Rudders for ships and twin-propeller ships with two rudders

Description

[0001] The present invention relates to a rudder for twin-propeller ships, wherein the rudder is configured to be arranged in the wake of a propeller of a twin-propeller ship, and wherein the rudder comprises an upper rudder section and a lower rudder section. The present invention further relates to a twin-propeller ship comprising a hull, two propellers, and two rudders. Technological background

[0002] Rudders positioned in the wake of a propeller are used to steer ships. When such a rudder is deployed, that is, deflected or pivoted, the water flowing around it creates a buoyant force that causes the ship to change direction.

[0003] Especially on large and medium-sized ships, the rudders must be particularly large to generate the lift required for sufficient steering. However, the drag caused by the size of large rudders negatively impacts the efficiency and fuel consumption of the ships.

[0004] Furthermore, twin-propeller ships are known, which have two propellers. Typically, the first propeller is located on the port side and the second on the starboard side of the hull. A rudder is positioned in the wake behind each propeller. The hull influences the water flow in the area of ​​the propellers and rudders, which are mounted laterally on the hull, causing additional turbulence in the currents, particularly in the propeller wakes. This turbulence also negatively impacts the efficiency of the propellers and rudders.

[0005] Therefore, in the state of the art, there is a need for a rudder, especially for twin-propeller ships, with which the flow resistance and turbulence in the propeller wake are reduced.

[0006] WO 2010 / 116799 A1 discloses a combination of a vertical rudder connected to a rudder shaft with several auxiliary rudders arranged on both sides of a central plane of the vertical rudder for a single-propeller vessel. The auxiliary rudders are connected to the vertical rudder via a rudder bulb.

[0007] KR 10-2015-0008568 A discloses a rudder with an upper section and a lower section, wherein the lower section has a forked design with auxiliary rudders arranged on both sides of a central plane.

[0008] From EP 3 103 715 A1, a steering device for ships is known, wherein two rudders are arranged on either side of a ship's propeller. The rudders are each pivotable about an axis extending outside the rudder.

[0009] From FR 1 106 851 A a rudder system is known in which two steering rudders are essentially semicircular in shape, and in which the wake of a propeller flows between the semicircularly shaped rudders.

[0010] US Patent 5,697,315 A describes a ship's rudder which has an essentially s-shaped rudder blade.

[0011] KR 10-2013-0055876 A discloses a twin-propeller ship with a rudder arranged in the wake of each propeller, the respective rudder being aligned at an angle α to a vertical direction.

[0012] From JP 2016-107715 A, a twin-propeller vessel is known with a pair of rudder bodies rotatably mounted on a hull via corresponding pivot shafts. The upper sections of the rudders are arranged so that they run vertically. The lower sections of the rudders are inclined towards the outside of the hull.

[0013] EP 2 163 472 A1 discloses a propulsion and steering device for a ship, the arrangement comprising a screw propeller and a rudder located behind the propeller. A fairing at the rear end of the propeller and a pear-shaped body attached to a rudder blade of the rudder form a streamlined body that is continuous except for a narrow gap between the fairing and the pear-shaped body. Description of the invention: Problem, solution, advantages

[0014] The present invention is based on the objective of providing a rudder for twin-propeller ships with which the flow resistance of the rudder and the turbulence of the wake of a propeller are reduced.

[0015] Furthermore, the present invention is based on the objective of providing a twin-propeller ship with which the aforementioned advantages can be achieved.

[0016] To solve the problem underlying the invention, a rudder for twin-propeller ships is proposed, wherein the rudder is designed to be arranged in the wake of a propeller of a twin-propeller ship, wherein the rudder comprises an upper rudder section and a lower rudder section, wherein the lower rudder section is bent or angled to one side of the rudder, wherein exactly one lower rudder section is provided, wherein a transition area is provided between the upper rudder section and the lower rudder section, wherein the transition area is partially arc-shaped, partially annular, or wedge-shaped, wherein the transition area, in the state of the rudder being arranged on the twin-propeller ship, lies at the level of the propeller axis, such that the upper rudder section lies above the propeller axis and the lower rudder section lies below the propeller axis.and wherein the upper rudder section has a suction side and a pressure side and / or wherein the lower rudder section has a suction side and a pressure side, such that in the state of the rudder arranged on the twin-propeller ship, a buoyancy force acting laterally in the direction of a ship's median plane, caused by an influence on the wake by a hull of the twin-propeller ship, is counteracted.

[0017] The rudder according to the invention is particularly suitable for medium-sized and large ships, such as tugboats, ferries, passenger ships, tankers and container ships.

[0018] The propeller according to the invention is designed to be arranged in the wake of a propeller of a twin-propeller ship. In particular, the rudder is not designed or intended to be arranged outside the wake of a propeller. Furthermore, the rudder is not designed or intended for an arrangement substantially to the side of a ship's propeller.

[0019] A key aspect of the rudder according to the present invention is that exactly one lower rudder section is provided. In particular, the rudder does not have two or more lower rudder sections. When installed on a twin-propeller vessel in the wake of one propeller, the upper rudder section is arranged vertically above the propeller axis. The lower rudder section is arranged accordingly below the propeller axis. An imaginary horizontal plane containing the propeller axis effectively divides the rudder, when installed on a twin-propeller vessel, into an upper and a lower half, with the upper rudder section corresponding to the upper half and the lower rudder section corresponding to the lower half. It should be noted that in the case of a non-horizontal wake field or wake turbulence, the upper and lower halves, respectively, are not the same.The upper and lower rudder sections can be determined by an imaginary plane through the center of the wake field or wake skew. Deviations from a horizontally oriented wake field or wake skew can occur due to influences of the ship's hull, which impose a velocity component on the wake field or wake skew that is directed vertically upwards and / or towards the ship's axis.

[0020] By providing exactly one lower rudder section, the surface area of ​​the rudder exposed to the water, especially the following current, is reduced, thus reducing the flow resistance compared to rudders known from the prior art with several auxiliary or stabilizing rudders.

[0021] According to the invention, the rudder comprises an upper rudder section and a lower rudder section, wherein the lower rudder section is bent or angled to one side of the rudder.

[0022] In a configuration on a twin-propeller ship with the rudder in a neutral position, the upper rudder section is essentially vertically oriented when viewed from behind. The lower rudder section, located below the upper section, is not vertically oriented, but rather at an angle to the upper section and the vertical. In other words, the lower rudder section is at an angle to an imaginary, straight downward extension of the upper rudder section. Specifically, a large portion of the lower rudder section is positioned laterally to this imaginary extension of the upper rudder section.

[0023] The lower rudder section can be angled or curved to one side of the rudder. In a curved design, the lower rudder section has a continuous or variable curvature to one side of the rudder. In an angled design, both the upper and lower rudder sections are essentially straight, and the rudder has a kink at the transition between the upper and lower sections.

[0024] Due to the lower rudder section being bent or angled to one side, the turbulence in the propeller wake is reduced, particularly when the rudder according to the invention is used on a twin-propeller vessel. Since, on a twin-propeller vessel, the lateral arrangement of each propeller next to the hull results in a one-sided influence on the flowing water, especially the propeller wake, the rudder according to the invention, with exactly one lower rudder section bent or angled to one side, is particularly suitable for reducing turbulence.

[0025] Furthermore, reducing turbulence in the flowing water, particularly in the propeller wake, increases the rudder's efficiency, allowing it to be shorter compared to conventional rudders. It also enables the use of a thinner rudder. These measures result in reduced drag and lower manufacturing costs.

[0026] Preferably, the upper rudder section and / or the lower rudder section are essentially straight. In particular, the upper rudder section and / or the lower rudder section are not curved or S-shaped.

[0027] Preferably, the upper rudder section has a receiving space for receiving a rudder shaft.

[0028] The rudder can thus be attached, suspended, or mounted on a twin-propeller vessel via the upper rudder section and a rudder shaft inserted into and secured to the upper rudder section. Preferably, the axis of rotation or pivot of the rudder runs through the upper rudder section, so that the axis of rotation or pivot of the rudder is not located outside the rudder.

[0029] A further advantage is that the rudder may not have any auxiliary or stabilizing rudders, and / or that the lower rudder section is not an auxiliary or stabilizing rudder.

[0030] The lower rudder section is therefore not an auxiliary or stabilizing rudder. In particular, with the exception of its curved or angled design or orientation relative to the upper rudder section, the lower rudder section is preferably designed like a conventional lower rudder section and has essentially corresponding dimensions. In contrast, auxiliary and stabilizing rudders are significantly smaller and serve less to change the course of a ship than to stabilize the ship's position in the water.

[0031] It may also be preferred that the lower rudder section is at an angle to the upper rudder section.

[0032] The angle between the lower rudder section and the upper rudder section can be determined on both sides of the rudder between the side walls of the rudder located on the respective side.

[0033] Preferably, the upper rudder section extends in an upper extension plane, wherein the upper extension plane is particularly preferably parallel to an upper leading edge and / or to an upper trailing edge of the rudder, and the lower rudder section extends in a lower extension plane, wherein the lower extension plane is particularly preferably parallel to a lower leading edge and / or to a lower trailing edge of the rudder, wherein the lower extension plane is at an angle to the upper extension plane.

[0034] Preferably, the rudder has an upper leading edge and, optionally, an upper trailing edge in its upper section. Furthermore, the rudder has a lower leading edge and, optionally, a lower trailing edge in its lower section. Both the upper and lower rudder sections also have sidewalls.

[0035] The upper and lower planes of extension essentially correspond to the respective median planes of the upper and lower rudder sections. When installed on a twin-propeller vessel, the upper plane of extension is essentially vertical. Furthermore, the rudder's axis of rotation, i.e., the rudder shaft, lies within the upper plane of extension when installed on a twin-propeller vessel. In the case of a symmetrical upper rudder section, the upper leading edge and / or the upper trailing edge also lie within the upper plane of extension. The profile of the upper rudder section is symmetrical to the upper plane of extension in the case of a symmetrical upper rudder section.The lower extension plane in the lower rudder section is to be defined accordingly and runs approximately along a median plane of the lower rudder section. In the case of a symmetrical lower rudder section, the lower extension plane divides the profile, particularly over its entire height, symmetrically. If the lower rudder section is continuously curved, the lower extension plane is chosen such that it is tangential to the surface formed by the airfoil chords in the lower rudder section at the tip or free end. The surface formed by the airfoil chords in the lower rudder section is created by connecting the airfoil chords from the tip of the lower rudder section to the transition to the upper rudder section.

[0036] Therefore, the preferred angle between the upper rudder section and the lower rudder section is that angle at which the lower extension plane is to the upper extension plane.

[0037] Furthermore, it can be provided that the angle is between 5° and 35°, preferably between 10° and 30°, particularly preferably between 15° and 25°, most preferably 20°.

[0038] The preferred rudder angle ranges ensure, particularly in the case of a twin-propeller vessel, that the turbulence caused by the influence of the hull on the propeller wake is sufficiently reduced. Furthermore, the vertical component of the lift force of the lower rudder section is so low in these preferred rudder angle ranges that the stability of the vessel in the water is not adversely affected.

[0039] A transition area is provided between the upper rudder section and the lower rudder section, wherein the transition area is partially arc-shaped, partially ring-shaped or wedge-shaped.

[0040] In a first embodiment with a lower rudder section angled towards one side of the rudder, a kink can be formed between the upper and lower rudder sections. The transition area between the lower and upper rudder sections is then essentially wedge-shaped in a rear view, with the apex of the wedge pointing towards the side of the rudder towards which the lower rudder section is angled. By providing an approximately wedge-shaped transition area, the upper and lower rudder sections can be manufactured essentially using methods known from the prior art.

[0041] However, it is also possible for the upper rudder section to transition into the lower rudder section via a partially arc-shaped or partially ring-shaped transition area. In a rear view of a rudder on a twin-propeller vessel in the neutral position, the projection of the transition area then resembles a section of an arc or a ring. In the case of a lower rudder section with a constant or variable curvature, the transition area can extend to the tip or the free end of the lower rudder section and form at least a portion of it.

[0042] Furthermore, it is preferably provided that the transition area, which is partially arc-shaped or partially ring-shaped, has a radius of curvature between 0.1 m and 10.0 m, preferably between 0.5 m and 5.0 m, and particularly preferably between 1.0 m and 2.0 m.

[0043] The transition area lies in the state of the rudder on the twin-propeller ship at the level of the propeller axis, so that the upper rudder section is above the propeller axis and the lower rudder section is below the propeller axis.

[0044] With particular advantage, the rudder has a height of between 5 m and 10 m, preferably between 6 m and 9 m, and especially preferably between 7 m and 8 m, in a side view from the upper end of the upper rudder section, in particular the rudder root, to the tip of the lower rudder section.

[0045] According to the invention, the upper rudder section has a suction side and a pressure side and / or the lower rudder section has a suction side and a pressure side.

[0046] Particularly when the rudder is arranged on a twin-propeller vessel, a design of the upper rudder section and / or the lower rudder section with a suction side and a pressure side is advantageous. On a twin-propeller vessel, the hull influences the wake of each propeller in such a way that it exhibits a velocity component directed vertically upwards and / or towards the ship's center plane. These velocity components result in an oblique flow towards the rudder, which in turn generates a lift force directed, in particular, laterally towards the ship's center plane. By designing the upper rudder section and / or the lower rudder section with a suction side and a pressure side, this constant, laterally acting lift force can be counteracted.

[0047] It is particularly preferred that the suction surfaces of the upper and lower rudder sections are arranged on the same side of the rudder. However, an embodiment is also conceivable in which the suction surface of the upper rudder section is arranged opposite the suction surface of the lower rudder section.

[0048] It is advantageous to provide that a first height of the upper rudder section is greater than a second height of the lower rudder section by a factor between 1 and 2, preferably between 1.1 and 1.8, more preferably between 1.2 and 1.5, and particularly preferably between 1.3 and 1.4.

[0049] The first height of the upper rudder section is measured from the rudder root to the transition area along the sidewall or the upper extension plane. The second height of the lower rudder section is measured from the transition area along the sidewall or the lower extension plane to the tip or free end of the lower rudder section.

[0050] A further advantage is that the upper and / or the lower rudder section can be twisted rudder sections.

[0051] A twisted rudder section is characterized by the fact that the leading edge and / or the trailing edge of the respective rudder section is offset laterally to port or starboard with respect to the median plane or extension plane of the rudder section.

[0052] By providing twisted rudder sections, the occurrence of cavitation and flow separation from the respective rudder section can be reduced or prevented.

[0053] It is advantageous to provide that the rudder includes a rudder bulb, the rudder bulb being preferably located at the transition area.

[0054] Preferably, the rudder bulb is arranged at the transition area, so that in the state arranged on the twin-propeller ship, the rudder bulb is located at the level of the propeller axis.

[0055] It is particularly advantageous that the rudder is a fin rudder and includes a fin, in particular a hinged fin, the fin preferably being arranged only on the upper part of the rudder.

[0056] If a hinged fin is provided, this fin encompasses the trailing edge of the rudder. It is particularly advantageous to have a fin only on the upper section of the rudder. By having a fin only on the upper section, the surface area of ​​the rudder fin is reduced compared to conventional rudder fins. A reduced surface area of ​​the rudder fin results in a less aggressive increase in lift force when the rudder fin is deflected, thus creating a flatter characteristic curve for the relationship between lift force and deflection angle, resulting in smoother steering behavior.

[0057] Another solution to the problem underlying the invention lies in providing a twin-propeller ship comprising a ship hull, two propellers and two rudders as described above, wherein a first rudder is arranged in the wake of a first propeller, and wherein a second rudder is arranged in the wake of a second propeller.

[0058] Preferably, a first propeller is located on the starboard side and a first rudder is arranged in the wake of the first propeller on the starboard side, and a second propeller is located on the port side of the ship's hull and a second rudder is arranged in the wake of the second propeller.

[0059] The rudder described above results in a particularly favorable reduction of turbulence in the wake of each propeller on a twin-propeller ship.

[0060] It can be advantageous to design the first rudder to be mirror-symmetrical to the second rudder.

[0061] A further advantage is that the lower rudder sections of the first rudder and the second rudder can be curved or angled towards the ship's hull.

[0062] The lower sections of the first and second rudders are thus curved or angled towards the hull, and therefore, when viewed from the rear, roughly follow the line of the hull. Since the hull influences the wake of the respective propeller and causes additional turbulence, this design allows for a particularly advantageous reduction of this turbulence.

[0063] A further advantage is that the upper rudder sections of the two rudders each have a suction side and a pressure side, with the suction sides being located on the side of the rudder facing away from the ship's hull.

[0064] In particular, it is advantageous if the twin-propeller ship is designed to steer to starboard, preferably only, by placing a rudder on the port side, and to steer to port, preferably only, by placing a rudder on the starboard side.

[0065] Another solution to the problem underlying the invention consists in the use of a rudder as described above on a twin-propeller ship. Brief description of the characters

[0066] The invention is explained in more detail below with reference to the figures. They show: Fig. 1 a perspective view of a rudder with an angled lower rudder section, Fig. 2 a side view of a rudder with an angled lower rudder section, Fig. 3 a rear view of a rudder with an angled lower rudder section, Fig. 4 a bottom view of a rudder with an angled lower rudder section, Fig. 5 a rear view of another rudder with a curved lower rudder section, and Fig. 6 a rear view of a twin-propeller ship with two rudders. Detailed description of the characters

[0067] Fig. 1Figure 1 is a perspective view of a rudder 100 with an upper rudder section 10 and a lower rudder section 11. The lower rudder section 11 is angled towards one side 12 of the rudder 100. The rudder 100 has exactly one upper rudder section 10 and exactly one lower rudder section 11, with no further rudder section being arranged below the upper rudder section 10 besides the single lower rudder section 11. A fin 14, pivotally attached to the upper rudder section 10, is arranged at the rear end 13 of the upper rudder section 10. A sliding pivot piston linkage 16 is attached to the upper end 15 of the fin 14 for pivoting the articulated fin 14. A sliding pivot piston (not shown), connected to a ship's hull, can be arranged in this linkage.

[0068] The upper rudder section 10 includes an upper leading edge 17. An upper trailing edge 18 of the upper rudder section 10 forms part of the fin 14. The lower rudder section 11 has a lower leading edge 19 and a lower trailing edge 20. Sidewalls 21 extend between the leading edges 17, 19 and the trailing edges 18, 20 on both the upper rudder section 10 and the lower rudder section 11. In the area of ​​greatest profile thickness, a recess 40 for receiving a rudder shaft is provided in the upper rudder section 10.

[0069] Fig. 2 The rudder shows 100 of the Fig. 1 in a side view from the direction of side 12, into which the lower rudder section 11 is angled. It is clearly visible that the hinged fin 14 is only pivotably connected to the upper rudder section 10.

[0070] Fig. 3 is a rear view of the rudder 100 of the Figs. 1 and 2A transition area 22, approximately wedge-shaped, is provided between the upper rudder section 10 and the lower rudder section 11. The upper rudder section 10 and the lower rudder section 11 are arranged above and below the transition area 22, respectively. The wedge shape of the transition area 22 causes the lower rudder section 11 to open to one side 12, which in the design of the Figs. 1 to 3The starboard side 23 is angled. Due to the wedge-shaped design of the transition section 22, the rudder 100 also has a kink 24 between the upper rudder section 10 and the lower rudder section 11. The upper rudder section 10 extends in an upper plane 25, which corresponds approximately to the median plane 26 of the upper rudder section 10. Similarly, the lower rudder section 11 extends in a lower plane 27, which corresponds approximately to the median plane 28 of the lower rudder section 11. The upper plane 25 and the lower plane 27 are at an angle 29 of approximately 20° to each other. Along the extension planes 25 and 27, a first height 37 of the upper rudder section 10 and a second height 38 of the lower rudder section 11 can also be determined, the first height 37 being greater than the second height 38 by a factor of between 1.2 and 1.5. The total height 39 of the rudder 100 is approximately 7 m.

[0071] Fig. 4 Figure 1 shows a view from below of the rudder 100. The lower rudder section 11 has an asymmetrical profile 30 with a suction side 31 and a pressure side 32. The pressure side 32 is located on the side 12 of the lower rudder section 11, into which the lower rudder section 11 is bent or angled. The upper rudder section 10 also has a suction side 33 and a pressure side 34. Fig. 3 ). This is similar to what is described in... Fig. 3 shown are the printed sides 32, 34 of the lower rudder section 11 and the upper rudder section 10 on the same side 12 of the rudder 100.

[0072] Fig. 5 Figure 1 shows a rear view of another embodiment of a rudder 100 with an upper rudder section 10 and a lower rudder section 11. The rudder 100 of the Fig. 5 is essentially identical to the Rudder 100 of the Figs. 1 to 4, however, it differs in a differently designed transition area 35. The transition area 35 of the rudder 100 is different from the transition area 22 of the Figs. 1 to 4 formed approximately in a semi-ring or semi-arc shape with a radius of curvature 36 between 0.5 m and 5 m. Due to the semi-ring or semi-arc-shaped transition area, the lower rudder section is curved towards one side 12 of the rudder 100 and the upper extension plane 25 and the lower extension plane 27 are at an angle 29 to each other.

[0073] Fig. 6 Figure 1 shows a rear view of a twin-propeller vessel 200. The twin-propeller vessel 200 has a first propeller 211 and a second propeller 212 on both sides of a hull 210. A first rudder 100a is located in the wake behind the first propeller 211, according to the... Figs. 1 to 4 arranged. In the wake behind the second propeller 212, a second rudder 100b is arranged according to the Figs. 1 to 4The first rudder 100a and the second rudder 100b are arranged as mirror images of each other. The lower rudder section 11a of the first rudder 100a is angled towards the hull 210. The lower rudder section 11b of the second rudder 100b is also angled towards the hull 210. The upper rudder section 10a and the lower rudder section 11a of the first rudder 100a have suction sides 31, 33, which are located on the side of the rudder 100a facing away from the hull 210. Similarly, the second rudder 100b has suction sides 31, 33 in both the upper rudder section 10b and the lower rudder section 11b, which are located on the side facing away from the hull 210.In addition, the rudders 100a, 100b have pressure sides 32, 34 in the upper rudder sections 10a, 10b and in the lower rudder sections 11a, 11b, which are each located on the side of the rudder 100a, 100b facing the ship's hull 210. List of reference symbols

[0074] 100 oars 100a First oar 100b Second oar 10 Upper rudder section 10a Upper rudder section 10b Upper rudder section 11 Lower rudder section 11a Lower rudder section 11b Lower rudder section 12 Side 13 Rear end 14 Fin 15 Upper end 16 Sliding pivot linkage 17 Upper leading edge 18 Upper trailing edge 19 Lower leading edge 20 Lower trailing edge 21 Sidewall 22 Transition area 23 Starboard side 24 Bend 25 Upper extension plane 26 Middle plane 27 Lower extension plane 28 Middle plane 29 Angle 30 Profile 31 Suction side 32 Pressure side 33 Suction side 34 Pressure side 35 Transition area 36 Radius of curvature 37 First height 38 Second height 39 Total height 40Aufnahmeraum 200Doppelpropellerschiff 210Schiffsrumpf 211Erster Propeller 212Zweiter Propeller

Claims

1. Rudder (100, 100a, 100b) for twin propeller ships (200), wherein the rudder (100, 100a, 100b) is configured to be arranged in the wake of a propeller (211, 212) of a twin propeller ship (200), wherein the rudder (100, 100a, 100b) comprises an upper rudder portion (10, 10a, 10b) and a lower rudder portion (11, 11a, 11b), wherein the lower rudder portion (11, 11a, 11b) is bent or angled towards one side (12) of the rudder, wherein exactly one lower rudder portion (11, 11a, 11b) is provided, wherein a transition region (22) is provided between the upper rudder portion (10, 10a, 10b) and the lower rudder portion (11, 11a, 11b), wherein the transition region (22) is configured in a partially arcuate, partially annular or wedge-shaped manner, wherein the transition region (22) is located at the height of the propeller shaft in the state when the rudder (100, 100a, 100b) is arranged on the twin propeller ship (200), such that the upper rudder portion (10, 10a, 10b) is located above the propeller shaft and the lower rudder portion (11, 11a, 11b) is located below the propeller shaft, and wherein the upper rudder portion (10, 10a, 10b) has a suction side (33) and a pressure side (34) and / or wherein the lower rudder portion (11, 11a, 11b) has a suction side (31) and a pressure side (32), such that in the state when the rudder (100, 100a, 100b) is arranged on the twin propeller ship (200) a buoyancy force that is caused by influencing of the wake by a hull (210) of the twin propeller ship (200) and acts laterally in the direction of a ship central plane is counteracted.

2. Rudder (100, 100a, 100b) according to claim 1, characterised in that the upper rudder portion (10, 10a, 10b) comprises a receiving space (40) for receiving a rudder post.

3. Rudder (100, 100a, 100b) according to either claim 1 or claim 2, characterised in that the rudder (100, 100a, 100b) does not have any auxiliary rudders or stabilising rudders, and / or in that the lower rudder portion (11, 11a, 11b) is not an auxiliary rudder or stabilising rudder.

4. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that the lower rudder portion (11, 11a, 11b) is at an angle (29) to the upper rudder portion (10, 10a, 10b), wherein in particular the angle (29) is between 5° and 35°, preferably between 10° and 30°, particularly preferably between 15° and 25°, very particularly preferably 20°.

5. Rudder (100, 100a, 100b) according to claim 4, characterised in that the upper rudder portion (10, 10a, 10b) extends in an upper extension plane (25), wherein the upper extension plane (25) preferably extends in parallel with an upper leading edge (17) and / or an upper trailing edge (18) of the rudder, and that the lower rudder portion (11, 11a, 11b) extends in a lower extension plane (27), wherein the lower extension plane preferably extends in parallel with a lower leading edge (19) and / or a lower trailing edge (20) of the rudder, wherein the lower extension plane (27) is at the angle (29) to the upper extension plane (25).

6. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that the partially arcuate or partially annular transition region (22, 35) has a radius of curvature (36) of between 0.1 m and 10.0 m, preferably between 0.5 m and 5.0 m, particularly preferably between 1.0 m and 2.0 m.

7. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that the upper rudder portion (10, 10a, 10b) has a suction side (33) and a pressure side (34), and that the lower rudder portion (11, 11a, 11b) has a suction side (31) and a pressure side (32), wherein the suction side (31) of the lower rudder portion (11, 11a, 11b) and the suction side (31) of the upper rudder portion (10, 10a, 10b) are arranged on the same side of the rudder or on opposing sides of the rudder.

8. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that a first height (37) of the upper rudder portion (10, 10a, 10b) is larger by a factor between 1 and 2, preferably between 1.1 and 1.8, further preferably between 1.2 and 1.5, particularly preferably between 1.3 and 1.4, than a second height (38) of the lower rudder portion (11, 11a, 11b).

9. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that the upper rudder portion (10, 10a, 10b) and / or the lower rudder portion (11, 11a, 11b) are twisted rudder portions.

10. Rudder (100, 100a, 100b) according to any of the preceding claims, characterised in that the rudder (100, 100a, 100b) comprises a rudder bulb, wherein the rudder bulb is preferably arranged on the transition region (22, 35), and / or that the rudder (100, 100a, 100b) is a finned rudder and comprises an in particular articulated fin (14) wherein the fin (14) is preferably arranged only on the upper rudder portion (10, 10a, 10b).

11. Twin propeller ship (200) comprising a hull (210), two propellers (211, 212) and two rudders (100, 100a, 100b) according to any of claims 1 to 10, characterised in that a first rudder (100a) is arranged in the wake of a first propeller (211), and in that a second rudder (100b) is arranged in the wake of a second propeller (212).

12. Twin propeller ship (200) according to claim 11, characterised in that the first rudder (100a) is configured mirror-symmetrically with respect to the second rudder (100b), and / or in that the lower rudder portions (11, 11a, 11b) of the first rudder (100a) and of the second rudder (100b) are curved or angled towards the hull (210).

13. Twin propeller ship (200) according to either claim 11 or claim 12, characterised in that the upper rudder portions (10, 10a, 10b) of the two rudders (100, 100a, 100b) each have a suction side (33) and a pressure side (34), wherein the suction sides (33) are arranged on the side of the rudder (100, 100a, 100b) facing away from the hull (210).

14. Twin propeller ship (200) according to any of claims 11 to 13, characterised in that the twin propeller ship (200) is configured, for steering to starboard, to lay, preferably only, one portside rudder (100, 100a, 100b), and for steering to portside to lay, preferably only, one starboard rudder (100, 100a, 100b).

15. Use of a rudder according to any of claims 1 to 10 in a twin propeller ship (200).