US20140205453A1

US20140205453A1 - Aquatic propulsion by means of oscillating fins

Info

Publication number: US20140205453A1
Application number: US14/238,878
Authority: US
Inventors: Jose San Gabino Ramirez
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-08-17
Filing date: 2012-08-14
Publication date: 2014-07-24
Also published as: WO2013024195A1; EP2746147A1; ES2411554B1; WO2013024195A4; ES2411554A1; EP2746147A4

Abstract

The aquatic propulsion proposed uses oscillating blades provided with independent, mutually parallel vertical shafts affixed, at the upper end thereof, to a single horizontal oar of planar profile. The blades or fins being of different length on the basis of the distance between the fastening point of the actual oscillation shaft thereof and the shaft on which the oar rocks. Propulsion is achieved when the user applies a force in traction or thrust on any of the two grips provided at either end of the handlebars, or in opposite directions on both at one and the same time. The movement is transmitted to the rotary shaft and then to the profile section on which the fins are arranged, which causes the fins to move transversely and alternately in both directions, causing displacement of the water and the propulsion of the swimmer or floating object or vehicle, in the intended direction.

Description

TECHNICAL FIELD

The invention relates to high-performance aquatic propulsion means using oscillating fins, intended specifically to propel small aquatic vehicles and floating surface objects, although it may also be used as underwater propulsion for divers and submarines.

PURPOSE OF THE INVENTION

As suggested by the title of the present description, the subject matter of the invention is aquatic propulsion means that use oscillating blades or fins transverse to the direction of travel to propel a floating object or vehicle, the novel features of which substantially reduce the stroke length of the surface of the blade at a neutral or negative angle, resulting in fewer oscillations about the longitudinal axis transverse to the waterline because they enable the propelling element to be as close as possible to the parallel lower plane of the vehicle, and for the axis of rotation of the oscillating arm or oar to be located in front of the keels of the axis of maneuver, improving the actual hydrodynamic coefficient and obtaining a propulsion efficiency that is much greater than had been achieved with these systems. Moreover, it allows the speed to be varied at frequencies of actuation and identical transverse strokes, and it makes it easy to swap the fins in seconds, including in the water, if they are damaged by impact or to replace them for others that enable the propulsion element to be adapted to the environment in which the vehicle is moving, either to obtain greater propulsion capacity, or with softer edges to be used in the presence of bathers.
Another purpose of the invention is to provide simple, powerful and highly maneuverable muscular propulsion that is suitable for use by children, old people and people with disabilities.

BACKGROUND TO THE INVENTION

The most powerful and simple known system for muscular propulsion in water is unquestionably the use of oscillating fins, used by thousands of species of fish and marine animals in all seas, rivers and lakes in the world, with the fastest reaching speeds exceeding 100 km/h. However, to date human beings have been unable to achieve even barely acceptable propulsion coefficients using alternating oscillating devices fitted with submerged fins, which may be partially flexible or rigid and shaped vertically or horizontally in relation to the vehicle.
A conventional oar with a stroke perpendicular to the longitudinal waterline can only achieve propulsion in one direction, which involves an unnecessary loss as it moves out of the water to return to the initial position. The propulsion achieved varies proportionally as a function of the angle, but always within positive parameters, with entry close to the stern at a minimum propulsion angle, travel towards the right angle where propulsion is neutral, before reducing again when moving towards the bow. The loss of energy is greater the closer the oar gets to the direction of travel, on account of which increasingly large oars are used to provide a greater stroke length close to neutral.
Unlike the conventional oar, propulsion using oscillating blades or fins with a stroke transverse to the direction of travel achieves maximum propulsion at the beginning of the stroke, reducing proportionately until the right angle, or parallel to the direction of travel, and in this exact position the direction of the water is transverse to the forward movement, which is useless for propelling us, but from this point it becomes negative, which brakes us.
The known prior art has attempted to address this problem by providing the oscillating device with a fin provided with an independent shaft concentric to the shaft of the mechanism of the oscillating oar or arm, and stops limiting the stroke of the fin, which enables it to oscillate in a direction opposite the direction of the profile until it reaches the stop position and from this point to acquire the same direction, at an angle opposite the profile, which is the propulsion position. However, the “accompanying” movement with no propulsion capacity until the stops are reached involves wasting a large percentage of the total stroke.
If, for example, in an oscillating oar 100 cm long, the fin represents 50% of the total, and both oscillate at angles of 90°, the “accompanying” stroke performed by the fin to reach the propulsion position between both limit stops represents practically 50% of the total, with no propulsion capacity. Furthermore, it requires the angle of actuation to be kept constant, because the angle of the fin remains with an invariable stroke of 90°, which means that each degree that we reduce increases the “accompanying percentage”, but what usually happens is that, when attempting to increase the speed of the vehicle, the user increases the actuating rhythm, usually reducing the angle proportionately, on account of which the increased frequency in fact reduces the propulsion capacity. Many attempts have been made to increase propulsion without resolving the problem, reducing the angle between the stops and increasing the proportional length of the blade, which increases the accompanying stroke by the same proportion, as well as reducing the positive stroke to the line parallel with the direction of travel entering before the negative angle. On account of this, there have been many attempts to try to use fins with a rigid frame and a flexible part in the central surface, with very poor results. Consequently, in practice, there are no known aquatic vehicles that are currently propelled using oscillating mechanisms of this type.
In ordinary propulsion using an oscillating fin or blade positioned vertically and moving transversely to the direction of travel, the oscillating shaft of the mechanism is located to the stern, behind the keel of the vehicle, which causes significant oscillations in course, contrary to the stroke of the blade in both directions of actuation, significantly worsening the actual hydrodynamic coefficient. In other versions with fins positioned horizontally, the undulating effect is caused on the longitudinal waterline, which has the same negative hydrodynamic effect.
The use of a fin oscillating across the direction of travel and positioned in front of a central keel arranged to the stern is known, which coincides with the fin at an angle very close to the line parallel to the direction of travel, however small it is on both sides of the stroke, which results in a significant loss of propulsion in the positive propulsion zone, without resolving the “accompanying” percentage and although the impact on the course is less than if the fin were oscillating behind the keel, it causes constant oscillations in the transverse waterline, on account of which it is not very stable in addition to providing substandard propulsion. There are also no known practical applications of this system at this time.
It improves the prior art in the propulsion using oscillating fins, reflected in propulsion essentially for diving, where the fins are attached to the sole of the diver's foot, in the same plane (at an angle of 90° to the leg) by means of footwear or similar, which extends from the end of the foot in two parallel straight profiles, which may be rigid or semi-rigid, between which the central body of the fin is divided into a plurality of oscillating segments transversal thereto, but in the same plane and of similar length, provided with independent shafts that are linked to the extremities thereof with each one of both profiles, such that the position of each segment in relation to the distance to the hip or knee joint (depending on whether the user moves the fins with straight legs and the instep of the foot extended to the maximum, or bent legs, where the length of the fins when idle is parallel to the swimmer, but shifted by a distance equal to the distance between the sole and the knee) and the corresponding axis thereof, is different, meaning that the accompanying stroke and the point of negative-angle entry are also different, which represents an enormous hydrodynamic problem to determine the optimum stroke to minimize the accompanying percentage or the entry into negative propulsion, which is different for each of the segments of the fin, which makes them very complicated to use, even more so bearing in mind that the swimmer or diver has to coordinate the stroke of both fins and the position of the instep simultaneously, which is very complicated, on account of which this type of fin has not replaced conventional fins.
According to the novel features of the present invention, the improved aquatic propulsion using oscillating fins is designed to make optimum use of the muscle energy used—which is finite—thereby substantially improving the efficiency of the oscillating fins of the propulsion element, also incorporating a suitable positioning of the elements of the mechanism and of the user, whose weight in small floating structures represents a significant percentage of the total mass, which has a significant impact on stability. For this purpose, the handlebars that actuate the oscillating mechanism, the axis of rotation thereof, the oar and the oscillating fins, in this order, as well as at least 50% of the user's mass are located centrally in relation to the transverse line of the vehicle, and in front of the keels of the axis of maneuver. To ensure that the oscillating movement of the fins during forward movement occurs very close to the keels located to the stern, in parallel and as far away as possible from the longitudinal center of the vehicle, given that a central keel is a destabilizing hydrodynamic obstacle, much more so than if there are two, and they are located on both sides, because even with oar opening angles greater than 50°, from 0° in both directions the maximum position of the blades is very close to the right angle or neutral, on account of which the water is propelled in a direction very close to the line parallel to the corresponding keel in both directions of the start of the stroke, with a high propulsion ratio, however towards the end of the stroke, the direction of the water changes towards the approaching keel, tending to balance the vehicle, instead of destabilizing it. With angles below 30° in both directions, a large percentage of the flow moved flows between the two keels, with no particular impact on the transverse or longitudinal waterline. However, since the length of the blades or fins is proportional and increases, the further away they are from the axis of rotation of the oar, the ones with a larger surface area and longer stroke are therefore the ones that move the greatest quantity of water and that are closest to the keels, on account of which the oscillating effect on the course is minimal, which would not be the case if the fins were to move behind the keels. Equally, the eccentric position of the blades in relation to the lower face of the oar, according to claim 5 of this report, enables this to be as close as possible in parallel to the structure of the vehicle, having a minimum impact on the center of gravity during forward movement, however, by lowering it during turning maneuvers, when moving the propulsion element from the central axis of the vehicle at a low depth in relation to the waterline, propelling it against the centrifugal force.
According to the aforementioned features, the handlebars and therefore the oar can rotate through 360° and the oscillating action can be performed in any position. The course is determined at all times by the intermediate point of the oscillating stroke.
There are no known propulsion methods such as the one proposed in the present invention, in which the corresponding oscillating fins have independent oscillating shafts that are eccentric in relation to the lower plane of a single profile or oscillating flattened straight oar.
Furthermore, there are no known propulsion methods incorporating oscillating fins arranged vertically in the same plane, of similar height, but in which the length of each fin is different, proportionally increasing in relation to the previous one as they move away from the axis of rotation of the oar in relation to the shaft thereof, consistently with the greater or lesser stroke of the oar in relation to each point of the length thereof, which guarantees the synchrony of all of the blades during the “accompanying” stroke between the respective limiting stops thereof.
Furthermore, there are no known mechanisms for limiting the oscillating stroke of the fins such as the one described in the present invention, which makes it possible to position all of the blades or fins at the same angle, and simultaneously to vary it at will at any time, regardless of the oscillating stroke of the oar, using an operating mechanism located at an accessible point of the handlebars, which makes it possible to determine, even for a child, the maximum angle reached by the fins in each direction, and in which position the operating handle related to same should be positioned to obtain the maximum propulsion capacity. Furthermore, said mechanism is totally unrelated to any structure that is not a direct part of the propulsion system, such that the actuating handlebars can be rotated in any direction without limitation and without altering the position determined in advance for the fins.

DESCRIPTION OF THE INVENTION

The invention relates to a set of steering handlebars with an oscillating action comprising a cylindrical profile (14) transverse to the direction of travel when in idle position, provided at the extremities thereof with as many levers or handles (16) and a central vertical prolongation (13) having a hollow square profile and intended to consistently and gaplessly connect with the square segment (12 b) of the upper end of the cylindrical rotary shaft (12 a) of the oscillating mechanism, which contains a cylindrical opening (48) that runs through the entire length thereof. At the bottom end, the shaft (12 a) is attached at an angle of 90° to the round end of the oar (11) which extends in a straight flattened profile transverse to the handlebars (14) and, at the opposite end, the oscillating shafts (9) of the blades (1, 2, 3, 4, 5) passed through the profile of the oar (11) from the upper plane and are attached to the plane, for which there is a large rectangular flattened head (27) and as many threaded holes (28) arranged equidistantly on both sides of the shaft (9) which are used to connect the conical head screws (49) passing through the profile (11) from the lower plane through the apertures (47) of conical profile provided to center and attach the shafts (9) to the oar (11), although the diameter of the hole (46) of profile similar to the screw is larger than the shaft. From this point, they extend in a straight and eccentric fashion in relation to the lower plane to the opposite end where, preceded by a conical point (10) they have as many peripheral slots (45), said shafts (9) being inserted into the respective apertures (51) thereof provided in one of the vertical edges of each fin (1, 2, 3, 4, 5), and when the conical end (10) of the shaft (9) meets the aperture of the slotted elastic segment (8), the diameter of which is less than the diameter of the shaft (9), it expands enabling it to pass through and subsequently is seated in said slot (45) such that it is perfectly attached but can be easily released by inserting a flat element into the slot of the segment (8) and rotating it slightly, which forces it to expand and enables it to be disconnected.
In parallel and in contact with the lower plane of the oar (11) there is a straight, flat plate (6) of similar width that has as many slots (32) as there are shafts (9) attached to the oar (11), which are provided to enable the movement of the plate (6) but also to limit it to the length of said slots, as they pass through said slots. On the same lower plane of said plate (6) are attached the stops (7), which are arranged in pairs and equidistantly on either side of each of the slots (32), and therefore of each of the parallel and eccentric shafts (9), in relation to a single flat oar (11), distributed longitudinally at a gradually increasing distance equivalent to the length of each of the fins (1, 2, 3, 4, 5) progressively from the shortest (1) that is closest to the axis of rotation of the oar, to the longest (5), which is placed at the distal end.
According to the invention, the oscillating stroke of the set of blades (1, 2, 3, 4, 5)—shown in the drawings as a set of five purely by way of example, but that could be a set of any number, provided the principle of proportional length is observed—is limited by as many stops (7) on each side, which are attached to the common flat plate (6), which can move forwards or backwards, and consequently so can the stops (7), enabling the maximum limit of the oscillating stroke of the blades (1, 2, 3, 4, 5) to be modified at will regardless of the oscillating stroke of the oar (11). Said plate (6) has an attachment element (43) at the end thereof closest to the rotary shaft (12 a) of the oar (11) that connects to the aperture (44) formed in the end of a piston (33) that runs through a guide element (26) to an articulated shaft (41) shared with the end of a connecting rod (34) that extends and connects to a shaft (40) seated in the end of the eccentric plate (35) attached to the central rotary shaft (21) of the articulated mechanism. Said shaft (21) passes from this point through the hollow inside (48) of the rotary shaft of the oar (12 a) to the opposite end thereof, where there is a periphery slot (36) provided to seat the corresponding elastic ring (37) that determines the position thereof on the shaft (12 a), but that enables it to rotate independently thereof, extending from this point, once the vertical square profile (13) attached to the handlebars (14) has been connected to the square segment (12 b) until it passes above the aperture (42), centered vertically on the aperture (48) in a semi circular plate (15) attached to the center of the handlebars (14). On the plane of said plate (15) there is a plurality of radial slots (17) equidistant from the aperture (42) and the shaft (21), the end of which is threaded (39) and has as many opposing planes (38) matching the structure of the hole (29) of the supporting element (18) provided along with the nut (22) as attachment elements to the shaft (21). At the opposite end, there is a vertical slot that houses the operating handle (19) that oscillates about a transverse shaft (25) that passes through the rotary supporting element (18) and said handle (19), the lower edge of which acts as a ratchet and passes the lower plane only when the end of the handle is parallel to the upper plane of the supporting element and is opposite the radial slots (17), forced at the inclined edge thereof by an elastic element (20) attached to the supporting element (18) when inserted into the slot (17) chosen by the user to determine the position at which the handle (19) is released, determining thereby the position of the plate (6) and the stops (7) in relation to the shafts (9) that limit the angle and the oscillating stroke of the blades (1, 2, 3, 4, 5), on account of which it can be adjusted, on the basis of the maximum angle reached in the alternating stroke of the handlebars (14) to obtain the maximum desired acceleration, without entering the negative angle.
Propulsion is generated when the user applies muscle force, traction or thrust, to either of the two handles (16) provided at each end of the handlebars (14), or in opposite directions on both simultaneously, said movement being transmitted to the rotary shaft (12 a) and then to the profile (11) on which the fins (1, 2, 3, 4, 5) are arranged, forcing them to move transversely and alternately in both directions, thereby moving the water and propelling the floating vehicle, object or swimmer in the desired direction, which corresponds to the midpoint of the oscillating stroke of the oar (11).
It should be noted that none of the elements that make up the structure of the propulsion system has any prior limitations that prevents it from rotating through 360°, on account of which the alternating oscillating movement can be applied at any time. The position in which the handlebars (14) are placed before being actuated enables the structure to move forwards or backwards or to turn in any direction.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In a preferred embodiment of the invention, the actuating handlebars, rotary shaft, oar and fins, in this order, as well as at least 50% of the user's mass are located on the center of the direction of travel, in front of the axis of maneuver formed by the two keels (53) located at the stern and as far away from one another as possible on either side of the floating object or vehicle in which the propulsion device is installed, but nonetheless locating the rotary shaft of the oar as closely as possible, such that the fin at the opposite end passes close to the keels, such that actuating the propulsion element causes minimum oscillations to the course and also reduces the turning circle of the vehicle, affording it extraordinary maneuverability.
A preferred embodiment of the invention includes the use of several oscillating fins with independent parallel shafts eccentric in relation to the lower plane of the single flattened oscillating profile, the widths of which vary in proportion to the distance between the corresponding shaft thereof and the rotary shaft of the oar, where the oscillating stroke of each of the blades is limited in both directions by stops attached to a common plate, the position of which may be varied at will in relation to all of the blades of the propulsion system at the same time, increasing or reducing the maximum angle, regardless of the angle of the oar, which makes it possible to choose the angle most suitable to the speed of movement at any time.
Equally, the use of shafts attached to a single straight profile and the rapid attachment system for the oscillating fins enable them to be swapped rapidly, retaining the length corresponding to the position thereof, whether they are taller or shorter, and even changing the number of fins to obtain the maximum possible propulsion power, in any environment and with any floating object or vehicle to which the propulsion system according to the present invention is applied.

DESCRIPTION OF THE FIGURES

The drawings included in this report are merely an example to assist comprehension of the invention, and are not limiting.
FIG. 1 shows the actuating mechanism with the propulsion system attached.
FIG. 2 shows the semicircular base and the radial slots, which are related to the ratchet mechanism.
FIG. 3 shows the components of the ratchet mechanism, supporting element, handle/ratchet and elastic element pressing against the handle.
FIG. 4 shows the articulated mechanism mounted on the rotary shaft and attachment means, and the means related to the plate that enable the angle of the blades to be adjusted and a cross-section of the limiting stops.
FIG. 5 shows the articulated mechanism of the changer.
FIG. 6 is a worm's eye view showing the oar and the blades positioned in front of the keels.
FIG. 7 shows the structure of the blades and the elastic segment to attach it to the shaft.
FIG. 8 shows a blade and the attachment profile of the shaft in two segments.
FIG. 9 shows the profile of the rotary shaft, the profile of the oar and the structure of the shafts, as well as the elements enabling them to be attached to the oar and to the blades.

Claims

1. Improved means for aquatic propulsion with high-performance oscillating fins that include means for reducing the negative-angle stroke length of an oscillating fin transverse to the direction of travel, characterized in that the oscillating fins (1, 2, 3, 4, 5), as shown in FIGS. 1 and 7 of the present description, of which there are five although there could be a different number, form a rigid propulsion member comprising segments of similar height but of different lengths arranged in the same longitudinal plane and fitted with independent oscillating shafts (9) that are parallel to one another, in which the greater or lesser length thereof depends on the distance between the oscillating shaft (9) thereof and the rotary shaft (12 a) of the oar (11), equivalent to the diametric stroke of the oar (11) in relation to each point of attachment of the corresponding shaft (9) thereof, the decreasing percentage being determined by the furthest separating distance, for example: if it is 10%, all of the fins will have a length equivalent to 10% of the distance between the shaft thereof and the rotary shaft of the oar, and so on.

2. The improved means for aquatic propulsion with high-performance oscillating fins as claimed in claim 1, characterized in that the oscillating alternating stroke of the fins (1, 2, 3, 4, 5) is limited in both directions by as many stops (7) arranged equidistantly on each side of the axis of oscillation thereof and attached to a straight flat movable plate (6) arranged in parallel and in contact with the lower plane of the oar (11), of similar width, between this and the blades (1, 2, 3, 4, 5), the longitudinal center of which includes a series of as many slots (32) as there are shafts (9) attached to the oar (11) that are provided to enable the plate (6) to move but also to limit said movement to the length of the slots, as they pass through said slots, the stops (7) being attached in the same lower plane of said plate (6), said stops limiting the stroke of the blades and being arranged in pairs and equidistantly on either side of each of the slots (32), and therefore each of the shafts (9), on account of which the movement of the plate (6) in either direction changes the maximum oscillating stroke thereof.

3. The improved means for aquatic propulsion with high-performance oscillating fins as claimed in claim 2, characterized in that said plate (6) has an attachment element (43) at the end thereof closest to the rotary shaft (12 a) of the oar (11), which connects with the aperture (44) in the end with a piston (33) that runs through a guide element (26) to an articulated shaft (41) shared with the end of a connecting rod (34) that extends and connects with a second shaft (40) arranged at the end of an eccentric plate (35) attached to the central rotary shaft (21) of the articulated mechanism, said shaft (21) running from this point through the hollow inside (48) of the rotary shaft of the oar (12 a) to the opposite end thereof, where there is a peripheral slot (36) designed to receive the corresponding elastic ring (37) that determines the position thereof on the rotary shaft (12 a), but that enables it to rotate independently thereof, extending from this point, once the vertical square profile (13) of the handlebars (14) has been connected to the square segment (12 b) of the shaft (12 a) until it passes above the aperture (42), centered vertically on the aperture (48) in a semi circular plate (15) attached to the center of the handlebars (14), on the plane of said plate (15) there being a plurality of radial slots (17) equidistant from the aperture (42) and the shaft (21), the end of which is threaded (39) and has as many opposing planes (38) matching the structure of the hole (29) of the supporting element (18) provided along with the nut (22) as attachment elements to the shaft (21), and at the opposite end, there being a vertical slot that houses the operating handle (19) that oscillates about a transverse shaft (25) that passes through the rotary supporting element (18) and said handle (19), the lower edge of which acts as a ratchet and passes the lower plane only when the end of the handle is parallel to the upper plane of the supporting element and is opposite the radial slots (17), forced at the inclined edge thereof by an elastic element (20) attached to the supporting element (18) when inserted into the slot (17) chosen by the user to determine the position at which the handle (19) is released, determining thereby the position of the plate (6) and the stops (7) in relation to the shafts (9) that limit the angle and the oscillating stroke of the blades (1, 2, 3, 4, 5), on account of which it can be adjusted, on the basis of the maximum angle reached in the alternating stroke of the handlebars (14) to obtain the maximum desired propulsion, without entering the negative angle.

4. The improved means for aquatic propulsion with high-performance oscillating fins, characterized in that the handlebars (14), rotary shaft (12), oar (11) and fins (1, 2, 3, 4, 5), in this order, are located in front of the two keels (53) located at the stern and as far away from one another as possible on either side of the floating object or vehicle in which the propulsion device is installed, but nonetheless locating the rotary shaft of the oar as closely as possible, such that the fin at the opposite end passes close to the keels, such that actuating the propulsion element causes minimum oscillations to the course and also reduces the turning circle of the vehicle.

5. The improved means for aquatic propulsion with high-performance oscillating fins as claimed in claims 1 and 2, characterized in that the vertical shafts (9) on which the fins (1, 2, 3, 4, 5) oscillate are attached only by the upper end thereof to a single flat profile, comprising the oscillating oar of the propulsion device (11), extending in a straight but eccentric manner in relation thereto, such as to bring the oar as close as possible and parallel to the sliding surface of the vehicle or floating object.

6. The improved means for aquatic propulsion with high-performance oscillating fins, characterized in that the shafts (9) on which the propulsion blades or fins (1, 2, 3, 4, 5) oscillate that pass through the flat profile of the oar (11) from the upper plane, have a large rectangular flattened head (27) and as many threaded attachment holes (28) arranged equidistantly on both sides of the shaft (9) that are connected with the conical head screws (49) passing through the profile (11) from the lower plane through the conical apertures (47) provided to center and attach the shafts (9) on the oar (11), although the diameter of the hole (46) through which the shaft (9) passes is larger than the shaft, this feature enabling damaged shafts (9) to be replaced, even if they receive sudden impacts in shallow environments that could otherwise render the propulsion device unusable.

7. The improved means for aquatic propulsion with high-performance oscillating fins as claimed in claims 1, 2 and 6, characterized in that said shafts (9) have a peripheral slot (45) at the lower end thereof preceded by a conical point (10) provided so that when the shaft (9) is inserted into the aperture (51) of the fin (1, 2, 3, 4, 5), when it meets the aperture of the slotted elastic segment (8) of the fin (1, 2, 3, 4, 5), the diameter of which is less than the diameter of the shaft (9), it expands, enabling the passage thereof and it is subsequently seated in said slot (45) so that it is perfectly attached, but can be changed easily by inserting a flat element into the slot of the segment (8) and rotating it slightly so that it expands and enables the disconnection thereof, and furthermore the expandable segment (8) may be omitted and replaced by the corresponding elastic ring of the type available on the market, or using shafts (9) with threaded ends, that are attached to the fin at the appropriate position by means of a lock nut, any of the systems mentioned enabling the rapid disconnection to enable the shafts or fins to be swapped.

8. The improved means for aquatic propulsion with high-performance oscillating fins as claimed in claim 6, characterized in that the set of oscillating blades (1, 2, 3, 4, 5) are configured with different lengths depending on the distance between the shaft (9) thereof and the rotary shaft of the oar (12 a), although the height thereof may be similar; the body of the fin (1, 2, 3, 4, 5) is made of a plate of rigid or semi-rigid material having a rounded profile (50) on one of the vertical edges thereof that extends partially in relation to the total height, the center of which is perforated (51) to receive the shaft (9), of slightly lesser diameter, on which it oscillates; the rounded profile (50) may be partially sectioned and split into two segments (23, 24) of specific height at the ends, also perforated, that reduce the total thickness of the body of the fin (1, 2, 3, 4, 5), improving the hydrodynamic coefficient thereof; from the lower end of the rounded profile (50), the body of the fin has an elastic segment of the same profile (8), the center of which is perforated at a diameter less than the diameter of the oscillating shaft (9) and has a diametric vertical slot (52) in the same plane as the body of the fin (1, 2, 3, 4, 5), which enables it to expand by inserting the conical point of the oscillating shaft and seating it ultimately in the peripheral slots (45) provided for this purpose in the shaft (9) such that it is perfectly attached, the disconnection of both being easily achieved by inserting a flat element into the slot of the expandable segment (8) that facilitates disconnection when rotated slightly.