WO2013110695A1

WO2013110695A1 - Magnus-effect rotor

Info

Publication number: WO2013110695A1
Application number: PCT/EP2013/051322
Authority: WO
Inventors: Jørn Paul Winkler
Original assignee: Winkler Joern Paul
Priority date: 2012-01-24
Filing date: 2013-01-24
Publication date: 2013-08-01

Abstract

The invention relates to a vessel comprising a deck (10), a Magnus-effect rotor (1) and a motor drive for rotating the Magnus-effect rotor around a longitudinal axis in an operational state, the rotor in its operational state being vertically mounted on the vessel and having a substantially cylindrical outer surface (2), and displacement means (7, 8) for displacing the rotor towards the deck (10) in an inoperational state.

Description

Magnus-effect rotor Field of the invention [0001] The invention relates to a Magnus-effect rotor, for example for use onboard a sea-going vessel.

Background of the invention [0002] Such a Magnus-effect rotor is known from US 4.602.584. It has long been known that a circular cylinder rotating about its longitudinal axis is capable of producing a lift force when placed in an air stream flowing perpendicular to the longitudinal axis of the cylinder, quite similar to the lift force produced by a wing when placed in a laminar air flow. This lift force is named after its discoverer, Heinrich Gustav Magnus, the German scientist who first investigated this phenomenon in 1853.

[0003] The Magnus-effect was first applied for propelling vessels in 1924 by Anton Flettner. Flettner used elongated cylinder structures, standing upright from the deck of the vessel, for propelling the vessel using the lift force mentioned (these structures were also called: "Flettner-rotors"). The advantage with respect to conventional sails was that the vessel was able to sail at sharper angles with respect to mildly opposing, thus relatively unfavourable, wind directions. Additionally, the Flettner-rotor was able to supplement the propulsion of fuel-powered vessel, thereby decreasing the fuel consumption of such a vessel.

[0004] However, in case of strong opposing winds essentially parallel to the desired sailing direction, or in wind conditions with severe gusts, the Flettner-rotor fails to provide any additional propulsion. In these conditions the rotor proves to be a great source of drag to due to the wind hitting the relatively large frontal surface of the rotor. Furthermore, in severe weather conditions with strong winds and high waves, the rotor proves to provide additional instability to the vessel due to the raised centre of gravity. [0005] In view of the foregoing, it is therefore an object of the invention to provide a vessel having a Magnus-effect rotor wherein drag of the rotor in unfavourable wind or weather conditions is reduced and wherein the centre of gravity of the rotor is lowered. Summary of the invention

[0006] Thereto, a vessel is provided comprising a deck, a Magnus-effect rotor and a motor drive for rotating the Magnus-effect rotor around a longitudinal axis in an operational state, the rotor in its operational state being vertically mounted on the vessel and having a substantially cylindrical outer surface, and displacement means for displacing the rotor towards the deck in an inoperational state.

[0007] The displacement means allow the rotor to be displaced towards the deck of the vessel to an inoperational state, such that susceptibility of the rotor to wind gusts et cetera is reduced and the centre of gravity is lowered during unfavourable conditions.

[0008] An embodiment relates to a fore mentioned vessel wherein the displacement means comprise a lower end of the rotor being rotatably supported by a lower rotor support structure that is hingeably connected to a deck structure arranged on the deck of the vessel, such that a substantially horizontal hinge axis is defined, wherein by pivoting the lower rotor support structure with respect to the deck structure around the hinge axis the rotor is tilted from the operational state to the inoperational state and vice versa, wherein in the inoperational state the rotor is substantially aligned with the deck. This provides for a relatively reliable mechanical tilting mechanism.

[0009] Another embodiment relates to a fore mentioned vessel wherein the displacement means comprise the rotor having an upper tubular element and a lower tubular element, whose centre lines are aligned with the longitudinal axis of the rotor, wherein the tubular elements can be displaced telescopically with respect to each other between the operational and inoperational states, wherein a biased spring element is arranged inside the rotor between the upper and the lower tubular element to facilitate the telescopic displacement from the inoperational to the operational state. Such a telescopic mechanism with a spring allows for easy collapsing of the rotor and for lowering its centre of gravity.

[0010] Another embodiment relates to a fore mentioned vessel wherein the rotor is rotatably supported by an internal rotor support structure, wherein the spring element is arranged between an upper end of the internal rotor support structure and an end plate arranged at an upper end of the upper tubular element. Thus, the spring element is shielded from external environmental conditions reducing wear thereof. [0011] An embodiment relates to a fore mentioned vessel wherein the rotor comprises a rigid cylinder, the rigid cylinder being constructed out of longitudinally connected, cylindrical sections, wherein at least one of the sections comprises longitudinally extending plates distributed along the circumference of the body section, wherein a lower or upper end of one of the plates is recessed longitudinally with respect to the respective lower/upper ends of the plates of the same body section that adjoin the recessed plate in the circumferential direction. This allows for a strong, yet light, construction of the rotor cylinder.

[0012] An embodiment relates to a fore mentioned vessel, the deck defining a deck level and a lower deck situated below the deck level, defining a lower deck level, wherein the rotor comprises a rigid cylinder that in the operational state has a lower end that is situated at a distance above deck level, wherein the rigid cylinder is mounted with the lower end on a shaft that extends downwards from the lower end of the cylinder past deck level to the lower deck level, the shaft having an outer diameter that is smaller than the outer diameter of the rigid cylinder, wherein a lower bearing is provided at the lower deck level for supporting the lower end of the shaft and for allowing rotation of the shaft around the longitudinal axis and the upper end of the shaft is rotatably supported by an upper bearing arranged in a rotor support structure arranged near the lower end of the cylinder, and the motor drive is connected to the shaft for rotating the rotor at a position between the lower and upper bearings. Because of the motor drive engaging the shaft between the two bearings, unwanted vibrations are significantly reduced. [0013] An embodiment relates to a fore mentioned vessel wherein the motor drive is arranged at deck level. This arrangement is convenient for allowing easy access to the motor drive for maintenance. [0014] Another embodiment relates to a fore mentioned vessel, wherein a lower and/or upper end of the rotor is/are provided with end plates. Such end plates are useful for reducing unwanted vorticity and turbulence near the rotor ends.

[0015] An embodiment relates to a fore mentioned vessel wherein the end plates comprise radially extendable and retractable segments. The segments can conveniently be retracted when moving the rotor to the inoperational state, such that less deck space is required.

[0016] An embodiment relates to a fore mentioned vessel wherein the end plates are made of an elastic material. During spin-up of the rotor the end plates will automatically be forced outwards due to centrifugal forces acting on them to reach a transversal orientation with respect to the rotor cylinder. During 'spinning down' of the rotor, e.g. before moving the rotor to the inoperational state, the end plates will move towards the rotor cylinder to substantially align therewith.

[0017] Another embodiment relates to a fore mentioned vessel wherein both the lower end and the upper end of the rotor are provided with end plates and a flexible material is provided between the end plates, connected to the rims of the end plates for forming a cylindrical rotor outer surface between the rims of the end plates. Thus, a rotor can be quickly and cheaply formed.

[0018] An embodiment relates to a fore mentioned vessel wherein the rotor has a height Hr and a maximum rotor outer diameter Dr, wherein the ratio Hr:Dr is smaller than or equal to 1. Thus, requirements with respect to the construction of the rotor can be less stringent, e.g. means for reducing vibrations may not have to be provided due to relatively low rotor height. Furthermore, the view from the pilothouse towards the bow of the vessel will improve significantly. [0019] A further embodiment relates to a fore mentioned vessel wherein the motor drive comprises a Tesla motor (M). This configuration allows the rotor to run with increased efficiency, due to decreased friction. Furthermore, rotor maintenance intervals may increase due to the lack of contact surfaces between the rotor cylinder and the motor M.

[0020] Preferably, the Tesla motor (M) is arranged inside the rotor to shield it from environmental conditions. [0021] Another embodiment relates to a fore mentioned vessel wherein, when the rotor is viewed in the operational state, the rotor diameter increases linearly or step-wise with increasing height. At increasing height above the deck of the vessel, or above water level, wind speed increases and wind angle changes, i.e. close to water level the wind angle corresponds to the vessel's direction of movement, but higher up the wind may come from a more sideways direction. By adapting the rotor diameter in the way mentioned, these variables can be taken into account.

[0022] Another embodiment relates to a fore mentioned vessel wherein in the inoperational state the rotor is substantially aligned with the deck of the vessel and the deck is provided with at least one cushion arranged in such a way that in the inoperational state the cushion is positioned near an end of the rotor. When the rotor lies on the deck it is vulnerable to damage due to deck operations. Therefore, the deck is provided with one or more cushions for protecting the ends of the rotor. [0023] An embodiment relates to a fore mentioned vessel wherein the cylindrical outer surface of the rotor comprises adjacent longitudinal parts that in the circumferential direction are connected by spring elements allowing the cylinder to radially expand and contract, wherein the spring elements are covered by coverings as to maintain a smooth cylindrical outer surface. The spring elements allow the cylinder to expand and contract, e.g. due to inflation or deflation of the cylinder by air, allowing the effective aerodynamic outer surface of the rotor to be changed. [0024] Preferably, the coverings thereto are made of a sufficiently elastic material, such as rubber.

Brief description of the drawings

[0025] Objects and advantageous aspects of the invention will be apparent from the detailed description of embodiments of the invention in conjunction with the drawings, in which:

[0026] Fig. 1 shows a schematic side view of a Magnus-effect rotor positioned in an operational position on the deck of a vessel,

[0027] Fig. 2 shows a schematic perspective view of part of the rigid cylinder of a Magnus-effect rotor of figure 1 ,

[0028] Fig. 3 shows a schematic side view of a Magnus-effect rotor with a partly conical internal support structure, [0029] Fig. 4 shows the Magnus-effect rotor of figure 3 with a device for collapsing the rotor,

[0030] Fig. 5 and fig. 6 show schematic cross-sectional side views of a Magnus-effect rotor which is extendable by means of a spring device,

[0031] Fig. 7 and fig. 8 show schematic cross-sectional side views of a Magnus-effect rotor of which the diameter can be changed,

[0032] Fig. 9 and fig. 10 show schematic cross-sectional side views of a Magnus-effect rotor of which the end plates are radially extendable,

[0033] Fig. 11 shows a perspective view of a light-weight Magnus-effect rotor structure, [0034] Fig. 12 shows a schematic side view of a vessel provided with a Magnus-effect rotor having a relatively low height and a relatively large diameter,

[0035] Fig. 13 shows a schematic side view of a Magnus-effect rotor positioned in an operational position on the deck of a vessel, wherein a Tesla motor is provided inside the rotor, and

[0036] Fig. 14 show a table comprising computational results of an optimization routine where optimal rotor diameter is shown as a function of rotor height.

[0037] Fig. 15a shows a Magnus-effect rotor with inflatable parts directly mounted on a central mast.

[0038] Fig. 16 shows a collapsed Magnus-effect rotor provided with cushions.

[0039] Fig. 17a shows a cross-sectional view of a Magnus-effect rotor, provided with spring elements for connecting adjacent longitudinal parts of the rotor cylinder. The rotor is shown in a contracted state. [0040] Fig. 17b shows a cross-sectional view of the Magnus-effect rotor of fig. 17a, wherein the rotor is shown in an expanded state.

Detailed description of the invention

[0041] Fig. 1 shows a schematic side view of a Magnus-effect rotor 1 positioned in an operational position on the deck 10 of a vessel. The rotor 1 as shown has a rigid cylindrical body 2 with an end plate 3 for reducing vorticity during operation. The rotor 1 is internally supported by a mast 4, which is relatively short compared to the length of the rotor 1. The mast comprises a motor drive (not shown) for rotating the rotor 1 via the internal rotor supports 5 which are rotatable with respect to the mast 4. The mast 4 extends below the cylindrical body 2 and comprises a mast support 6 there. The mast support 6 is placed on a hingeable rotor support 7. The rotor support 7 is hingeable with respect to a deck rotor support 8, being connected thereto with a bearing 9, such that the rotor support 7 with the rotor 1 can be moved from an operational position, as shown, to an inoperational position in which the rotor 1 is substantially aligned with the deck 10. [0042] Fig. 2 shows a schematic perspective view of part of the rigid cylinder of the Magnus-effect rotor of figure 1. It shows the rigid cylinder being constructed out of longitudinally aligned plates 14. The plates 14 are assembled into longitudinally connected, cylindrical body sections 11, 12 and 13. Every second plate 14 of a body section 11 , 12, 13 is recessed longitudinally with respect to two transversally adjoining plates 14 of the same body section 11 , 12, 13. The plates 14 are preferably made out of metal, for example aluminium. The plates 14 of the different body sections 11, 12, 13 can be interconnected for example via welds.

[0043] Fig. 3 shows a schematic side view of a Magnus-effect rotor 16 with a partly conical internal support structure 18. The rotor 16 comprises a cylindrical outer support structure 17 with end plates 19 and 22. The support 28 is placed on a deck 26. The rotor 16 is rotatably placed on a support 28 with a bearing 23 to achieve rotatability. The rigid outer shell of the rotor cylinder is not shown for clarity. The upper part of the internal support structure 18 has a cylindrical shape, the middle part 20 of the internal support structure 18 has a conical shape and the lower part 29 of the internal support structure 18 has a cylindrical shape again, though with a smaller diameter than the upper part. The lower part is used as a shaft for driving the rotor around its longitudinal axis. The lower part 29 is thereto placed with its lower end in a bearing 25, which allows rotation of the internal support structure 18 and the outer support structure 17 around a longitudinal axis. A motor drive 24 placed on the deck 26 drives the rotor 16 via the shaft. The motor drive 24 can for example exert its driving force on the rotor 16 via a belt-drive or a chain.

[0044] Fig. 4 shows the Magnus-effect rotor 30 of figure 3 with a device for collapsing the rotor. The lower part of the rotor of figure 4 is shown with the internal structure 31 and end plate 32. The lower end of the shaft is positioned in bearing 40. The rotor is shown having an extension 33 towards the lifting device. The extension 33 is connected to a motor drive 34. The lifting device comprises a lower rotor support 36 hingeably connected to a deck rotor support 37. The rotor support 36 is also provided with a pulley 36a which connects via one or more cables or ropes (not shown) to a pulley 37a on the deck rotor support 37. The rotor 30 can be collapsed by pushing rotor support 36 away from deck rotor support 37 via the hydraulic extension mechanism 38. The rotor 30 can be erected again by retracting the cable or rope running between pulleys 36a and 37a, such that the rotor supports 36 and 37 are rotated towards each other.

[0045] Fig. 5 and fig. 6 show schematic cross-sectional side views of a Magnus-effect rotor 42, 42' which is extendable by means of a spring device 44, 44'. Fig. 5 shows the rotor 42 in a retracted condition, whereas fig. 6 shows the rotor 42' in an extended condition. The change of rotor length can be used to change the aerodynamic properties and thus the performance of the rotor. In fig. 5 the rotor 42 is shown having an upper cylindrical section 43 and a lower cylindrical section 45. The lower cylindrical section 45 is rotatably positioned on a mast 46. The lower cylindrical section 45 has ring- shaped reinforcements at spaced-apart positions along the length of the cylindrical section 45. The upper cylindrical section 45 is rotatably connected to the mast 46 via an upper conical support 48. A lower conical support 49 is connected to a lower part of the lower cylindrical section 45 and is rotatable around the mast 46. The lower conical support 49 provides stability to the rotor 42 and reduces vibrations when the rotor is rotating. A spring device 44, the spring device 44 being of the spiral type, is provided between the upper conical support 48 and an end plate 47. The spring device 44 is shown in a compressed condition and supports the upper cylindrical section 43. Other spring devices, such as with a scissor mechanism, can also be used. Fig. 6 shows the spring device 44' in a relaxed condition, wherein the upper cylindrical section 43 is lifted upwards. Due to the longer length of the rotor 42' more aerodynamic lift can be generated. A certain amount of overlap between the upper cylindrical section 43, 43' and the lower cylindrical section 45 is however needed in order to prevent excessive vibrations of the upper cylindrical section 43, 43'. [0046] Fig. 7 and fig. 8 show schematic cross-sectional side views of a Magnus-effect rotor 50, 50' of which the diameter can be changed by means of radial expansion and contraction of support discs 52, 52'. Fig. 7 shows the rotor 50 in a small diameter configuration, whereas fig. 8 shows the rotor 50' in a large diameter configuration. A cylindrical section 54, 54' is shown being supported by support discs 52, 52' positioned along the length of a rotor support mast 51. The support discs 52, 52' each comprise a number of radial segments 53, 53' which can be radially extended or retracted with respect to the mast 51, much like a diaphragm. The cylindrical section 54, 54' comprises a number of clamshell sections (not shown) which can be radially and, if necessary, partly tangentially retracted along with the segments 53, 53' in order to create a rotor with a smaller or a larger diameter. The end plates as shown are also formed by two of the support discs 52, 52'. Fig. 8a shows the Magnus-effect rotor from above. The radial segments 53, 53' can be seen in an extended state, i.e. being radially extended with respect to the support discs 52, 52'. It is also possible to extend the inflatable parts mentioned in this patent application in such a radial fashion. Preferably the cylindrical section is compartmentalized in order to prevent the occurrence of leaks.

[0047] Fig. 9 and fig. 10 show schematic cross-sectional side views of a Magnus-effect rotor 60, 60' of which the end plates 63 are provided with radially extendable end plate segments 62, 62'. Fig. 9 shows the rotor 60 with retracted end plate segments 62, 62'. With the extendable end plate segments 62, 62' the aerodynamic performance of the end plates can be influenced. Alternatively, analogous to the rotor shown in fig. 7 and fig. 8, a cloth or another type of flexible material can be provided connecting the rims of both end plates, such that a rotor outer surface is formed. The end plate segments 62, 62' themselves can be made of an elastic material and can have a frisbee-like shape, such that when the elastic end plate segments 62, 62' are slack, i.e. when the rotor is not turning or turning slowly, and the rotor is accelerated subsequently, the end plate segments 62, 62' expand to form a frisbee-like disc.

[0048] Fig. 11 shows a perspective view of a light-weight Magnus-effect rotor structure 70. Fig. 11 shows a structure for the cylindrical or tubular part of a Magnus-effect rotor, comprising a spiral-shaped structure 71 extending along the length of the rotor structure 70 for providing rigidity, and a skin 72 made out of flexible material connected to that spiral-shaped structure 71 for creating an aerodynamic surface. The skin can for example be made of a weather-resistant synthetic material. [0049] Fig. 12 shows a schematic side view of a vessel provided with a Magnus-effect rotor 75 comprising a central cylinder 78 provided with end plates 76 at its longitudinal ends. The rotor 75 has a height H_r and a diameter D_r. The height H_r is relatively small with respect to the diameter D_r. The ratio H_r:D_r can for example be smaller than or equal to 1. In the example as shown the ratio H_r:D_r is approximately 1 :5. The rotor 75 as shown comprises an inflatable compartment 77 for changing the effective rotor diameter Di, where 'effective diameter' means the diameter of the cylindrical rotor part actually involved in creating the rotor's propulsive force. Due to the inflatability of the compartment 77 the effective diameter Di can be changed while the rotor is operational. The ratio H_r:Di will, however, also be relatively small, but in any case greater than the ratio H_r:D_r. The relatively large diameter Di enables the rotor to be spun at a lower rotational speed. Thus, requirements with respect to the construction of the rotor can be less stringent, e.g. means for reducing vibrations may not have to be provided. Furthermore, the view from the pilothouse towards the bow of the vessel will improve significantly.

[0050] Fig. 13 shows a schematic side view of a Magnus-effect rotor 80 positioned in an operational position on the deck of a vessel, wherein a Tesla motor M is provided inside the rotor cylinder 83 for driving the rotor. Again the rotor 80 comprises a longitudinal cylinder 83 and an end plate 82. The motor M is positioned on top of the short mast 84 carrying the rotor 80. The inner circumference of the rotor cylinder 83 near the Tesla motor M is provided with magnets 81 at spaced-apart positions. This configuration allows the rotor 80 to run with increased efficiency, due to decreased friction. Furthermore, rotor maintenance intervals may increase due to the lack of contact surfaces between the rotor cylinder 83 and the motor M. The rotor cylinder 80 itself also advantageously shields the motor M from the environment.

[0051] Fig. 14 show a table comprising computational results of an optimization routine where optimal rotor diameter is shown as a function of rotor height. The computational results are a result of the insight that at increasing height above the deck of the vessel, or above water level, wind speed increases and wind angle changes, i.e. close to water level the wind angle corresponds to the vessel's direction of movement, but higher up the wind may come from a more sideways direction. The first table column shows the height above water level, while the fifth column shows the optimal rotor diameter at that height, at a rotational speed of 200 RPM. In the lower part of fig. 14 two schematic drawings are shown of a rotor design making use of such optimized diameters. The lower left drawing shows a rotor with a linearly increasing diameter with increasing height. The lower right drawing shows a rotor with a step-wise increasing diameter with increasing height.

[0052] Fig. 15a shows a Magnus-effect rotor 90 with inflatable parts 94. The inflatable parts 94 are directly mounted on a central mast 91 via bearings 92. The advantage of this configuration with respect to the embodiment of a Magnus-effect rotor as shown in fig. 12 is that the use of a central drum can be avoided. This saves a lot of weight. Fig. 15b shows the Magnus-effect rotor of fig. 15a in a deflated state. The inflatable parts 94, 94' are preferably provided with rubber reinforcements 93 at the connection of the inflatable parts 94 with the bearings 92 due to the increased stress being present there.

[0053] Fig. 16 shows a collapsed Magnus-effect rotor 100. The rotor 100 is positioned between two cargo hatches 101. With the rotor 100 lying on the deck 102, it is vulnerable to damage due to deck operations. Therefore, the rotor 100 as shown is provided with cushions 103 for protecting the ends of the rotor 100. The cylindrical part of the rotor 100 is provided with an elongated cushion 104.

[0054] Fig. 17a shows a cross-sectional view of a Magnus-effect rotor 110, provided with spring elements 111 for connecting adjacent longitudinal parts 113 of the rotor cylinder. The spring elements 111 allow the cylinder to expand and contract, e.g. due to inflation or deflation of the cylinder by air. The rotor 110 is shown in a contracted state. Coverings 112 are provided to cover the spring elements 111 and maintain a smooth outer surface of the cylinder. Fig. 17b shows a cross-sectional view of the Magnus- effect rotor 110', wherein the spring elements 11 1 ' and the rotor 110' are shown in expanded state. The coverings 112, 112' are made of a sufficiently elastic material.

Claims

1. Vessel comprising a deck (10, 26, 102), a Magnus-effect rotor (1, 16, 30, 42, 42', 50, 50', 60, 60', 70, 75, 80, 90, 90', 100, 110, 110') and a motor drive (24, 34, M) for rotating the Magnus-effect rotor around a longitudinal axis in an operational state, the rotor in its operational state being vertically mounted on the vessel and having a substantially cylindrical outer surface, and displacement means (7, 8, 9, 36, 37, 38, 39, 44, 44') for displacing the rotor towards the deck in an inoperational state.

2. Vessel according to claim 1, wherein the displacement means comprise a lower end of the rotor (1, 30) being rotatably supported by a lower rotor support structure (7, 36) that is hingeably connected (9, 39) to a deck structure (8, 37) arranged on the deck of the vessel, such that a substantially horizontal hinge axis is defined, wherein by pivoting the lower rotor support structure (7, 36) with respect to the deck structure (8, 37) around the hinge axis the rotor (1, 30) is tilted from the operational state to the inoperational state and vice versa, wherein in the inoperational state the rotor (1, 30) is substantially aligned with the deck.

3. Vessel according to claim 1, wherein the displacement means comprise the rotor (42, 42') having an upper tubular element (43, 43') and a lower tubular element (45), whose centre lines are aligned with the longitudinal axis of the rotor, wherein the tubular elements can be displaced telescopically with respect to each other between the operational (43) and inoperational states (43'), wherein a biased spring element (44, 44') is arranged inside the rotor between the upper and the lower tubular element to facilitate the telescopic displacement from the inoperational to the operational state.

4. Vessel according to claim 3, wherein the rotor (42, 42') is rotatably supported by an internal rotor support structure (46), wherein the spring element (44, 44') is arranged between an upper end of the internal rotor support structure and an end plate (47, 47') arranged at an upper end of the upper tubular element.

5. Vessel according to one of the preceding claims, wherein the rotor comprises a rigid cylinder, the rigid cylinder being constructed out of longitudinally connected, cylindrical sections (11, 12, 13), wherein at least one of the sections (11, 12, 13) comprises longitudinally extending plates (14) distributed along the circumference of the body section (11, 12, 13), wherein a lower or upper end of one of the plates (14) is recessed longitudinally with respect to the respective lower/upper ends of the plates (14) of the same body section (11, 12, 13) that adjoin the recessed plate in the circumferential direction.

6. Vessel according to claim 1, the deck (26) defining a deck level and a lower deck situated below the deck level, defining a lower deck level, wherein the rotor (16) comprises a rigid cylinder (17) that in the operational state has a lower end that is situated at a distance above deck level, wherein the rigid cylinder (17) is mounted with the lower end on a shaft (29) that extends downwards from the lower end of the cylinder past deck level to the lower deck level, the shaft having an outer diameter that is smaller than the outer diameter of the rigid cylinder, wherein a lower bearing (25) is provided at the lower deck level for supporting the lower end of the shaft and for allowing rotation of the shaft around the longitudinal axis and the upper end of the shaft is rotatably supported by an upper bearing (23) arranged in a rotor support structure (28) arranged near the lower end of the cylinder, and the motor drive (24) is connected to the shaft for rotating the rotor at a position between the lower and upper bearings.

7. Vessel according to claim 6, wherein the motor drive (24) is arranged at deck level.

8. Vessel according to one of the preceding claims, wherein a lower and/or upper end of the rotor (60, 60') is/are provided with end plates (63).

9. Vessel according to claim 8, wherein the end plates comprise radially extendable and retractable segments (62, 62').

10. Vessel according to claim 8 or 9, wherein the end plates are made of an elastic material.

11. Vessel according to one of the claims 8-10, wherein both the lower end and the upper end of the rotor are provided with end plates and a flexible material is provided between the end plates, connected to the rims of the end plates for forming a cylindrical rotor outer surface between the rims of the end plates.

12. Vessel according to one of the preceding claims, wherein the rotor (75) has a height Hr and a maximum rotor outer diameter Dr, wherein the ratio Hr:Dr is smaller than or equal to 1.

13. Vessel according to one of the preceding claims, wherein the motor drive comprises a Tesla motor (M).

14. Vessel according to claim 13, wherein the Tesla motor (M) is arranged inside the rotor.

15. Vessel according to one of the preceding claims, wherein, when the rotor is viewed in the operational state, the rotor diameter increases linearly or step-wise with increasing height.

16. Vessel according to one of the preceding claims, wherein in the inoperational state the rotor (100) is substantially aligned with the deck (102) of the vessel and the deck is provided with at least one cushion (103) arranged in such a way that in the inoperational state the cushion is positioned near an end of the rotor.

17. Vessel according to one of the preceding claims, wherein the cylindrical outer surface of the rotor (110, 110') comprises adjacent longitudinal parts (113) that in the circumferential direction are connected by spring elements (111, 111 ') allowing the cylinder to radially expand and contract, wherein the spring elements are covered by coverings (112, 1 12') as to maintain a smooth cylindrical outer surface.

18. Vessel according to claim 17, wherein the coverings (112, 112') are made of a sufficiently elastic material.