Abstract: A method and a system for determining a safe under keel clearance of an ultra-large ship are provided. The method comprises: acquiring operation parameter values of the ship; obtaining fluid pressure according to the values; obtaining a squat force and a trim moment of the ship according to the pressure; establishing a mirror image model based on speed potential to establish a squat clearance calculation model for the ship; determining a half-wave rising height with above calculation model; obtaining draught and trim changes according to the squat force and the trim moment, to determine a maximum squat clearance of the hull; determining the safe under keel clearance; and controlling the squat clearance of the ship according to the safe under keel clearance of the ship, to avoid navigation dangers, and improve the loading rate.

Abstract: The invention discloses a kind of single shaft driven level 3 of axial flow pump, including: power source, pumping out, transmission shaft, export fixed vane, the third stage impeller, the second impeller, the first stage impeller, imported fixed vane, pump inlet, the first transmission cone gear, the first cone gear transmission device, the second driving cone gear and the second cone gear transmission device, the invention can realize the opposite steering of the two adjacent impellers by fixing the guide vane and the bevel gear transmission in the impeller hub. With compact structure and small axial size, this single-shaft driven three-stage counter-rotating axial-flow pump can greatly improve the head of the axial pump and widen the efficient zone.

Abstract: This application includes an electric powered surfboard equipped with drive units that emerge out onto the surfboard's bottom surface to power it forward. Once a wave is caught the drive units can retract back up into the surfboard's body as the power is shut off by the surfer. Then instantly, flush fitting glide doors close, allowing the surfboard's bottom to return to a planing surface with no protrusions, except for fins to detract from the surfboard's critical gliding ability when surfing waves. Also, there's a crowned deck shape that allows thin rail sensitivity for turning performance and a motor battery arrangement that provides mass centralization of weight. All this, combined with several wireless control means define this new fine handling motorized surfboard.

Abstract: This new art offers an improvement to conventional surfboards as well as any previous motorized jet surfboards. This application includes an electric powered surfboard equipped with high volume jet drive units that power it forward and significantly improve a surfer's wave fielding and catching ability. Once a wave is caught the drive unit can be shut off by the surfer. Then instantly, two flush fitting glide doors close the jet tube intake openings allowing the surfboard's bottom to return to a planning surface with no protrusions, except for fins, and no water filled jet tubes left open to detract from the surfboard's critical gliding ability when surfing waves. Also, there's a crowned deck shape that allows thin rail sensitivity for turning performance and a motor battery arrangement that provides mass centralization of weight. All this, combined with several wireless control means define this new fine handling motorized surfboard.

Abstract: A high mass/low pressure liquid propulsion device which includes:—two counter-rotating impellers mounted inside a housing;—an inlet which in use allows inflow of liquid into the housing on a first side of said impellers; an outlet which in use allows outflow of liquid from the housing on a second side of said impellers opposite to said first side;—means for driving said impellers;—wherein the improvement comprises the provision of means for reversing the drive to said impellers, such that the direction of flow of liquid through the device is reversed and liquid enters the device through said outlet, passes through said impellers, and leaves the device through said inlet.

Abstract: A propulsion system may include a cylindrical support member and a tubular rotatable member rotatably mounted within the support member that may be adapted to permit fluid flow therethrough. The tubular rotatable member may extend past a down stream end of the support member. An exemplary embodiment of a propulsion system may also disclose a vane attached on an interior surface of the tubular member and may include a blade which extends in a direction toward a rotational axis of the rotatable member such that rotation of the tubular member and the vane attached thereon draws fluid into the tubular member to accelerate the fluid flow through the tubular member. Additionally, a nozzle may be attached to the down stream end of the support member and include a primary nozzle and a secondary nozzle within the primary nozzle. The secondary nozzle may be engaged with the primary nozzle by a stator.

Abstract: A submersible, water circulation system for enclosed tanks such as used by municipalities, fire districts, and industries. The system includes a driving unit having a shell extending along an axis with a pump supported within the shell. The shell has at least one inlet and at least one outlet and is positionable on the floor of the tank with the outlet facing upwardly. In operation, the pump continuously draws an incoming flow of water from outside of the driving unit adjacent the tank floor through the inlet of the driving unit and preferably drives all of the continuously incoming flow out through the upwardly facing outlet. The upwardly facing outlet is preferably a thin, elongated slot that creates a thin, substantially planar discharge of water therethrough that presents a very large surface area for its volume and induces water adjacent the shell to move upwardly with it.

Abstract: A marine jet pump with an adjustable venturi. An annularly compressible ring is affixed coaxially to the aft end of the pump housing. A collar coaxial to the ring is moveable coaxial to the ring. In a constricted mode the collar is mechanically forced over the aft end of the ring thereby reducing the diameter of the ring. In a dilated mode the collar is mechanically withdrawn to a predetermined degree from over the aft end of the ring allowing the ring to revert to it naturally dilated state. The transition between dilated mode and constricted mode can occur under full power.

Abstract: There is provided a water jet propulsion device 10 for a water vehicle, comprising a main duct 12 having a main inlet 14 that is arranged to be submerged in use and a main outlet 16; a pump disposed between the main inlet 14 and the main outlet 16; and a plurality of injection nozzles 40, 50, 60, 70 each arranged to selectively eject a jet of fluid into a different region A, B, C, D susceptible to cavitation, so as to re-energise the fluid flow in that region.

Abstract: A marine propulsion system comprising, in one embodiment: a fuel-filled tank; an air compressor that generates compressed air; an engine that receives fuel from the tank, wherein the air compressor is powered by the engine; and at least one hot gas generator that receives compressed air from the air compressor, the hot gas generator comprising: (a) a combustion chamber having an inlet and an outlet, the compressed air injected into the combustion chamber at the inlet, the combustion chamber adapted to produce hot gas; (b) an injection nozzle that receives fuel from the tank, the injection nozzle positioned proximate to the inlet of the combustion chamber, the injection nozzle adapted to spray the fuel into the combustion chamber; and (c) an exhaust Coanda nozzle positioned at the outlet of the combustion chamber through which the hot gas produced in the combustion chamber is discharged from the hot gas generator.

Abstract: A quiescently flush resilient portion of a water jet exit channel that distends under controlled fluidic pressure to narrow the flow channel to trade off power for speed in a water-jet-powered watercraft and/or to suppress impeller cavitations during standing starts. The resilient portion may be a continuous annular portion or may be segmented for thrust vectoring. The resilient portion may be built into a water jet exit channel or may be in an add-on nozzle that can be attached to the water jet exit channel, especially for aftermarket improvements. The control system, the water jet exit structure, the water jet, and the watercraft and included. A resilient ring with top and bottom radially outwardly extending flanges mounted on a rigid ring and compressed within a canister between an annular canister floor and a compressive annular cap may provide the plenum and resilient portion of the water jet exit channel.

Abstract: A marine jet drive, for a boat having a transom and a drive shaft extending through the transom, the boat afloat in a water body, includes a support casing disposed aft of the transom and a pump shaft within the support casing, the pump shaft having an end connectable to the drive shaft. The jet drive includes a jet pump having a chamber and a blade coupled to a portion of the pump shaft extending into the chamber. The chamber is attached to and supported by the support casing aft of the support casing. The chamber has an inlet for receiving water into the chamber and an outlet. The blade is coupled to the portion of the pump shaft for co acting with the chamber to draw water into the chamber inlet and discharge water in a reactive jet out the chamber outlet to reactively propel the boat.

Abstract: The present invention relates to a hydraulic propeller enhancement method for enhancing the propelling force of a hydraulic propeller. The present invention uses a gas release outlet in the propeller at the area where the high-speed axial flow of water passes for guiding in a gas by means of a negative pressure subject to Bernoulli's principle. Thus, subject to Bernoulli's principle, gas compressible characteristic and Boyle's law and the arrangement of the contracted end piece of the nozzle to work as an air compressor for compressing air bubbles, the invention uses one single gas guide device and a negative pressure suction force to guide in air bubbles to enhance the propelling force of the hydraulic propeller.

Abstract: There is provided a water jet propulsion device 10 for a water vehicle, comprising a main duct 12 having a main inlet 14 that is arranged to be submerged in use and a main outlet 16; a pump disposed between the main inlet 14 and the main outlet 16; and a plurality of injection nozzles 40, 50, 60, 70 each arranged to selectively eject a jet of fluid into a different region A, B, C, D susceptible to cavitation, so as to re-energise the fluid flow in that region.

Abstract: A jet propulsion device and method for controlling movement of the jet propulsion device, where liquid inlets are positioned at a distance from the surface of the device. Preferably, the inlets are positioned in the stabilizing fins of the device. When the device reaches a certain speed, a Riabouchinsky cavity forms around the device, and the radius of the Riabouchinsky cavity is substantially equal to the distance between the inlets and the longitudinal axis of the device.

Abstract: A quiescently flush resilient portion of a water jet exit channel that distends under controlled fluidic pressure to narrow the flow channel to trade off power for speed in a water-jet-powered watercraft and/or to suppress impeller cavitations during standing starts. The resilient portion may be a continuous annular portion or may be segmented for thrust vectoring. The resilient portion may be built into a water jet exit channel or may be in an add-on nozzle that can be attached to the water jet exit channel, especially for aftermarket improvements. The control system, the water jet exit structure, the water jet, and the watercraft and included. A resilient ring with top and bottom radially outwardly extending flanges mounted on a rigid ring and compressed within a canister between an annular canister floor and a compressive annular cap may provide the plenum and resilient portion of the water jet exit channel.

Abstract: The present disclosure relates to a jet pump tail cone insert for a jet pump. The jet pump tail cone insert comprises a cap, a body and an end member. The end member has a plurality of projections configured to matingly receive a plurality of forks of the body. When connected together, the body and the end member have a plurality of receivers configured to receive stator vanes of a bearing hub of the jet pump. The body and the end member are configured to be proximate the stator vanes. The cap is configured to matingly couple to the body. The jet pump tail cone insert encompasses a portion of the bearing hub of the jet pump. The jet pump tail cone insert occupies within the bearing hub thereby increasing a flow rate of water through the jet pump.

Abstract: The present invention's methodology for designing a fluid propulsion intake configuration of a marine vessel considers the integral geometry of the inlet together with a portion of the hull, with respect to which the inlet's entrance opening is flush. The inventive methodology typically includes definition of an inlet reference line (an “axial” description, straight and/or curved, of the inlet), cross-planes (each of which perpendicularly intersects the inlet reference line), a footprint (a planar outline of the inlet's entrance opening), an inlet shaping line (a projection of the footprint onto the hull portion), inlet flow lines (angularly spaced about the circumference of the inlet shaping line, each connecting the cross-planes), two fairing reference curves (one at the inlet's entrance opening and the other on the hull portion, thereby demarcating a fairing therebetween that is consistent with the inlet flow lines), and a lip nose (at the inlet's entrance opening).

Abstract: A pump or turbine is disclosed which includes a housing provided with at least one chamber, a rotor, which is rotatably mounted on a shaft in the chamber, an inlet, which communicates with the chamber at least at the location of the shaft, and an outlet channel, which communicates with the chamber at least at the periphery of the rotor. The pump or turbine moreover comprises at least one bypass channel, a first end of which opens into the outlet channel of the pump and a second end of which forms an inlet. The bypass channel may be used for increasing the propelling force or for pumping slurries, for example.

Abstract: Presented is a fluid propulsor for propelling a vehicle that incorporates a Coanda Effect Inducer (CEI), more commonly called an inlet fluid inducer in this application, in its inlet to induce fluids passing by the vehicle to turn uniformly toward a powered fluid energizing device such as a rotor of the propulsor. This concept enhances the efficiency of the rotor and the overall efficiency of the propulsor. The rotor is preferably at least primarily enclosed in a housing and the rotor may operate either fully submerged in liquid or in a partially liquid and partially gaseous environment. The CEI and the powered fluid energizing device are, in the preferred embodiment, installed in an inlet housing of the propulsor. Fluid flow directing devices may be incorporated to separate liquid from gas flowing to the rotor in some instances.

Abstract: To provide a water jet propeller that enables an efficient flow of water from a water flow duct to an impeller housing even if an inner periphery of the impeller housing has an inside diameter smaller than the inside diameter of a rear end portion of the water flow duct. A water jet propeller has a stator disposed at a rear end portion of an impeller housing. An impeller is disposed inside the impeller housing. The water jet propeller expels a water jet by rotating the impeller. The water jet propeller further has the impeller disposed so as to circumvent a front end portion of an inner periphery of the impeller housing. The impeller housing includes a liner disposed over a region facing the impeller and representing the inner periphery of the impeller housing, except for the front end portion. The front end portion is formed to have an inside diameter that gradually increases forwardly.

Abstract: A water jet propulsion apparatus having an engine producing an exhaust gas, a pump driven by the engine, a nozzle in fluid communication with the pump, and an exhaust passageway communicating between the engine and the nozzle is disclosed. The exhaust passageway is connected the nozzle at a point in the nozzle where the water flow velocity is being increased, and prior to the water being expanded. By mixing the exhaust with the water while the water flow velocity is being increased, the result is a decrease the density of the mixture and an increase the total mass flow rate, thus resulting in increased thrust.

Abstract: A water intake grill for attachment to a water intake port of a jet watercraft. The water intake grill comprising a plurality of elongate members situated in between and mounted to fore and aft mounts. The fore mount comprising a base having an angularly orientated bottom surface for receiving and attaching first ends of the elongate members and an angularly orientated top surface for mounting atop thereof a singular key element having an overall geometric configuration substantially coinciding with the geometric configuration of a first inward socket integral to a forward wall section of the water intake port. The aft mount comprising a horizontally positioned base having rearward and forward sections, the rearward section having a primary key element in association with a cylindrical riser and the forward section having a secondary key element that extends across the width of the aft mount and includes an angular edge for receiving and attaching second ends of the elongate members.

Abstract: A foil shaped lifting body is attached by means of a strut to the underwater body of a vessel in such a manner as to cause a standing wave to be developed when the vessel is in operation in order that the standing wave will induct water into machinery intakes. The technology of this invention is particularly applicable to the operation of waterjet marine propulsion systems.

Abstract: Presented is a way to reduce the wave drag of high speed ships by ingesting wave energy into water propulsors disposed at the bow and/or on the sides of the main hull of the ship. A forward secondary bow disposed at a lower portion of the main bow of the ship is an optimum location to have bow water propulsor water inlets. Performance of the water propulsors can be enhanced by using Coanda effect water energizers at the inlets to the water propulsors. Water propulsor discharge is preferably into an air layer on the underside of the ship's main hull.

Abstract: The present disclosure relates to a jet pump tail cone insert for a jet pump. The jet pump tail cone insert comprises a cap, a body and an end member. The end member has a plurality of projections configured to matingly receive a plurality of forks of the body. When connected together, the body and the end member have a plurality of receivers configured to receive stator vanes of a bearing hub of the jet pump. The body and the end member are configured to be proximate the stator vanes. The cap is configured to matingly couple to the body. The jet pump tail cone insert encompasses a portion of the bearing hub of the jet pump. The jet pump tail cone insert occupies within the bearing hub thereby increasing a flow rate of water through the jet pump.

Abstract: A fouling removal system for use in a water-jet drive system is described. The fouling removal system includes a cutter arm assembly and an optional cutter stud. The cutter arm assembly includes a pivotable cutting blade located adjacent to the intake grate and arranged to sever any debris, such as seaweed and eel grass, clogging the intake grate. The cutter arm assembly may be tied into existing watercraft hydraulic systems to use a hydraulic cylinder to cause movement of the cutting blade across the surface of the intake grate. The optional cutter stud is located adjacent to the impeller within the water-jet drive system housing. The cutter stud acts to sever debris associated with the impeller blades, which, if left on the blades, would reduce the efficiency of the impeller. The present fouling system is capable of removing debris from the intake grate and impeller of a water-jet drive while a watercraft is stationary or is operating at any speed, including full speed.

Abstract: A seal pressure vent system for a waterjet propulsion apparatus including a water intake section and a pumping unit. The pumping unit is designed such that in operation the seal pressure vent system provides a fluidic path for the flow of high pressure water away from a lip seal assembly toward a near ambient pressure region. The seal vent system includes a plurality of fluid passageways formed in a stator structure in conjunction with a water barrier ring, a tail cone including an extended flange, or a modified stator web structure.

Abstract: The present disclosure relates to a jet pump tail cone insert for a jet pump. The jet pump tail cone insert comprises a cap, a body and an end member. The end member has a plurality of projections configured to matingly receive a plurality of forks of the body. When connected together, the body and the end member have a plurality of receivers configured to receive stator vanes of a bearing hub of the jet pump. The body and the end member are configured to be proximate the stator vanes. The cap is configured to matingly couple to the body. The jet pump tail cone insert encompasses a portion of the bearing hub of the jet pump. The jet pump tail cone insert occupies space proximate the bearing hub within the pump, thereby increasing a flow rate of water through the jet pump.

Abstract: A foil shaped lifting body is attached by means of a strut to the underwater body of a vessel in such a manner as to cause a standing wave to be developed when the vessel is in operation in order that the standing wave will induct water into machinery intakes. The technology of this invention is particularly applicable to the operation of waterjet marine propulsion systems.

Abstract: A variable marine jet propulsion system incorporates a motor, a variable-pitch propeller pump in a spherical housing, a variable housing and a variable inlet duct, and a microcontroller. The pump, the nozzle and the inlet are controlled by the microcontroller, which is programmed to control the pump as a continuously variable power transmission for maintaining efficient motor operation, the nozzle for maintaining efficient pump operation, and the inlet for maintaining efficient recovery of the total dynamic head of the incoming water. The spherical pump housing maintains close fits to the propeller vane tips for more efficient operation at all pitches, including zero and reverse pitches. Zero pitch results in no effective pumping action, effectively a true neutral in fluid power transmission. Reverse pitch in combination with the large variable nozzle provides reverse flow and consequently reverse thrust, which eliminates the need for the “backing bucket”.

Abstract: A highly efficient watercraft propulsion system that operates continually submerged and relies on a non-circular variable area pump discharge opening which is configured, positioned and oriented so as to maximize the hydraulic reaction between the high velocity water jet stream and the surrounding body of water and is driven by a positive displacement pump.

Abstract: A multistage axial-flow pumping or marine propulsion device having fixed or variable pitch stators between rotors. Stator vanes are designed to lower internal fluid speed without sacrificing total pressure as working fluid travels toward the discharge nozzle. A variable pitch stator controls the amount of energy, i.e., torque, imparted to the working fluid at successive rotor sections. A variable inlet guide vane provides throttling of mass flow rate independently of rotor speed. An exit guide vane provides flow straightening and pressure maintenance at the discharge nozzle. A variable area throat at the discharge nozzle controls the exit velocity of the water jet according to boat speed and/or desired propulsive efficiency. Advantageously, the device enables a shipmaster to set performance characteristics of a vessel at any desired speed, loading, horsepower setting, or operating characteristic of the power plant.

Abstract: The invention relates to a propulsion system for a fast seagoing ship, especially a naval ship, which comprises a propulsion system driven by at least one water jet produced by a pump assembly with an outlet nozzle for water, and a propeller jet produced by at least one propeller. The water jet carries along gases that are introduced downstream of the pump assembly, especially exhaust gases of at least one drive device which especially comprises a power generation device and a generator. The water jet is generated in at least one water jet drive by means of a pump that is, e.g., driven by an electric motor and whose drive power is generated by e.g. a generator assembly.

Abstract: A tail cone assembly for a watercraft jet pump includes a tail cone body with a shuttle recess, a self-actuated shuttle biased into the shuttle recess, and a pump back pressure inlet orifice through the tail cone body and into the shuttle recess. The shuttle may have a rear portion with an outer conical surface of at least two different conical slopes that are positioned to determine two discrete stages of jet pump discharge area. The shuttle recess may include a side wall with a grit exhaust groove therein. The grit groove and inlet orifice may both be positioned at gravitational low points within the assembly. The assembly may further include a grit screening device associated with the inlet orifice that restricts grit having a size greater than or equal to a shuttle clearance from entering the inlet orifice.

Abstract: A waterjet propulsion apparatus having a five blade rotor and an eight blade stator that are located within housing sections that define a water flowpath. The housing and hub are designed such that in operation a nonuniform loading arises on the rotor blades whereby greater pressure impinges on the tip area of the rotor blade than at the hub area of the rotor blade. This configuration increases the efficiency of the waterjet while minimizing negative effects of cavitation.

Abstract: A propulsion system designed to propel submarine and surface vessels by discharging fluid rearwardly with a reaction of increased force that is approximately twenty percent greater than that possible with conventional propeller systems. Its conical/tapered housing is mounted to the inside bottom surface and transom of a marine vessel hull whereby a keyhole-shaped inlet opening directs a large volume of seawater into the housing's wider end. Seawater then flows across several increasingly smaller propellers positioned within the housing. A reverse and steering assembly with a movable gate can be optionally aligned with the discharge end of the housing to control the direction of marine vessel movement. Size is not a limiting factor for the present invention and its operation is virtually silent. Also, its inlet opening is always below the water level so priming is never needed and no transmission is required. Recreational, commercial, and military applications are contemplated.

Abstract: The present invention provides a jet pump assembly that includes a rotatable shaft adapted to be operationally coupled to a power source. An impeller is operationally connected to the rotatable shaft. A housing surrounds at least a portion of the rotatable shaft operationally coupled to the impeller. In addition, a single bearing is disposed between the housing and the rotatable shaft, permitting rotation of the rotatable shaft therein. The bearing has at least an inner race operationally coupled to the rotatable shaft and an outer race operationally coupled to the housing. The bearing also includes at least two sets of rolling components disposed, side-by-side between the inner and outer races, permitting rotation of the inner and outer races with respect to one another.

Abstract: A watercraft, equipped with a jet propulsion system with improved efficiency of operation is disclosed. Structures are disposed within a water passage of the jet propulsion system at a position upstream of the jet propulsion unit that modulate the amount of water that is allowed to pass through the water passage. The structures can be a flexible fluid filled bag, an adjustable ride plate, and an additional water passage. Each of the structures allow a greater amount of water into the water passage during acceleration than during constant speed travel of the watercraft.

Abstract: An impeller for a jet propulsion device includes at least one fluid channel formed on each impeller blade. During impeller rotation, a fluid back-flow is generated through the fluid channels. The back-flow advantageously sweeps cavitation bubbles away from the impeller blades and inhibit their implosion on the blade surfaces and/or inner housing surface which lies adjacent the blade tips. This desirably reduces erosion and provides a long-life and efficient propulsion device.

Abstract: Variable venturi for use in jet propulsion systems of watercraft include discharge openings with selectively variable discharge areas that enable a venturi controller to selectively maximize top speed, acceleration, and/or fuel efficiency. The variable venturi may include a plurality of circumferentially-spaced, squeezable, flexible sections that selectively move radially inwardly to alter the discharge area. Alternatively, the variable venturi may include a flexible venturi with a variably-shaped flexible discharge opening. Alternatively, the variable venturi may include a main rear discharge opening and a plurality of additional discharge openings with selectively openable valves, whereby selective opening of the valves effectively increases the discharge area. Alternatively, the variable venturi may have a movable end flap that selectively varies the discharge area.

Abstract: To provide a jet propulsion watercraft that allows a step, a vent hole, and the like to be easily provided on a bottom surface thereof. A ride plate of a jet propulsion watercraft is a member, which is formed into a substantially rectangular shape in compliance to an opening in a bottom surface of a hull bottom. The ride plate is provided with a lock tab at a front edge thereof, and bolt holes are made in a right and left end portion thereof. The ride plate is further provided with a step portion that forms part of a general bottom surface, since it is flush with the general bottom surface, a higher level surface that forms a flat surface higher than the step portion by a predetermined distance, and a pair of vent holes that pass vertically through the higher level surface at a position therein closer to the step portion.

Abstract: A water jet propulsion apparatus having a duct forming a channel, an impeller disposed in the duct, a bearing of the impeller provided in the duct, and a cap closing the rear end of the bearing. In addition, at least one stream-straightening groove is formed in an external face of the cap. In the internal face of the duct, a stationary vane is formed in a portion facing toward the cap. Accordingly, a rotational component of a water stream close to the external face of a cap the bearing is substantially reduced, the size of the cap may be reduced, and cap position is not controlled by the position of the stationary vane.

Abstract: The instant invention presents enhancements to waterjet propulsors used for propelling marine vehicles including a way to bleed off aerated boundary layer water from the inlet of the waterjet propulsor, air fences to further help in preventing aerated boundary layer water from entering the inlet of the waterjet propulsor, and a way to preclude water from entering the waterjet's water inlet when the waterjet is not operating and the marine vehicle is moving forward at high speed.

Abstract: To provide a jet propulsion boat that enables preventing the occurrence of cavitation. In a jet propulsion boat that jets water pressurized and accelerated by a water jet pump from a rear jet nozzle and is propelled by its reaction, a turbocharger is provided to an engine for driving the water jet pump and in case the rate of the rise of engine speed is a predetermined value or more, delay control is applied to the rise of the boost pressure of the turbocharger.

Abstract: To provide a jet propulsion boat which can be efficiently propelled by disposing a steering nozzle closer to the bottom of the boat. A jet propulsion boat includes a jet propulsion apparatus driven by an engine at the stern. A jet nozzle for jetting water is provided at the rear portion of the jet propulsion apparatus. A steering nozzle is swingably supported by the jet nozzle so as to adjust the direction of a stream of water jetted from the jet nozzle. In the jet propulsion boat, an outlet side of the jet nozzle is covered with an inlet side of the steering nozzle and the vertical diameter D2 of the inlet of the steering nozzle is set to be smaller than the transverse diameter D1 of the inlet.

Abstract: An underwater propulsion system and method are more efficient and reduce vortex wake effects. A submersible has a cylindrically-shaped hull, a nose portion connected forward and a sinusoidal-shaped tapered portion aft coaxially symmetrically disposed around a longitudinally extending axis. The tapered portion has a leading end the same diameter as the hull, a symmetrical apex at its trailing end on the longitudinal axis, and symmetrical rounded laterally extending contours and rounded longitudinally extending contours. An internal pump creates volumes of pressurized water from ambient water for equal-distantly-spaced-apart jets extend through the tapered portion in a circumferential row extending around the tapered portion. The jets point in an asymptotical relationship with respect to a down slope surface of the tapered portion and emit jetted water that creates a spinning toroidal vortex of swirling jetted water along the down slope of the tapered portion.

Abstract: To enable a thrust force acting on an impeller shaft to be received by a sufficiently large bearing member. A water jet propulsion apparatus is provided with a stator forming a channel. An impeller is rotatably disposed in the stator. An impeller shaft is rotatably supported by bearing members and provided in front and rear portions of a bearing disposed in the stator and coupled to the rear part of the impeller. The bearing member on the rear side which receives a thrust force of the impeller shaft is larger than the bearing member on the front side. Both of the bearing members and on the front and rear sides are assembled on the bearing from the rear.

Abstract: A method and apparatus for propelling a surface vehicle through the water comprised of a submerged portion, including both a stern propulsion unit and a bow propulsion unit. Either unit may be a pumpjet, the bow unit may include a counter-rotating nose hub having attached spirally wound, twin centrifugal propeller blades. The foremost bow propeller is dedicated to stealth and the next-in-line bow propeller is dedicated to supercavitation. Specially-designed vortex loops that connect the pressure side to the intake side of a propulsion unit may be included in the blades, shroud or hub areas. Further, slightly diverged jet exhaust and variable special surface texturing reduce surface friction drag on the vehicle body. The submarine propulsion system is used to power a surface vessel, supported by two or more hydrofoils which combine a submerged midcraft foil with a wave-piercing variety. The surface craft has the capability of submerging and maneuvering.

Abstract: An air suction device for a surface boat having a filter element of paper type arranged in an air suction passage of an engine. The filter element is composed of a core made of a filter material and a permeable waterproof sheet arranged at the upstream side surface of the core in the air suction passage.