Wave-powered devices configured for nesting

Abstract

A wave-powered water vehicle includes a) a first component which is a float that travels on or near the water surface; b) a second component which is wave actuated and travels below the first component; and c) a means whereby the first component engages the second component and/or the second component engages the first component; wherein the engagement means provides lateral support of one component for the other, and thereby minimizes lateral movement of one against the other when the components are fitted together.

Claims

1. A wave-powered device comprising: (1) a float; (2) a wave-actuated component; (3) a flexible tether having a first end connected to the float and a second end connected to the wave-actuated component; and (4) a closure component that comprises a winch mounted to pivot about pitch axis of the tether, the winch having a spool to which the tether is connected, the closure component having a first state in which the tether is wound onto the winch to secure the float and the wave-actuated component together as an assembly that can be moved as a unit, and a second state in which the tether is unwound from the winch to permit the wave-actuated component to move away from the float wherein the winch is mounted on the float; wherein, when the closure component is in the second state and the float is placed on or near the surface of still water, the float floats on or near the surface of the still water, the tether extends downwards from the float and under tension, and the wave-actuated component is submerged below the float, and when the closure component is in the second state and the float is placed on or near the surface of wave-bearing water, the float floats on or near the surface of the wave-bearing water, the tether extends downwards from the float, and the wave-actuated component is submerged below the float, and interacts with the water to generate forces that are transmitted to the tether.

2. The wave-powered device of claim 1 wherein the float has top, bottom, and side surfaces, and comprises float side components that extend downwards generally parallel to the side surfaces to create a space defined by the bottom surface and the float side components, and the wave-actuated component is at least partially within that space.

3. The wave-powered device of claim 1 wherein the wave-actuated component comprises components that extend upwards from the wave-actuated component and that interact with components of the float to locate the wave-actuated component in a fixed position in relation to the float, and/or the float comprises components that extend downwards and that interact with components of the wave-actuated component to locate the wave-actuated component in a fixed position in relation to the float.

4. The wave-powered device of claim 1 wherein: the wave-actuated component comprises fins that, when the wave-powered device is in wave-bearing water, rotate about an axis to generate the forces that are transmitted to the tether; and the wave-actuated component includes members that extend downwards from the wave-actuated component and that, when the closure component is in the first state and the assembly is placed on a horizontal surface, separate the fins from the horizontal surface.

5. The wave-powered device of claim 1 wherein the winch comprises wiping elements that clean the tether when the tether is drawn through the winch.

6. The wave-powered device of claim 1 wherein: the tether has a substantially flat configuration to reduce drag; and the winch has a spool that rotates about an axis parallel to a longitudinal axis of the float so that the tether can be wound onto the spool without twisting.

7. The wave-powered device of claim 1 wherein: the first-mentioned winch is relatively close to the fore end of the float; the wave-powered device further comprises a second winch that is relatively close to the aft end of the float; and the wave-powered device further includes a second tether attached to the second winch.

8. The wave-powered device of claim 1, and further comprising: (1) wireless communications equipment; (2) a computer system; (3) a satellite-referenced position sensor (4) a horizontal direction sensor that senses direction in a horizontal plane; and (5) a steering actuator; the computer system (a) being linked to the communications equipment, the position sensor, the horizontal sensor and the steering actuator, and (b) containing, or being programmable to contain, instructions to control the steering actuator in response to signals received from the communications equipment, or from the position sensor and the horizontal direction sensor, or from signals received from another sensor on the vehicle.

9. The wave-powered device of claim 1 wherein the float is formed with a hollow configured to engage the wave-actuated component when the winch is in the first state.

10. The wave-powered device of claim 1 wherein the tether has a substantially flat configuration to reduce drag; the winch has a spool that rotates about an axis perpendicular to the pitch axis so that the tether can be wound onto the spool without twisting; and the tether is not required to flex against its wide axis as the wave-powered device undergoes pitch motion.

11. A wave-powered water vehicle, comprising: a) a first component that is a float that travels on or near the water surface; b) a second component that is wave actuated and travels below the first component; c) a flexible tether that connects the first and second components; and (d) a winch, mounted so as to pivot about pitch axis of the tether, the winch being built into the first component, wherein the winch is operable to assume a first state in which the tether is wound onto the winch, whereby one of said components may be secured against the other, and a second state in which the tether is unwound from the winch, whereby one of said components can move away from the other.

12. The wave-powered water vehicle of claim 11 wherein the first component is formed with a hollow configured to engage the second component when the winch is in the first state.

13. A wave-powered water vehicle, comprising: a float that travels on or near the water surface; a wave-actuated component that travels below the float; a flexible tether connecting the float and the wave-actuated component; and a winch, mounted to the wave-powered water vehicle so as to pivot about pitch axis of the tether, the winch having: a first state in which the tether is wound onto the winch to secure the float and the wave-actuated component together as an assembly that can be moved as a unit, and a second state in which the tether is unwound from the winch to permit the wave-actuated component to move away from the float.

14. The wave-powered water vehicle of claim 13 wherein the winch is mounted on the float.

15. A wave-powered water vehicle, comprising: a float that travels on or near the water surface, the float having a longitudinal roll axis and a transverse pitch axis; a wave-actuated component that travels below the float; a flexible tether connecting the float and the wave-actuated component, wherein the tether has a substantially flat configuration with wide and narrow axes to reduce drag when the tether is oriented with its narrow axis directed parallel to pitch axis of the tether; and a winch, mounted to the wave-powered water vehicle so as to pivot about pitch axis, wherein the winch has a spool that rotates about an axis perpendicular to the pitch axis of the tether so that the tether can be wound onto the spool without twisting, and the winch is operable to assume first and second states where: in the first state, the tether is wound onto the winch to secure the float and the wave-actuated component together as an assembly that can be moved as a unit, and in the second state, the tether is unwound from the winch to permit the wave-actuated component to move away from the float.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a pictorial view showing the operation of a wave-powered device (WPD) in still water (fins/wings in neutral position), when a wave lifts the float (up-stroke), and when the WPD sinks into the wave trough (down-stroke);

(2) FIG. 2A is a perspective view taken from above of a WPD having two rigid tethers and a wave-actuated component having two horizontal rigid spines (side beams) and a fin system between the rigid spines, with the tethers in their extended positions;

(3) FIG. 2B is a perspective view taken from above of the WPD of FIG. 2A with the rigid tethers in their retracted positions so that the WPD is in a bundle configuration with the float sitting atop the wave-actuated component;

(4) FIGS. 3A and 3B are perspective views taken from the bottom of the WPD of FIGS. 2A and 2B;

(5) FIG. 4 is a perspective end view of a WPD showing three wing racks;

(6) FIG. 5A is an end view of the WPD of FIG. 4 with the wing racks having been retracted and nested;

(7) FIG. 5B is an enlarged view showing additional details of the nested wing racks shown in FIG. 5A;

(8) FIG. 6 is an end view showing two WPDs of the type shown in FIG. 5A, both in their retracted configurations stowed in a container;

(9) FIG. 7A is a perspective view from the bottom showing a WPD of the type shown in FIG. 5A with the wing racks retracted and a sensor payload array lowered through a central opening in the wing racks;

(10) FIG. 7B is a perspective view from the top showing the wing racks lowered and the sensor payload array deployed below them;

(11) FIGS. 8A, 8B, 8C, and 8D are end, top, side, and bottom views of a configuration suitable for compact stowing and transport where the wing rack or racks can nest in a recess in the bottom of the float;

(12) FIG. 9 shows four such nested WPDs being transported on a flatbed trailer;

(13) FIG. 10A is a perspective view showing two-spring arrangement for controlling the movement of a fin (not shown), which is part of a wave-actuated component such as any of the WPDs described herein, viewed looking from between the spines (side beams);

(14) FIG. 10B is a partially cutaway perspective view showing the two-spring arrangement with one end of each spring embedded in the fin, viewed looking from outside the spines (side beams);

(15) FIG. 11 is a graph of spring torque as a function of fin (wing) angle;

(16) FIGS. 12A and 12B are external and cutaway perspective views of a winch that can be used with embodiments of the present invention; and

(17) FIG. 13 is a is a block diagram of a control system of the type that might be used in any of the WPDs discussed herein for directing the WPD along a desired path; and

(18) FIG. 14 is a block diagram schematically showing some of the ways that a representative WPD communicates with outside entities.

DESCRIPTION OF SPECIFIC EMBODIMENTS

(19) Overview

(20) FIG. 1 is a side view showing three images of a wave-powered water vehicle. The vehicle comprises a float 10 resting on the water surface, and a swimmer or glider 20 hanging below, suspended by a tether 30. The float 10 comprises a displacement hull 11 and a fixed keel fin 12. The swimmer comprises a rudder 21 for steering and wings or fins 22 connected to a central beam of the rack 23 so as to permit rotation of the wings around a transverse axis within a constrained range, and provide propulsion.

(21) In still water (shown in the leftmost panel), the submerged swimmer 20 hangs level by way of the tether 30 directly below the float 10. As a wave lifts the float 10 (middle panel), an upwards force is generated on the tether 30, pulling swimmer 20 upwards through the water. This causes the wings 22 of the swimmer to rotate about a transverse axis were the wings are connected to the rack 23, and assume a downwards sloping position. As the water is forced downward through the swimmer, the downwards sloping wings generate forward thrust, and the swimmer pulls the float forward. After the wave crests (rightmost panel), the float descends into a trough. The swimmer also sinks, since it is heavier than water, keeping tension on the tether. The wings rotate about the transverse axis the other way, assuming an upwards sloping position. As the water is forced upwards through the swimmer, the upwards sloping wings generate forward thrust, and the swimmer again pulls the float forwards.

(22) Thus, the swimmer generates forward thrust when either ascending or descending, resulting in forward motion of the entire craft.

(23) Engaging and Securing Components of the Vehicle for Storage and Transport

(24) Embodiments of the invention provide a technology for combining components of a multi-component wave-powered water vessel in a way that they can be stored or transported on land with minimal difficulty or damage.

(25) One of the elements of this technology is an engagement means, wherein the components are configured to fit together in a manner that provides lateral support one component to another, and thereby minimizes lateral movement of one against the other when fitted together. In a two-way engagement means, the components are also configured to provide support one component to another in the longitudinal dimension, and thereby minimize longitudinal movement of one against the other when fitted together.

(26) Lateral engagement means and optionally two-way engagement means between a float (the vessel body traveling on or near the surface of the water) and a swimmer (the rack of wings or fins that travels under water and provides locomotive force) may be provided by configuring the float and swimmer so that they fit together one inside the other, or are configured so that projections from one component, the other component, or both receive and engage the other component.

(27) In one such configuration, the swimmer has a smaller width and optionally a smaller length compared with the outermost edges of the float. The float is provided with a compartment or is hollowed out at the bottom to a depth whereby when the swimmer is secured to or contained within the hollow, the hollow conforms closely to the shape of the swimmer, thus providing lateral and potentially longitudinal stability. The roles of the components may be reversed, so that the float fits into a hollow in the swimmer. In another configuration, the swimmer has lateral beams or brackets on both sides that extend upwards to brace inwards against the sides of the float. The roles of the components may be reversed, so that the float has a lateral bracket on both sides that extends downwards to brace inwards against the sides of the swimmer. More complex configurations can also be designed where the float and swimmer are both provided with brackets, and the brackets interdigitate to provide lateral support and thereby minimize lateral movement of one against the other.

(28) Another element of the technology is an integral securing means, whereby one component is secured against and either above or below another component in a manner that the components may be moved together on land without one component sliding against another. The securing means is integral in the sense that it is built into one component, the other component, or both, so that it is always present and not removed after deployment of the vessel into the water. In this way, it is made available to resecure the vehicle back on land after a course of duty on the water.

(29) One such integral securing means is a connection between the components that may connect the components at a distance, but can be reduced in the length of the connection until the components are urged against one another. For example, when a float suspends a swimmer by way of a tether, the float may be provided with a locking or ratcheting winch to draw the swimmer upwards against the bottom of the float. Alternatively or in addition, components of the vessel may be equipped with integral securing means such as a clasp, clamp, or bolt that mates with and may be secured against a complementary element of another component after the components are brought together.

(30) FIGS. 2A and 2A are perspective views from the upper left side of another wave-powered water vehicle having a different configuration. FIG. 2A shows the vehicle as it is deployed in the water. In this example, the float 10 is connected to the swimmer 20 by two tethers 30. The float 10 comprises a displacement hull 11 with a side panel 13 on each side. The rudder 14 is now placed on the float. Upward facing solar panels 15 generate electrical power to supply the electronics (not shown) that are contained in one or more sealed compartments 16. The electronics control navigation, and have an antenna 17 to transmit data and receive instructions wirelessly to other vessels and/or a control unit on shore. The swimmer 20 comprises a rack 23 now positioned to support the wings 22 on either side. The rack 23 comprises a side beam 24 on each side that is configured to engage the hull 11 of the float. The rack 23 also comprises downward facing support legs 25 to support the entire vehicle from below when on land.

(31) FIG. 2B shows the vehicle when the swimmer 20 has been secured underneath the float 10 for transport or storage of the vehicle out of the water.

(32) FIGS. 3A and 3B are perspective views from the lower left side of the same two-tether wave-powered vehicle. FIG. 3A shows the vehicle as it is deployed in the water. Each tether 30 is secured to the swimmer at a midpoint 31 on a transverse beam 27 between the two side beams 24 of the rack 23. Each tether passes through an opening 18 in the hull 11 of the float so that they may be winched up together to lift the swimmer 20. The hull 11 also has four couplers 19 to secure the swimmer 20 to the float for transport.

(33) FIG. 3B shows the vehicle as it is secured for transportation or storage. The swimmer 20 is secured to the hull 11 of the float by retraction of the tethers that are joined at a midpoint 31 of two transverse beams 27, and closing the couplers 19 against transverse beams in the swimmer. The rudder 14 mounted on the float fits into a corresponding notch 26 on the rack 23 of the swimmer. The side beams 24 of the rack extend upwards to engage the sides 13 of the float.

(34) In these figures, the side beams of the swimmer 20 constitute an engagement means by extending upwards so that they may engage opposite side panels of the float. There are also two types of securing means. One type is the two winches for bringing the two tethers up and into the float. When they are drawn in so that the swimmer is in the upmost position, the swimmer is secured against the bottom of the float. The other integral securing means is the four couplers 19 on the bottom of the float, which lock onto transverse beams of the swimmer.

(35) Wave-Powered Vehicle Having Multiple Tiers of Fins that Nest Together

(36) FIG. 4 shows a model of a wave-powered water vehicle that has multiple tiers of fins. Each of the three tiers (20a, 20b, and 20c) comprises a rack with a side beam on each side (24a, 24b, and 24c), and transverse beams (27a, 27b, and 27c) between the to sides. The upper tier 20a, the middle tier 20b, and the lower tier 20c are each secured to the tethers 30 at the midpoint 31 of the transverse beams 27. Each tether is mounted to a winch 32 in the float 10 to retract the three tiers against the float for storage or transport.

(37) FIG. 5A shows a cut-away view of the three tiers 20 secured to the float 10. The winch 32 has been used to pull the tiers 20 against the bottom of the hull 11. The tiers 20 nest together so as to reduce the height of the vehicle when the components are secured against each other for transport or storage.

(38) FIG. 5B shows a detail of the tiers nested together. The uppermost tier 20a has a side beam 24a of each side that extends upwards to engage the corresponding side panel 13 of the float from below, and extends downwards to engage the corresponding side beam 20b of the middle tier 20b from above. The middle tier 20b is narrower in width so as to fit between the side beams 24a of the upper tier 20a. The middle tier has a side beam 24b on each side that extends upwards to engage the corresponding beam 24b of the upper tier from below on the inside, and extends downwards to engage the corresponding beam 24c of the lower tier 20c from above. The lower tier 20c is still narrower in width so as to fit between the side beams 24b of the middle tier 20b. The lower tier has a side beam 24c on each side that extends upwards to engage the corresponding beam 24b of the middle tier 20b from below on the inside, and extends downwards to provide a support leg for the entire vehicle to rest on when out of the water for transport or storage.

(39) Thus, each tier is nested into the one above it by being narrower in width. The difference is about two times the thickness of the side beams, so that the side beam of each tier may engage the side beam of the tier above it. Since there is a close tolerance between the outermost side of the middle and lower tiers with the inside of the side beam of the tier above, the tiers are engaged one to another. Since there is a close tolerance between the inside of the top tier with the outer panel of the hull, the nested racks are engaged with the float. They may be secured in position by way of the tether winches, a lockable coupling mechanism, or both.

(40) As an alternative nesting and engagement means, the nesting of the tiers may be done the other way up, so that the bottom tier is the widest, and the next tier is narrower to the extent required for the side beams to engage the side beams of the tier below it from the inside. As a third alternative, the tiers have substantially the same width, and nest by having side beams that splay downwards to fit over the tier below.

(41) FIG. 6 shows two wave-powered water vehicles, each with three tiers of wings. The nesting allows the tiers to be packed closer together, reducing the height of the vehicle secured out of the water so that the two may be transported or stored one on top of the other in a standard sized metal shipping container.

(42) Wave-Powered Vehicle Having an Opening for Dispensing a Payload or Equipment

(43) In some instances, a wave-powered water vehicle of this invention may be wanted to dispense a large payload, or to lower equipment. For such purposes, the vehicle may be provided with a large opening (typically at or near the center of floatation) through which such payload or equipment may be dropped or lowered.

(44) FIG. 7A shows such a vehicle in a perspective view from the lower right side. There is a plurality of racks 20 comprising propulsion wings 22. The racks are shown drawn against the bottom of the float 10 by retracting the tethers 30 up into the float each using a winch 32. All of the tiers of wing racks 20 and the bottom of the hull of the float 10 have been provided with openings 52 that substantially align downwards. This enables the user to deploy equipment 50 (such as monitoring or sensor equipment) or a payload through the hole either by dropping, or by lowering on a line 51 that extends from a winch 53 or lowering motor that is aboard the float.

(45) FIG. 7B shows a detail of the vehicle in a perspective view from the upper right side. Here, three tiers of wing racks 20a, 20b, and 20c have been lowered to the downwards (propulsion providing) configuration using the tethers 30. Each of the three racks comprise an opening 52 made by omitting or cutting out a portion of the wings corresponding to the hole on each tier. Here, the wing racks are further stabilized and aligned above each other using guide wires 33 at the front and back of the racks. This helps align the opening in each rack 20 in rough seas so that the payload 50 may be passed on the line 51 directly through the holes 52 without substantially disturbing any of the racks.

(46) Catamaran Style Wave-Powered Vehicles

(47) FIGS. 8A, 8B, 8C, and 8D depict a wave-powered vehicle having a float comprising two floating elements or pontoons that track over the water in parallel one beside each other. FIG. 8A is a transverse cut-away view; FIG. 8B is a perspective from above showing solar panels on the top surface; FIG. 8C is a cut-away view down the middle; FIG. 8D is a perspective from below the rack of propulsion wings. The two pontoons are connected over the top, which provides a platform for mounting solar panels and electronic equipment. The cavity formed between the two pontoons provides a cavity that engages the swimmer from each side. Here, the swimmer is shown with a single wing rack, although multiple nesting wing racks can also be used. There are matching rudders at the end of each pontoon. In this example, there is also a propeller drawing power from a battery to provide locomotive power to the vessel when wave action is insufficient to drive the vehicle at the desired speed.

(48) FIG. 9 shows four catamaran-style wave-powered vehicles mounted on a truck. The vehicles are stored inside a shipping container mounted on a truck. In this drawing, the sides and top of the shipping container have been cut away to show the storage configuration. Sizing the swimmer or wing racks to be retractable between the two pontoons of each catamaran compacts the storage size. This allows four of the wave-powered vehicles to be stored and transported in a single standard-sized shipping container.

(49) Spring Arrangement for Controlling Wing Rotation with Gradations of Torque

(50) FIGS. 10A and 10B show a two-spring arrangement for controlling the movement of fin, which is part of a wave-actuated component such as is shown in FIG. 2A. The spring arrangement constrains upward and downward rotation of the fins within two ranges requiring increasing torque. FIG. 10A is an upper perspective of the spring arrangement on the foremost fin or wing (not shown) to the right side beam 24 from behind on the inside, with the fin removed. FIG. 10B is an upper perspective of the same spring arrangement from behind on the outside, with the beam drawn transparently and showing a portion of the fin.

(51) The fin is rotationally mounted to the side beam 24 by way of an axle 40 that passes transversely through the fin 22 just behind the leading edge 221 with the elevator portion of the fin 222 extending behind. The spring arrangement comprises a first and second springs 41 and 42. The first spring is wound around the axle 40 (shown in this example on the inside of the side beam 24. The first spring 41 extends from the axle at one end 411 to form a hook portion disposed to provide a point of attachment for the fin. In this embodiment, the other end of the first spring, not shown, is fixed to the side beam.

(52) The second spring is also wound around the axle 40 in the same direction as the first spring 41. In this example, the second spring is thicker, and therefore stiffer, than the first spring. The second spring 42 extends from the axle at one end 424 to form a hook portion disposed to provide a point of attachment for the fin. The second spring 42 extends from the axle at the other end 424 to form a hook portion disposed to travel between an upper stop 422 and a lower stop 423 mounted on the side beam 24.

(53) With this configuration, the first spring 41 is engaged to control the upward and downward rotational movement of the wing but the second spring is notas long as the movement is within the range defined by the stops for the second spring. When the rotation of the wing goes beyond what is permitted by the stops, then the second spring 42 becomes engaged. As a consequence, the torque required to rotate the wing is now determined by both springs, and more torque is required to rotate the wing further in the same direction.

(54) FIG. 11 is a graph showing the torque required to alter the angle of a wing of the vehicle in either direction from a neutral position. The torque required to operate the wing within the inner range is determined by the first spring alone, beyond which the torque required to alter the angle in either direction is determined by the combined torque of both springs.

(55) Winch Design and Use

(56) In another aspect of the invention, a WPD includes one or more winches (or their equivalent) that can store and release a tether before the WPD is launched, and/or can control the length of the tether when the WPD is in use, and/or can gather up the tether when the WPD is taken out of use, e.g., removed from the water completely. Preferably, when using a winch, the tether is free from electrical connections. If the tether does contain electrical connections, the winch system is more complicated. For example, the electrical connections will need to exit the center of the winch spool with slip rings or similar devices. Tethers without electrical connections may be thinner, enabling more wraps and greater length on the same diameter spool of a winch. Through the use of one or more winches, it is possible to obtain one or more of the following advantages: (1) to optimize the distance between the float and the wave-actuated component, depending on the actual expected wave and wind conditions (for example, longer to capture energy from slow, deep waves; shorter to reduce tether drag in high frequency wind chop). (2) to reduce the distance between the float and wait-actuated component in order to get over under-sea obstacles or to release the swimmer if it is stranded in shallow water. (3) to clean the tether, at regular or irregular intervals, by pulling the tether upwards through wipers, thus removing or reducing fouling which produces undesirable drag on the tether. (4) to simplify deployment and recovery, particularly when the float and the wave-actuated component are designed so that they can be close to each other, e.g., in a nested configuration, for example when the float and the wave-actuated component can form a single tight bundle which is suitable for shipping and/or storage and which can be easily deployed into an operating condition in response to physical and/or electrical and/or electronic commands. (5) when there are two tethers, to remove twist by using the winch or winches to pull both tethers upward.

(57) FIGS. 12A and 12B are drawings of a winch that may be used to raise and lower the tethers that attach the float to the swimmer or wing racks in a wave-powered vehicle of this invention. Typically, each tether has its own winch, which are coordinated to raise the swimmer simultaneously. FIG. 12A shows the winch with the cover closed. FIG. 12B is a perspective of the winch with the covering cut away to show what's inside. The tether 30 is rolled onto a spool 61 driven by a worm drive 63 attached to an electric motor 62. The tether winds and unwinds from the spool over a pulley 64 downwards through an opening 65 in the covering.

(58) The tether 30 is flat and streamlined, so it will not flex easily in the pitch axis. A 160 mm OD spool may support 10 m of tether if the tether is 2 mm thick. To allow the tether to pivot in pitch, the entire winch assembly is mounted on bearings at either end so that it pivots along a center axis 66. It has a cylindrical cover that is foam filled to displace water. The float will have a corresponding cylindrical opening so that minimum empty space is allowed to fill with water.

(59) Wipers (not shown) are positioned in the winch assembly to clean slime and scum off of the tether before it is wound on the spool. This removes bio-fouling and may periodically be done to improve vehicle speed performance. The tether may include magnetic markers and magnetic sensors, such as hall effect sensors, may be positioned to measure movement of the tether. Alternatively, the tether may have variable magnetic permeability and a magnet may be one side of the tether as it enters the winch area while a hall sensor is on the other side. Since scum may change the effective thickness of the tether, this system can help maintain the correct deployed length.

(60) Multiple e.g., Dual Tethers

(61) In another aspect of the invention, a WPD comprises a first tether that is attached (i) to the float at a first float location, and (ii) to the wave-actuated component (or swimmer) at a first swimmer location, and (2) a second tether that is attached (i) to the float at a second float location that is different from the first float location, and (ii) to the swimmer at a second swimmer location that is different from the first swimmer location, and the WPD has at least one of the following features (i.e., having one of the following features or a combination of any two or more of the following features): (1) At least one of the tethers is secured to a winch secured to the float. In one embodiment, both tethers are secured to the same winch. In another embodiment, one of the tethers is secured to a first winch and the other secured to a second winch. Optionally, the winch is mounted so that it can pivot along a center axis. (2) The horizontal distance between the front of the float and the first float location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the float. (3) The horizontal distance between the rear of the float and the second float location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the float. (4) The horizontal distance between the front of the swimmer and the first swimmer location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the swimmer. (5) The horizontal distance between the rear of the swimmer and the second swimmer location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the swimmer. (6) At least one of the tethers has a substantially flat configuration, for example with an average thickness of 1-3 mm, thus facilitating the handling of the tether, particularly when the tether is to be wound up on a winch.

(62) The use of dual tethers can reduce the likelihood that the tethers will become twisted; can enable a longer and narrower float shape (which reduces drag and increases speed); and by moving the connections and mechanisms associated with the tether to the fore and aft sections of the float, makes it possible to provide a larger central area of the float for payloads of all kinds, for example communications equipment and sensors and other scientific instruments. In addition, the use of two tethers can simplify recovery of a WPD. Recovering a WPD that has only a single tether can be difficult because pulling up on the single tether requires lifting the swimmer against the resistance of the fins to the water. When there are two tethers, pulling on only one of the tethers tilts the swimmer and the fins attached to it so that the resistance of the fins is reduced. This is true, whether or not the WPD makes use of a winch to shorten the tether.

(63) A WPD having a single tether generally has a tether termination assembly and load distribution structure at the center of the float, thus occupying the center of the float. The use of two spaced-part tethers frees up the center of float, which for many purposes is the most valuable part of the float desirable components. For example, the best part of the float for tall antennas is the center, where they can cast a shadow on at most half of solar panels mounted on the upper surface of the float (shading just part of a solar panel can completely disable it if, as is often the case, the cells are wired in series and shut off like transistors when dark.) Also, tall antennas have no steering effect on the float due to wind if they are at the center. When the WPD has two tethers, the center area of the float may be free for payloads with integrated antennas, i.e., antennas that are integrated with a dry box, or kept entirely within a dry area, thus reducing the danger that routing wires to the antennas will be damaged by moisture. In addition, placing most or all of the payload at the center of float makes it easier to balance the float fore and aft, and thus reduces the danger that the float will nose in or nose up.

(64) When the WPD has two tethers, the float preferably contains a means to steer the float, such as a rudder at the tail end of the float. The wave-actuated component (swimmer) provides thrust as it is lifted and lowered due to wave action. Torque from the float is transmitted to the wave-actuated component by the separation of the two tethers. The wave-actuated component thus points in the same direction as the float after a steering lag, caused by the inertia and fluid resistance to rotation of the wave-actuated component.

(65) In one configuration, there is a fore tether and an aft tether, preferably on a relatively long narrow float. While the tethers are taut, the wave-actuated component is held parallel with the float. Particularly when the wave-actuated component is held relatively level, a spring and stop system can control the angle of fins well, so that the fins operate at a favorable angle of attack during up and down motions with various speeds and amplitudes. The wave-actuated component can for example have a parallel bar structure with fin support shafts crossing between bars like ladder steps. The position of the fins can for example be controlled by a spring assembly that maintains the fins as a desired neutral position, e.g., a level position, when the springs are not moving and that will resist upward and downward motion. The spring profile may be adjusted so that the wings tend to stop at an angle that is optimized for maximum lift.

(66) In another configuration, there are right and left tethers. These may connect to a single monolithic wing. The wing can move as a unit, pivoting at a point at which both the tethers are attached to the wing. A weight below the wing causes it to nose down and dive forward when lowered. The attachment point to the tethers is forward of the center of wing area so that the wing will nose up and pull forward when raised by the tethers. As in the fore-aft configuration the rudder that steers the float, also indirectly steers the glider by the separation of the two tethers.

(67) In other configurations, 3 or 4 tethers may be used to stabilize the glider. This is useful especially in large systems. On the other hand, the presence of too many tethers is undesirable because each tether represents additional drag.

(68) Communications and Control

(69) FIG. 13 is a is a block diagram of a control system of the type that might be used in any of the WPDs discussed herein for directing the WPD along a desired path. This figure duplicates FIG. 5 in the above-referenced U.S. Pat. No. 7,371,136.

(70) FIG. 14 is a block diagram schematically showing a representative WPD's on-board electronics and some of the ways that the representative WPD communicates with outside entities. As mentioned above, the WPD uses satellite location systems and radio to communicate data back to an operator and to receive navigation and other commands, and has on-board computers and sensors that allow it to navigate or hold position autonomously, without regular human interaction or control.

(71) The float contains core electronics including: satellite position sensor (GPS), radio communications (preferably sat-comm such as Iridium), an orientation sensing means such as a magnetic compass, batteries, navigation controller that uses information from the GPS and compass to control the rudder and steer the vehicle. The float may also include solar panels and various payload electronics such as environmental sensors or observation equipment such as radio monitors, cameras, hydrophones. All core electronics may be housed in the same enclosure, preferably at the tail end of the float. By keeping all the core electronics together, there is no need for wet connectors or cables in the core system. This is great reliability benefit. (solar panels and winches will connect with wet connectorssolar can be redundant so one connector can fail without taking the system down and winches are not necessary for basic functionality.) Since the GPS and sat-comm antennas are short, they will not shade the solar panels. Also the tail end is the least frequently submerged part of the float. (Submersion obscures the antennas.) however, as discussed above, with dual-tether embodiments, it is possible to house electronics and the like at the center of the float because the tether connections are near the end.

Terminology

(72) The term comprises and grammatical equivalents (e.g., includes or has) thereof are used herein to mean that other elements (i.e., components, ingredients, steps, etc.) are optionally present. For example, a water vehicle comprising (or that comprises) components A, B, and C can contain only components A, B, and C, or can contain not only components A, B, and C but also one or more other components. The term consisting essentially of and grammatical equivalents thereof is used herein to mean that other elements may be present that do not materially alter the claimed invention. The term at least followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example at least 1 means 1 or more than 1, and at least 80% means 80% or more than 80%. The term at most followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, at most 4 means 4 or less than 4, and at most 40% means 40% or less than 40%. When, in this specification, a range is given as (a first number) to (a second number) or (a first number)-(a second number), this means a range whose lower limit is the first number and whose upper limit is the second number. For example, from 5 to 15 feet or 5-15 feet means a range whose lower limit is 5 feet and whose upper limit is 15 feet. The terms plural, multiple, plurality, and multiplicity are used herein to denote two or more than two items.

(73) Where reference is made herein to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously (except where the context excludes that possibility), and the method can optionally include one or more other steps that are carried out before any of the defined steps, between two of the defined steps, or after all the defined steps (except where the context excludes that possibility). Where reference is made herein to first and second elements, this is generally done for identification purposes; unless the context requires otherwise, the first and second elements can be the same or different, and reference to a first element does not mean that a second element is necessarily present (though it may be present). Where reference is made herein to a or an element, this does not exclude the possibility that there are two or more such elements (except where the context excludes that possibility). Where reference is made herein to two or more elements, this does not exclude the possibility that the two or more elements are replaced by a lesser number or greater number of elements providing the same function (except where the context excludes that possibility). The numbers given herein should be construed with the latitude appropriate to their context and expression; for example, each number is subject to variation that depends on the accuracy with which it can be measured by methods conventionally used by those skilled in the art.

(74) Unless otherwise noted, the references to the positioning and shape of a component of the vehicle refer to that positioning and shape when the vehicle is in still water. The terms listed below are used in this specification in accordance with the definitions given below.

(75) Leading edge (or leading end) and trailing edge (or trailing end) denote the front and rear surfaces respectively of a fin or other component as wave power causes the vehicle to move forward.

(76) Fore and aft denote locations relatively near the leading and trailing edges (or ends) respectively.

(77) Aligned denotes a direction that lies generally in a vertical plane that is parallel to the vertical plane that includes the axial centerline of the swimmer. Axially aligned denotes a direction that lies generally in the vertical plane that includes the axial centerline of the swimmer.

(78) Transverse denotes a direction that lies generally in a vertical plane orthogonal to the vertical plane that includes the axial centerline of the swimmer.

(79) Where reference is made herein to a feature that generally complies with a particular definition, for example generally in a vertical plane, generally laminar, or generally horizontal, it is to be understood that the feature need not comply strictly with that particular definition, but rather can depart from that strict definition by an amount that permits effective operation in accordance with the principles of the invention.

CONCLUSION

(80) In conclusion, it can be seen that the embodiments of the invention provide structures and methods that can improve the handling of WPDs during storage, transport, launch, and recovery.

(81) In the Summary of the Invention and the Detailed Description of the Invention above, and the accompanying drawings, reference is made to particular features of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect, a particular embodiment, or a particular figure, that feature can also be used, to the extent appropriate, in the context of other particular aspects, embodiments, and figures, and in the invention generally. It is also to be understood that this invention includes all novel features disclosed herein and is not limited to the specific aspects of the invention set out above.

(82) While the above is a complete description of specific embodiments of the invention, the above description should not be taken as limiting the scope of the invention as defined by the claims.