"A STABILIZING DEVICE FOR A SHIP OR CRAFT, A SHIP COMPRISING SUCH DEVICE, A METHOD FOR MOVING THE STABILIZING DEVICE"

[0001] The present invention applies in the field of the anti-roll stabilizing devices, for a ship or craft, based on the hydrodynamic action of fins of a retractable type.

[0002] In the navigation field, is often felt the need to stabilize the craft to avoid or at least partially reduce excessive oscillations thereof, generated by the wave motion of the sea at which it is.

[0003] Particularly, during navigation, the craft undergoes annoying oscillations about its longitudinal axis, or roll oscillations.

[0004] In order to guarantee passengers and crew on-board comfort levels consistent with the high standards required by the market, the practice is widespread and well-established to provide, sometimes even from the first steps in designing a naval vessel, for the use of stabilizing systems suitable to considerably reduce the effect of the roll motions.

[0005] A known and very widespread system is the stabilization carried out by stabilizer fins that, exploiting the hydrodynamic characteristics of the wing profiles and using the modern control systems, are able to sensibly reduce the roll movements.

[0006] The above-mentioned stabilizer fins, which are indispensable for a safe and comfortable navigation even in the presence of very severe sea states, since they are hydrodynamic attachments exiting the bottom underneath the free water surface, inevitably produce a hydrodynamic resistance opposing the forward movement of the ship, whichever the hydrodynamic angle of attack at which they are operated is.

[0007] In order to at least partially reduce the drag resisting the ship forward motion, stabilizer fins of the "retractable" type are known, which, under favourable sea weather conditions, are retracted into special structural recesses that are obtained in the bottom.

[0008] However, the known stabilizing systems comprising retractable stabilizer fins have important drawbacks.

[0009] In fact, the same presence of the retractable stabilizer fins involves anyhow a considerable increase in the drag resisting the ship forward motion, even if the fins are in the retracted position and in any situations in which the ship has to navigate at a non ^¬ zero speed.

[0010] This drawback is caused by the fact that a high contribution to the drag resisting the ship forward motion is provided by the presence of structural recesses in bottom, indispensable to make the fins to reenter them when the former are in the retracted position, while locally deflecting the usual hydrodynamic flow of the water along the bottom, resulting in more or less pronounced vorticity phenomena, which in any event increase the resistance to the motion of the ship.

[0011] This drag resisting the ship forward motion negatively affects the fuel consumption to cover a predetermined distance.

[0012] The drawback described above occurs both under conditions of extended fins and under conditions of retracted fins, since the drag contribution due to the recesses interrupting the bottom continuity is anyway present, independently from the fin position between the retracted position and the extended one.

[0013] Therefore, the known stabilizing devices with a retractable fin suffer the drawback of opposing a resistance to the ship forward motion during the entire service life of the ship, both in the case of an extended fin, and in the case of a retracted fin.

[0014] Several devices are known, comprising stabilizer fins that can be folded into a recess obtained within the hull, in which the compartment opens towards the exterior of the bottom, for example, those disclosed in the patent documents GB825134A, GB1352308, JP9323697, EP0754618, JP11129986, but none of such documents shows any solutions whatsoever to the need of reducing the drag of the ship caused by the recesses for receiving the fin.

[0015] Some attempts for reducing the drag are also known, which however remain defective and failing in solving the problem, such as those described in FR2538340-A1 , DE2121091, EP2096027, US3837313.

[0016] These documents, while achieving good results in decreasing the drag when the fin is in the retracted position, use closing hatches when the fin is retracted, are not effective in solving such problem when the fin is in the extended position. In fact, they are not able to prevent the hydrodynamic flow of water along the bottom from being deflected at the recess when the fin is extended, not offering any solutions to the problem under such operative condition. The solution proposed in GB 802 105 A by DEUTSCHE WERFT AG shows a device for damping the roll of ships by means of stabilizer fins that are capable of angular movements rotating from an extended position to a position that is folded within the ship hull, which can be closed by a slidable bulkhead. However, this known solution force to implement a very bulky fin housing compartment in order to allow the bulkhead to close it when the fin is retracted. Furthermore, the proposed solution, while partially obstructing the compartment opening, even when it covers the opening, does not allow restoring the bottom continuity.

[0017] Particularly the document US3837313 shows a hydrofoil having a bow door and a wing with a vertical strut that is movable between a raised position and a position that is lowered into the slot, and it further has two doors cooperating when they are closed to form a bow portion in an aerodynamic shape, in which such doors are movable towards an open position in which the wing strut is free to move along the slot between the fully lowered position and the fully raised position.

[001.8] Neither this document is able to close the recess when the fin is extended, i.e., exactly when the need is most felt to pose the minimum hydrodynamic resistance. Therefore, the need is strongly felt of reducing the resistance given by the openings formed in the continuity of the ship bottom for the sticking out and folding of stabilizer fins while reducing the overall dimensions of these devices not only in terms of extent on the bottom surface, but also of the volume that is occupied within the hull.

[0019] The object of the present invention is to devise and provide a stabilizing device having retractable 0

6

stabilizer fins that allow meeting the above-mentioned needs and at least partially obviating the drawbacks reported herein above with reference to the prior art.

[0020] Particularly, the task of the present invention is to provide a stabilizing device for a craft or ship comprising a stabilizer fin that is retractable into a recess in the bottom, while allowing considerably reducing or eliminating the hydrodynamic resistance exerted by the water against the recess at any positions of the fin.

[0021] Such an object is achieved by a stabilizing device as defined in the appended claims, the definitions of which are an integral part of the present description.

[0022J Furthermore, such object is achieved by a ship comprising such stabilizing device and by a method for moving such stabilizing device.

[0023] Further characteristics and advantages of the present invention will be apparent from the description set forth below of preferred embodiment examples, given by way of illustrative, not-limiting example, with reference to the appended figures, in which:

[0024] - Fig. 1 illustrates a perspective view of a stabilizing device according to the invention, in which the fin is in the retracted position and the hatches are closed; P T/IB2014/060250

7

[0025] - Fig. 2 illustrates a perspective view of the device of Fig. 1, in which the fin is in the extracted position and the hatches are open;

[0026] - Fig. 3 illustrates a perspective view of a device according to the invention with the fin in the extended position, provided with handling means;

[0027] - Fig, 4 illustrates a perspective view of the device according to the invention with the fin in the extended position, in which the holding compartment is not shown for the sake of clarity;

[0028] - Fig. -5 illustrates a perspective view of the device according to the invention in which the fin is in an intermediate position between the extended position and the retracted position;

[0029] - Fig. 6 shows only schematically a cross-section of a ship having two stabilizing devices according to the invention;

[0030] -Fig. 7 illustrates a perspective view of the device according to a further embodiment in which the fin provided with a flap is in the extended position and a first hatch partially closes the opening having the largest transverse dimensions of the hull;

[0031] -Fig. 8 illustrates a perspective view of the device according to a further embodiment in which the fin not provided with a flap is in the extended position, and a first hatch partially closes the opening having the largest transverse dimensions of the hull;

[0032] -Fig. 9 illustrates a perspective view of the device according to a further embodiment in which the fin is in the retracted position and a second hatch partially closes the opening having the largest transverse dimensions of the hull;

[0033] -Fig. 10 illustrates a perspective view of the device according to a further embodiment in which the fin, with opposite inlet edge and outlet edge without a flap, is in the extended position, and a first hatch partially closes the hull opening;

[0034] Fig. 11 illustrates a perspective view of the device according to a. further embodiment in which the fin, with opposite inlet edge and outlet edge provided with a flap, is in the extended position and a first hatch partially closes the hull opening.

[0035] Herein below reference will be made to a "longitudinal axis of the ship" to indicate an axis that connects the bow with the stern of the ship; a "hull" will be referred to, to indicate the set of all the structures composing the ship body; a "bottom" to indicate the surface externally defining the hull beneath the floating line; a "keel" to indicate the essential continuous element of the hull, extending longitudinally from the stern to the bow.

[0036] With reference to the figures, a stabilizing device according to the invention, for a ship or craft, is generally indicated with the reference 1.

[0037] Particularly, the stabilizing device 1 comprises a stabilizer fin 10 movably connected to the hull, and movable between a retracted position in which the _' fin 10 is contained in a recess 30 extending in the hull starting from the bottom, and an extracted position in which the fin 10 projects from the ship bottom 2 through this recess.

[0038] Therefore, the bottom has an opening 31, 32 allowing the sticking out of the fin from the bottom, and the recess 30 originates from this opening 31, 32.

[0039] In accordance with an embodiment, the recess is formed by a holding compartment 30 defining the recess itself, in which a wall of the holding compartment comprises the opening 31, 32.

(0040] Such a stabilizer fin 10 has the task of stabilizing the ship during the navigation thereof, reducing the roll movement of the same ship as much as possible.

[0041] Preferably, the stabilizing device is associated to the ship at least in a pair. In other terms, two stabilizing devices are arranged on opposite sides of the ship and symmetrically with respect to a symmetry plane passing through the ship keel.

[0042] In this manner, the two symmetrically arranged devices are configured to mutually cooperate, for example, by a control and actuators that rotate the fins in a controlled way about an oscillation axis 0-0 and in an interval of angular positions ranging between predetermined maximum values.

[0043] Thus, each of the two stabilizing devices acts in a coordinated manner reducing the undesired roll of the ship along a longitudinal axis of the ship itself.

[0044] The fin 10 of each stabilizing device 1 is operatively submersed throughout the use thereof, so as to act dynamically against the destabilizing thrust exerted by the water during navigation or when stationing.

[0045] In fact, such a fin 10 may exert its braking action with respect to the roll movement even when the ship 2 is not travelling, but it is stationed at a position.

[0046] The fin 10 of the stabilizing device may have transversally a wing profile, and extends mainly in a main extension direction transversal to the bottom 3, for example, substantially orthogonal to the bottom 3, so as to optimize the hydrodynamic forces exchanged with the water in which it is immersed.

[0047] This main extension direction can be substantially parallel to the oscillation axis 0-0, or coincident with the oscillation axis 0-0.

[0048] In accordance with an embodiment, the holding compartment 30 has a box-like shape, having a bottom wall 35 opposite the opening 31, 32, and side walls 36 connecting the bottom wall 35 to the opening 31, 32.

{0049] According to an embodiment, the side walls are in the number of four, substantially parallel two by two.

[0050] In accordance with an embodiment, the holding compartment 30 is waterproof, in other words, it is configured so as not to allow the passage of water through it.

[0051] In accordance with an embodiment, the holding compartment 30 comprises a front wall 37 opposite said bottom wall 35, and said front wall is shaped according to the profile of the ship bottom 3 in an assembling position of the stabilizing device 1, and the front wall 37 comprises the opening 31, 32.

[0052] Therefore, in accordance with an embodiment, the holding compartment 30 is a piece that can be secured to the bottom at an opening specifically obtained in the bottom.

[0053] In such a case, the front wall 37 can be mounted in a corresponding hole obtained in the ship bottom 3, said hole having the same shape of an outer contour 38 of the front wall 37.

[0054] In this manner, the holding compartment 30 can be mounted by aligning the front wall 37 to the bottom 3 with continuity of shape, and firmly securing such front wall 37 to the bottom, for example, by welding.

[0055] The front wall 37 may extend outwardly beyond the side walls 36 and transversally to the side walls 36 forming an assembling flange 39.

[0056] Such assembling flange 39 can be secured to the bottom at a hole in the bottom having the same shape of the outer edge 38 of the assembling flange 39 so that the front wall 37, together with the flange 39, are flush with the bottom 3, with continuity of shape. .

[0057] Alternatively, the holding compartment 30 can be secured to the bottom 3 by overlapping the flange 39 to the bottom 3.

[0058] In accordance with an alternative embodiment, the holding compartment is made in a single piece with the bottom 3 itself.

[0059] The stabilizing device 1 comprises fin handling means 50 configured to move the fin 10 between an extended position, in which the fin 10 projects from the bottom 3 through the opening 31, 32, and a retracted position, in which the fin 10 is retracted into the holding compartment 30. [0060] In accordance with an embodiment, the fin handling means 50 are rotation means and are configured to rotate the fin 10 between the retracted position and the extended position with respect to the holding compartment 30 about a rotational axis R-R.

[0061] In accordance with an embodiment, the rotational axis R-R lies on a plane orthogonal to the ship longitudinal axis, and particularly, but not necessarily, substantially parallel to the bottom 3 at the point where it is mounted.

[0062] According to an embodiment, the stabilizing device comprises a connecting body 20 suitable to connect the stabilizer fin 10 to the hull 2, or, alternatively, to the holding compartment 30, in which the connecting body 20 supports the fin 10 and it can be rotated together with the fin 10 with respect to the hull 2 between an extended position of the fin 10, in which the fin 10 projects from the hull 2 through the opening 31, 32, and a retracted position of the fin 10, in which the fin 10 fully reenters the hull 3 through the opening 31, 32.

[0063] The stabilizing device 1 comprises a first closing hatch 62 integrally secured to the connecting body 20, suitable to at least partially close the opening 31, 32 when the fin 10 is in the extended position. The first hatch 62 is shaped so as to restore the shape and continuity of the bottom 3 when the fin 10 is in said extended position.

[0064] In accordance with an embodiment, the stabilizing device 1 comprises a second hatch 61 integrally secured to the connecting body 20, in which said second hatch 61 is suitable to at least partially close the opening 31, 32 when the fin 10 is in said retracted position. The second hatch 61 is shaped with an outer surface thereof suitable to restore the shape and continuity of the bottom 3 when the fin 10 is in the retracted position.

[0065] In accordance with an embodiment, the first hatch 62 and the second hatch 61 are substantially the same one to the other and arranged mutually angled according to an angle corresponding or substantially equal to the maximum angular displacement of the connecting body 20 between a first angular position thereof corresponding to the extended fin and a second angular position thereof corresponding to the retracted fin.

[0066] In accordance with an embodiment, the opening 31, 32 is formed by an opening portion allowing the sticking out of the connecting body 31, and a contiguous opening portion 32 allowing the sticking out of the fin 10.

(0067] In accordance with an embodiment, the first hatch 62 or, in addition, the second hatch 61, is suitable to at least partially close the opening portion allowing the sticking out of the connecting body 31.

[0068] In accordance with an embodiment, the first hatch 62 defines a first outer accompanying surface 42, configured to restore the bottom 3 shape at the opening portion 31, allowing the sticking out of the connecting body 20, when the first hatch 62 is closed.

[0069] In accordance with an embodiment, the second hatch 61 defines a second outer accompanying surface 41, configured to restore the bottom 3 shape at the opening portion 31, allowing the sticking out of the connecting body 20, when the second hatch 61 has reentered.

[0070] In accordance with an embodiment, the first hatch 62 and the second hatch 61 are made in a single piece with the connecting body 20, for example, they form a first side and a second side of the connecting body 20.

[0071] In accordance with an embodiment, the fin handling means 50 comprise a linear actuator 51, for example, a hydraulic cylinder.

[0072] In accordance with an embodiment, the linear actuator.51 has a first end 52 hinged at a stationary point 53, for example, belonging to the holding compartment 30, or, alternatively, at a point of the hull 2, and a second end 54 hinged at an arm 55 integral to the connecting body 20, so that a rotation of the connecting body 20 corresponds to a linear movement of 60250

16

the linear actuator.

[0073] In accordance with an embodiment, the hydraulic cylinder 51 is hydraulically connected to a hydraulic control unit 56. In this manner, the control unit 56 is configured to drive the movements of the hydraulic cylinder, hence the movements of the connecting body 20, hence the movements of the fin 10 between the retracted position and the extracted position.

[0074] In accordance with an embodiment, the stabilizing device comprises at least one openable shutter 43, 44 configured to close the opening portion 32 not affected by the hatches 61, 62 when said stabilizer fin 10 is in the extended or retracted position.

[0075] In accordance with an embodiment, the at least one openable shutter 43, 44 is connectable to the hull 2 by a waterproof passage bulkhead that allows the rotation thereof so as to keep the opening 32 open during the movement of the stabilizer fin 10 between the extended position thereof and the retracted position thereof.

[0076] In accordance with an embodiment, the at least one shutter 43, 44 is hinged to the front wall 37 or the holding compartment 30, along a major side thereof.

[0077] In accordance with an embodiment, there are two distinct shutters 43 and 44 configured to mutually cooperate in order to close or open the second portion 32 of the compartment 30 opening.

[0078] In accordance with an embodiment, the two shutters 43 and 44 are configured to move in a simultaneous or mutually synchronized manner.

[0079] In accordance with an embodiment, the at least one shutter 43, 44 comprises an automatic opening and closure actuator 45.

[0080] In accordance with an embodiment, the stabilizing device 1 comprises a support shaft, or neck 12 suitable to connect the stabilizer fin 10 to the connecting body 20, in which said shaft or neck has its axis coincident with the oscillation axis 0-0.

[0081] In accordance with an embodiment, the first hatch 62 surrounds the support shaft, or neck 12, allowing to close the opening 31, 32, with the fin in the extended positio .

[0082] In accordance with an embodiment, the stabilizing device 1 comprises oscillation means to rotate the fin 10 about the oscillation axis 0-0, when the fin is in the extended position, to oppose the roll motions.

[0083] In accordance with an embodiment, said oscillation means comprise an oscillation actuator of the hydraulic type, which is actuated by a hydraulic control unit (not shown in the figures) or the electric type.

[0084] Furthermore, the oscillation shaft is a support shaft or support neck that is able to oscillate, or, in other words, to bring the fin 10 to rotate about the oscillation axis or rotational axis 0-0.

[0085] In accordance with an embodiment, the stabilizing device comprises motorized means for the rotation of the stabilizer fin about the axis 0-0 of the support shaft, or neck 12 of the stabilizer fin 10 to oppose in use the ship roll motion.

[0086] In accordance with an embodiment, the axis 0-0 of the support shaft, or neck 12 of the stabilizer fin 10, is transversal to the fin rotational axis R-R.

[0087] In accordance with an embodiment, said stabilizing device comprises a control, preferably fed back as a function of the measured instantaneous oscillations of the ship, so configured as to drive the motorized rotation means .

[0088] According to an embodiment, said control is a control fed back based on a signal derived from the measurement of the speed and the instantaneous accelerations of the ship.

[0089] In accordance with an embodiment,, shown in Fig. 2, the fin 10 may comprise a flap 71 hinged to the fin 10 along an edge 72 of the fin, for example, along a rear edge of the fin 10 with respect to the ship navigation direction. [0090] In accordance with an embodiment, the fin rear edge 72 is rectilinear.

[0091] In accordance with an embodiment, the flap 71 comprises motorized or non-motorized actuating means (not shown) .

[0092] In accordance with another aspect of the present invention, the above-mentioned objects and advantages are met by a ship or craft comprising at least one pair of stabilizing devices 1 as described above.

[0093] In accordance with a further aspect of the present invention, the above-mentioned objects and advantages are met by a method for moving a retractable stabilizer fin 10 to stabilize a ship or craft having a hull 2 defined by a bottom 3 having an opening 31, 32.

[0094] The method comprises a step of providing a connecting body 20 suitable to connect the stabilizer fin 10 to the hull 2, said connecting body 20 supporting said fin 10.

[0095] Furthermore, the method comprises a step of providing a first closing hatch 62 integrally secured to the connecting body 20, said first hatch 62 being suitable to at least partially close an opening portion 31 allowing the sticking out of the connecting body 20.

[0096] Furthermore, advantageously, the method comprises a step of rotating said connecting body 20 together with 0250

20

said stabilizer fin 10 with respect to the hull 2 between a retracted position of said fin 10, so that said fin 10 goes completely back into said hull 2 through said opening 31, 32, and an extended position of said fin 10, so that said fin 10 projects from said hull 2 through said opening 31, 32 in said bottom 3, at least partially closing said opening portion allowing the sticking out 31 of the connecting body 20 when said fin 10 is in the extended position by said first hatch 62, arranging said first hatch 62 flush with said bottom 3, and restoring the bottom 3 shape at the opening 31, 32.

[0097] In accordance with an embodiment, a further step is provided for, of providing at least one openable shutter 43, 44 movably connected to the holding compartment 30 to keep an opening portion 32 closed, allowing the sticking out of the fin when the fin 10 is kept in the extended position and when the fin 10 is kept in the retracted position, and to keep the one opening portion 32 open, allowing the sticking out of the fin during the movement of the fin 10 between the extended position and the retracted position.

[0098] In accordance with an embodiment, the method for moving the fin 10 from the retracted position to the extended position comprises the steps of:

- opening at least one shutter 43, 44/ - rotating the fin 10 from the retracted position to the extended position so that the second surface 42 closes the opening portion 31 allowing the sticking out of the connecting body 20;

- closing at least one shutter 43, 44 so as to close the opening portion allowing the sticking out of the fin from the opening 32.

[0099] In accordance with an embodiment, the method for moving the fin 10 from the extended position to the retracted position comprises the steps of:

- opening at least one shutter 43, 44;

- rotating the fin 1 from the extended position to the retracted position so that the first surface 41 closes said opening portion 31 allowing the sticking out of the connecting body 20 from said opening;

- closing at least one shutter 43, 44 so as to close the opening portion 32 allowing the sticking out of the fin.

[00100] The stabilizing device for a ship or craft according to the invention allows achieving important advantages.

[00101] In fact, such a device allows eliminating at any moment of the operative life of the ship in which it will travel at a non-zero speed, the resistance aliquot due to the presence of recesses in the bottom with consequent reduction of the fuel consumptions. [00102] The presence of the first hatch and the second hatch allows not interrupting or altering the motion of the water along the bottom, limiting to the utmost the formation of turbulent movements and considerably reducing the ship drag.

[00103] The hatches 41, 42 secured to the connecting body 20 ensure the achievement of an extremely sturdy structure, capable of resisting the high mechanical action exerted by the medium (water) .

[00104] Another further advantage is given by a very compact and robust structure by virtue of the fact that the accompanying surfaces, whether they be plates or faces of the connecting body, are integrally and rigidly connected to the connecting body and free from further mechanical handling devices.

[00105] The complete absence of such mechanisms for moving the hatches with respect to the connecting body offers the advantage that possible incrustations of a vegetal or animal origin, which are very frequent for submersed in mare, do not hinder in any way the proper movement of the fins between the retracted position and the extended position, and vice versa.

[00106] Another further advantage is given by a very compact and robust structure by virtue of the fact that the accompanying surfaces, whether they be plates or faces of the connecting body, are integrally and rigidly connected to the connecting body and free from further mechanical handling devices.

[00107] Another advantage is the considerable decrease of the cavitation effect that could be started at the mouth of the recess opening, if it were not closed by the first or the second accompanying surfaces.

[00108] Another advantage of the invention is to provide a stabilizing device for crafts or ships that allows at the same time to close the fin holding compartment when the fin is extracted, while allowing the rotation of the fin about an oscillation axis thereof.

[00109] To the above-described embodiments of the device, those of ordinary skill in the art, in order to meet contingent needs, will be ^' able to make modifications, adaptations, and replacements of elements with functionally equivalent other ones, without for this departing from the scope of the following claims. Each of the characteristics described as belonging to a possible embodiment can be implemented independently from the other embodiments described.

[00110] In accordance with an embodiment, as it can be noted, for example, in Fig. 7, a fin 10 provided with flap 71 has, in the extended position, a first hatch 42 that partially closes the opening 31 having the largest transverse dimensions of the hull.

[00111] In accordance with an embodiment, as it can be noted, for example,, in Fig. 8, a fin 10 that is not provided with a flap is in the extended position and a first hatch 42 partially closes the opening 31 having the largest transverse dimensions of the hull.

[00112] In accordance with an embodiment, as it can be noted, for example, in Fig. 9, a fin 10 is in the retracted position and a second hatch 43 partially closes the opening 31 having the largest transverse dimensions of the hull.

[00113] In accordance with an embodiment, as it can be noted, for example, in Fig. 10, a fin 10, with opposite inlet edge 80 and outlet edge 72 without a flap is in the extended position and a first hatch 42 partially closes the hull opening 31;

[00114] In accordance with an embodiment, as it can be noted, for example, in Fig. 11, a fin 10, with opposite inlet edge 80 and outlet edge 72 provided with a flap 71 is in the extended position and a first hatch 42 partially closes the hull opening 31.

[00115] In accordance with an embodiment, said stabilizer fin 10 comprises a shaped profile having a front edge with respect to the ship navigation direction, or inlet edge 80, and a rear edge with respect to the ship navigation direction, or outlet edge 72. Said outlet edge 72 faces said opening 32 during the rotation with respect to the hull 2 to bring the fin 10 to said retracted position.

[00116] In accordance with an embodiment, said connecting body 20 rotates together with said fin 10 with respect to the hull 2 between an extended position of said fin 10, so that said fin 10 projects from said hull 2 through said opening 31, 32 in said bottom, and a retracted position of said fin 10, so that said fin 10 rotates (according to the arrow R) with the current with respect to the usual navigation direction of the ship travelling forward (according to the arrow V) .

[00117] In accordance with an embodiment, the fin 10 comprises a flap 71 hinged to the fin 10 along a fin edge 72.

[00118] In accordance with an embodiment, said fin edge is the rear edge or outlet edge 72 of the fin 10 with respect to the ship navigation direction V.

]00119] In accordance with an embodiment, the flap 71 comprises actuating means for the rotation thereof with respect to the fin 10 body.

[00120] In accordance with an embodiment, said stabilizer fin 10 comprises a shaped profile having a front edge with respect to the ship navigation direction, or inlet edge 80, and a rear edge with respect to the ship navigation direction, or outlet edge 72, and in which said outlet edge 72 faces the side opposite said opening 32 during the rotation R with respect to the hull 2 to bring the fin 10 to said retracted position.

100121] In accordance with an embodiment, said connecting body 20 rotates together with said fin 10 with respect to the hull 2 between an extended position of said fin 10, so that said fin 10 projects from said hull (2) through said opening 31, 32 in said bottom, and a ^; retracted position of said fin 10, so that said fin 10 rotates (according to the arrow R) counter-current with respect to the usual navigation direction of the ship travelling forward (according to the arrow V) .

[00122] In accordance with an embodiment, the fin 10 comprises a flap 71 hinged to the fin 10 along a fin edge 72 and said fin edge is the rear edge or outlet edge 72 of the fin 10 with respect to the ship navigation direction facing the side opposite said opening 32 during the rotation R with respect to the hull 2 to bring the fin 10 to said retracted position. For example, the flap 71 comprises actuating means for the rotation thereof with respect to the fin 10 body.