be arranged at an underside of the hull module; and wherein the hull module, the electric power module, and the driveline module constitute independent sub-assemblies in the form of modules which can be assembled to form the watercraft.

2. The watercraft according to claim 1, wherein the driveline system is configured to operate independent of the hull module.

3. The watercraft according to claim 1, wherein the driveline module and the electric power module operate externally to the hull module during operation of the watercraft.

4. The watercraft according to claim 1, wherein the electric power module and the driveline module are detachably attached on opposite sides of the hull module.

5. The watercraft according to claim 1, wherein the hull module comprises at least one through-hole extending through the hull module.

6. The watercraft according to claim 5, wherein the through-hole extends from an upper surface of the hull module to a bottom surface of the hull module.

7. The watercraft according to claim 5, wherein the through hole provides an opening for mechanical and electrical connection there through between the electric power module and the driveline module.

8. The watercraft according to claim 5, wherein an external side of the hull module forms an open compartment configured to receive the electric power module.

9. The watercraft according to claim 5, wherein the through-hole fluidly connects an upper side with a lower side of the watercraft.

10. The watercraft according to claim 8, wherein the through hole is in fluid communication with the open compartment.

11. The watercraft according to claim 8, wherein the open compartment is configured to allow water to flow therein when the power module is arranged in the open compartment to thereby enable the power module to become at least partially submerged in water.

12. The watercraft according to claim 11, wherein water that flows into the open compartment is allowed drain through the hull module via the through hole.

13. The watercraft according to claim 1, wherein an underside of the hull module comprises an elongated recess or depression extending in a longitudinal direction of the hull module and configured to receive the driveline module.

14. The watercraft according to claim 1, wherein the watercraft is a hydrofoiling watercraft, a motorized surfboard, a motorized wake board, a jetski/water scooter, an over water drone, an underwater drone, an underwater craft, an underwater personal craft, a submarine, or a boat.

15. A driveline module comprising: a motor in driving connection with an impeller; a stator arranged downstream of the impeller; and a nozzle arranged downstream of the stator; wherein the motor, the impeller, the stator, and the nozzle form a water jet arrangement.

16. The driveline module according to claim 15, further comprising a casing surrounding the impeller and the stator.

17. The driveline module according to claim 16, wherein the casing and the motor are respectively configured to be attached to a hull connection which fixates the positions of the casing and the motor.

18. The driveline module according to claim 15, wherein an electric speed controller constitutes a sub-module of the driveline module.

19. The driveline module according to claim 15, wherein the driveline module is independently waterproof.

20. The driveline module according to claim 15, wherein the motor is disposed an axial distance apart from the impeller to form a gap, such that a drive axle extends through a void space.

21. The driveline module according to 20, wherein the gap has an axial length (λ) configured to cooperate with a cavity of a hull module such as to minimize hydrodynamic losses and facilitate water ingestion of the water jet arrangement.

22. The driveline module according to 21, wherein the axial length (λ) is configured to, during use, facilitate that water flowing along the driveline module is provided a sufficient distance upstream of the impeller to attain a flow direction that is substantially parallel to the drive axle.

23. The driveline module according to 21, wherein the cavity is formed by providing a gradual transition between the hull module and a depression in the hull module configured to receive the driveline module.

24. The driveline module according to claim 15, further comprising hydrofoil wings and/or struts.

25. The driveline module according to claim 15, further configured to be at least partially received in a hull module.

26. The driveline module according to claim 21, wherein the axial length (λ) of the gap is in the range 10 to 30% of the length of the driveline module.

27. The driveline module according to claim 15, wherein the stator is configured to reduce turbulence downstream of the impeller.

28. The driveline module according to claim 16, wherein the casing comprises inlet guide vanes configured to protect the impeller and to facilitate that a flow of water into the casing is directed in a direction of a longitudinal extension of the casing.

29. A driveline system for a watercraft, the driveline system comprising: a power module; and the driveline module according to claim 15.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0108] Embodiments of the invention will be described in further detail below in the shape of non-limiting examples and with reference to the accompanying drawings, in which:

[0109] FIG. 1 shows a perspective side view of the watercraft according to an embodiment of the invention.

[0110] FIG. 2 shows an assembled view of the embodiment of FIG. 1.

[0111] FIG. 3 shows a driveline system according to one embodiment of the invention.

[0112] FIG. 4 shows an isometric view of the driveline module according to an embodiment of the invention.

[0113] FIG. 5 shows an isometric top view of a hull module according to an embodiment.

[0114] FIG. 6 shows an isometric top view of a hull module according to an embodiment and a thereto assembled driveline module according to an embodiment.

[0115] FIG. 7 shows an isometric top view of a hull module according to an embodiment and a thereto assembled power module according to an embodiment.

[0116] FIG. 8 shows a perspective side view of the watercraft according to an embodiment.

[0117] FIG. 9 shows an isometric bottom view of the watercraft according to an embodiment.

[0118] FIG. 10a shows a schematic cross-sectional view along the A-A line of FIG. 9.

[0119] FIG. 10b shows a schematic cross-sectional view along the B-B line of FIG. 9.

[0120] FIG. 11 shows details of the hull module and the driveline module according to embodiments.

[0121] FIG. 12a is a schematic illustration of a fluid flow.

[0122] FIG. 12b is another schematic illustration of a fluid flow

[0123] FIG. 13 shows a schematic illustration of a water-jet arrangement according to an embodiment.

DETAILED DESCRIPTION

[0124] The invention will now be explained with reference to the accompanying drawings.

[0125] FIG. 1 shows a watercraft 10 according to one embodiment of the invention wherein the hull module 20 of the watercraft 10 is in the form of a board. According to general aspects the hull module 20 is fluid tight or waterproof. In this particular embodiment the board itself is also buoyant on its own merit and may comprise an empty shell-type hull. The hull module 20 has a front end 22 and a rear end 21 with the hull extending there between.

[0126] The hull module 20 comprises means for receiving the electric power module 50 here in the form of a shelf-like compartment 24 facilitating that an electric power module 50 is safely received and retained in the hull module 20 without risk of dislodging during operation of the watercraft 10. The electric power module 50 may comprise a shape corresponding to an external surface, such as the top-part of the hull module and thus become flush with edges of the hull module 20 and/or compartment 24 upon attachment to the hull module 20/compartment 24. Attachment means 23, 53 may be provided in the hull module 20 and/or on the electric power module 50 for detachable attachment of the electric power module 50 to the hull module 20. The attachment means 23, 53 may comprise releasable attachment means, such as a snap-in function.

[0127] The compartment 24 thus constitutes an external surface of the hull module 20 which may abut the electric power module 50. Preferably, the electric power module 50 is disposed flush with an upper surface of the hull module 20 when the electric power module 50 is received in the hull module 50.

[0128] A through-hole 11 in the form of a through hole extends through the hull module 20. Thus, the inner surface of through-hole 11 constitutes an external surface of hull module 20 such that no water is allowed to enter the hull module. According to aspects the hull module is independently waterproof or hermetically sealed. Thus, the hull module 20 may be buoyant regardless its orientation in relation to water.

[0129] The through-hole 11 is adapted to receive a connector 35 of a driveline module 30. The driveline module 30 is adapted to be attached to a bottom external surface of the hull module 20. Thus, the entire driveline module 30 is submerged in fluid, such as water, during operation of the watercraft 10. The driveline module and/or the electric power module 50 may comprise power electronics for operating the watercraft. Such power electronics is known in the art and is not the subject of the current disclosure.

[0130] The driveline module 30 comprises at least one motor 31 in driving connection with at least one propelling member 32, 139 via at least one drive shaft 33. The motor 31 may be comprised in a motor unit which also may comprise power electronics. The propelling member 32 may for example comprise one or more propellers. The driveline module 30 may comprise casing or pods surrounding the propelling member.

[0131] The propelling member 32 and the motor 31 is separated by a spacing or gap having of length λ. The gap may be in the form of a void 52, i.e. a void space between the motor 31 and the impeller 139 or pod 40. The casing 40 and the motor 31 are respectively attached to a hull connection 34 which fixates the positions casing 40 and motor 31 in relation to each other. Thus, the casing 40 and the motor unit 31 are according to aspects not in direct contact with each other.

[0132] FIG. 2 shows the watercraft 10 as described in conjunction with FIG. 1. In FIG. 2 the watercraft is assembled. The driveline module 30 is attached to the bottom of the hull module 20 such that substantially the entire driveline module 20 or the entire driveline module 20 is submerged during operation, i.e. when the watercraft is launched into water.

[0133] During operation the water will provide passive water cooling to the driveline module 20 and in particular to the motor 31. However, as the watercraft makes speed over water, the water flowing around the driveline module 20 will provide efficient cooling.

[0134] It should be noted that due to the gap 52 of length λ, it is facilitated that the water enters the propelling member 31 at an advantageous angle with respect of the pitch of the propellers of the propelling member, i.e. the blades of the propelling member 31. The water may thus enter the casing 40 and/or the propelling member 31 in a direction substantially parallel the drive axle 33, thereby increasing efficiency and performance of the driveline system 60 i.a. by achieving greater speeds of the watercraft 10. The length of λ may correspond to about 5 to 50% of the length of the driveline module, preferably about 10 to 30%.

[0135] The watercraft 10 may be controlled by various means such as a speed control disposed on the electric power module 50 and/or on the driveline module 30. The watercraft 10 may also be controlled via remote control, for example by means of a remote control unit 70.

[0136] The watercraft 10 may be suitable for personal transport or leisure. For example, a user may stand on the board or lay down on the board during operation. In a further example the user may lay down on the board and control the watercraft by operating the remote control unit 70.

[0137] FIG. 3 shows a driveline system 60 formed by the driveline module 30 and the electric power module 50. The driveline system 60 can operate independently the hull module 20. One possible interpretation of the term “operate” is that the driveline system 60 is self-sustained in terms of providing a functioning driveline i.e. comprising power supply in the form of the electric power module 50, power transformation to kinetic energy by means of said motor 31 and propelling force by means of said propelling member 32.

[0138] FIG. 4 show a further embodiment of the driveline module invention which unless specified comprise the same features as has been described in relation to FIGS. 1-3.

[0139] In the embodiment of FIG. 4 the driveline module comprises struts 38 and hydrofoil-wings 39. The struts 38 and wings 39 facilitates that the watercraft 10 can to some extent lift over the water to enable the watercraft 10 to ride over the water and therefore enable less drag in the water and therefore decreasing the energy-consumption of the watercraft 10 and also increasing the speed of the watercraft 10.

[0140] According to one aspect, the invention relates a method of assembling a modular electric motorized watercraft 10. The electric motorized watercraft 10 comprising a hull module, a driveline module and a power source module. The method may comprise the steps of; receiving a requirement relating to a desired functionality of the watercraft; selecting a hull module from the group comprising; hydrofoiling watercraft, surfboard, jetski/water scooter, over water drone, underwater drone, submarine or boat; detachably attaching the driveline module to said hull module; detachably attaching said power source module to said hull module; connecting said power source module to said driveline module. According to aspects of the method, the watercraft 10 consists of the hull module, the electric power module the driveline module.

[0141] In a simple form of the invention, the modular electrically motorized watercraft 10 comprises a hull module 20 and a driveline system 60 shown in FIG. 3. The driveline system 60 comprises an electric power module 50 and a driveline module 30. The driveline system 60 is capable of operating independently the hull module 20. Thus, the driveline system 60 is, when assembled, fully water proof. This feature has the advantage that it can operate externally the hull module 20 during operation of the watercraft 10 such that no electrical components, or no components essential for the basic function of the watercraft has to be integrated in the hull module. Thus, the hull module 20 may comprise only a dead shell. The driveline module 30 is adapted to be attached to an underside of the hull module, typically to a bottom external surface of the hull module 20. In particular the motor 31 is arranged underneath the watercraft 10.

[0142] The hull module 20 is preferably independently waterproof and may also be independently buoyant, i.e., the hull module may in some embodiments not be buoyant, for example if the watercraft is an underwater craft. Further, the power module 50 and driveline module 30 may each be individually waterproof.

[0143] The modules 20, 30, 50 may constitute individual parts. The modules constitute independent sub-assemblies in the form of modules which can be assembled to a fully functional watercraft.

[0144] The driveline module 30 and the power module 50 may be fully connected by means of a single connector 35, for example a plug and socket arrangement.

[0145] The watercraft 10 may comprise one or more driveline modules 30 connected to the hull module 20.

[0146] Substantially the entire driveline module 30 is submerged in a surrounding fluid during operation of the watercraft 10. The driveline module 30 comprises a water jet arrangement 137 comprising at least one impeller in driving connection with a motor 31 of the driveline module 30 via a driving axle 33. The motor 31, the axle 33 and the water jet arrangement 137 are preferably arranged along a straight line. The motor 31 is disposed with an axial distance apart from the propelling member 32. In particular, the motor 31 and the water jet arrangement 137 are preferably entirely submerged during operation of the watercraft 10. However, connecting means, in the form of connector 35 may extend upwards from the driveline module 30 and into the hull module 20, preferably through the hull module 20 via a through hole 11, as will be further explained herein. One possible meaning of the term “through hole” is that it extends through the whole entity, i.e. in this case the whole entity of the hull module 20.

[0147] The electric power module 50 and the driveline module 30 are respectively configured to establish electric connection with each other and mechanical connection, preferably releasable mechanical connection with each other.

[0148] The electric power module 50 is configured to be attached an external side of the hull module 20 and thus forms an external side of said watercraft 10, typically an upper side of the watercraft 10 and on which surface a user of the watercraft 10 can be positioned.

[0149] The electric power module 50 and the driveline module 30 may be detachably attached on opposite sides of said hull module 20. This facilitates that the power module 50 can easily be switched out for another power module for example when the batteries are depleted, and so without pivoting or turning the hull module 20, for example when floating on water,

[0150] The driveline module 30 comprises at least one motor 31 in driving connection with a respective propelling member 32 by means of a drive axle 33 and preferably the propelling member 32 is disposed at a rear end 21 of the watercraft 10. The propelling member 32 may be an impeller of a water jet arrangement 137, as will be further explained herein.

[0151] As mentioned, the hull module 20 comprises at least one through hole 11 extending through said hull module 20, as derivable inter alia from FIGS. 1 and 5. The through hole 11 may extend from an upper side of said hull module 20 to a lower side of said hull module 20.

[0152] This configuration has a number of advantageous effects, as has been made apparent herein. As mentioned, it facilitates that the power module 50 can be switched for a new one without pivoting the hull module 20.

[0153] The through hole 11 is adapted to facilitate connection between the power module 50 and the driveline module 30. In some embodiments, the through hole 11 receives the connector 35 of the driveline module 30.

[0154] Thus, the through hole 11 provides an opening for mechanical and electrical connection there through, hence between the electric power module 50 and the driveline module 30, this is shown in FIGS. 1 and 6.

[0155] The hull module 20 is configured to receive the electric power module 50 as shown in FIG. 7. An external side of the hull module 20 may form an open compartment 24 in the form of an open basin 24 configured to receive the electric power module 50, preferably from above the hull module 20. The compartment 24 is illustrated in FIG. 5. The inner walls of the compartment will thus prevent the power module from lateral movements or dislodging.

[0156] The driveline module 30 may comprise an electronic speed controller 36 (ESC). In some embodiments, the ESC 36 is disposed in a portion of the driveline module positioned vertically directly underneath the through-hole 11. The said portion of the driveline module 30 may comprise the connector 35. This has the effect that the ESC will be passively cooled by means of water flowing from the through-hole 11 under the action of gravity. This is achieved since the through-hole 11 fluidly connects point A above the hull module 20 with point B below the hull module 20 of the watercraft 10 and also during operation of the watercraft 10. Thus the driveline module 30, and in particular the ESC may be water-cooled passively by means of gravity, e.g. during operation in water.

[0157] The through hole 11 further facilitates that, when the watercraft is in operation i.a. when a user makes speed over water, water is pushed upwards from beneath the hull module 20, through the trough-hole 11 to the compartment 24, and thereby cools the power module 20.

[0158] Further, the power module 50 and the compartment 24 are configured such that there is a slot 37 between the power module 20 and the compartment 24 when the power module 20 is arranged in the compartment 24. Thereby, water from the ambient, e.g. splashing over the hull module 20, is allowed to fill up the compartment 24 via the slot 37 and thus flow around, surround and at least partially submerge the power module 20, providing it with passive cooling.

[0159] As explained, the driveline module 30 may comprise hydrofoil wings 39 and struts 38 to enable a foiling ride of said watercraft 10. This is further illustrated in FIG. 6, where an optional foil 39 is shown. The optional foil may be configured to provide a minor lifting power to the watercraft, such as to only raise the nose or front end of the hull module 20 when making speed over water while the water jet arrangement 137 remains completely submerged.

[0160] The electric power module 50 and said driveline module 30 connect electrically and mechanically via the through-hole 11. Thus, the electric power module 50 and the driveline module 30 connect electrically and mechanically externally said hull module 20. The through hole 11 is formed removed from the edges of the hull module 20, preferably substantially at a transversally centered position of the hull module 20. Thus, the through hole 11 comprises a circumferential rim and the hull module 20 extends continuously around/about the through-hole 11. The through hole 11 extends from a bottom surface of the hull module 20 to a top surface of the hull module 20. The through hole thereby fluidly connects an upper side to a lower side of the hull module 20 also when the watercraft is assembled.

[0161] The electric power module 50 and/or the driveline module 30 may at least partially extend into the through hole 11 as shown in FIGS. 1 and 6. This has the advantage that there are no electrical wires extending between the power module 50 and the driveline module 30 as they connect solely by means of releasable connectors. This has the further advantage that the connector 35 extends above a bottom surface of the compartment 24 as shown in FIG. 6.

[0162] The through hole 11 opens to and/or is in communication with the open compartment 24 as shown in FIG. 5. Hence, the compartment 24 opens to the ambient and/or may constitute a depression in the hull module 20 which is open to ambient elements such as water during operation of the watercraft 10.

[0163] Each one of the electric power module 50 and/or the driveline module 30 comprises respective electric connection means 35 and releasable mechanical connection means 35 for connecting to each other. Wherein the electric connection means 35 and/or the releasable mechanical connection means 35 is disposed externally the hull module 20.

[0164] The electric connection means 35 and/or the releasable mechanical connection means 35 may be disposed in the compartment 35 as in the embodiment illustrated in FIG. 6. The mechanical connection 35 comprises a watertight connection. The mechanical connection means 35 may alternatively comprises a watertight connection disposed immediately adjacent the through hole 11. Alternatively, the electric power module 50 and/or the driveline module 30 at least partially extends into said through-hole 11.

[0165] The mechanical connection 35 physically and sealingly connects, releasably locks and holds the electric power module 50 and the driveline module 30 together. The mechanical connection 35 may comprise a releasable snap-in function.

[0166] The electric connection means 35 and releasable mechanical connection means 35 comprises a waterproof blind-mate connection 35 configured to connect the power module 50 to the driveline module 30 simultaneously as the power module 50 is received in the compartment 24.

[0167] The through hole 11 provides a passage for cooling water through the hull module 20. The compartment 24 is configured to facilitate passive water cooling to the power module 50, in particular when the power module 50 is received in the compartment 24.

[0168] The compartment 24 is configured to allow water to flow therein when the power module 50 is received therein to thereby at least partially submerge the power module 50 in cooling water. The water that flow into said compartment 24 is allowed drain through the hull module 20 via the through hole 11. Thus, water accumulated in the compartment is drained under the action of gravity via the through hole 11 to provide passive cooling to the driveline module 30. Hence, the through hole may be arranged to drain cooling water that flow into the compartment through the hull module.

[0169] The electronic speed controller 36 may be configured to control the operation of the driveline module. Further, the electronic speed controller 36 may be further configured to control the operation of the motor 31.

[0170] In some embodiments, the remote control unit 70 is operatively connected to the electronic speed controller 36 for controlling the watercraft, e.g. the driveline module. In some embodiments, the remote control unit 70 may be operatively connected to the electronic speed controller 36 via a communication unit. The communication unit may be disposed on the power module 50. The communication unit may be powered by means of said power module 50, e.g. the battery of the power module.

[0171] In some embodiments, the remote control unit 70 is operatively connected to the electronic speed controller 36 by means of electric wire or cable. In some embodiments, the remote control unit 70 may be connected to the electronic speed controller 36 via the communication unit by means of electric wire or cable. In some embodiments, the communication unit is coupled to the electronic speed controller 36 by means of contact pins.

[0172] In some embodiments, the remote control unit 70 is wirelessly connected to the electronic speed controller 36. In some embodiments, the remote control unit 70 is wirelessly connected to the electronic speed controller 36 via the communication device. The communication device may be wirelessly connected to the electronic speed controller 36.

[0173] In some embodiments, the watercraft or driveline module may further comprise at least one amplifier, each of which being configured to strengthen the signals between the remote control unit 70 and the communication unit and/or the signals between the remote control unit 70 and the electronic speed controller 36 and/or the signals between the electronic speed controller 36 and the communication unit.

[0174] In some embodiments, at least one amplifier for strengthening the signals between the remote control unit 70 and the electronic speed controller 36 and/or the communication unit may be disposed on the external side of the hull module 20 or on the electric power module.

[0175] In some embodiments, at least one amplifier for strengthening the signals between electronic speed controller 36 and the remote control unit 70 and/or the communication device may disposed on the electric power module 50 or the external side of the hull module 20.

[0176] Referring in particular to FIGS. 8 to 10, an underside of the hull module 20 may comprise an oblong depression 150 extending in the longitudinal direction of the hull module 20 and configured to receive at least a portion of the driveline module (30). The depression 150 is preferably elongated. The longitudinal axis of the depression 150 is substantially parallel the longitudinal axis of said driveline module 20.

[0177] The depression 150 may have a length corresponding to the driveline module 20. The depression 150 brings about the advantageous effect that the hydrodynamic resistance of the watercraft is greatly improved. Also, by arranging the driveline module 20 partially submerged into the hull module 20, i.e. in the depression 150, the maneuverability of the watercraft is improved.

[0178] Referring to FIGS. 9 and 10a, the said depression 150 has a cross sectional shape corresponding to a semi-circle or semi-cylindrical shape which envelopes substantially half of a corresponding cylindrical shape of the driveline module 20, in particular the motor 31 (or a motor casing) and the cylindrical casing of the propelling member 32, 139, i.e. the pod 40.

[0179] The surface of the hull module 20 adjacent a portion of the depression 150 in the immediate vicinity of the gap 52 between the motor 31 and the pod 40 may comprise evened out edges to form a smooth gradual transition 151 between the surface of the hull module 20 and the depression 150. Hence, the width of the depression 150 is substantially wider in the vicinity of the gap 52, as shown in FIGS. 10b and 11. The gradual transition 151 between the surface of the hull module 20 and the depression 150 forms a cavity 51 extending around the gap 52, i.e. extends over the vicinity of the drive axle 33. Thereby the axle 33 extend through a void which faces the open water during operation, this facilitates increased water-ingestion of the water jet arrangement 137.

[0180] Thanks to the gap 52 being configured to cooperate with the cavity 51 by adapting the length λ thereof, the driveline module 30 facilitates improved maneuverability of the watercraft 10 while maintaining a high efficiency of the water jet arrangement and low hydrodynamic losses. FIG. 12a is a schematic side-view of how the configuration of the gap 52 achieves that the angles of deflection/diversion α′, α″ of a fluid flow F to be ingested is minimized along the driveline module 30. Also shown in FIG. 12a is the waterline W of the watercraft 10, the depression 150 and the bottom surface S of the hull module 20. As derivable, the fluid flow F, i.e. water to be ingested is provided a sufficient distance to flow into the cavity 51 by means of a small angle of diversion α′ relative to the bottom surface of the hull module 20 and subsequently provided sufficient distance to attain a flow direction parallel the drive axle 33 (not shown in FIG. 12a) by means of a small angle of diversion α″. Thus, the angles of deflection α′ and α″ are minimized by providing the gap 52 with the length λ between the impeller 139 and the motor 31, while still the motor 31 and the water-jet arrangement 137 are both submerged and coaxially arranged in the hull module 20. This principle also applies for water flowing into the open cavity 51 from the vicinity of the cavity 51, for example from the flanks 25 on each side of the open cavity 51 as shown in FIG. 12b; the gap 52 with the length λ and the gradual transition 151 facilitates hydrodynamically advantageous flow path which minimizes the angles of diversion β′ and β″ and thus energy losses of water flowing into the cavity 51 from the vicinity of the cavity 51, for example from the flanks 25 on each side of the cavity 51.

[0181] The watercraft 10 may be a hydrofoiling watercraft, a surfboard, jetski/water scooter, over water drone, underwater drone, underwater craft, underwater personal craft, submarine, boat.

[0182] In general, the modules 20, 30, 50 are independent sub-assemblies and may thus comprise independent parts. In particular one or more of the modules 30 and 50 may be independent sub-assemblies arranged in a single housing, whereby the connector 35 is integrated or extends from the housing.

[0183] The hull module 20 does not have any waterproof compartments for electronics, motors, gasoline or similar since all necessary electrical components are integrated in the driveline system 60. Also, no electrical parts are integrated in the hull module. The power module 50 may comprise one or more of battery cells, a computer, battery management system, switches.

[0184] The motor 31 is typically installed in a waterproof container or casing of the driveline module 30.

[0185] An external surface, preferably an upper surface of the hull module 20 comprises a shelf-like compartment 24 configured to receive and retain the electric power module 50.

[0186] An inner surface of the through-hole 11 constitutes an external surface of the hull module 20 such that no water is allowed to enter the hull module 20. The through-hole 11 penetrates the entire hull module 20, thus the through-hole 11 allows immediate access to the underside of the hull module 20 from the upper side of the hull module 20 via the through hole 11.

[0187] The through-hole 11 is adapted to receive a connector 35 of the driveline module 30. The through hole 11 preferably has a diameter sized to form a circumferential slot about the connector 35. A fluid passage between the inner circumference of the through hole and the connector 35.

[0188] The water jet arrangement 137 of the driveline module 30 comprises a casing or pod surrounding the propelling member 32. The casing 40 and the motor unit 31 are not in direct contact with each other. The motor 31 and the propelling member 32 are separated by a gap 52 having the length λ λ may be in the range of 10 to 30% of the length of the driveline module 20, preferably between 10 to 20%.

[0189] The depression 150 may extend along approximately between 20 to 40% of the length of the hull module 20, preferably about 33%.

[0190] The casing or pod 40 and the motor 31 are respectively attached to a hull connection 34 which fixates the positions of the pod 40 and the motor 31.

[0191] Now referring to FIGS. 9 and 13, the propelling member 32 may be an impeller 139 disposed in the pod 40. The pod 40 comprises a stator 140 downstream the impeller 32. The pod 40 also comprises a nozzle portion 141 downstream of the stator 140. Optionally, the pod 40 also comprises inlet guide vanes 138 configured to protect the impeller 139 and to facilitate that a flow of water into the pod 40 is directed in the direction of the longitudinal extension of the pod 40. The stator 140 facilitates reduced turbulence aft/downstream of the impeller 139 and thus increases the efficiency of the driveline module 20. Further, the stator also facilitates that the water jet created by the water jet arrangement 137 is straightened, i.e. directed in a longitudinal direction of the water jet arrangement 137. The nozzle portion 141 of the pod 40 comprises a section with decreasing inner diameter of the pod 40, and thus facilitates an increase in the velocity of the exiting water jet at an exit of the nozzle portion 141. The pod 40, the stator 140 and optionally the inlet guide vanes 138 are made or provided as one entity or as an assembly. The diameter of the pod 40 is preferably greater than the diameter of the motor casing.

[0192] The connector means 35 of said driveline module 30 may be received in the power module 50, as derivable from FIGS. 1 and 6.

[0193] The driveline system 60, also referred to as the propulsion system, comprises the power module 50 and the driveline module 30. The driveline module 30 is configured to be mounted to an underside of a hull module 20 of said watercraft. The driveline system 60 is independently waterproof and capable of operating independently the hull module 20. Hence, the power module 50 and driveline module 30 work together externally the hull module 20.

[0194] In a preferred embodiment, the driveline system comprises the electronic speed controller (ESC) 36 arranged surrounded by water to provide the ESC 36 with passive cooling from the surrounding water in which it is submerged during operation.

[0195] I should be appreciated that embodiments of the disclosure are generally combinable unless specified.