Abstract: An underwater two-phase ramjet engine propulsion unit, includes an inlet for receiving a flow of water, compressed gas injector for injecting compressed gas into the flow of water, a mixing chamber for mixing the compressed gas with the flow of water to provide a two-phase flow of working fluid and a nozzle for accelerating the two-phase flow of working fluid so as to generate a two-phase jet. The propulsion unit can be implemented with a fixed geometry or with a variable geometry. The propulsion unit includes a supersonic gas injector as well as a subsonic gas injector. The propulsion unit includes a control system the controlling the compressor, supersonic gas injector, the subsonic gas injector, the geometry of the propulsion unit, and the direction of the thrust vector.

Abstract: A sliding-blade water jet propulsion apparatus has an oval-shaped chamber and a water channel extending generally tangential to the chamber with a cylindrical rotor rotatably mounted eccentrically in the chamber. The rotor has at least two rectangular blades slidably mounted in slots extending through the cylindrical rotor in mutually perpendicular relation and each blade is independently movable relative to the other in a radial direction. Each blade has a guide element extending from opposed sides and through the opposed end walls of the rotor which are slidably received in guide grooves in the chamber end walls. The guide elements traveling in the guide grooves cause the blades to extend and retract radially with their outer ends following the inner periphery of the chamber side wall and a portion of the water channel with a constant clearance.

Abstract: A thrust propulsion mechanism (10) for a boat (12) includes an outlet conduit (22) extending athwartships from a first outlet port (16) to a second outlet port (16') in the hull (18). A paddle-wheel impeller (24) is mounted within the hull for rotation about an axis of rotation (34) by a reversible motor (30). A circumferential paddle (58) portion of the paddle-wheel impeller extends into an aperture (26) defined centrally in the top wall of the outlet conduit. An inlet conduit (20) extends athwartships from a first inlet port (14) to a second inlet port (14'), and intermediate thereof supplies water to the center of the paddle-wheel impeller. Water is discharged from the paddle-wheel impeller through one of the outlet ports, dependent on the direction of rotation of the paddle-wheel impeller, to create thrust by a combined paddle-wheel and centrifugal pump action.

Abstract: The invention is directed to an improved water jet propulsion system for a marine vehicle. The water jet propulsion system of the present invention incorporates an unconventional and compact design including a short, steep, hydrodynamically designed inlet duct adapted for mounting to the surface of the vehicle hull and extending internally thereof, a water jet pump having an inlet end attached to the outlet end of the inlet duct, a motor for rotating the pump impeller, a drive shaft located completely outside of the flow path connecting the motor with the pump impeller, a flow passage for discharging accelerated flow received from the pump in a generally rearward direction, and a steering and reversing mechanism pivotably mounted about a substantially vertical axis to the aft portion of the vehicle hull for redirect accelerated flow received from the outlet nozzle so as to provide maneuvering capability to the vehicle.

Abstract: A hydrodynamic propulsion device possessing an expansion chamber located downstream of a cross-sectional widening for the inflow of a medium which is to be expelled through a discharge nozzle. The propulsion device is constructed as a static propulsion mechanism without movable components, in that the gaseous operating medium is produced in the propulsion device through the reaction of a hydrofuel, such as NaK with water.

Abstract: An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

Abstract: An exhaust-through-the-hub system described herein includes an apparatus for discharge of exhaust gases from a marine outboard motor to the outer perimeter of an attached pump jet. Exhaust gas is ducted downwardly through the central body of the motor and rearwardly into a plenum cavity positioned in the pump jet. At least one hollow stator vane receives the exhaust gas and discharges the exhaust gas through the stator housing at a substantial depth below the water line, thereby resulting in a quieter running engine. The exhaust-through-the-hub system provides forward thrust when the motor is in forward gear and reverse thrust when the motor is in reverse gear.

Abstract: A water jet propulsion assembly for a jet ski-type watercraft includes an annular duct including a first section within which an impeller is located, a second section having a group of sloping vane members extending radially therethrough and a third section formed with a group of straight vane member extending partially radially inwardly from the inside surface of the outermost duct wall. The duct terminates in a nozzle for expelling water flowing therethrough. The second section of the duct includes radially inner and outer wall portions and the inner portion has a cap member secured to a rear end thereof. The cap member extends into the third duct section and is formed with another group of straight vane member which extend radially outwardly. The vane members function to convert the swirling water flow created by the impeller into a linear flow that is directed through the nozzle. The sloping and straight vane members are divided to permit more efficient molding of the vane sections by die casting.

Abstract: A solid particle fuel is introduced into a reaction zone of a continuous w conduit between pump and turbine flow sections thereof within a turbojet engine. The fuel reacts on contact with the motive liquid within the reaction zone and produces bubbles of a non-condensible gas as a reaction product during rotation of the engine rotor to which pump and turbine blading is fixed within the pump and turbine flow sections of the conduit.

Abstract: A hydrojet turbine drive 10 is described with a first turbine assembly 40 including a first compressor rotor 46 with blades 48 having a water pitch for drawing water into the turbine drive 10. The water is driven against the walls of a housing 18 and into a first stator 56 resulting in a portion of the water breaking down into its gaseous components. The water-gas fluid is reoriented and directed by the first stator 56 into a second turbine assembly 42 including a second compressor rotor 68 the blades 72 of which define a gas pitch. The circular flow therefrom is forced into a second stator 70 whereat additional water is reduced to its gaseous components. The water-gas fluid is directed by the second stator 70 into a third turbine assembly 44 including a third compressor rotor 88 the blades 94 of which also have a gas profile.

Abstract: Break-up activity of water by injection of hot propellant gas into channels f a thrust expansion engine is suppressed to prevent rapid cooling of the gas, utilizing one or more methods including injection of a secondary inflow of the propellant gas and/or the water under lower pressures into the channels, injection of a viscosity enhancer and/or surfactant into the inflow stream of the water and restricting outflow of the water from the channels by means of convergent nozzles.

Abstract: A jet propelled watercraft that is pivotal about a transversely extending horizontally disposed axis for raising the jet propulsion unit from the body of water in which it is operating and also for trim adjustment of the jet propulsion unit. A trim plate is affixed to the under side of the jet propulsion unit and spans a pair of side walls defining the tunnel opening in which the jet propulsion unit is received for providing trim adjustment of the watercraft upon trim movement of the jet propulsion unit. Sealing arrangements are disclosed for providing sealing around the jet propulsion unit water inlet opening during the trim adjustment.

Abstract: A recoilless propulsion unit fireable from an enclosure utilizes a releasy sealed multi-holed nozzle member to expel a fluid therefrom by a closed-breech type piston that is activated by a propellant charge. The propulsion unit after firing has minimum impact of overpressure, noise on both the launch crew and has no flash or smoke signature emitted therefrom.

Abstract: A ductless wall thruster for a marine vessel has a housing with a plenum chamber therein and, at a forward end of the housing, at least one inlet opening surrounding an outlet opening. An impeller is rotatably mounted within the housing so that when the impeller is rotated, it draws water into the housing and discharges it through the outlet opening to create a thrust. Preferably, there is a plurality of equally dimensioned inlet openings defined by stationary vanes inclined in a direction opposite the normal direction of rotation of the impeller. The outlet opening is preferably defined on a forward end of a central impeller housing in which the impeller is mounted, with the impeller having a flow area therethrough which is greater than the flow are through the outlet opening.

Abstract: A jet propulsion engine submergible in water for driving a water craft wherein a drive shaft is connected to an internal combustion engine for rotation thereof. A first turbine is mounted on the drive shaft for rotation therewith for providing a first high velocity stream of water axially through the propulsion engine. A propeller is journalled on the drive shaft adjacent to and downstream of the first turbine for rotation independently of the drive shaft. A second turbine is mounted on the drive shaft adjacent to and downstream of the propeller for rotation therewith for generating a second high velocity stream of water axially through the propulsion engine. The speed of the propulsion engine increases through the effects of the first and second high velocity streams of water for driving the water craft while the propeller becomes less effective until it is rendered free wheeling at cruising speeds of the water craft.

Abstract: A waterjet propulsion system for a watercraft including a duct disposed on the bottom of the watercraft with the opening facing backward, a device to produce waterjet in the duct and a steerable nozzle fitted on the duct opening. Inside the nozzle, a flow guide extending forwardly beyond a supporting axis for the nozzle is formed integrally with the nozzle. For the flow guide, a plate or plates fitted vertically respectively including or parallel to the nozzle centerline or a cylinder mounted coaxially with the nozzle can be preferably employed.

Abstract: A liquid turbojet engine includes an elongated shaft, a housing mounted about the shaft with the shaft being rotatable relative to the housing about the shaft longitudinal axis, a conduit fixed to the shaft within the housing filled with an inert motive liquid and nozzles for inducing combustible gas bubbles in the motive liquid. The conduit has a compression section extending generally radially from the shaft, a combustion section extending generally axially and parallel to the shaft and from the compression section at a radial distance from the shaft, and an expansion section extending generally radially relative to the shaft axis from an end of the combustion section remote from the compression section. The bubble nozzles are located at the inlet of the compression section. The motive liquid enters through an inlet in the housing. The burned bubbles are discharged with the motive liquid through an exit nozzle in the housing.

Abstract: A propeller thruster installation includes a propeller unit rigidly supported in an inner tunnel tube which in its turn is elastically coaxially supported in an outer tunnel tube which is rigidly secured to the hull of a ship. In order to reduce the transmission of noise and vibrations from the propeller unit to the interior of the ship an annulus between the outer and inner tunnel tubes is filled with, a continuously maintained "bubble curtain" of air.

Abstract: A body surrounded by a fluid is moved in a predetermined direction by a driving unit (1) which produces a negative pressure, whereby the fluid is sucked from the environment, the velocity of the flowing fluid relative to the body is increased by energy supply and the fluid is ejected at said increased velocity in opposition to the direction of movement. The fluid is sucked through an arcuate channel (5, 6) which is fixed on the body and which changes the direction of flow of the fluid such that the directional vector of the sucked fluid flowing into the channel (5, 6) and the vector in the direction of movement of the body form an angle which differs from 180.degree. and at low speeds preferably are disposed in the same direction.

Abstract: A drive mechanism particularly for flat-bottomed watercrafts with at least one centrifugal pump or the like producing a water jet, which pump is arranged closely above the intake opening within the watercraft and within an elbow which is pivotal for controlling the watercraft and the blades or the like of which pump are connected by a ring or the like.

Abstract: Water directing apparatus for the jet pump inlet of a watercraft having a planing surface within which the inlet is formed. The apparatus is carried by the planing surface and includes a pair of laterally spaced apart, longitudinally extending side fins projecting downwardly of the planing surface. Curvilinear, transversely disposed upstream and downstream vanes are oriented to direct water into the inlet, the angles of attack of the vanes being established to direct boundary layer water into the inlet without separation. The vane combination achieves water flow directional change with minimum drag and flow separation. An embodiment is disclosed employing a vane movable in response to inlet passage pressure.

Abstract: A steering and propulsion system for a ship, including two side by side, fore and aft pipes underneath a ship's hull, and compressed air or steam delivered through tubes around an exterior of the hull to the two pipes, and controls to eject forwardly or rearwardly out from the pipes.

Abstract: A thruster for use underwater having a rotor which may be optionally rotated either clockwise or counterclockwise. The rotor includes blading, perferably radially symmetrical about the rotor radius line, and a limited discharge area such that fluid is discharged from said limited discharge in a direction substantially perpendicular to a rotor radius line passing through the approximate center of the limited discharge area.

Abstract: A self retracting screen for turbomachinery comprised of a number of interlocking wires, the wire ends being pivotally attached to the periphery of the normal inlet of the turbomachinery. Preferably, the wires are elliptical, or streamlined, in cross-section such that the major diameters of the elliptical cross-section of the wires when the screen is closed are substantially parallel to the turbomachinery inlet stream.

Abstract: A marine propulsion water jet system which operates at high efficiency and automatically adjusts itself to maintain a relatively constant primary injection water velocity over a wide speed range. The propulsion system includes a fluid flow amplifier by which a high velocity principal water flow is injected into a slower velocity secondary water flow to form a water jet. The fluid flow amplifier includes an adjustable orifice through which the principal water flow is injected into the secondary water flow and the size of the orifice is automatically adjusted in order to maintain a relatively constant water jet velocity.

Abstract: An improved rigid impeller held for driven rotation within the housing of a water jet drive for boats. The impeller includes a hub connectable to the output shaft of a motor, a plurality of impeller blades integrally formed with, and radially extending from, the hub, and an annular ring rigidly connected or integral with and between the outer ends of the impeller. The annular ring has a circular outer surface concentric with the axis of the hub and adapted to closely mate with, and rotate within, a mating circular surface formed in the interior of the housing such that water is efficiently driven through the housing from its inlet in the bottom of the hull of the boat through and discharging from its outlet in the transom of the boat.

Abstract: A propeller assembly, a so-called rotatable thruster, for propelling, manoeuvering, steering and/or positioning a watercraft, floating docks, pontoons and in particular offshore platforms, includes a propeller (1) having an embracing propeller shroud (2) and mounted on a propeller shaft journalled in a gear housing (3). The gear housing accommodates a bevel gearing through which the propeller shaft is connected to a drive shaft extending through a tubular support strut (4), which is connected at its lower end to the gear housing in order to support the same. The upper end of the support strut is arranged to be rotatably mounted in an opening in a bottom part of the hull of the watercraft, with the propeller shaft extending substantially horizontally, so that the drive shaft can be connected to drive machinery located within the hull and such that the assembly can be rotated about a rotational axis coinciding with the axis of the drive shaft, by means of rotational machinery located within the hull.

Abstract: A water jet propelled craft equipped at the rear section of the craft with a water jet pump driven by an engine. A cylindrical member is provided so as to extend backwards around the rear end of a pump outlet nozzle of the water jet pump, and an outlet of exhaust gas from the engine opens backwards between the outer surface of the pump nozzle and the inner surface of the cylindrical member.

Abstract: The marine jet propulsion unit of this invention, in preferred form, has a pair of laterally adjacent blade carriers, each having a vertical outer surface movable in a horizontal orbit and to which blades are fixed that project edgewise outwardly. Each blade has a surface facing in the direction of its orbital movement that is concavely curved along its height. The two blade carriers, at opposite sides of a fore-and-aft extending vertical plane of symmetry, are driven in opposite orbital directions such that each has a driving portion remote from the plane of symmetry that moves rearward in an acceleration channel and has an opposite forwardly moving portion adjacent to the plane wherein its blades are interleaved with those of the other. Water entering a forward intake is guided in two streams, one to the front end of each acceleration channel, and the rear end of each acceleration channel is communicated with a discharging outlet nozzle.

Abstract: A gas powered engine for use in combination with a pressurized gas source to propel the gas powered engine through a fluid medium such as water comprising an engine housing having a plurality of blades formed on the outer periphery thereof held in fixed spaced relationship to an outer hollow substantially frustum housing by an attachment structure to cooperatively form a fluid flow chamber therebetween, the engine housing comprising a hollow substantially cylindrical housing to operatively house a drive assembly therein, the drive assembly comprising a drive shaft assembly coupled to the attachment structure in fixed relationship relative to the hollow substantially cylindrical housing, having a gas distribution structure mounted thereon, and a cylinder assembly and a swash plate assembly rotatably mounted thereon, the gas distribution structure being operatively disposed between the pressurized gas source and the cylinder assembly to selectively feed and discharge pressurized gas to and from the cylinder ass

Abstract: In a semi-axial flow pump used in a small-sized boat which is intended to travel in shallow water, a truncated-conical liner of wear-resistant material is force fitted into the inner surface of a passage portion within which an impeller is mounted. The liner has cylindrical portions at its both ends, which are effective to forcibly fit the liner into the pipe passage portion.

Abstract: A water jet unit for ships, comprises a propeller pump having a pump housing connected on its inlet side with an inlet channel and on its outlet side with a water-jet directing outlet means. The pump housing has a hub housing which is arranged centrally in the flow path of the water through the pump housing and which is carried by guide vanes extending radially between the wall of the pump housing and the hub housing. The impeller is mounted on the end of a pump shaft extending into the pump housing through the inlet channel and is journalled in the hub housing by means of an axial bearing and a radial bearing. Both bearings are spherical and have a substantially common center.

Abstract: A steering apparatus for an outboard jet engine utilizes a channel or conduit along the underside of a boat hull in combination with a channel or conduit extension member to guide water to the inlet port of the jet outboard propulsion apparatus, the bottom lip of the inlet port being disposed proximate the extended bottom surface of the underside of the boat hull with the top lip or rim of the inlet port being disposed proximate the extended top surface of the channel of conduit along the hull to permit propulsion and steering of the boat while the boat hull is planing along the surface of water only inches or centimeters above the bed of the lake, river or ocean.

Abstract: A pyrotechnic delay system for controlling the time of events from initian of an initial ignition impulse to ignition of a secondary output.

Abstract: Propulsion unit for a marine vessel intended for operation under severe ice conditions comprises a multi-bladed propeller, which may be of fixed or controllable pitch, a stationary duct, which may take the form of a nozzle, within which the propeller runs and is protected peripherally against ice damage, and, at the forward and aft ends of the duct, water-guide members in the form of vanes and/or blades which are more massive than is required by their water-guiding functions and which restrict the size of ice masses that can encounter the propeller by entering the duct at its opposing ends. The duct may embrace the propeller peripherally around the full 360.degree.. The water-guide members may be secured at their outer ends to the duct and at their inner ends to ring members co-axial with the propeller. The upper quadrant of the duct may be secured to the hull of the vessel and the lowest portion of the duct to a skeg extending beneath the duct.

Abstract: The straightening vanes of a waterjet pump are designed to produce a low-pressure area, and the downstream side of the rotor drum is located inside said low-pressure area to eliminate the need for an axial thrust control seal.

Abstract: A water-jet drive mechanism for driving and controlling a watercraft includes a substantially cylindrical support housing which is supported for rotational movement about a substantially vertical pivot axis in a cylindrical recess in the undersurface of the watercraft, with its undersurface flush with that of the watercraft. A centrifugal water pump is encased in the support housing so that its inlet and its discharge nozzle open through the undersurface of the support housing. The pump drive shaft is inclined and lies in a vertical plane arranged at an angle to the direction of water discharge from the nozzle. A normally open ventilating valve provided in a wall of the pump is closed by the flow of water through the pump.

Abstract: A variable inlet for a marine jet propulsion system comprising a movable lip, a center splitter serving to divide said inlet into upper and lower passages and coupled for movement proportional to that of said lip to assure equality of the areas of said upper and lower passages, and apparatus for varying the outward projection of said splitter to vary the diffusion ratio of said upper and lower passages.

Abstract: A propulsion motor for an underwater vehicle such as an anti-submarine weapon. The motor includes a propulsion chamber into which water is admitted and then rapidly expelled through an exhaust nozzle, developing thrust to propel the vehicle. Gas generators are used to develop the successive hydropulses to expel the water following each filling of the motor chamber with water. In one particular embodiment of an anti-submarine weapon which is directed through the air to the vicinity of a submarine by a rocket motor, the hydropulse underwater propulsion system can use the same chamber as the rocket motor.

Abstract: The invention relates to a method for producing a thrust in manoeuvering engines for watercraft and a manoeuvering engine constructed for the same, whereby the method comprises the annular driving water jet supplied to the diffuser and enveloping a first suction water jet is fed to a second suction water jet supplied to the diffuser inner wall surface, while the manoeuvering engine is constructed in such a way that the rear part of the engine casing is provided with an inlet port having a smaller diameter than the outlet port and located in the vicinity of the outlet port of the front engine part, whereby for the optimum adaptation of the exit mixing jet velocity to the vehicle speed a water jet exit cross-section regulating device is provided.

Abstract: A reversible hydrojet boat drive for the substantially nonturbulent nozzling of water during the forward mode, and effective non jamming seal function during the reverse mode, and comprised of an exact nozzle continuation of the exit passage of the pump, particularly the top wall thereof, and the compatible eccentric relation of the surrounding seals of the reverse gate centered below the axis of gate rotation, thereby to avoid jamming and to eleviate strain on the control system therefor.

Abstract: A hydro-jet drive for watercraft. A device is provided applicable for mounting in the hull of a boat by which a jet stream can be created and directed in any desired direction for movement of the boat accordingly. There is provided an elbow having an intake portion and a substantially horizontal discharge opening. The elbow is rotatable on an axis of rotation and contains a suitable motor driven impeller. A motor driven device is provided for rotating the elbow about the axis of rotation thereof for effecting discharge in an operator determined direction. The axis of rotation of the impeller is arranged eccentrically with respect to the axis of rotation of the elbow. The device is particularly adaptable for shallow draft vessels.

Abstract: A propeller nozzle or duct having means for admitting fluid under pressure into the area of cavitation for the purpose of inhibiting bubble formation and implosion to suppress cavitation and reduce cavitation erosion, the means comprising walls forming an annular passage within the nozzle or duct, a passage communicating between the annular passage and the space within the nozzle or duct below the horizontal centerline thereof, and a passage communicating between the annular passage means and an area above the horizontal centerline coincidental with the zone of potential cavitation within the nozzle or duct and positioned substantially in the plane of the propeller such that fluid subjected to an augmented pressure under the influence of the propeller blade below the horizontal center line will be at an incremental pressure above that of the fluid above the horizontal center line to thereby promote the flow of fluid from the former location to the latter location through the passage there communicating to the

Abstract: An improved hydraulic engine for boats and the like is provided which preferably includes a rearwardly facing concave impingement surface, along with nozzle apparatus for directing a stream of pressurized water against the impingement surface in order to move the boat forwardly through the water. An oppositely oriented, concave, flow-directional surface is disposed in partial opposition to the impingement surface for deflecting non-pressurized water against the impingement surface as the boat moves through the water. The below water portion of the engine is housed in an open-ended casing, and can be rectangular or circular configuration.

Abstract: Water-jet propulsion unit for vessels which includes a water duct having an inlet and outlet portions and an impeller disposed in the water duct. The outlet portion has a variable outlet nozzle which can discharge water downwardly when desired to produce a lift force for lifting the stern of the vessel. The arrangement provides an improved rolling stability under a stationary condition and is also effective to decrease a drag force under the "hump" condition.

Abstract: Axial flow turbomachinery having an impeller with a plurality of contoured blades mounted within a diffuser throat and about a central rotatable hub. This blade shape is defined by the ratio of the blade root and tip chords to the minimum midsection blade chord, which is between about 1.25 and about 2.25. The ratio of blade pitch at the root and tip sections as compared with the blade midsection pitch is preferably between about 1.0 and about 1.4.This configuration of a preferred diffuser is described by the following relationship: ##EQU1## Where A.sub.t is the diffuser cross-sectional area at the diffuser throat, A.sub.o is the diffuser cross-sectional area at the outlet, l is the diffuser length from the diffuser throat to the diffuser outlet, x is a distance along the diffuser measured from the diffuser throat toward the diffuser outlet, A.sub.x is the diffuser cross-sectional area x distance from the diffuser throat and n is a value between about 2 and about 4.

Abstract: The jet propulsion engine employs a duct modified from a theoretical taper to be enlarged in transverse cross-section along the duct by an amount equal to the area of a cross-section through impellers and stators at any point along the duct. The tube radius at any point r.sub.

Abstract: A water jet propulsion system for moving a boat through the water includes apparatus for varying the thrust of the jet by varying the size of the stream of water being discharged from the nozzle of the jet propulsion unit. The apparatus for constricting the size of the stream of water also serves to direct the thrust of the stream upwardly or downwardly as desired as the stream discharges rearwardly of the boat so as to counteract any tendency of the boat to "porpoise". Interconnected closure members located respectively in the flow path leading directly to the nozzle and in a forwardly directed secondary flow path serve to close off the latter when the water is being passed under pressure via the nozzle and vice versa.

Abstract: A radially vaned rotor is mounted for rotation about a horizontal axis extending athwartships of a boat. A housing encircles the major portion of the rotor and has an axial inlet and a downwardly directed peripheral outlet. The tips of the rotor vanes project through the housing peripheral outlet below the surface of the water surrounding the boat. When the boat is traveling at low speed, the rotor functions as the impeller of a centrifugal pump drawing water into the housing through the axial inlet and discharging the water through the peripheral outlet to propel the boat. The outlet can be shifted circumferentially fore and aft to alter the direction of water discharged therethrough. At high speed, planing of the boat elevates the housing so that only air is drawn through its axial inlet and discharged through its peripheral outlet, the majority of boat-propelling force being produced by the paddle wheel action of the rotor vane tips.

Abstract: A propulsion unit for a vessel of the type having a compartment watertightly sealed from the remainder of the vessel. The propulsion unit includes a cylindrical housing vertically supported within the compartment. A pump having a drive shaft is supported within the housing, the drive shaft extending into the housing coaxial therewith. A deflector is rotatably supported at the outlet of the housing about an axis coaxial with the axis of the drive shaft.