Abstract: A system and method for a for a wave energy converter device that is an axisymmetric point absorber which operates in a tension only condition over a large stroke that can operate in the given wave environment so as to eliminate the need for end stops in normal operation whereby the wave energy converter device has a floating hull with an interior Power Take Off (PTO) that uses an impedance control scheme for impedance matching with the wave environment in which it is deployed so as to maximize electrical power output as compared with a passively operating device of similar size.

Abstract: Disclosed is a system for deploying, stationing, and translocating buoyant wind- and wave-energy converters and/or other buoyant structures or devices, as well as farms of same. Also disclosed is a novel apparatus and/or machine comprising a farm of buoyant wave energy converters deployed by said method and/or configured to be deployed by said method.

Abstract: A system that maintains the relative and/or absolute geographical positions of two or more buoyant devices floating in a body of water. A plurality of formation restoring tethers are disclosed which permit the unrestricted vertical movement of networked buoyant devices, while resisting increases in their lateral separations by providing restoring forces to oppose such separations. Tensioning mechanisms incorporated into the tethers generate the resistance to the lateral separations of two or more entities by transforming such separations into an increase in the potential energy stored within such tensioning mechanisms, the potential energy of which is released in the process of restoring the original separations and/or positions of the displaced buoyant devices.

Abstract: A wave power generation device comprises a floating energy harvester (1), a plurality of energy conversion levers (2) and a plurality of energy transferring rods (3) suspended around the floating energy harvester (1); one end of the energy transferring rod (3) is connected to the floating energy harvester (1), and the other end is sleeved onto the lower end of the energy conversion lever (2); the energy transferring rod (3) transfers energy harvested from a horizontal movement of a wave by the floating energy harvester to the energy conversion lever (2), and follows the vertical motion of the energy conversion lever (2) as the surface of the sea rises and falls; an upper end of the energy conversion lever (2) is connected to a first working mechanism (102), and a lower end of the energy conversion lever (2) is submerged in seawater.

Abstract: A system that maintains the relative and/or absolute geographical positions of two or more buoyant devices floating in a body of water. A plurality of formation restoring tethers are disclosed which permit the unrestricted vertical movement of networked buoyant devices, while resisting increases in their lateral separations by providing restoring forces to oppose such separations. Tensioning mechanisms incorporated into the tethers generate the resistance to the lateral separations of two or more entities by transforming such separations into an increase in the potential energy stored within such tensioning mechanisms, the potential energy of which is released in the process of restoring the original separations and/or positions of the displaced buoyant devices.

Abstract: A wave energy converter has blades (54, 56, 57, 59) on frames (51, 52) rotating about a pivot joint (53) on a structure (4, 52, 502, 505, 86). There is reciprocating rotary motion of the frame with respect to the structure, providing reciprocating rotary input power to a mechanism (73, 94, 98). The mechanism (98) may be arranged so that the reciprocating input power is transferred to uni-directional power via pulleys (101, 106) and sprag clutches (102, 107).

Abstract: A power generator may include a digital programmable governor, a plurality of power modules. The power modules have working fluid including compound gas and a magneto-responsive liquid column disposed therein, a thermal generator capable of adding heat to the working fluid, one Or more cooling exchangers configured to remove heat from the working fluid, at sets of electro-hydro-dynamic actuators, and a plurality of bidirectional turbines. The sets of electro-hydro-dynamic actuators are disposed proximate to the power modules, responsive to control of the digital programmable governor and in association with a thermal cycle of adding heat to and removing heat from the working fluid, provide influence to drive reciprocal flows of the working fluid through the power modules. The bi-directional turbines are disposed to receive the reciprocal flows and perform a kinematically independent conversion of the operating medium reciprocal flows to rotary motion power output.

Abstract: A system and method for generating energy from tuning the natural frequency of masses relative to a ground plane and an external force. In some embodiments the external force is the action of the waves. The system has a first mass movable relative to the ground plane, wherein the external force induces an oscillation in the first mass relative to the ground plane. A second movable mass is carried by and movable relative to the first movable mass. The second movable mass creates kinetic energy as the result of varying the position of the second movable mass relative to the first mass. The system adjusts or tunes the frequency of various components in relation to the natural frequency of the waves. The energy created by the relative motion can be converted to various forms of energy including electrical energy.

Abstract: A generator including: a member having a cable wound thereon, the cable having a free end; a spring for storing energy as the cable is unwound from the member by pulling on the free end; and an electromagnetic generator operatively connected to the member such that rotation of the member is transferred to an input side of the electromagnetic generator after the cable is unwound from the member and the stored energy in the spring turns the member.

Abstract: The present invention concerns a rotating apparatus related to water power, particularly related to wave power, and related to conversion of energy, for instance to generate electricity. The apparatus according to the invention may comprise one or more axially connected horizontally arranged floating or neutrally buoyant rotors that are driven by a number of fins that in turn are driven by wave waterflows and/or linear waterflows, said rotors being adapted for rotation, said rotation being non-changing and independent of the direction of the waterflows. The rotational energy is preferably converted to electricity by built-in generators. In addition, the apparatus comprises an arrangement so that the apparatus is adapted to move into a position corresponding to the direction of the waterflows.

Abstract: The invention is a wave energy device which optimizes energy conversion from waves with a stable submerged platform coupled to compliant chain of floats (“pods”) which are connected to the platform by piston pumps. Wave action drives pumps to deliver pressurized water to a hydro turbine coupled to an electric generator for delivery of electric power to shore via a submarine cable. Alternatively, the pressurized water may be delivered to shore through pipes on the ocean floor, to generate electric power, also as input flow for reverse osmosis potable water production and for cooling applications.

Abstract: A device that converts wave energy to electrical or chemical energy includes a buoy adapted to float on a water surface, a venturi tube, and a rigid or flexible means of connecting the buoy and the venturi tube. The venturi tube defines a lumen through which water flows downwardly when the buoy moves upwardly and upwardly when the buoy moves downwardly. A constriction is formed in the lumen to create a venturi effect for water flowing upwardly and downwardly through the lumen. A turbine is positioned in the lumen at the constriction where water flow is at a maximum rate. The turbine is connected to a generator so that the venturi effect is harnessed to generate power. Multiple embodiments are included.

Abstract: The invention relates to a wave power plant, comprising at least one floating power plant body and means for converting movement of the floating power plant body into a rotary motion for power take off. The floating power plant body (1) is adapted to perform a gyrating motion in response to waves.

Abstract: The invention is a wave energy device which optimizes energy conversion from waves with a stable submerged platform coupled to compliant chain of floats (“pods”) which are connected to the platform by piston pumps. Wave action drives pumps to deliver pressurized water to a hydro turbine coupled to an electric generator for delivery of electric power to shore via a submarine cable. Alternatively, the pressurized water may be delivered to shore through pipes on the ocean floor, to generate electric power, also as input flow for reverse osmosis potable water production and for cooling applications.

Abstract: The generator comprises a float (1) which is movable in response to wave motion in a body of water, a submersible reaction member (2) of adjustable buoyancy, with at least two buoyancy configurations, connected to the float and arranged to resist movement of the float caused by the wave motion, an energy converter (5) for converting such reciprocal movement to useful energy; and biasing means such as a spring 6 for directionally biasing the reciprocal movement. Displacement of the float relative to the reaction member is permitted and reciprocal movement generated in response to such displacement.

Abstract: A system for extracting long wavelength ocean wave energy and for extracting rotational wave energy uses a plurality of boom elements connected to at least one hinge element for movement about the hinge element in a direction of the vertical force of a wave and for movement about the hinge element in a direction of the transverse force of a wave, and the hinge element includes a shaft transverse to the boom elements with a blade mounted to the shaft for rotational movement of the shaft in the direction of the rotational force of a wave.

Abstract: A reaction mass and a spring are configured to form an “oscillator”. The reaction mass is coupled to, and can wrap around, a first pulley via a first belt/cable. The spring is coupled to, and can wrap around, a second pulley via a second belt/cable. The first and second pulleys are mechanically linked together and are mounted so they rotate in tandem. The diameter of the second pulley is different than the diameter of the first pulley to cause the reaction mass to travel a different distance than the spring in response to the up down motion of the reaction mass. The first and second pulleys may be circular with the second pulley being made smaller than first. Alternatively, the first pulley may be circular and the second pulley a cam of varying radius.

Abstract: Disclosed is an apparatus and method for wave power generation of an underwater type, which can be float underwater and can efficiently generate wave power. The apparatus includes a housing formed to have an open bottom end and fixedly connected to the seafloor, a shaft extending from a bottom surface of a top end of the housing, a floater having a top end opened to surround the shaft, positioned at a lower portion of the housing and reciprocating in a perpendicular direction with respect to the housing, and a linear generation unit converting kinetic energy based on the reciprocating motion of the floater into electrical energy.

Abstract: Provided is a wave-power generator capable of adjusting a natural period (natural frequency) in response to a changing wave period. The wave-power generator includes a weight that is installed in a floating body via a spring and that linearly reciprocates in response to a fluctuation of a water surface and a generator that generates power by being driven based on the linear reciprocating motion of the weight. An additional-mass body for adding a mass to the mass of the weight is further included.

Abstract: A device for converting wave-motion power having a float, which, in use, is vertically movable in response to the wave-motion; the motion being transmitted to an input shaft which rotates with reciprocating rotary motion and is connected to an output shaft by way of a transmission unit. The transmission unit transfers torque from the input shaft to the output shaft along two torque paths and has two freewheels that are arranged respectively along the two paths, and are configured so as to make the rotation of the output shaft unidirectional, independently of the rotation direction of the input shaft.

Abstract: A wave power generator that can efficiently perform power generation in response to ocean-wave periods, which are waves of varying period, is provided. A vibration receiving portion that is provided in a float floating at a wave surface and that performs power generation by means of vibrations exerted thereon; a mass body that applies a mass loading on the vibration receiving portion from above; a plurality of elastic members that support the mass body in series; and a plurality of locking mechanisms that restrict/release the motion of the plurality of elastic members are provided.

Abstract: An apparatus for generating energy from the action of waves in a body of water is provided, the apparatus comprising a flexible planar member for extending across the surface of the body of water, the flexible member having a lower surface which, in use, is in contact with the surface of the water; an energy generating system coupled to a portion of the flexible member, the energy generating system operable to generating energy from the movement of the portion of the flexible member.

Abstract: An improved apparatus for extracting power from waves is provided. The apparatus (10) comprises at least one pair of buoyant body members (12A,12B) connected to one another by a coupling (14) which permits relative rotation between the body members (12A,12B) about first and second non-parallel axes of rotation (A,B). The apparatus further comprises a power extraction system comprising at least one power extraction element (16) having a first end connected to a first of the body members (12A) and a second end connected to a second of the body members (12B) such that the element resists and extracts power from the relative rotation between the body members (12A,12B).

Abstract: An apparatus is provided for harnessing ocean wave energy, wherein the apparatus relieves excessive loadings on components to avoid damage thereof in adverse wave conditions. The apparatus includes a buoyant actuator and a pump anchored within the body of water. Fluid at high pressure is pumped ashore by the pump, energy is extracted as useful work at an on-shore plant, and the resultant reduced pressure fluid is returned to the offshore pump to be re-energized. The buoyant actuator is operably connected to the pump by tether and is buoyantly suspended within the body of water above the pump. The buoyant actuator is provided with a connector that includes a damping mechanism configured to maintain a substantially rigid connection between the hollow body and the tether until such time as loading therebetween exceeds a prescribed load whereupon the damping mechanism facilitates limited relative movement therebetween to relieve the loading.

Abstract: An energy conversion device, a removable assembly for use with the energy conversion device and an associated methods. The energy conversion device comprises a flexible diaphragm configured to be located between a first fluid and a second fluid and being moveable in response to variations in at least one of the first and second fluids to permit energy transfer between said fluids; and a limit apparatus configured to limit movement of the diaphragm at a limit position, wherein the limit apparatus defines a contoured contact surface configured to be engaged by the diaphragm when in its limit position.

Abstract: An energy conversion system including an annular member disposed around a shaft and at least partially defining a first radial flow passage that is fluidly coupled to a wave chamber and a second radial flow passage that is fluidly coupled to a port; a first plurality of nozzle vanes extending at least partially through the first radial flow passage, and configured to impart a first exit swirl angle in a fluid; a turbine wheel coupled to the shaft, disposed radially between the shaft and the annular member, defining an axial flow passage that is fluidly coupled to the first and second radial flow passages, and including a first plurality of impulse blades; and a second plurality of nozzle vanes disposed around the shaft, extending at least partially through the second radial flow passage, and configured to impart a second exit swirl angle in the fluid.

Abstract: An offshore energy plant has a wave energy plant configured to convert energy of a circulating orbital flow of wave motion into mechanical energy of a rotor shaft or crankshaft, for example using the wave harrow principle. The energy plant additionally has at least one wind turbine.

Abstract: A wave energy converter includes a flexible pipe and an inlet. The flexible pipe floats on the water surface, following the wave form. Slugs of water and air enter, one after the other, through the inlet. Because the flexible pipe follows the shape of the wave, water is transported through a manifold to a pressure chamber connected to a generator. The inlet consists of a hollow, inflexible pipe attached to the throat of the flexible pipe. The inflexible pipe is fixedly attached to a buoyancy tank or plurality thereof. The buoyancy tanks are arranged in a vertical plane or in tandem, with the inflexible pipe passing along the plane vertical to the fore and aft axis of the buoyancy tank and the frontward portion projecting sufficiently ahead of the buoyancy tank with the flexible pipe terminating at a singular outlet. The entire apparatus is facing towards the oncoming waves.

Abstract: System for multiple harnessing and complemented conversion of energy from sea waves, which includes a structure of vertical guides (12) along which a floating body (1) moves, and a first submerged tank (2) of captive gas (3), held up by said floating body (1), characterized in that it includes a second submerged tank (5) with captive gas (3), attached to said floating body (1), with said first tank (2) and second tank (5) being connected to each other, in such a way that they exchange their respective volumes of gas (3) due to the effect of changes of pressure of water column (4) caused by the waves. Improves the energy harnessing performance of the system.

Abstract: The apparatus for converting the motions of waves or sea swells into mechanical motion and then into usable energy. A energy transfer medium (101) situated within the unobstructed internal cavity of a containing enclosure (102) in order to recreate the magnitude and direction of a wave or sea swell inside the containing enclosure. The recreated wave consequently generates an imbalance in the mass distribution of the containing enclosure. This allows a pivoting rotating element (103) joint situated at a central point between a base (104) and the containing enclosure to take advantage of the mass imbalance in order to produce movement. A series of energy collecting devices (128) situated on the base harvests this movement and transforms it into usable energy.

Abstract: A closed-loop hydraulic apparatus 200 for converting wave energy comprises a pump 201 for pumping a fluid through the apparatus 200. The pump 201 includes a body 202 defining a chamber 203, and a piston 207 that partitions the chamber 203 into a working side 208 and a blind side 209. A buoyant actuator is connected to the piston 207. An inlet 64 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the inlet 64 and into the working side 208 of the chamber 203. An outlet 63 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the working side 208 of the chamber 203 to the outlet 63. A hydraulic controller 102 is operable to control the pump 201 by controlling the pressure of the fluid at the inlet 64 and the outlet 63 so as to optimise the output of the pump 201 in response to tidal variations and/or sea state. The pressure of the fluid at the inlet 64 and the outlet 63 is controlled in accordance with a control algorithm.

Abstract: A wave energy converter (WEC) buoy includes at least one pitch-driven WEC (“PDWEC”) device. Each PDWEC device includes two reaction masses which are placed at diametrically opposite ends of a container designed to float along the surface of a body of water and to move in response to the pitching motion of the waves. The reaction masses are interconnected so that when one reaction mass moves up, the diametrically opposed reaction mass moves down, and vice-versa. The movement of the reaction masses drives power take off (PTO) devices to produce useful energy. The reaction masses may be interconnected by any suitable linking system. One or more PDWEC device may be combined with a heave responsive device to produce a WEC buoy which can produce a power output in response to pitch or heave motion.

Abstract: A wave energy converter (WEC) system includes WEC devices which can function to produce useful energy (power) efficiently in response to heave motion and/or pitch motion and/or roll motion. Pitch responsive devices are deployed around the outer periphery of a container and one (or more) heave responsive device is located about the center of the container. The pitch responsive devices may be of the type defined as PDWECs which include two reaction masses which are primarily operable in response to pitching motion or they may be of the type which includes one reaction mass operable in response to pitch and/or heave motion.

Abstract: The generally up and down movement of a reaction mass is converted into rotary motion which is used to drive a rotary hydraulic spring comprised of a rotary hydraulic pump motor and an accumulator to produce a “spring” function. The invention is particularly applicable to wave energy converters (WECs) having a reaction mass which needs to be coupled to a spring to ensure its oscillation and to cause it to be centered about its center of travel. The linear up-down motion of a reaction mass may be converted via a linear-to-rotary translator to rotary motion to drive a rotary hydraulic pump/motor so as to provide spring action to the reaction mass and ensure its oscillation and proper positioning.

Abstract: A wave power generator that can efficiently perform power generation in response to ocean-wave periods, which are waves of varying period, is provided. A vibration receiving portion that is provided in a float floating at a wave surface and that performs power generation by means of vibrations exerted thereon; a mass body that applies a mass loading on the vibration receiving portion from above; a plurality of elastic members that support the mass body in series; and a plurality of locking mechanisms that restrict/release the motion of the plurality of elastic members are provided.

Abstract: A system for extracting long wavelength ocean wave energy and for extracting rotational wave energy uses a plurality of boom elements connected to at least one hinge element for movement about the hinge element in a direction of the vertical force of a wave and for movement about the hinge element in a direction of the transverse force of a wave, and the hinge element includes a shaft transverse to the boom elements with a blade mounted to the shaft for rotational movement of the shaft in the direction of the rotational force of a wave.

Abstract: A method and apparatus for harnessing power associated with ocean waves and converting that power into electricity. The apparatus is a buoy that houses a vertically oriented central shaft, a pendulum, and a generator. As the buoy tilts from the vertical under the influence of wave motion, the pendulum is accelerated and rotates about the central shaft. A centrally-placed generator is mechanically coupled to, and driven by, the rotating pendulum so that the pendulum's kinetic energy is converted into electricity. The electricity may be stored at or near the buoy or transferred to a remote facility. Moreover, a fin array located along the bottom of the buoy serves as an anti-torque mechanism and improves the operational efficiency of the electricity production. The method involves employing use of the centrally located generator and the fin array to efficiently harness wave power.

Abstract: An energy conversion system comprising a support structure upstanding within a volume of water subject to the occurrence of both wave motion and tidal flow, a first apparatus mounted from the support for deriving usable power from the tidal flow, and a second apparatus operationally supported relative to the support structure for deriving usable power from the occurrence of wave motion independently from that derived from tidal flows and power transfer apparatus for facilitating the transfer of such usable powers to a land based location, or for making some alternative use of such power elsewhere.

Abstract: The generator comprises a float (1) which is movable in response to wave motion in a body of water, a submersible reaction member (2) of adjustable buoyancy, with at least two buoyancy configurations, connected to the float and arranged to resist movement of the float caused by the wave motion, an energy converter (5) for converting such reciprocal movement to useful energy; and biasing means such as a spring 6 for directionally biasing the reciprocal movement. Displacement of the float relative to the reaction member is permitted and reciprocal movement generated in response to such displacement.

Abstract: System for multiple harnessing and complemented conversion of energy from sea waves, which includes a structure of vertical guides (12) along which a floating body (1) moves, and a first submerged tank (2) of captive gas (3), held up by said floating body (1), characterised in that it includes a second submerged tank (5) with captive gas (3), attached to said floating body (1), with said first tank (2) and second tank (5) being connected to each other, in such a way that they exchange their respective volumes of gas (3) due to the effect of changes of pressure of water column (4) caused by the waves. Improves the energy harnessing performance of the system.

Abstract: Device for absorption of wave energy, comprising a floating body (2) adapted to move as a result of the influence of waves, and energy transmission means (9, 10, 13, 14, 15, 16, 7, 36, 42) for transmitting the movement of the floating body (2) to a generator, characterized in that the floating body (2) is movably arranged on a guiding rod (1) which is flexibly supported in a structure (4).

Abstract: A device that converts wave energy to electrical or chemical energy includes a buoy adapted to float on a water surface, a venturi tube, and a rigid or flexible means of connecting the buoy and the venturi tube. The venturi tube defines a lumen through which water flows downwardly when the buoy moves upwardly and upwardly when the buoy moves downwardly. A constriction is formed in the lumen to create a venturi effect for water flowing upwardly and downwardly through the lumen. A turbine is positioned in the lumen at the constriction where water flow is at a maximum rate. The turbine is connected to a generator so that the venturi effect is harnessed to generate power. Multiple embodiments are included.

Abstract: Apparatus for extracting energy from waves comprises a float device coupled to a shaft such that vertical movement of the float devices drives the shaft. Movement of the float device is generated by the wave motion, and the mass of the float device is such that its natural frequency of vertical oscillation is substantially resonant with the frequency of a sea wave. The mass of the float device can be adjustable to achieve this.

Abstract: A system and method for actuating a load by means of the conversion of hydraulic energy to reciprocating movement of a piston assembly within a chamber. The piston assembly includes a float, and the fluid within the chamber is alternately withdrawn into fluid conveying pipes or channels and returned to the chamber under the influence of gravity.

Abstract: A gyro wave-activated power generator utilizing wave energy which has, as a component, a control moment gyro, and which comprises a floating body (1), a control moment gyro (5) supported by the floating body, and a power generator (10) connected to the gimbal shaft of the gyro through a gearing to increase speed(9), and is characterized by the gimbal (6) of the gyro being rotated by the movement of the floating body by wave energy to drive the power generator (10) for power generation.

Abstract: Apparatus for converting the motion of sea wave energy to electrical energy includes one or more float driven linear generators, in which the inertial mass of the float and any linkage means to the linear generator is minimised. In order to generate electrical power consistently upon both the upstroke and downstroke of the float, the moving part of the generator is so sized that its gravitational weight acting upon the float, together with that of the float itself and any intermediate linkage means, is substantially equal to half the total buoyancy of the float.

Abstract: Apparatus for converting energy contained in surface waves on a body of water to useful energy comprises a float from which is suspended a fully or effectively fully submerged inverted cup-shaped member having a closed top end and an open bottom end. Disposed within the top space is a compressible fluid separated by a flexible membrane from a column of water filling the bottom open end of the submerged member. Passing surface waves cause pressure variations at the bottom end of the member causing changes in the water column height and corresponding changes in the buoyancy of the member. The buoyancy changes induce vertical oscillations of the member relative to the float and known means are used for converting the relative movements of the float and submerged member to useful energy. Preferably, the float vertically oscillates in synchronization with the passing waves, and the vertical movements of the float increase the relative movements between the float and the submerged member.

Abstract: A floating modular system for the protection of harbours and the transformation of energy, consisting of: a plurality of modules (1) made of metal and/or reinforced marine concrete box-structure, comprising internal air spaces (2) for determining the floating thereof and a lower flooded room (4) for the stabilization, under the impact of the sea waves against the level surfaces (6) for their reflection, for the protection of the opposed harbour environment (AP), provided with floating quays (7); a series of floats (8) applied to the wave front of the modules (1), operated by the wave motion for absorbing their energy by double effect pumps (9) with the successive transformation into electric energy; a self-levelling system for the anchorage of each of the modules (1), with self-distributed traction; a system for balancing the tide variations and for levelling the modules (1); a system of joints for coupling the modules (1) according to the extension.

Abstract: A wave energy converter comprises an acceleration tube (14) attached to a buoyant body (11). An intermediate section of the acceleration tube defines a working cylinder (16), with openings in the acceleration tube above and below the working cylinder allowing unobstructed flow of water between the working cylinder and the body of water in which the acceleration tube is immersed. A working piston reciprocates in the working cylinder. A relief passage at each end of the working cylinder is controlled by the working piston to allow unrestricted flow pass the working piston when the piston moves past a predetermined position at the end of the working cylinder. An energy absorbing device (19, 20) is connected to the working piston. A restoring device (19C, 20C) is provided to apply a return force to the working piston towards the working cylinder, if and when the working piston moves past the predetermined position.

Abstract: A wave energy converter includes a buoyant body (11) and an acceleration tube (14) dependent from and attached to the buoyant body (11) and having an upper end near the buoyant body and a lower end remote from the buoyant body. A section of the acceleration tube intermediate the upper and lower ends of the acceleration tube defines a working cylinder (16) and openings in the acceleration tube (14) above and below the working cylinder (16) allow substantially unobstructed water flow between the working cylinder and a body of water in which the acceleration tube is immersed. A working piston (17) is reciprocable in the working cylinder. An energy-absorbing device (18, 19, S) includes paired resiliently extendable hose pumps (18, 19) operated by the working piston (17). One end of each hose pump within a pair is attached to the operating piston (17) on opposite sides thereof, and the other end is anchored to the unit which consists of the buoyant body (11) and the acceleration tube (14).