WO1994010029A1

WO1994010029A1 - A device for extracting energy from moving water particles

Info

Publication number: WO1994010029A1
Application number: PCT/AU1993/000517
Authority: WO
Inventors: David John Joseph Dipnall
Original assignee: David John Joseph Dipnall
Priority date: 1992-10-29
Filing date: 1993-10-08
Publication date: 1994-05-11

Abstract

A device (10) for extracting energy from moving water particles so as to drive an apparatus such as a boat or a power generating device. The device (10) comprises a plurality of blades (18) extending about a real or an imaginary centre axis (22). The blades (18) are arranged to move in response to forces applied by the water particles and biasing means (24) is provided for harnessing a reactive force generated in response to the movement of the blades (18) so as to enable at least a portion of the reactive force todrive the apparatus.

Description

A DEVICE FOR EXTRACTING ENERGY FROM OVTNG WATER PARTICLES

The present invention relates to a device for extracting energy from moving water particles and in particular, to a device for extracting energy from waves so as to drive marine vessels or power generators.

Numerous devices have previously been developed for extracting energy from waves. Such devices are generally realised in the form of wave operated propulsion devices. Examples of such devices can be seen in Australian patent application no.41498/78, U.S. patent 2021815, US patent 2367765, US patent 2996034 and British patent 1447758. However, the devices described in these patents suffer from the disadvantage that they only extract energy from water particles that move in a vertical plane (i.e. the particles that move vertically up and down in the wave.) As the water particles in any complex wave environment move in a disordered or chaotic path, it can readily be appreciated that devices only responsive to water particle movement in a vertical plane extract a small proportion of the energy of any wave. This means that there is a large proportion of a wave's energy that is not captured by such devices and is consequently lost. Due to this failure to make use of all of the wave's energy, the devices described in the previously mentioned patents are relatively inefficient and have not proved to be very successful.

The present invention seeks to provide an efficient and improved device for extracting the kinetic energy of the water particles of a wave. More particularly, the present invention seeks to capture omni-directional wave motion.

According to a first aspect of the present invention there is provided a device for extracting energy from moving water particles so as to drive an apparatus, said device comprising a plurality of blades extending about a real or an imaginary centre axis, said plurality of blades being arranged to move in response to forces applied by said moving water particles and means for harnessing a reactive force generated in response to the movement of said plurahty of blades so as to enable at least a portion of the reactive force to drive the apparatus.

According to a first embodiment of the invention said plurality of blades are connected together along a first portion so that they extend radially about said real or imaginary centre axis and wherein said means for harnessing said reactive force comprise biasing means attached to said apparatus.

According to a second embodiment of the invention the device further comprises a central support. Each of said plurality of blades preferably has an outer leading comer and an inner leading corner, the inner leading corner of each blade being connected to the central support and the outer leading corner being connected to an adjacent outer support. Preferably, the plurahty of blades form at least one set of blades which are attached to the central support in a spaced arrangement along the length thereof, and wherein the blades of said at least one set are also spaced radially around the central support so as to maximise the angular separation between adjacent blades of said at least one set.

According to a third embodiment of the invention the plurality of blades form at least one set of blades, said at least one set of blades being secured to a support member in a manner whereby each blade of said at least one set is rigidly connected to a radial arm of the support member.

Preferably, the plurahty of blades form a plurality of sets of blades and wherein the positioning of the blades of longitudinally adjacent sets of blades is staggered so as to maximise the separation of the blades of adjacent sets, to thereby maximise the space in which each blade can move before it contacts an adjacent blade.

According to a fourth embodiment of the invention said plurality of blades form at least one set of blades and wherein each blade has an outer leading comer portion integrally formed with a tension arm, said tension arm having an end part arranged to be coimected to either a support device or the outer leading comer portion of a blade of an adjacent set having an identical orientation.

According to a fifth embodiment of the invention said plurality of blades form at least one set of blades, said set of blades extending radially about a longitudinal central support.

According to a second aspect of the invention there is provided an apparatus, such as a marine vessel, fitted with a device according to the first aspect of the invention.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of a device according to a first embodiment of the invention;

Figure 2 is a side view of the device shown in Figure 1 illustrating a first mechanism for mounting the device to a support;

Figure 3 is a side view of the device shown in Figure 1 illustrating a second mechanism for mounting the device to a support;

Figure 4 is a schematic side view of a device according to a second embodiment of the invention having multiple sets of blades (only two shown) and illustrating one blade of each set only;

Figure 5 illustrates the radial positioning of the blades of a device according to the second embodiment of the invention and wherein each set of blades comprises five individual blades;

Figure 6 illustrates the longitudinal arrangement of the five blades of the set of blades shown in Figure 5;

Figure 7 is a schematic side view of the device shown in Figure 4 as deflected.

Figure 8 is a top plan view of the device shown in Figure 7;

Figure 9 is a schematic perspective view of a device according to a third embodiment of the invention having multiple sets of blades (only two shown), each set having three blades;

Figure 10 is a side view illustrating the connection of a number of the sets of blades shown in Figure 9;

Figure 11 illustrates the connection of an end of one of the radial arms of the set shown in Figure 9 to the support wire;

Figure 12 is a side view of a blade in accordance with a fourth embodiment of the invention;

Figure 13 is a top plan view of the tension arm of the blade shown in Figure 12;

Figure 14 is a sectional view along the line A-A in Figure 12;

Figure 15 illustrates a schematic side view of one arrangement of blades according to a fifth embodiment of the invention.

Figure 15A illustrates an end view of one of the sets of blades shown in Figure 15.

Figure 16 illustrates a side view of a modified blade in accordance with the fifth embodiment of the invention.

Figure 17 illustrates a side view of a modified blade in accordance with the fifth embodiment of the invention.

Figure 18 illustrates a side view of a modified blade in accordance with the fifth embodiment of the invention.

Figures 18A to 18C illustrate cross-sectional views of the blade shown in Figure 18 respectively along lines B-B, C-C and D-D.

Figure 19 is a front view of a marine apparatus fitted with a device according to an embodiment of the invention; and

Figure 20 is a side view of the marine apparatus as shown in Figure 19.

Figure 1 illustrates somewhat schematically a perspective view of a device 10 for extracting energy from moving water particles. The device 10 is arranged to be mounted to a support 12 which is connected to a vessel (not shown) so that the device 10 is below the wave surface 14 and within the zone 16 of active water particle movement. Although Figure 1 only depicts one device 10 mounted to the vessel it is envisaged that multiple such devices 10 would be mounted thereto.

The device 10 includes a plurahty of rigid or semi-rigid blades 18 which are of generally planar shape and are interconnected along their inner edge 20 so that the blades 18 combine to form an integral set of blades. When the device 10 is in its at rest position, the inner edge 20 of each of the blades 18 extends co-axially with a longitudinal central axis 22 shown as line A-A in Figure 1. The set of blades is connected to the support 12 by a flexible type joint 24 such as that illustrated in Figures 2 and 3. The set of blades are connected to the flexible type 24 at a point forward of their centre of lateral resistance.

When the set of blades of the device 10 is in the zone 16 of active water particles, water particles which are moving because of wave movement will impact on the surfaces of the blades 18. As a result of the impact force of the water particles on the blades 18 the blades will be caused to deflect away from their at rest position. The amount of deflection of the set of blades will vary depending on the impact force applied by the water particles and the spring or return force of the flexible type joint 24. The water particles striking the blades 20 will be caused to move rearwardly along the surface of the blades 18 until they pass the blades 18 and are free to resume unrestrained movement.

As a result of the water particles striking the blades 18 and causing the set of blades to deflect away from the at rest position, a component of forward thrust is generated and transferred via the flexible type joint 24 to the vessel, so as to drive the vessel in a direction coaxial to the longitudinal central axis 22.

The spring force which tends to return the set of blades to the central at rest position is stored as potential energy in the flexible type joint 24. This spring force is released when the deflection force from the water particles lessens and thereby the set of blades returns to the central at rest position. Any such movement of the set of blades causes a further deflection of water rearwardly over the blades 18 and thereby causes a further forward thrust force to be transferred to the vessel.

As can be determined from mathematical analysis, the stronger the return force of the flexible type joint 24, the smaller the forward thrust applied to the vessel and the faster the potential speed of the vessel. In contrast, if the flexible type joint 24 exhibits a weak return force, the forward thrust applied to the vessel is greater, but the potential speed of the vessel is decreased.

Figure 2 illustrates a first arrangement of the flexible type joint 24. In this arrangement the flexible type joint 24 comprises a tension spring 26 which is hingedly connected at a point 28 to the set of blades. A hydraulic or mechanical spring tension adjustment mechanism 30 is provided to adjust the spring or return force of the attachment mechanism 24. This enables the thrust and/or speed of the vessel to be regulated.

Figure 3 illustrates an alternative flexible type joint 24' comprising a closed coil tension spring 32 which is directly attached to the support 12.

It should be noted that the flexible type joints 24, 24' are designed to prevent the set of blades from being deflected on an angle of 90 ° from the central axis.

Figure 4 illustrates a second embodiment of the invention. This second embodiment of the invention differs from the first embodiment in that each set of blades is not secured to its own individual support. Rather, each set of blades is connected to a common set of support rods or wires which are connected in tension between at least a pair of supports 102 (see Figure 20) which extend from the vessel. This connection of each set of blades to the common set of support rods or wires will be explained in more detail subsequently. Figure 4 illustrates a single blade 40 of each of two sets of blades A, B which are connected to a central support 42. Each set of blades actually comprises a plurahty of blades 40 which are spaced radially around the central support 42. Thus, if a set of blades has three blades 40, the blades 40 are spaced radially around the central support 42 at every 120 °. Similarly, for a four blade arrangement the blades 40 are spaced apart by 90 °.

According to the size of the vessel and the power required to drive the vessel, the number of sets of blades mounted thereto will vary. As shown in Figure 4, there are only two sets of blades A, B which are spaced longitudinally along the central support 42. Each blade 40 has an outer leading corner 44 and an inner leading corner 46. The inner leading corner 46 of each blade 40 is secured to the central support 42. The inner leading comer 46 may be secured by a pivot pin 49 which fits securely within a bush 50 mounted in an aperture in the central support 42.

The outer leading comer 44 of each blade 40 is attached to a support wire or rod 48. The connection of the blades 40 to the support wire or rod 48 is such that blades 40 of identical radial orientation about the central support 42 are secured to the same outer support wire 48. Thus, in a blade arrangement having three blades 40, three support wires 48 respectively positioned at 0 °, 120 ° and 240 ° orientations about the central support 42 would be provided. The arrangement of the blades 40 about and longitudinally along the central support 42 is such as to maximise the possible movement or deflection of the blade 40 before it contacts an adjacent blade. It is important to maximise the possible movement or deflection of each blade 40 so as to maximise the forward thrust transferred to the vessel. It is also equally important to minimise any cutaway made to the blade 40 in order to maximise the surface area of the blade 40.

The outer leading corner 44 of each blade 40 may be attached to the support wire or rod 48 in one of two manners. Either, the outer leading comer 44 may be rigidly secured to the outer support wire or rod 48 or alternatively, the support wire or rod

48 may simply pass through an aperture in the outer leading comer 44 and be otherwise imconstrained.

Either or both of the attachments of the inner leading corner 46 to the central support 42 and the outer leading comer 44 of the blade 40 to the support wire 48 must be such that when the blade 40 is caused to deflect, a return force is generated. The reaction to this return force has a force component which endeavours to displace the blades 40 forwardly. This return or thrust force is transferred to the vessel along the support wire or rod 48. Figures 7 and 8 illustrate the movement of the blades 40 and support wire 48 when the blades 40 are deflected by the impact force of the moving water particles. In arrangements wherein the outer leading corner 44 is not rigidly secured to the outer support wire or rod 48 (i.e. support wire 48 merely passes through an aperture in outer leading comer 44) a spacer or compression tube 50 is provided over the support wire 48 and between longitudinally adjacent blades 40'. The spacer tube 50 is arranged to transfer the forward force generated through movement of the blades 40 to the vessel.

Figures 5 and 6 illustrate a set of blades according to a second embodiment of the invention having five individual blades 40. In order to maximise the permissible movement or deflection of the blades 40 before they contact an adjacent blade 40 and in order to minimise the amoimt of blade cutaway, a special arrangement of the blades, of each set is preferred. This arrangement is illustrated in Figures 5 and 6.

Figure 5 schematically illustrates the five blades 40 of the set of blades extending radially from the central support 42. The five blades 40 are spaced at 72 ° intervals about the central support 42 and are labelled as blades A, B, C, D and E in the anti¬ clockwise direction. However, as seen from Figure 6, in the longitudinal direction the blades 40 are spaced along the central support 42 so that they are positioned in the order A, C, E, B and D. By adopting this orientation and ordering of the blades 40 of the set the permissible movement or deflection of each blade 40 is maximised, while minimising the amoimt of cutaway needed to prevent contact between radially adjacent and longitudinally spaced blades 40. When a plurahty of sets of blades according to Figures 5 and 6 are mounted to a vessel, each set of blades would be oriented longitudinally and radially as shown in Figures 5 and 6.

Figures 9 to 11 illustrate a third embodiment of the invention. This embodiment makes use of support wires 48 to mount the sets of blades in a similar manner to the embodiments of the invention shown in Figures 4 to 8. However, in this third embodiment, each of the blades 60 of a set of blades are connected to a rigid blade support member 62 which is in turn connected to the support wires or rods 48. By adopting the use of such a support member 62 to connect the blades 60 of a set of blades, the need for a central support 42 is eliminated.

Each blade support member 62 has a number of radial arms 64 equal to the number of blades 60 of the set of blades. The blades 60 are made of a flexible material and are connected along their leading edge 66 to one of the radial arms 64 of the support member 62. The free end 66 of each of the radial arms 64 is connected to one of the support wires or rods 48. Radial arms 64 of each of the sets of blades having the same radial orientation are connected to the same support wire or rod 48. The connection of each of the radial arms 64 to the support wire or rod 48 may be rigid or alternatively the blade support members 62 may be free to slide along the support wire or rod 48. Figure 11 illustrates a rigid connection between the free end 66 of a radial arm 66 and the support wire 48. The free end 66 is connected to the support wire 48 by means of a locking screw 69.

When the free ends of the radial arms 64 are not rigidly secured to the support wires or rods 48, a spacer or compression tube 70 is provided on the support wires 48 between adjacent radial arms 64 so as to prevent relative movement therebetween (Figure 10). In this manner, forward thrust forces generated upon movement of the blades 60 by the water particles will be transferred via the compression tubes 70 to the supports 14 and then to the vessel.

Figures 12 to 14 illustrate a fourth embodiment of the invention. This embodiment of the invention is similar to the second and third embodiments of the invention. However, instead of mounting the outer leading comer of each blade to a support wire 48, each blade 80 has an integrally formed tension arm 82 which can be coimected to a longitudinally adjacent blade 80 of identical radial orientation. When a vessel is fitted with a plurality of sets of such blades 80, the first and last set of blade of each row of blade sets mounted to the vessel are attached to a support 14 in tension.

Each set of blades may comprise any number of blades 80. As stated previously, the blades 80 of each set are formed as a one piece unit and include at each of their outer leading comers an integral tension arm 82. Each tension arm 82 is arranged to be connected to a longitudinally adjacent blade 80' of identical radial orientation by virtue of a retaining screw 84. As the tension arms 82 are rigid and the connection between adjacent blades 80' of identical radial orientation is also rigid there is no necessity for spacer or compression tubes.

One advantage of this embodiment of the invention is that it can be easily disassembled for repair. As each set of blades is formed as a distinct module, a set of blades in the middle of a row of sets can be quickly replaced by unscrewing the relevant retaining screws.

Figures 15 to 18C illustrate a fifth embodiment of the invention. As can be seen from these Figures, the construction of each of the blades 90 is such that it is supported by a central support 92, such as a tube or rod 92, which is mounted in tension between supports extending from a vessel.

The tube or rod 92 providing support to the blade 90 may be a separate entity (see Figures 16 and 17) or alternatively may be integral with the blades 90 (see Figure 15). When the tube or rod 92 providing support to the blades 90 is formed integrally with the blades 90, any number of blades 90 may be moulded or otherwise constructed together to form a module of blades. Any number of modules can be linked together in tension between adjacent supports. Figure 15 illustrates a plurahty of sets of blades 90 which are integrally moulded to a central support 92. To increase rearward deflection of water particles in contact with the blade 90, each blade 90 is formed with a plurahty of smaller blades 90A (see Figure 15A).

Figure 16 illustrates a set of blades 90 in which each set of blades 90 are pinned to the support tube 92. A spacer or thrust tube 96 is provided between adjacent sets of blades.

Figure 17 illustrate a set of blades in which the blade 90 of the set are mounted to a radial arm support 98. Spacer or thrust tubes 96 are provided between adjacent sets of blades.

Figure 18 illustrates a flexible blade arranged to be connected to a central support tube or rod 92. The lateral stiffness and flexing characteristics of the blade 90 are controlled by variations in the sectional thickness of the blade 90. The various cross- sections of the blade along lines B-B, C-C and D-D are illustrated in Figures 18A to 18C.

Figures 19 and 20 illustrate a vessel 100 for use with the devices of Figures 1 to 18. The vessel 100 is designed so as to ensure that it remains as stable as possible. In this way, it is possible to maximise the magnitude of the waves relative to the structure of the vessel and therefore maximise the amount of possible forward thrust. To ensure the vessel's stability it is desirable for the vessel 100 to have a centre of buoyancy which remains as close as possible to its calm-water position when the vessel 100 is in a wave environment.

The vessel 100 shown in Figure 20, has a plurahty of sets of blades in accordance with any one of the second to fifth previously described embodiments fitted between the supports 102 which extend below the cock pit 105 of the vessel.

It is envisaged that in order to ensure maximum rearward deflection of water particles, a blade may have a plurahty of smaller blades extending from the planar surfaces thereof (see for example Figure 15A).

In each of the described embodiments it is desirable that the buoyancy of the set of blades is neutral so as to provide no upward or downward force when the set of blades is on the at rest position.

In each of the described embodiments the torque required to return the blade to its central at rest position may be achieved through mechanical spring means, the inherent elastic properties of the blade material, the tension in the support wires or rods or a combination thereof.

It is envisaged that embodiments of the invention would have application in toys, leisure craft, cruising vessels, large ocean going vessels, emergency propulsion system and power generation etc.

The described embodiments are particularly advantageous because they seek to capture omni-directional wave motion. Each set of blades comprises a plurality of blades so as to enable capture of wave motion from nearly all directions. As a consequence of this, the efficiency of the described embodiments is increased when compared to prior art devices.

The embodiments of the invention have been described by ay of example only and modifications are possible within the scope of the invention.

Claims

CLAIMS:

1. A device for extracting energy from moving water particles so as to drive an apparatus, said device comprising a plurality of blades extending about a real or an imaginary longitudinal centre axis, said plurahty of blades being arranged to move in response to forces applied by said moving water particles and means for harnessing a reactive force generated in response to the movement of said plurahty of blades so as to enable at least a portion of the reactive force to drive the apparatus.

2. A device according to claim 1 wherein said plurahty of blades are connected together along a first portion so that they extend radially about said real or imaginary centre axis and wherein said means for harnessing said reactive force comprise biasing means attached to said apparatus.

3. A device according to claim 2 wherein said biasing means comprises a tension spring.

4. A device according to claim 2 wherein said biasing means comprises a length of elastic material.

5. A device according to claim 1 further comprising a central support and wherein each of said plurahty of blades has an outer leading comer and an inner leading comer, the inner leading comer of each blade being connected to the central support and the outer leading corner being connected to an adjacent outer support.

6. A device according to claim 5 wherein said plurahty of blades form at least one set of blades, wherein the blades of said at least one set are attached to the central support in a spaced arrangement along the length thereof, and wherein the blades of said at least one set are also spaced radially around the central support so as to maximise the angular separation between adjacent blades of said at least one set.

7. A device according to claim 6 wherein there is a plurahty of sets of blades and wherein the outer leading comers of blades of identical radial orientation are attached to the same outer support.

8. A device according to claim 6 or claim 7 wherein said at least one set of blades has five blades, said five blades being spaced radially about said central support and being identified in turn as blades A, B, C, D and E respectively and wherein said blades are spaced along the length of the central support so that the blades are positioned in order A, C, E, B and D.

9. A device according to any one of claims 5 to 8 wherein the central support comprises a tube, a rod or a wire.

10. A device according to claim 9 wherein the outer support comprises a tube, a rod or a wire.

11. A device according to any one of claims 5 to 10 wherein the inner leading comer of each blade is connected to the inner support by means of a pivotal connection which may or may not provide a torsional return force.

12. A device according to any one of claims 5 to 11 wherein the outer leading comer of each blade is connected to the outer support by means of a pivotal connection which may or may not provide a torsional return force.

13. A device according to any one of claims 5 to 11 wherein the outer leading comer of each blade is connected to said outer support in a shdable manner and wherein the separation between longitudinally adjacent blades of identical radial orientation is maintained by spacer means mounted on said outer support.

14. A device according to any one of claims 5 to 13 wherein the harnessing means comprises said adjacent outer support.

15. A device according to claim 1 wherein the plurahty of blades form at least one set of blades, said at least one set of blades being secured to a support member in a manner whereby each blade of said at least one set is rigidly connected to a radial arm of the support member.

16. A device according to claim 15 wherein a free end of each radial arm is secured to an adjacent outer support.

17. A device according to claim 15 wherein the plurahty of blades form a plurahty of sets of blades and wherein the positioning of the blades of longitudinally adjacent sets of blades is staggered so as to maximise the separation of the blades of adjacent sets, to thereby maximise the space in which each blade can move before it contacts an adjacent blade.

18. A device according to claim 17 wherein blades of the same radial orientation of each of the sets have their outer leading corner connected to the same outer support.

19. A device according to any one of claims 15 to 18 wherein the outer leading comer of each blade is connected to said outer support in a shdable manner and wherein the separation between longitudinal adjacent blades of identical radial orientation is maintained by spacer means.

20. A device according to any one of claims 16 to 19 wherein the harnessing means comprises said adjacent outer support.

21. A device according to claim 1 wherein each of said plurahty of blades form at least one set of blades, and wherein each blade has an outer leading comer portion integrally formed with a tension arm, said tension arm having an end part arranged to be connected to either a support device or the outer leading comer portion of a blade of an adjacent set having an identical radial orientation.

22. A device according to any one of the preceding claims wherein the blades are shaped so as to maximise the possible movement of each blade before it contacts an adjacent blade.

23. A device according to any one of the preceding claims wherein each blade has at least one further blade extending from a surface thereof.

24. A device comprising a plurahty of substantially planar vanes arranged radially about a longitudinal axis, each vane being supported at a point or on an axis forward of the centre of lateral resistance of the blade and being arranged such that the blades always return to an at rest position after deflection.

25. A device according to claim 1 wherein said plurahty of blades form at least one set of blades, said set of blades extending radially about a longitudinal central support.

26. A device according to claim 25 wherein the sole support for the said at least one set of blades comprises said central support.

27. A device according to claim 25 or claim 26 wherein the central support is integrally formed with said at least one set of blades.

28. An apparatus fitted with a device according to any one of the preceding claims.

29. An apparatus according to claim 28 wherein the device is mounted to at least one pillar extending from the apparatus.

30. An apparatus according to claim 29 wherein the device is mounted between at least a pair of pillars which extend from the apparatus.

31. An apparatus fitted with a device according to claim 21 and wherein first and last blades of a longitudinal row of blades are attached in tension to said apparatus.

32. An apparatus according to any one of claims 28 to 31 wherein the apparatus is a marine vessel and wherein the design of the vessel is such that the wave action causes minimal buoyancy changes.

AMENDED CLAIMS

[received by the International Bureau on 18 February 1994 (18.02.94); original claims 1-32 replaced by amended claims 1-33 (5 pages)]

1. A device for extracting energy from wave induced water particle movement, said device comprising a plurahty of blades extending radially about a real or an imaginary longitudinal central axis and means for producing a reactive force in response to the kinetic energy of the water particles striking the blades, a proportion of said reactive force being arranged to drive said device in a desired direction, said energy extraction being apphcable to all water particle movement directions other than opposite to the desired direction of drive.

2. A device according to claim 1 wherein said plurality of blades are connected together along a first portion so that they extend radially about said real or imaginary centre axis and wherein said means for producing said reactive force comprise biasing means attached to said apparatus.

5. A device according to claim 1 further comprising a central support and wherein each of said plurahty of blades has an outer leading comer and an inner leading corner, the inner leading corner of each blade being connected to the central support and the outer leading corner being connected to an adjacent outer support.

6. A device according to claim 5 wherein said plurality of blades form at least one set of blades, wherein the blades of said at least one set are attached to the central support in a spaced arrangement along the length thereof, and wherein the blades of said at least one set are also spaced radially around the central support so as to maximise the angular separation between adjacent blades of said at least one set. 7. A device according to claim 6 wherein there is a plurality of sets of blades and wherein the outer leading corners of blades of identical radial orientation are attached to the same outer support.

13. A device according to any one of claims 5 to 11 wherein the outer leading corner of each blade is connected to said outer support in a shdable manner and wherein the separation between longitudinally adjacent blades of identical radial orientation is maintained by spacer means mounted on said outer support.

14. A device according to any one of claims 5 to 13 wherein the harnessing means comprises said adjacent outer support. 15. A device according to claim 1 wherein the plurality of blades form at least one set of blades, said at least one set of blades being secured to a support member in a manner whereby each blade of said at least one set is rigidly connected to a radial arm of the support member.

17. A device according to claim 15 wherein the plurality of blades form a plurahty of sets of blades and wherein the positioning of the blades of longitudinally adjacent sets of blades is staggered so as to maximise the separation of the blades of adjacent sets, to thereby maximise the space in which each blade can move before it contacts an adjacent blade.

21. A device according to claim 1 wherein each of said plurahty of blades form at least one set of blades, and wherein each blade has an outer leading comer portion integrally formed with a tension arm, said tension arm having an end part arranged to be connected to either a support device or the outer leading corner portion of a blade of an adjacent set having an identical radial orientation. 22. A device according to any one of the preceding claims wherein the blades are shaped so as to maximise the possible movement of each blade before it contacts an adjacent blade.

24. A device according to claim 1 wherein each blade is substantially planar and is supported at a point or on an axis forward of the centre of lateral resistance of the blade and is arranged such that the blade always returns to an at rest position after deflection.

25. A device according to claim 1 wherein said plurality of blades form at least one set of blades.

31. An apparatus fitted with a device according to claim 21 and wherein first and last blades of a longitudinal row of blades are attached in tension to said apparatus. 32. A device for extracting energy from moving water particles so as to drive an apparatus forward, said device comprising a plurality of blades extending radially about a real or an imaginary longitudinal central axis, said plurahty of blades offering resistance to water particle movement in any direction other than rearwardly, parallel to said longitudinal central axis and minimal resistance to water particle movement rearwardly, parallel thereto, said blades being individually or collectively provided with a biasing means tending to return them to a central fore-and-aft rest position, said biasing means producing a reactive force to the kinetic energy of moving water particles striking the blades, a proportion of which said reactive force is in a forward direction providing a forward force to drive the apparatus.

33. An apparatus comprising a device according to any one of the preceding claims wherein the apparatus is a marine vessel and wherein the design of the vessel is such that the wave action causes minimal buoyancy changes.