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Title:
AQUATIC PROPULSION SYSTEM
Document Type and Number:
WIPO Patent Application WO/2011/047431
Kind Code:
A1
Abstract:
An aquatic propulsion system comprising a body (104), a propulsion means to propel the body through water and an energy storage device adapted to be charged and discharged wherein in use, as the energy storage device is discharged, the propulsion means moves in a first direction during which the propulsion means propels the system through the water. The propulsion means typically comprises a tail (106) extending to the rear of the body (104) and a fin (114) which is attached to the tail.

Inventors:
PAPP ARPAD (AU)
Application Number:
PCT/AU2010/001397
Publication Date:
April 28, 2011
Filing Date:
October 21, 2010
Export Citation:
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Assignee:
PAPP ARPAD (AU)
International Classes:
B63H16/08; B63H1/36; B63H16/18
Foreign References:
US3605676A1971-09-20
US20070054591A12007-03-08
CN201198365Y2009-02-25
US20050016437A12005-01-27
Attorney, Agent or Firm:
WRAYS (56 Orde StreetWest Perth, WA 6005, AU)
Download PDF:
Claims:
The Claims Defining the Invention are as Follows:

1. An aquatic propulsion system comprising: a body adapted to support an operator; a propulsion means to propel the body through water; an energy storage device adapted to be charged and discharged; wherein in use, as the energy storage device is discharged the propulsion means moves in a first direction during which the propulsion means propels the system through the water.

2. The aquatic propulsion system according to claim 1 wherein the energy storage device is an elastic member charged through elastic deformation and discharged by allowing it to return to its pre-charged state, the propulsion means being connected to the elastic member.

3. The aquatic propulsion system according to claim 2 wherein the elastic member comprises at least one coiled spring.

4. The aquatic propulsion system according to claim 2 wherein the elastic member comprises at least one elastic band.

5. The aquatic propulsion system according to any of the preceding claims wherein the energy storage device is charged using a power source.

6. The aquatic propulsion system according to claim 5 wherein the power source is derived through motion of the operator.

7. The aquatic propulsion system according to claim 6 wherein the elastic member is connected to at least one handle via at least one rope like element to enable the operator to charge the elastic member by pulling the at least one handle.

8. The aquatic propulsion system according to claim 7 further comprising at least one footrest for supporting the operator's feet while pulling the handle.

9. The aquatic propulsion system according to any one of the preceding claims wherein the propulsion means comprises a tail.

10-The aquatic propulsion system according to claim 9 wherein the tail extends to the rear of the body.

11. The aquatic propulsion system according to any one of claims 9 to 10 wherein a fin is attached to the tail.

12. The aquatic propulsion system according to any one of claims 1 to 9 wherein the propulsion means comprises a repulsive member.

13. The aquatic propulsion system according to claim 11 further comprising at least one fin supporting member that enables the fin to be held in preferred orientations during the charging and discharging of the energy storage device.

14. The aquatic propulsion system according to claim 13 wherein each of the at least one fin supporting members comprises at least one coiled spring.

15. The aquatic propulsion system according to any one of claims 7 to 14 wherein the handle is flexibly supported relative to the body.

16. The aquatic propulsion system according to any one of claims 7 to 15 wherein the at least one rope is wound around a first pulley at or near the handle.

17. The aquatic propulsion system according to any one of claims 9 to 16 wherein the elastic member is wound around a second pulley located relatively close to the tail.

18. The aquatic propulsion system according to claim 17 wherein the second pulley is flexibly supported to allow movement of the second pulley during the charging and discharging of the energy storage device.

19. The aquatic propulsion system according to any one of the preceding claims further comprising a support board attached to the body, the support board being adapted to support the operator using the aquatic propulsion system.

20. The aquatic propulsion system according to claim 19 wherein the support board further comprises a keel attached to the support board.

21. The aquatic propulsion system according to claim 20 wherein the elastic member extends into the keel or support board.

22. The aquatic propulsion system according to any one of claims 19 to 21 wherein the support board is flexibly attached to the body.

23. The aquatic propulsion system according to any one of the preceding claims wherein the aquatic propulsion system further comprises a flexible skin encompassing at least part of the aquatic propulsion system wherein the flexible skin defines an outer shape of at least part of the aquatic propulsion system.

24. The aquatic propulsion system according to any one of the preceding claims further comprising ballast or flotation devices.

25. The aquatic propulsion system according to any one of the preceding claims further comprising armouring, cages or other reinforcement to protect a person using the system.

26. The aquatic propulsion system according to any one of the preceding claims further comprising one or more air accumulators for storing air.

27. The aquatic propulsion system according to claim 26 further comprising means for a person to use air from the one or more air accumulators for breathing.

28. The aquatic propulsion system according to any one of claims 26 to 27 wherein the power source for charging the energy storage device is derived through discharge of the one or more air accumulators.

29. The aquatic propulsion system according to any one of claims 26 to 28 further comprising an air compressor for compressing air into the air accumulator.

30. The aquatic propulsion system according to claim 29 further comprising a solar electric panel for powering the air compressor.

31. The aquatic propulsion system according to any of the preceding claims adapted for use to propel a kayak, surfboard, boat or other watercraft.

32. An aquatic repulsive propulsion system comprising a body adapted to support an operator; a repulsive propulsion means to propel the body through water; an energy storage device adapted to be charged slowly and discharged rapidly, wherein, in use, as the energy storage device is discharged, the repulsive propulsion means moves in a first direction during which the repulsive propulsion means propels the system through the water.

33. The aquatic repulsive propulsion system according to claim 32 wherein the energy storage device is an elastic member charged slowly through elastic deformation and discharged rapidly by allowing it to return to its pre-charged state, the repulsive means being connected to the elastic member.

34. An aquatic propulsion system substantially as herein described with reference to the accompanying drawings.

35. The aquatic propulsion system according to any one of claims 13 to 16 wherein a jolted telescopic tube system is guiding the energy storage device to channel the energy to the repulsive member.

36. The aquatic propulsion system according to any one of claims 17 to 18 wherein the movement of the elastic member around the flexibly supported second pulley is transformed to the fin by a butterfly joint.

37. An aquatic propulsion system comprising a body adapted to support an operator; a propulsion means to propel the body through water; an energy storage device adapted to be charged and discharged; wherein in use, as the energy storage device is charged the propulsion means moves in a first direction during which the propulsion means propels the system through the water.

38. an aquatic repulsive propulsion system comprising a body adapted to support an operator; a repulsive propulsion means to propel the body through water; an energy storage device adapted to be charged slowly and discharged rapidly, wherein, in use, as the energy storage device is charged, the repulsive propulsion means moves in a first direction during which the repulsive propulsion means propels the system through the water.

39. An aquatic propulsion system as substantially herein described with reference to the drawings.

Description:
AQUATIC PROPULSION SYSTEM

Field of the Invention

The present invention generally relates to an aquatic propulsion system.

The aquatic propulsion system according to the invention has been devised particularly, although not solely, to propel a person through water. The aquatic propulsion system may, however also be used to propel a kayak, surfboard, boat or other watercraft.

Background Art

Efficient propulsion through water has always been a challenge, especially when the human body is used as the power source. There are many products aimed at improving a person's ability to swim, dive or otherwise move through water faster and easier. However, the existing products do not efficiently use the back and leg muscles, which are the strongest muscles in the human body, to cause forward motion through water. Most existing products use the muscles of the human body in an inefficient manner or rely on clumsy and unnatural movements.

A specific problem with the use of the human body as a power source, even when using the leg muscles, is the fact that the leg is much more powerful when used during the leg extension motion than when used during the opposite leg retraction motion. Even the leg extension motion is limited to an extent by the speed at which the human is able to perform such a motion.

Furthermore the existing products provide little or no protection to the human body. The presently available diving, surfing and swimming equipment serve to help a person breathe underwater or enable a person to move faster, but do not effectively reduce a person's vulnerability to the dangers of the ocean. Water is an alien environment for humans and their relative clumsiness when in the water leaves them vulnerable to various dangers. These dangers include sea currents, predators such as sharks and crocodiles, crashing waves and human conditions such as fatigue and cramps. Many of the existing products are complicated, bulky, heavy, expensive to produce and unreliable or are limited to use either only along the top surface of the water or otherwise only when submerged.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

It is against this background, and the difficulties and problems associated therewith, that the present invention has been developed.

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided an aquatic propulsion system comprising: a body adapted to support an operator; a propulsion means to propel the body through water; an energy storage device adapted to be charged and discharged; wherein in use, as the energy storage device is discharged the propulsion means moves in a first direction during which the propulsion means propels the system through the water.

Preferably, the energy storage device is an elastic member. The elastic member may be charged through elastic deformation and discharged by allowing it to return to its pre- charged state. The propulsion means may be connected to the elastic member.

In one aspect of the invention the elastic member comprises at least one coiled spring.

In another aspect of the invention the elastic member may comprise a at least one elastic band. Preferably the energy storage device is charged using a power source.

In one aspect of the invention, the power source is derived through motion of the operator.

Preferably, the elastic member is connected to at least one handle via at least one rope like element to enable the operator to charge the elastic member by pulling the at least one handle.

The aquatic propulsion system may further comprise at least one footrest for supporting the operator's feet while pulling the handle. The footrests may be placed at either side of the body so that, in use, the aquatic propulsion system is located between the legs of the operator.

The support provided to the operator's feet is advantageous because it ensures that the muscle power produced primarily by the operator's legs, back and arms can be utilised.

Through use of this invention, specifically by employing the energy storage device, the power generated by relatively weak power sources such as the human body can be used to generate large forces and apply those forces effectively for efficient aquatic propulsion.

In contrast to existing products, the present invention provides a means for storing energy produced by a person's muscles during movement and subsequently rapidly releasing that stored energy resulting in a movement with more force and speed than would have been possible without the energy storage device.

Preferably, the propulsion means comprises a tail.

Preferably, the tail extends to the rear of the body.

Preferably, a fin is attached to the tail.

Preferably, there is at least one fin supporting member that enables the fin to be held in preferred orientations during the charging and discharging of the energy storage device. ln one aspect of the invention, each of the at least one fin supporting members may comprise at least one coiled spring.

The ability to hold the fin in preferred orientations during the charging and discharging of the energy storage device is advantageous because it allows for more efficient propulsion while moving the tail.

Preferably, the handle is flexibly supported relative to the body

Preferably, the rope like member is wound around a first pulley at or near the handle.

The rope may also be channelled through a telescopic tube system, guided by a first pulley which is fixed to a telescopic tube system at, or near the handle.

A telescopic tube system may guide the energy storage device to channel the energy to the repulsive member.

Preferably, the elastic member is wound around a second pulley located relatively close to the tail.

Preferably, the second pulley is flexibly supported to allow movement of the second pulley during the charging and discharging of the energy storage device.

The fact that the second pulley is flexibly supported may further help to increase the level of stored energy.

The ability of the second pulley to move during the charging and discharging of the energy storage device is advantageous because it allows for more efficient propulsion while moving the tail.

Preferably, the aquatic propulsion system further comprises a support board attached to the body, the support board being adapted to support the user using the aquatic propulsion system. The advantage of the support board is that it supports a person using the aquatic propulsion system securely, can be adapted to assist with flotation and provides a measure of physical mechanical protection to the person's upper body.

In one embodiment, the aquatic propulsion system can be considered to be a Repulsive and Protective Aquatic Driver (RPAD).

The support board may further comprise a keel attached to the support board.

The elastic member may extend into the keel.

Preferably, the support board is flexibly attached to the body.

Preferably, the aquatic propulsion system further comprises a flexible skin encompassing at least part of the aquatic propulsion system wherein the flexible skin defines an outer shape of at least part of the aquatic propulsion system.

Preferably, the aquatic propulsion system further comprises ballast or flotation devices.

The advantage of the ballast or flotation devices is that it allows the present invention to be used along the top surface of the water as well as to dive and move completely submerged below the surface of the water. This is an advantage because it provides more freedom of movement than currently available products.

Preferably, the aquatic propulsion system further comprises armouring, cages or other reinforcement to protect a person using the system. In such an embodiment, the aquatic propulsion system can be considered to be an Armoured Repulsive and Protective Aquatic Driver (ARPAD).

The present invention is a system that enables a person to swim, dive or otherwise move through water faster, easier and with less vulnerability to both attacks from predators and injury from coral reefs, other collisions or crashing waves. The present invention results in aquatic pursuits being safer and more enjoyable whilst using the invention. The present invention is strong enough to provide protection, but is also flexible enough to give good maneuverability and enables a person to move through water faster than other human powered systems while still being comfortable to use.

The aquatic propulsion system may further comprise one or more air accumulators for storing air.

The aquatic propulsion system may further provide means for a person to use air from the one or more air accumulators for breathing.

In another aspect of the invention, the power source for charging the energy storage device may be derived through discharge of the one or more air accumulators.

The aquatic propulsion system may further comprise an air compressor for compressing air into the air accumulator.

The aquatic propulsion system may further comprise a solar electric panel for powering the air compressor.

The aquatic propulsion system may also be adapted for use to propel a kayak, surfboard, boat or other watercraft.

According to another aspect of the invention there is provided an aquatic repulsive propulsion system comprising a body adapted to support an operator; a repulsive propulsion means to propel the body through water; an energy storage device adapted to be charged slowly and discharged rapidly, wherein, in use, as the energy storage device is discharged, the repulsive propulsion means moves in a first direction during which the repulsive propulsion means propels the system through the water. Preferably, the energy storage device is an elastic member charged slowly through elastic deformation and discharged rapidly by allowing it to return to its pre-charged state, the repulsive means being connected to the elastic member.

According to an aspect of the invention there is provided an aquatic propulsion system comprising: a body adapted to support an operator; a propulsion means to propel the body through water; an energy storage device adapted to be charged and discharged; wherein in use, as the energy storage device is charged the propulsion means moves in a first direction during which the propulsion means propels the system through the water.

According to another aspect of the invention there is provided an aquatic repulsive propulsion system comprising a body adapted to support an operator; a repulsive propulsion means to propel the body through water; an energy storage device adapted to be charged slowly and discharged rapidly, wherein, in use, as the energy storage device is charged, the repulsive propulsion means moves in a first direction during which the repulsive propulsion means propels the system through the water.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: Figure 1 is a sectional side view showing the aquatic propulsion system according to a first embodiment;

Figure 2 is a sectional side view detailing the area surrounding the main pulley and fin according to the first embodiment;

Figure 3 is a general arrangement isometric view showing the aquatic propulsion system according to the first embodiment;

Figure 4 is a side view showing the aquatic propulsion system according to the first embodiment in use by an operator;

Figure 5 is a sectional side view showing the aquatic propulsion system according to a second embodiment;

Figure 6 is a sectional side view detailing the area surrounding the main pulley, fin and internal structure of the aquatic propulsion system according to the second embodiment;

Figure 7 is a sectional side view detailing the area surrounding the main pulley of the aquatic propulsion system according to a third embodiment;

Figure 8 is a sectional side view showing the aquatic propulsion system according to the third embodiment;

Figure 9 is a perspective side view showing how a flexible fin support strip can be attached to the fin of the aquatic propulsion system according to any of the abovementioned embodiments.

Best Mode(s) for Carrying out the Invention

Referring to figure 1 , the invention according to a first embodiment is in the form of an aquatic propulsion system 102, comprising a body 104 and a propulsion means in the form of a tail 106 extending to the rear thereof.

There is also a support board 108 attached to the body 104 which supports the upper body of a person using the aquatic propulsion system. The support board 108 may be either flexibly or rigidly attached to the body 104.

The body 104, comprises internal frame members 110 which add strength and rigidity. Attached to the internal frame members 110 and protruding through either side of the body 104 are foot rests 112 which support the feet of an operator using the aquatic propulsion system.

The body is typically covered by a flexible outer skin made from rubber, latex or other suitable material. Ballast or flotation devices (not shown) can also be attached to the internal frame members and are typically contained in areas that are surrounded by the flexible skin.

There is a fin 114 attached to the tail 106. Attached to the fin 114, there is at least one fin supporting member 124.

There is also a handle 116 that is attached to the internal frame members 110 via a flexible handle support 118. The flexible handle support 118 comprises a relatively large diameter coiled spring. The handle 116 is connected to a main tension spring 120 by a rope like member 122 which is guided by at least one support pulley 144. The rope 122 is connected to the main tension spring 120 at a first connection point 126. Both the tail 106 and the fin supporting member 124 are also connected to the first connection point 126. A main compression spring 128 is also connected to the first connection point 126 and is located co-axially to the rope 122 from the first connection point 126 to a second attachment point 130 that is securely mounted on the internal frame members 110.

The main tension spring 120 is routed from the first connection point 126 to a first attachment point 132 via a main pulley 134, a first main tension spring guide 136 and a second main tension spring guide 138. The main pulley 134 is attached to the internal frame members 110 via a flexible pulley support 140. The flexible pulley support 140 typically comprises a relatively large diameter coiled spring, attached at one end to the internal frame members 110 and at the other end to the main pulley centre shaft, on either side of the main pulley 134.

In use, the operator using the aquatic propulsion system 02, will place both their feet on the foot rests 112, thus placing the body of the aquatic propulsion system between their legs, while supporting their upper body by lying on the support board 108. The person will then bend their knees and use their hands to grab the handle 116. Keeping their arms straight, the person will then extend their legs, thereby pulling the handle 116 further away from the main pulley 134. In so doing the main tension spring 120 will be extended and placed under tension, thereby storing potential energy. At the same time, the main compression spring 128 will be compressed as the first connection point 126 moves closer to the second attachment point 130, thereby storing further potential energy. The tension in the main tension spring 120 will exert force on the main pulley 134 which will cause the flexible pulley support 140 to flex in the direction of the second attachment point 130. At the same time the movement of the first connection point 126 will cause a corresponding movement in the tail 106 and the fin supporting member 124 which will flex the fin 114 from a resting form to a tensioned form.

When the person has fully extended their legs and thus stored the maximum amount of potential energy in both the main tension spring 120 and the main compression spring 128, the person then releases the handle 116. The sudden release of the handle 116 causes a rapid discharge of the stored potential energy whilst both the main tension spring 120 and the main compression spring 128 return to their pre-charged states. This causes a rapid movement of the tail 106 and the fin supporting member 124 which will flex the fin 114 back from a tensioned form to a resting form. This rapid movement of the tail 106 and the fin 114 propels the aquatic propulsion system 102 through the water. Next the person using the aquatic propulsion system 102 bends their knees as before and grabs the handle 116 again and the whole process is repeated consecutively for continuous movement through the water.

The handle can be released at any moment according to the desired energy level required for propulsion.

The second main tension spring guide 138 may be attached to the support board 108 by means of a keel 142. The second main tension spring guide 138 is preferably attached flexibly to the first main tension spring guide 136 via a flexible attachment 150.

Referring to figure 2, the tail section of the invention according to the first embodiment of the aquatic propulsion system is shown in more detail. Here it can be clearly seen that the fin supporting member 124 attached to the fin 114. The first connection point 126 is the point of connection of the fin supporting member 124, the main compression spring 128 and the main tension spring 120.

The main tension spring 120 is routed around the main pulley 134. The main pulley 134 is supported by a flexible pulley support 140 which typically comprises a relatively large diameter coiled spring as shown.

Referring to figure 3, the invention according to the first embodiment is shown as a general arrangement isometric view of the aquatic propulsion system 102.

The body is typically covered by the flexible outer skin 146 made from rubber, latex or other suitable material.

Referring to figure 4, the invention according to the first embodiment is shown while in use by an operator. In use, the operator using the aquatic propulsion system 102, will place both their feet on the foot rests 112, thus placing the body of the aquatic propulsion between their legs, while supporting their upper body by lying on the support board 108. The person will then bend their knees and use their hands to grab the handle 116. Keeping their arms straight, the person will then extend their legs, thereby pulling the handle 1 6 which will cause the support board (with the operator on it) to bend on the flexible attachment 150 towards the handle. This will cause a corresponding movement which will flex the fin 114 from a resting form to a tensioned form.

When the person has fully extended their legs, the person then releases the handle 116 instantly. The sudden release of the handle 116 causes the fin 114 to rapidly move back from a tensioned form to a resting form. This rapid movement can be described as a repulsive movement. This rapid movement propels the aquatic propulsion system 102 through the water. Next the person using the aquatic propulsion system 102 bends their knees as before while the flexible attachment 150 pulls the supporting board backwards which will enable the person to grab the handle 116 again and the whole process is repeated consecutively for continuous movement through the water.

Referring to figure 5, the invention according to a second embodiment is in the form of an aquatic propulsion system 502, comprising a body 504 and a propulsion means in the form of a fin 514 extending to the rear thereof.

There is typically also a support board 508 attached to the body 504 which supports the upper body of a person using the aquatic propulsion system. The support board 508 may be either flexibly or rigidly attached to the body 504.

The body 504, comprises internal frame members 510 which add strength and rigidity. Attached to the internal frame members 510 and protruding either side of the body 504, there are foot rests 512 which support the feet of a person using the aquatic propulsion system.

The body is typically covered by a flexible outer skin made from rubber, latex or other suitable material. Ballast or flotation devices can also be attached to the internal frame members and are typically contained in areas that are surrounded by the flexible skin.

Attached to the fin 514, there are two fin supporting members 524. These are typically strong and flexible laminated strips so they can accommodate the outer skin as well.

There are also two handles 516 that are attached to the internal frame members 510 via flexible handle supports 518. The flexible handle supports 518 typically comprise a relatively large diameter coiled spring. The handles 516 are connected to a main tension spring 520.

The main tension spring 520 is routed between both of the handles 516 via a main pulley 534. The main pulley 534 is attached to the internal frame members 510 via a flexible pulley support 540. The flexible pulley support 540 typically comprises a relatively large diameter coiled spring, attached at one end to the internal frame members 510 and at the other end to the main pulley centre shaft, on either side of the main pulley 534.

In use, an operator using the aquatic propulsion system 502, will place both their feet on the foot rests 512 while supporting their upper body by lying on the support board 508. The support board 508 is preferably attached flexibly to the body 504.

While an operator using the aquatic propulsion system is extending their legs, the support board 508 may be made to slide further from the body 504 by means of sliding telescopic tubes. These sliding telescopic tubes can be square tubes with an internal tension spring lightly pulling the support board 508 towards the body 504 while the operator using the system bends their knees.

The operator will then bend their knees and use their hands to grab either one of the handles 516. Keeping their arms straight, the operator will then extend their legs, thereby pulling the handle 516 further away from the main pulley 534. At the same time the support board 508 will slide out away from the body 504. In so doing the main tension spring 520 will be extended and placed under tension, thereby storing potential energy. The tension in the main tension spring 520 will exert force on the main pulley 534 which will cause the flexible pulley support 540 to flex in the direction of the handle 516 being pulled. At the same time the fin 514 will be moved and flexed from a resting form to a tensioned form.

When the operator has fully extended their legs and thus stored the maximum amount of potential energy in the main tension spring 520, the operator then releases the handle 516. The sudden release of the handle 516 causes a rapid discharge of the stored potential energy whilst the main tension spring 520 returns to its pre-charged state. This causes a rapid movement of the fin supporting member 524 which will flex the fin 514 back from a tensioned form to a resting form. This rapid movement of the fin 514 propels the aquatic propulsion system 502 through the water. Next the operator using the aquatic propulsion system 502 bends their knees as before and grabs either one of the handles 516 again and the whole process is repeated consecutively for continuous movement through the water.

The operator using the system may release the handle at any stage of the movement according to the desired level of energy and thus force required.

Referring to figure 6, the tail section of the invention according to the second embodiment of the aquatic propulsion system 502 is shown in more detail and while in a tensioned form. The two handles 516 are attached to the internal frame members 510 via flexible handle supports 518. The flexible handle supports 518 comprise relatively large diameter coiled springs as shown. The body 504 is shown with internal frame members 510 and foot rests 512. It can be seen that the flexible fin supporting member 524 is attached to the fin 514. The main tension spring 520 is routed between the two handles 516 around the main pulley 534. The main pulley 534 is supported by the flexible pulley support 540 which comprises a relatively large diameter coiled spring as shown. In figure 6 the aquatic propulsion system 502 is depicted where one of the handles 516 has been pulled, and it can be seen that the corresponding flexible handle support 518 has flexed towards the direction of pull. It should be understood that in the present embodiment the position shown in figure 6 represents one of two symmetric possible methods of operation, the other being when the opposite handle 516 is pulled.

The flexible fin supporting member 524 is attached to the main compression spring 528 through the outer telescopic tubes 547, slightly put back, being offset from the first connection point 526 at one end and attached to the middle of the fin 514 at the other end. The outer telescopic tubes may carry foam or airbags 548 for buoyancy purposes which can slide under the sectional U-shaped body cover 554.

Referring to figure 7, the tail section of the invention according to a third embodiment is shown, detailing the attachment and the moving of a tail section, particularly the joining of a flat fin 714 section to a U-shaped butterfly joint through an elastically flexible side cover 757.

The butterfly joint 760 enables the transfer of movement of a main tension spring 720 to a flat fin section 759 and covering the side of the pulley 734 as well as shaping the rubbery side of the fin throughout its movement.

A flexible fin supporting member 724 is also shown, showing how it buckles, creating a pushing down ridge in the upper section of the fin while in the down section of the fin it is bent and pulled by the butterfly joint 760 via the side cover 757.

Referring to figure 8, the invention according to the third embodiment is in the form of an aquatic repulsive propulsion system 702 where the driven body 704 can be any kind of watercraft (from a submarine to a boat) or the keel of such watercraft.

The reinforced pulling rope 722 can be pulled by any means at one end and anchored at the other alternately (symmetrical system), guided by a support pulley 744, channelled through telescopic tubes 747 to be connected by the inner fixing jointer 762 to pull the main tension spring 720.

As the main tension spring 722 is pulled it will exert force on the main pulley 734 with the help of the butterfly joint which will cause the flexible pulley support 740 to flex in the direction of the jolted second attachment point 730 thereby storing energy in both springs.

At the same time the main compression spring 728 will be compressed as the first connection point 726 moves closer to the second (jolted) attachment point 830. The second (jolted) attachment point allows the telescopic tubes 747 (a,b,c) and the main compression springs on it to move up and down in correspondence with the movement of the flexible pulley support 740.

The resulting (later) movement of the tail and fin supporting member 724 due to its fixing on the biggest telescopic tube 767 and that is fixed slightly back on the main compression spring causing it to buckle up causing a ridge, as seen in figure 7.

This synchronised movement in the tail and fin supporting member 724 will flatten the fin 714 from its resting mode to its tensioned but still slightly concave mode.

The butterfly joint 760 transfers the movement of the main tension spring 720 around the main pulley 740 to the flat fin section 759 as well as covering the side of the main pulley 734 all the way as the wheel of the pulley 734 turns.

Figure 8 consists of:

720 Main tension spring which goes around the pulley and is fixed at both ends to the reinforced pulling rope(s);

734 the Pulley;

740 Pulley supporting tension spring, fixed to the main frame;

704 Main frame; 722 Reinforced pulling ropes fixed to the main tension spring as well as to the smaller inner telescopic tubes via fixing points 762;

760 Butterfly joint that joins together with bolt joint as well as joint by eyestraps 763 on both sides of the pulley to the main tension spring. It also accommodates and transforms the fins into flat ones with rubbery sides

747a smaller diameter telescopic tubes: supporting the compression springs; 747b bigger diameter telescopic tubes supporting the compression spring 728a; 747c bigger (outer) telescopic tubes; 728a main compression springs;

728b weaker compression springs to be compressed first;

759 multi-layer fins with rubbery sides 757 from the flat surface to the rounded butterfly joint surface;

770 Ridge which can bend either way to push down or up the flip potentially made of multi layer strong and flexible strips which in the middle holds the elastic rubbery side cover;

771 Cover strip of the ridge from the outer telescopic tubes to the middle of the flat fins;

762 Inner fixing jointer, joining the main spring 720 to the reinforced rope 722 as well as to the smaller 747a telescopic tubes;

773 Eyestraps to fix the main tension spring 720 to the butterfly joint 760 on both sides of the pulley;

754 Sectional body cover U-shaped similar way to the butterfly flip joining at the axle of the pulley to cover it on the sides and slotted on the ridge of the main body to allow the ridge cover to slide in and out and open at both end to slide on the main body as the axle moves; 730 jolts to allow the telescopic tubes up and down movements;

744 small support pulleys to allow the reinforced ropes smooth and easy running;

757 Rubbery side cover from the flat section of the fins to the butterfly joint;

748 Additional foam ballast tank or airbag (optional for submersibles only) for buoyancy purpose; and

769 Elastic (rubbery) skin (optional).

Referring to figure 8, the invention according to the third embodiment is in the form of an aquatic repulsive propulsion system 702 where the driven body 704 can be any kind of watercraft (from a submarine to a boat) or the keel of such watercraft.

The reinforced pulling rope 722 can be pulled by any means at one end and anchored at the other alternately (symmetrical system), guided by a support pulley 744, channelled through telescopic tubes 747 to be connected by the inner fixing jointer 762 to pull the main tension spring 720.

As the main tension spring 722 is pulled it will exert force on the main pulley 734 with the help of the butterfly joint which will cause the flexible pulley support 740 to flex in the direction of the jolted second attachment point 730 thereby storing energy in both springs.

At the same time the main compression spring 728 will be compressed as the first connection point 726 moves closer to the second (jolted) attachment point 830. The second (jolted) attachment point allows the telescopic tubes 747 (a,b,c) and the main compression springs on it to move up and down in correspondence with the movement of the flexible pulley support 740.

The resulting (later) movement of the tail and fin supporting member 724 due to its fixing on the biggest telescopic tube 767 and that is fixed slightly back on the main compression spring causing it to buckle up causing a ridge, as seen in figure 7.

This synchronised movement in the tail and fin supporting member 724 will flatten the fin 714 from its resting mode to its tensioned but still slightly concave mode.

The butterfly joint 760 transfers the movement of the main tension spring 720 around the main pulley 740 to the flat fin section 759 as well as covering the side of the main pulley 734 all the way as the wheel of the pulley 734 turns.

Figure 9 shows how a flexible fin support strip can be attached to a fin with a elastic rubbery side cover as it is overlapping the rubber side cover of the fin at its narrowest point.

The fin (with its side cover) attaches thereby to a butterfly joint, while the fin support goes to a outer telescopic tube attachment with its side cover covering the side of the butterfly joint completely.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. For example, the propulsion means may comprise a propeller or similar as opposed to a fin.

Throughout the specification, unless the context requires otherwise, the word

"comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.