US20120079975A1

US20120079975A1 - Rudder for ships

Info

Publication number: US20120079975A1
Application number: US13/252,938
Authority: US
Inventors: Matthias Kluge; Dirk Lehmann
Original assignee: Becker Marine Systems GmbH and Co KG
Current assignee: Becker Marine Systems GmbH and Co KG
Priority date: 2006-11-13
Filing date: 2011-10-04
Publication date: 2012-04-05

Abstract

The invention relates to a rudder for ships with propeller drive, in which the propeller is arranged to rotate about a propulsion axis, with a rudder blade (15) and a flow body (20) arranged on the rudder blade (15), whereby the flow body designed in a bulb or zeppelin shape is arranged as an extension of the propulsion axis in the region of the rudder blade and is designed to self-destruct or self-detach in the event of an increase in the effect of force, blow, impact or pressure.

Description

TECHNICAL FIELD

The invention relates to a rudder for ships.

PRIOR ART

Rudders of ships with a propeller drive these days often have a so-called Costa bulb (a stream-lined body of revolution integral with a rudder and directly in line with the propeller). The purpose of the so-called Costa bulb or propulsion bulb is that a bulge, which is designed to be bulb-shaped or zeppelin-shaped and constitutes a flow body, is configured as an extension of the propulsion axis in the region of the rudder blade. The purpose of this flow body is that the overall profile of the hub is extended to the point where there is only minimal turbulence of the wake.
This type of Costa bulb is known for example from patents DE 198 44 353 A1, DE 84 23 818 U and DE 82 24 238 U.
The effect of the Costa bulb is a result of its bead-shaped configuration, by which it is distinguished from the rudder or respectively rudder blade, resulting in favorable flow.
The Costa bulb protrudes laterally relative to the rudder blade and in the event of an impact, a blow or pressure the Costa Bulb is in the immediate impact zone. This means that the Costa Bulb would be damaged before the actual rudder blade would be damaged.
However, in the event of an impact, a blow or pressure on the prior art Costa bulb the rudder blade would also be affected, because the Costa bulb transfers the force acting on it to the rudder blade and there is thus the added danger of damage to the rudder blade.

SUMMARY OF THE INVENTION

The purpose of the invention is to provide a rudder blade for ships, which in spite of favorable flow due to external effects, is less susceptible to damage or destruction due to the effect of an impact, a blow or pressure and that the flow body is independently destroyed or self-released in the event of such pressure, blow or impact.
At the same time it is advantageous if the flow body divides the rudder blade, viewed in the vertical direction, into two areas (A, B), whereby both areas are designed identically or not identically in profile. In this respect it is effective if the longitudinal middle lines of the areas of the rudder blade are not superposed with the middle line of the flow body and respectively form an angle α therewith.
It is also effective if the angle α between the longitudinal middle line of a region of the rudder blade and the middle lines of the flow body are different for both of the areas (A, B).
In terms of the invention it is advantageous if the flow body has predetermined break-off sites, which lead to the destruction of the flow body in the event of the increased effect of force, a blow, an impact or pressure on the flow body. At the same time it is a further advantage if the predetermined break-off sites are designed as predetermined break-off lines. Also, it is effective if the predetermined break-off lines are oriented in the longitudinal and/or transverse direction of the flow body. But it is also advantageous if the predetermined break-off lines are distributed in a reticulated manner over the flow body.
In terms of the invention it is effective if the predetermined break-off sites or predetermined break-off lines are designed as material weaknesses, material reductions, shear lines and/or perforations.
In an advantageous embodiment it is effective if the flow body comprises metal or a non-metallic material or a metal-non-metal mixture.
In another advantageous embodiment it is effective if the flow body comprises a carbon-fiber composite material.
In a further advantageous embodiment it is effective if the material has embedded carbon fibers, graphite fibers and/or fiberglass.
In yet another advantageous embodiment it is effective if the flow body comprises a synthetic material or synthetic materials.
In an advantageous embodiment it is effective if the flow body comprises synthetic material, such as polyoxymethylene, polyformaldehyde or polyacetates.
In a particularly advantageous configuration the flow body comprises two individual bowl-shaped longitudinal bodies conforming to the flow body and held, in longitudinal edge regions, on the outer wall faces of the rudder blade via predetermined break-off lines. The edge regions of both bowl-shaped longitudinal bodies facing the propeller are connected via predetermined break-off lines to a spherical cap-shaped component, in turn connected solidly or detachably to the rudder blade.
The advantage of the inventive configuration of the flow body of a rudder blade of a rudder for ships is that due to the possibility of the flow body being destroyed or self-released while in the event of pressure, blow or impact effect the rudder is not impaired. There is also the possibility that conventional rudder blades can be retrofitted with the inventive flow body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in greater detail hereinbelow on the basis of an embodiment by way of the drawings, in which:

FIG. 1 is a diagrammatic view of the stem of a ship with a drive propeller and the rudder blade of a rudder, whereby the rudder blade is fitted with the inventive bulb-shaped flow body,

FIG. 2 is a diagrammatic view of the rudder blade with a flow body comprising three components in the state of destruction in an exploded view,

FIG. 3 is a frontal elevation of the rudder blade with the flow body in the state of destruction,

FIG. 4 is a diagrammatic view of the rudder blade with the flow body,

FIG. 5 is a rear elevation of the rudder blade with the flow body,

FIG. 6 is a side elevation of the rudder blade with the flow body,

FIG. 7 is a frontal elevation of the rudder blade with the flow body,

FIG. 8 is a plan view from above of the rudder blade with the flow body, and

FIG. 9 is a plan view from below of the rudder blade with the flow body.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the stem 11 of a ship 10 with a drive propeller 12 and a rudder 13, whereof the rudder blade 15 is fitted with a bulb-shaped or zeppelin-shaped flow body 20, preferably designed as a hollow body and which can be integrated into the rudder blade 15 and can comprise two or more components 21, 22, attached to the outer wall faces 15 a, 15 b of the rudder blade 15. The flow body 20 can also be designed as a full body. In the extension of the propulsion axis a bulge, which forms the flow body 20, also known as propulsion bulb or Costa bulb, is designed in the region of the rudder blade 15. The flow body 20 is designed such that in the event of a pressure, blow or impact effect it is self-destroying or self-releasing.
To achieve the possibility of self-destruction, the flow body 20 comprises individual wall sections, interconnected via predetermined break-off lines 40 in the form of material weaknesses, material reductions, shear lines, or perforations. Such break-off lines for use in other fields are generally known to those skilled in the art of materials/design engineering and related fields. Rudders are not mass-produced articles but are rather single-unit productions that are adapted in terms of their dimensions, materials and the like for each individual ship. Hence, the specific dimensions and placement of break-off lines will differ for each individual rudder. A person skilled in the art will be able to determine the rated break points for the break-off lines 40 and how to configure the same.
Generally, the material weaknesses, material reductions, shear lines or perforations comprise a thinning or reduction in thickness of the wall of the flow body 20 near the points of attachment to the rudder blade 15 and/or the other parts of the flow body 20. Preferably, the thinning or reduction in thickness of the wall does not pass completely through the wall of the flow body 20. The predetermined break-off lines 40 are preferably designed and arranged on the inner surface such that there are no wrinkles, depressions, grooves, slots or the like in the outer surface of the flow body 20, which is hollow. Thus, the flow body 20 has a smooth outer surface to reduce drag or turbulence around the flow body 20. This is accomplished by arranging the material weaknesses, material reductions, shear lines or perforations on the inner surface of the flow body 20.
Preferably, the material weaknesses, material reductions, shear lines or perforations are configured as indentations, depressions, notches or grooves in the thickness of the material from the inside-out, without passing completely through the wall of the flow body 20. The indentations, depressions, notches or grooves, i.e., reductions in thickness, of the wall are configured such that a pre-determined thickness of material remains on the outer surface of the flow body 20 on top of the indentations, depressions, notches or grooves. Ideally, the indentations, depressions, notches or grooves would reduce the thickness of the wall of the flow body 20, by anywhere from 1% to 99%, keeping in mind that enough material must remain to support structural integrity of the flow body 20.
These material weaknesses, material reductions, shear lines or perforations are configured such that the flow body 20 maintains structural integrity under pre-determined normal operating force conditions, i.e., stresses. In the event of a blow, an impact or pressure on the flow body 20 in excess of the pre-determined normal operating force conditions, the material weaknesses, material reductions, shear lines or perforations are configured to lose structural integrity such that the flow body 20 separates from the rudder 15. Normal operating conditions will vary from ship-to-ship, depending upon the size of the vessel, the force from the wake of the propeller, and the configuration of the rudder 15, among other factors. A person skilled in the art knows how to calculate force vectors and loads on the flow body 20 to determine the required dimensions or thickness of material to maintain structural integrity under normal operating conditions and lose structural integrity when normal operating conditions are exceeded, which dimensions will vary from ship-to-ship based upon the particular rudder design.
The material weaknesses, material reductions, shear lines or perforations may comprise continuous indentations, depressions, notches or grooves in the material or be discontinuous, i.e., dashed or interrupted. The predetermined break-off lines 40 may be configured in a longitudinal direction and/or run transversely to the longitudinal direction of the flow body 20. The predetermined break-off lines 40 may also be irregular in their placement on the flow body 20 or distributed in a reticulated manner over the flow body 20. In a preferred embodiment, the break-off lines 40 are disposed adjacent to the edges of the flow body 20 where it is attached to the rudder 15, as depicted in FIGS. 2, 4 and 6. In this configuration, a blow, an impact or pressure in excess of the pre-determined normal operating conditions will cause the flow body 20 to separate from the rudder 15 at the break-off lines 40 so as to leave as little material as possible on the rudder 15.
An essential element of the inventive design of the rudder blade 15 is that the flow body 20 self-destroys or detaches in the event of the effect of an impact, a blow or pressure. The self-destruction or detachment occurs at the point of the material weaknesses, material reductions, shear lines or perforations forming the break-off lines 40. This ensures that no excessive force is transferred through the flow body 20 to the rudder blade 15 itself so that any impairment to the rudder blade 15 resulting from substantial damage or destruction can be prevented.
FIG. 2 shows the view of a rudder blade 15 having a flow body 20, made up of three individual parts 50, 51, 55. Here the parts 50, 51 form the sides of the flow body 20 on the sides of the rudder blade 15 and the part 55 forms the front, i.e. the substantially somewhat hemispherical end section facing the propeller 12. Arrows X, X1, X2 indicate that the parts 50, 51, 55 in these directions are disassembled from the rudder blade 15. Typically, the parts 50, 51, 55 of the flow body 20 are bowl-shaped and preferably form no solid bodies, rather just form a hollow body in the assembled state, built onto the rudder blade 15.
Then the flow body 20 comprises two individual bowl-shaped longitudinal bodies 50, 51, conforming to the flow body, which in the region of their longitudinal edges 50 a, 51 a are held via predetermined break-off lines 40 on the outer wall faces 15 a, 15 b of the rudder blade 15. The edge regions 50 a, 51 b of both bowl-shaped longitudinal bodies 50, 51 facing the propeller 12 are connected via predetermined break-off lines 40 to a spherical cap-shaped component, connected solidly or detachably to the rudder blade 15 (FIGS. 2 and 3).
It is further evident from FIG. 2 that the rudder blade 15 is not a homogeneous component, but rather is formed from an upper area A and a lower area B. The upper area A has at least on its front side a curve or cut, which is bent or oriented more to the left, and the lower area B has at least one curve or cut, which is bent or oriented more to the right. At the interface of both areas A and B this difference is evident from the fact that both front areas are designed as tabs, which do not match one another congruently, but stand apart from one another approximately y-shaped. The longitudinal middle lines LM1 of both areas A and B are not congruent or parallel. Also, the longitudinal middle lines LM1 of the areas A and B do not lie on the middle line ML of the flow body 20.
FIG. 3 shows a view of the rudder blade 15 with the flow body 20 having parts 50, 51 and 55. It should be noted that the areas A and B can be different so that the longitudinal middle lines LM1 breach the leading edge at LM1 and thus lie outside the middle line ML of the flow body 20. In another embodiment of the invention, not illustrated here, the upper area A can however also be identical to the lower area B, such that either the deviation of the longitudinal middle line LM1 to the middle line ML of the flow body 20 is the same and different at a zero angle, or can be equal to zero.
FIG. 8 and FIG. 9 in each case show a view of the rudder blade 15 from below or respectively from above. Evident in each case is the angle α between the longitudinal middle line LM1 of both upper and lower areas (A and B) of the rudder blade 15 and the middle line ML of the flow body 20. The angle α (alpha) exists between the longitudinal middle line (LM1) of upper area (A) and the middle line (ML) of the flow body 20. The angle β (beta) exists between the longitudinal middle line (LM1) of lower area (B) and the middle line (ML) of the flow body 20. The angles α and β may be the same or different.
FIG. 4 shows a rudder blade 15 with a flow body 20 in a side elevation from the rear left. Here, the areas A and B are apparent. In the rear area the areas A and B are identical, whereas in the frontal region they are designed different (see also FIG. 2).
FIG. 5 shows the rudder blade 15 in a view from behind and FIG. 7 shows a frontal view. In each case the flow body 20 can be clearly viewed.
FIG. 6 shows the inventive rudder blade 15 with the flow body 20, whereby the flow body has predetermined break-off sites for better self-destruction in the event of the effect of an impact or a blow or pressure. The predetermined break-off sites are advantageously provided as predetermined break-off lines 40, and are distributed over the surface of the flow body—as described above.
As depicted in FIGS. 8 and 9 the rudder blade 15 has a cross-sectional area 16, the longitudinal middle line LM1 of which is offset at an angle α to the middle line ML of the flow body 20, so that the leading edge stringer strip 70 of the rudder blade 15 facing the drive propeller 12 is not aligned with the middle line ML of the flow body 20.
The flow body 20 is advantageously comprised of metal. Though in another embodiment it can also be formed out of a non-metallic material, such as a carbon fiber composite material preferably with embedded carbon fibers, graphite fibers and/or fiberglass. A metal-non-metal mixture can also be employed.
In another embodiment the flow body 20 can also be made of synthetic material or synthetic materials, such as polyoxymethylene, polyformaldehyde or polyacetates. These materials typically have a high gliding quality, which is advantageous for friction in water.
The inventive rudder blade 15 with the flow body 20 is used advantageously in fully suspended rudders.
It is also effective if the flow body 20 is integrated in the rudder blade 15 or the flow body 20 is attached half and half for example on both sides of the rudder blade 15.
As is evident in FIGS. 2, 3 and 4, the leading edge stringer strips 70, 71 of both superposed rudder blade regions A and B facing the propeller 12 are offset to one another such that the leading edge stringer strip 70 of the upper rudder blade region A is offset to the port side P and the leading edge stringer strip 71 is offset to the to the starboard side S. The reverse offsetting is also possible. The outer wall faces 15 a, 15 b of the rudder blade 15 are united in an end strip 75 averted or facing way from the propeller 12 (twisted rudder).
By the leading edge stringer strip 70, 71 of both rudder blade regions A and B being offset to one another, so that the leading edge stringer strip of the upper rudder blade section is offset to the port side and the leading edge stringer strip of the lower rudder blade section is offset to the starboard side or the leading edge stringer strip of the upper rudder blade section is offset to the starboard side and the leading edge stringer strip of the lower rudder blade section is offset to the port side, in each case resulting in two mirror-inverted cross-sectional profiles of both rudder blade regions.
The advantage of such a rudder blade 15 designed according to the invention having two mirror-inverted cross-sectional profiles is first that it prevents vapor lock and it also prevents erosion phenomena on the rudder, occurring through cavitation in fast ships with high-load propellers. The special configuration of the rudder blade contributes to a drop in fuel consumption. There is an improvement in efficiency, in addition to considerable cavitation protection. There is also substantial reduction in weight.

Claims

1. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15), wherein the flow body (20) includes individual sections defined by break-off lines in the flow body (20), said break-off lines comprising material weaknesses, material reductions, shear lines or perforations in the flow body (20) whereby the flow body (20) is self-destructive or self-releasing in the event of a force, a blow, an impact or pressure on the flow body, whereby damage to the rudder blade is reduced or prevented when the flow body (20) self-destructs or self-releases, wherein the predetermined break-off lines (40) extend generally along a length or transverse to a longitudinal axis of the flow body (20).

2. The rudder as claimed in claim 1, wherein the predetermined break-off lines (40) are distributed in a reticulated manner over the flow body (20).

3. The rudder as claimed in claim 1, wherein the flow body (20) comprises a spherical cap-shaped component (55) connected solidly or detachably to the rudder blade (15) and two individual bowl-shaped longitudinal bodies (50, 51) detachably connected by the break-off lines (40) to outer wall faces (15 a, 15 b) of the rudder blade (15) and the spherical cap-shaped component (55).

4. The rudder as claimed in claim 3, wherein the flow body (20) and the bowl-shaped longitudinal bodies (50, 51) are comprised of carbon fiber composite materials, fiber composite materials with embedded graphite fibers, fiberglass, a metal-non-metal mixture, or a synthetic material.

5. The rudder as claimed in claim 1, wherein the rudder blade (15) has a cross-sectional area (16) with a longitudinal middle line (LM1) that is offset at an angle α to a middle line (ML) of the flow body (20), so that a leading edge stringer strip (70; 71) of the rudder blade (15) facing the propeller (12) is not aligned with the middle line (ML) of the flow body (20).

6. The rudder as claimed in claim 1, wherein the flow body (20) comprises a synthetic material.

7. The rudder as claimed in claim 6, wherein the synthetic material is one of the group consisting of polyoxymethylene, polyformaldehyde and polyacetates.

8. The rudder as claimed in claim 1, wherein the predetermined break-off lines (40) are irregular.

9. The rudder of claim 1, wherein the flow body (20) divides the rudder blade (15) into upper and lower areas (A and B) each having a longitudinal middle axis line (LM1) from a front edge thereof to a back edge thereof wherein the longitudinal middle axis lines (LM1) of the upper and lower areas (A and B) of the rudder blade (15) are not aligned with a middle line (ML) of the flow body (20) and each form an angle therewith, wherein the angle (α) between the longitudinal middle axis line (LM1) of the upper area (A) and the middle line (ML) of the flow body (20) is different from the angle (β) between the longitudinal middle axis line (LM1) of the lower area (B) and the middle line (ML) of the flow body (20).

10. The rudder as claimed in claim 9, wherein first and second leading edge stringer strips (70, 71) of the upper and lower rudder blade areas (A and B) facing the propeller (12) are offset to one another such that the first leading edge stringer strip (70) of the upper rudder blade area (A) is offset to either a port side (P) or a starboard side (S) and the second leading edge stringer strip (71) of the lower rudder blade (B) is offset to the opposite starboard side (S) or port side (P), whereby outer wall faces (15 a, 15 b) of the rudder blade (15) are joined in an end strip (75) facing away from the propeller (12).

11. The rudder as claimed in claim 9, wherein the upper and lower areas (A and B) have an identical profile.

12. The rudder as claimed in claim 9, wherein the upper and lower areas (A and B) have different profiles.

13. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) includes individual sections defined by break-off lines in the flow body (20), said break-off lines comprising material weaknesses, material reductions, shear lines or perforations in the flow body (20) whereby the flow body (20) is self-destructive or self-releasing in the event of a force, a blow, an impact or pressure on the flow body, whereby damage to the rudder blade is reduced or prevented when the flow body (20) self-destructs or self-releases;

wherein the flow body (20) divides the rudder blade (15) into upper and lower areas (A and B) each having a longitudinal middle axis line (LM1) from a front edge thereof to a back edge thereof wherein the longitudinal middle axis lines (LM1) of the upper and lower areas (A and B) of the rudder blade (15) are not aligned with a middle line (ML) of the flow body (20) and each form an angle therewith, wherein the angle (α) between the longitudinal middle axis line (LM1) of the upper area (A) of the rudder blade (15) and the middle line (ML) of the flow body (20) is different from the angle (β) between the longitudinal middle axis line (LM1) of the lower area (B) and the middle line (ML) of the flow body (20); and

wherein the break-off lines (40) extend generally along a length or transverse to a longitudinal axis of the flow body (20).

14. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the break-off lines (40) are distributed in a reticulated manner over the flow body (20).

15. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) comprises a spherical cap-shaped component (55) connected solidly or detachably to the rudder blade (15) and two individual bowl-shaped longitudinal bodies (50, 51) detachably connected by the break-off lines (40) to outer wall faces (15 a, 15 b) of the rudder blade (15) and the spherical cap-shaped component (55).

16. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) divides the rudder blade (15) into upper and lower areas (A and B) each having a longitudinal middle axis line (LM1) from a front edge thereof to a back edge thereof wherein the longitudinal middle axis lines (LM1) of the upper and lower areas (A and B) of the rudder blade (15) are not aligned with a middle line (ML) of the flow body (20) and each form an angle therewith, wherein the angle (α) between the longitudinal middle axis line (ML1) of the upper area (A) of the rudder blade (15) and the middle line (ML) of the flow body (20) is different from the angle (β) between the longitudinal middle axis line (LM1) of the lower area (B) and the middle line (ML) of the flow body (20); and

wherein the longitudinal middle line (LM1) of the upper area A is offset at the angle α to the middle line (ML) of the flow body (20) and the longitudinal middle line (LM1) of the lower area B is offset at the angle β to the middle line (ML) of the flow body (20), so that a leading edge stringer strips (70; 71) upper and lower areas (A and B) of the rudder blade (15) facing the propeller (12) are not aligned with the middle line (ML) of the flow body (20).

17. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein first and second leading edge stringer strips (70, 71) of the upper and lower rudder blade areas (A and B) facing the propeller (12) are offset to one another such that the first leading edge stringer strip (70) of the upper rudder blade area (A) is offset to either a port side (P) or a starboard side (S) and the second leading edge stringer strip (71) of the lower rudder blade (B) is offset to the opposite starboard side (S) or port side (P), whereby outer wall faces (15 a, 15 b) of the rudder blade (15) are joined in an end strip (75) facing away from the propeller (12).

18. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) divides the rudder blade (15) into upper and lower areas (A and B) each having a longitudinal middle axis line (LM1) from a front edge thereof to a back edge thereof wherein the longitudinal middle axis lines (LM1) of the upper and lower areas (A and B) of the rudder blade (15) are not aligned with a middle line (ML) of the flow body (20) and each form an angle therewith, wherein the angle (α) between the longitudinal middle axis line (LM1) of the upper area (A) of the rudder blade (15) and the middle line (ML) of the flow body (20) is different from the angle (β) between the longitudinal middle axis line (LM1) of the lower area (B) and the middle line (ML) of the flow body (20);

wherein the break-off lines (40) extend generally along a length or transverse to a longitudinal axis of the flow body (20); and

wherein the break-off lines (40) are irregular.

19. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) includes individual sections defined by break-off lines in the flow body (20), said break-off lines comprising material weaknesses, material reductions, shear lines or perforations in the flow body (20) whereby the flow body (20) is self-destructive or self-releasing in the event of a force, a blow, an impact or pressure on the flow body, whereby damage to the rudder blade is reduced or prevented when the flow body (20) self destructs or self-releases;

wherein the areas (A and B) have identical profiles.

20. A rudder for ships, comprising a rudder blade (15), which is associated with a propeller (12) arranged on a driven propulsion axis, and a flow body (20) having a bulb-shaped or zeppelin shaped configuration arranged on the rudder blade (15) as an extension of the propulsion axis in a region of the rudder blade (15);

wherein the flow body (20) divides the rudder blade (15) into upper and lower areas (A and B) each having a longitudinal middle axis line (LM1) from a front edge thereof to a back edge thereof wherein the longitudinal middle axis lines (LM1) of the upper and lower areas (A and B) of the rudder blade (15) are not aligned with a middle line (ML) of the flow body (20) and each form an angle therewith, wherein the angle (α) between the longitudinal middle axis line (LM1) of the upper areas (A) of the rudder blade (15) and the middle line (ML) of the flow body (20) is different from the angle (β) between the longitudinal middle axis line (LM1) of the lower area (B) and the middle line (ML) of the flow body (20); and

wherein the upper and lower areas (A and B) have different profiles.