Abstract: A motorized watercraft may include an elongated hull extending along a longitudinal central axis (L) and a propulsion system. The propulsion system may include a drive module. The drive module may be mounted to the elongated hull. The drive module may include a motor and a propelling member. The motor may be in driving connection with the propelling member. A bottom surface of the elongated hull may be provided with a first channel and a second channel that respectively extend along the elongated hull on each side of the longitudinal central axis (L).

Abstract: A jet pump includes a propulsion system including an impeller coupled to a rotatable shaft configured to receive torque from an engine and an exhaust system including an exhaust flow path configured to direct exhaust from the engine to an exterior of the watercraft, wherein the exhaust system is separate from the propulsion system. The propulsion system includes a water intake configured to take in water from a body of water, the water intake including an intake grate and a base, and an exhaust system including an exhaust flow path configured to direct exhaust from the engine to an exterior of the watercraft, wherein the base of the water intake is configured to be coupled to an exterior surface of a hull of the watercraft.

Abstract: Various aspects provide for “parking” an apparatus in a “parking position.” A parking position may be a configuration of an apparatus that minimizes damage resulting from extended exposure during periods of inactivity. An apparatus may comprise a marine apparatus, which may be configured to be disposed in an environment comprising saltwater, salty air, brackish water, freshwater, and the like. An apparatus may comprise a propulsion system (e.g., for a ship) and/or a steering system. Some aspects include a water jet based propulsion system having a scoop and a nozzle operable to redirect the water jet, providing a range of forward/backward and port/starboard thrusts. A control cylinder and/or a linkage may be parked in a configuration that segregates damage incurred during periods of inactivity to portions of an apparatus not needed for normal operation.

Abstract: Described is a hull with a transom for supporting an outboard jet motor; a tunnel disposed in a bottom surface of the hull and extending to the transom; an adapter disposed where the transom and the tunnel meet, the adapter comprising a shrouded opening for communication with the outboard jet motor at an intake of the outboard jet motor; wherein the tunnel is configured for directing a flow of water through the tunnel, into the adapter, and into the intake of the outboard jet motor. Also described is a directional device which receives the jet output of the outboard jet motor and provides a capability for making vertical or horizontal adjustments to the jet output or reversing the jet output, and a boat which includes the boat hull and directional device.

Abstract: Provided is an exhaust porting apparatus (10) for a turbocharged internal combustion engine (4) which includes a turbocharger (6) that is conventionally arranged in fluid communication with the exhaust (8), the turbo in turn facilitating forced air induction back into the engine via air intake (5). The apparatus (10) comprises a housing (12) that defines an inlet port (14) and an outlet port (16). The apparatus (10) also includes a valve member 18 which is arranged within the housing (12). The valve member (18) is generally displaceable between a high-velocity gas inlet position, wherein the valve member (18) allows unobstructed fluid flow between the inlet and outlet ports (14) and (16), and a low-velocity gas inlet position, wherein the valve member (18) obstructs fluid flow through the outlet port 16 whilst allowing unobstructed fluid flow into the inlet port (14).

Abstract: A multi-vane impeller for use upon a watercraft such as a jet ski is provided having an integral hydraulic compression ring permanently affixed to the outer end portions of the vanes. The impeller eliminates a need for the wear ring portion which is commonly provided on most jet skis, and is expected to improve efficiency and reduce maintenance costs. It is envisioned that the impeller would be provided as standard or optional equipment on new jet ski designs as well as being made available as an add-on kit for existing jet skis.

Abstract: Described, in general, is an apparatus and related methods for removing debris from the leading edge of drive shaft housing of a sailboat. In a preferred embodiment, the apparatus comprises: a sleeve in the shape of a leading edge of a drive shaft housing, the sleeve featuring first and second line guides; a blade track along said first line guide; a first section of line; a second section of line; and a slug with a blade; wherein first and second lines are spliced with the slug and positioned in the two line guides so that (a) the slug is in the first line guide with the blade exposed at the line track and (b) pulling the first or second line guide moves the slug within the first line guide and the blade along the blade track.

Abstract: A water vessel having variable geometry is described. The water vessel comprises: a frame; a plurality of hulls coupled to the frame, each one of the plurality of hulls coupled to the frame by a folding mechanism and configured to move, relative to the frame, between a deployed configuration and a stowed configuration in which at least one dimension of the water vessel is reduced in respect of the deployed configuration; a plurality of thruster assemblies configured to provide thrust to the water vessel, each one of the plurality of thruster assemblies being coupled to a respective one of the plurality of hulls; and a protective device coupled to a respective one of the plurality of thruster assemblies, the protective device for preventing intake of foreign objects into the respective one of the plurality of thruster assemblies.

Abstract: An inlet grate for a water jet propulsion system to be used in a watercraft has a water passage having an inlet defined by a forward and a rearward area with respect to the watercraft. The inlet grate comprises a first end portion adapted to be connected to the forward area of the inlet and a second end portion adapted to be connected to the rearward area of the inlet as well as at least one elongated member extending from the first end portion toward the second end portion. The inlet grate also comprises at least one deflector having a forward end and a rearward end, the forward end being adjacent to the first end portion of the inlet grate.

Abstract: A water vessel having variable geometry is described. The water vessel comprises: a frame; a plurality of hulls coupled to the frame, each one of the plurality of hulls coupled to the frame by a folding mechanism and configured to move, relative to the frame, between a deployed configuration and a stowed configuration in which at least one dimension of the water vessel is reduced in respect of the deployed configuration; a plurality of thruster assemblies configured to provide thrust to the water vessel, each one of the plurality of thruster assemblies being coupled to a respective one of the plurality of hulls; and a protective device coupled to a respective one of the plurality of thruster assemblies, the protective device for preventing intake of foreign objects into the respective one of the plurality of thruster assemblies.

Abstract: An inlet grate for a water jet propulsion system to be used in a watercraft has a water passage having an inlet defined by a forward and a rearward area with respect to the watercraft. The inlet grate comprises a first end portion adapted to be connected to the forward area of the inlet and a second end portion adapted to be connected to the rearward area of the inlet as well as at least one elongated member extending from the first end portion toward the second end portion. The inlet grate also comprises at least one deflector having a forward end and a rearward end, the forward end being adjacent to the first end portion of the inlet grate.

Abstract: An inlet grate cleaning system for a water jet propulsion system to be used in a watercraft. The water jet propulsion system has a water passage, the water passage has an inlet and the inlet has a forward area and a rearward area with respect to the watercraft. The inlet grate cleaning system comprises a pump and at least one water intake fluidly connected to the pump. At least one water outlet is also fluidly connected to the pump. The pump is adapted for pumping water from the at least one water intake to the at least one water outlet to create at least one jet of water. The at least one water outlet is positioned so as to direct the at least one jet of water toward an inlet grate.

Abstract: A water intake grill for attachment to a water intake port associated with a jet watercraft, the water intake grill comprising a plurality of elongate members mounted to and in between fore and aft mounts. The fore mount comprising a base having an angularly orientated bottom surface for attaching first ends of the elongate members and an angularly orientated top surface for mounting atop thereof a key element having an overall geometric structure suited to fit within a mount socket integral to a forward wall section of the water intake port. The aft mount comprising a horizontally positioned base for accepting thereon at least one spacer and mounting thereto an extension support to support apart therefrom a cross support member for attaching second ends of the elongate members.

Abstract: A cutting system for fouling removal systems used in water-jet drive systems is described. The cutting system includes an actuation system for facilitating movement of a cutting blade that resides outside of the water flow area for the intake of the jet drive system. The cutting system also includes one or more guide tines to restrict movement of the cutting blade away from the surface of the grate. An optional cutter stud is formed as a single structure including two members forming a single angle, one member for mounting and the other for cutting. The single-angled configuration maximizes cutting efficiency while minimizing disruption of water flow to the propulsion system.

Abstract: A device for cutting weeds carried by water inducted into a housing includes an intake, an outlet, an impeller for pumping water from the intake to the outlet as the impeller rotates about an axis, the impeller including a blade formed with a leading edge facing the intake, and a baffle secured against movement and including a cutting edge located adjacent the leading edge when the leading edge rotates to the location of the cutting edge.

Abstract: An inlet grate for a water jet propulsion system to be used in a watercraft has a water passage having an inlet defined by a forward and a rearward area with respect to the watercraft. The inlet grate comprises a first end portion adapted to be connected to the forward area of the inlet and a second end portion adapted to be connected to the rearward area of the inlet as well as at least one elongated member extending from the first end portion toward the second end portion. The inlet grate also comprises at least one deflector having a forward end and a rearward end, the forward end being adjacent to the first end portion of the inlet grate.

Abstract: A water intake grill for attachment to a water intake port associated with a jet watercraft, the water intake grill comprising a plurality of elongate members mounted to and in between fore and aft mounts. The fore mount comprising a base having an angularly orientated bottom surface for attaching first ends of the elongate members and an angularly orientated top surface for mounting atop thereof a key element having an overall geometric structure suited to fit within a mount socket integral to a forward wall section of the water intake port. The aft mount comprising a horizontally positioned base for accepting thereon at least one spacer and mounting thereto an extension support to support apart therefrom a cross support member for attaching second ends of the elongate members.

Abstract: A cutting system for fouling removal systems used in water-jet drive systems is described. The cutting system includes an actuation system for facilitating movement of a cutting blade that resides outside of the water flow area for the intake of the jet drive system. The cutting system also includes one or more guide tines to restrict movement of the cutting blade away from the surface of the grate. An optional cutter stud is formed as a single structure including two members forming a single angle, one member for mounting and the other for cutting. The single-angled configuration maximizes cutting efficiency while minimizing disruption of water flow to the propulsion system.

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 optionally situating atop thereof a removable key element having an overall geometric structure substantially coinciding with the geometric configuration of a mount 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 for optionally accepting and resting atop of each thereof at least one removable spacer and an angular edge for receiving and attaching second ends of the elongate members.

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 optionally situating atop thereof a removable key element having an overall geometric structure substantially coinciding with the geometric configuration of a mount 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 for optionally accepting and resting atop of each thereof at least one removable spacer and an angular edge for receiving and attaching second ends of the elongate members.

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 device for cutting weeds carried by water inducted into a housing includes an intake, an outlet, an impeller for pumping water from the intake to the outlet as the impeller rotates about an axis, the impeller including a blade formed with a leading edge facing the intake, and a baffle secured against movement and including a cutting edge located adjacent the leading edge when the leading edge rotates to the location of the cutting edge.

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: Steering and reversing apparatus for a waterjet-powered marine vessel, the waterjet having an intake duct, a diffuser, and a steering nozzle and producing a rearward water stream flowing from the steering nozzle, the apparatus comprising: a nozzle pivot pivotably attaching the nozzle to the diffuser about a substantially vertical axis perpendicular to the water stream; at least one reversing duct affixed to and positioned substantially below the nozzle and having an opening to the nozzle; a reverse deflector pivotably attached to the diffuser about a horizontal axis substantially perpendicular to the water stream and having a sealing portion; and a nozzle sealing face having an exit shape mating with the sealing portion of the reverse deflector at any angular position of the steering nozzle, whereby, when the reverse deflector is pivoted such that the sealing portion mates with the nozzle sealing face, the water stream is deflected forward and underneath the vessel through the opening to the nozzle, steerably

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.

Abstract: A vessel propulsion system having a suction casing (4) configured with a suction inlet (4a) opening at a vessel bottom (1b), a suction flow path (4b) inclined to rearwardly ascend from the suction inlet (4a), and an impeller chamber (4c) formed horizontal, and disposed at a bottom of a stern, a delivery casing (10) connected to the suction casing (4) and submerged under a draft of the stern, and a set of forward and reverse rotatable axial flow blades (8) disposed in the impeller chamber (4c) of the suction casing (4).

Abstract: A screen system for marine thrusters having at least one constrictor for reducing exit jet cross-sectional area to increase exit jet velocity of a thruster.

Abstract: A mechanism for cleaning out an inlet grate of a water jet propulsion system. The mechanism includes an actuator and a wiper. The actuator penetrates and is supported by a through-hull housing installed in an opening in the hull. The actuator is linearly displaceable relative to the through-hull housing by manipulation of a handle or other operator input device or system. An inlet grate comprising a plurality of cantilever tines is pivotably mounted to and supported by the through-hull housing. A weed wiper is connected to the end of the actuator remote from the end that is actuated by the boat operator. When the actuator is displaced downward, the weed wiper moves downward along a linear path. At the point in the wiper displacement where the wiper bar engages the tines of the inlet grate, the downwardly displacing weed wiper causes the grate to pivot downward. During this action, the wiper slides across the grate and pushes any weeds or other debris entangled on the grate toward the ends of the tines.

Abstract: An inlet grate mounted within the inlet channel of a watercraft, where the inlet grate contains a pivotally mounted divider vane disposed laterally across the inlet channel and biased by a torsional spring into a neutral position. The hydrodynamic forces of water moving through the grate alter the angle of the lateral vane, thus inducing equality of upper and lower inlet water volumes as well as pressure, proportionate to watercraft speed, thereby improving the efficiency of the watercraft's jet pump assembly without requiring the use of electromechanical devices.

Abstract: A jet powered boat may be provided with a water monitor for fire fighting purposes. The conduit for the monitor is connected to an opening through the bottom of the hull to draw water vertically from beneath the hull. Two motors are provided in the boat. One motor is configured to propel water through the monitor conduit to the water monitor. The other motor is configured to propel water through a propulsion jet at the rear of the boat. In one embodiment, a second propulsion jet is provided at the rear of the boat, connected to the conduit for the water monitor. A baffle at the intersection of the second propulsion jet and the monitor conduit may be operated to selectively direct water to either the monitor or the propulsion jet. In this embodiment, the two motors may be placed symmetrically on either side of the longitudinal centerline of the boat.

Abstract: A water jet propelling type outboard motor (1) is provided with a casing member (50), a frame (10), a motor (11), a gear case (13), a vertical driving shaft (12), a horizontal following shaft (14), a power transmission mechanism (15), and an impeller (5). The casing member (51) has a front end water suction inlet (3a), a rear end jetting outlet (6a), a first inside space (51) extending from the suction inlet (3a) obliquely upward and rearward, and a second inside space (52) extending generally horizontally from a rear end of the first inside space (51) up tot he jetting outlet (6a). The frame (10) extends upwardly from the casing member (50) to be mounted on a ship body (2). The motor (11) is mounted on the frame (10). The gear case (13) is disposed laterally forward of the second inside space (52) and generally vertically above the water suction inlet (3a). The vertical driving shaft (12) extends from the motor (11) downward to be inserted into the gear case (13).

Abstract: An arrangement for mounting a water jet apparatus to a hull of a marine craft. The hull has generallly horizontal and vertical sections and sidewalls which define a cavity in which an inlet housing of the water jet apparatus is installed. The inlet housing has a top section which abuts an exterior surface of the horizontal hull section and a front section which abuts an exterior surface of the vertical hull section. A top mounting plate abuts an interior surface of the horizontal hull section, while a front plate abuts an interior surface of the vertical hull section. One set of fasteners hold the top mounting plate, the horizontal hull section and the top section of the inlet housing together. Another set of fasteners hold the front plate, the vertical hull section and the front section of the inlet housing together.

Abstract: A marine craft has with an inlet ramp, which increases in height as the inlet ramp extends rearward, and a cavity which communicates at its front with the rear of the inlet ramp. The cavity is open at its bottom and its rear. The marine craft is propelled by a jet pump apparatus having an inlet housing which is installed in the aforementioned hull cavity. The inlet housing defines an inlet volume in flow communication with the inlet ramp and a water tunnel in flow communication with the inlet volume. The inlet volume has a height which increases as it extends rearward. The inlet ramp and the inlet housing each have a lower U-shaped boundary, which boundaries are connected to form a generally rectangular inlet for water being sucked in by the water jet.

Abstract: A blockage preventing apparatus used for a water jet propulsion unit (2) is provided with a screen (6), springs (22), an engagement protrusion (21) and an engagement end portion (20a). The screen (6) is rotatably supported with respect to the front end of a suction port (7) and movable between a closed position at which the screen covers the suction port (7) and an open position shifted downward from the suction port (7). The springs (22) urge the screen (6) to the closed position through a working shaft (17). The engagement protrusion (21) is provided at the working shaft (17) and moves together with the screen (6). The engagement end portion (20a) moves from the first position and moves beyond the second position. When the engagement end portion (20a) moves from the first position to the second position, the engagement end portion (20a) is engaged with and presses the engagement protrusion (21) to thereby move the screen (6) from the closed position to the open position.

Abstract: A jet powered boat may be provided with a water monitor for fire fighting purposes. The conduit for the monitor is connected to an opening through the bottom of the hull to draw water vertically from beneath the hull. Two motors are provided in the boat. One motor is configured to propel water through the monitor conduit to the water monitor. The other motor is configured to propel water through a propulsion jet at the rear of the boat. In one embodiment, a second propulsion jet is provided at the rear of the boat, connected to the conduit for the water monitor. A baffle at the intersection of the second propulsion jet and the monitor conduit may be operated to selectively direct water to either the monitor or the propulsion jet. In this embodiment, the two motors may be placed symmetrically on either side of the longitudinal centerline of the boat.

Abstract: A pump-jet type of outboard propulsion unit within a surrounding fluid mem for marine craft or the like, is protectively enclosed within cylindrical shrouding which forms an axial flow passage about the exhaust channel of the propulsion unit through which flow of the fluid medium is induced by rotation of impeller blades. Inflow of the fluid medium to the flow passage is modified at an inlet end of the shrouding by a plurality of angularly spaced vanes attached thereto and extending forwardly therefrom at an angle.

Abstract: An operator-actuated inlet grate clean-out mechanism which can be actuated by pushing and pulling a cable or rotating a shaft from the driver's seat of a boat. A weed wiper which is arranged to push weeds off of a pivotable cantilever-tine inlet grate as the wiper travels along the tines and toward the aft tips of the tines. As the wiper sweeps along the inlet grate tines, it bears against the inlet grate and causes the grate to swing downward to a position where the aft tips of the cantilever tines are spaced from the pump jet housing. Because the weeds wrap and ball around the inlet grate, they also slide off easily when pushed or dragged by the sweeping wiper bar.

Abstract: A marine jet propulsion system for a boat or the like comprises a power plant for rotating a drive shaft. A gear system is connected to the drive shaft and is configured to engage and rotate an impeller shaft. An impeller mounted to the impeller shaft is enclosed within a housing having a water inlet opening and a jet stream exit opening. The gear system includes a pinion gear connected to the drive shaft and engaging a pair of opposed ring gears, the ring gears being thus rotatable by the pinion gear in opposite directions. A clutch system is provided for selectively causing the impeller shaft to alternatively be engaged by one or the other of the ring gears and thereby selectively rotating the impeller in opposite directions.

Abstract: A water jet propulsion device for a vessel in which a suction inlet 4 is open at a vessel bottom part in a vicinity of a stern, water suctioned from the suction inlet 4 to a suction duct 5 is pressurized by a spiral blade 10 provided in an impeller housing 6, and jet water is ejected from an ejection duct 13 backward of the stern, and moreover, on an impeller shaft 7 provided in the impeller housing 6 are disposed a plurality of those spiral blades 10 with slipped phases, outer peripheral parts 10b of the spiral blades 10 are close to an inner circumferential surface of the impeller housing 6, and outer circumferential end parts 10c of the spiral blades 10 are extended to a suction side, and further in a fluid passage behind the spiral blades 10 are provided guide vanes 12, and cavitations and a rolling of a vessel body in a high-speed travelling are reduced, and a travel performance is improved.

Abstract: A weed grate for a watercraft having a jet propulsion unit. The weed grate includes a plurality of cantilever tines each joined to a pivot rod. The cantilever tines extend across the inlet opening for the jet drive to prevent debris from entering through the water inlet opening. A spring member is mounted between the cantilever tines and a mounting frame such that the spring member provides an outward rotational bias force against the rotatable cantilever tines. During operation of the watercraft, if a mass of weeds becomes clogged in the cantilever tines, the upward and inward suction force of the jet drives causes the cantilever tines to rotate upward against the rotational bias force and allow the weeds to be ingested by the jet drive.

Abstract: A watercraft intake debris cleaner is provided including a watercraft having an outlet opening formed in a rear face thereof with a water propulsion mechanism mounted therein. An inlet opening is formed in a bottom face of the watercraft. A channel interconnects the inlet and the outlet for allowing fluidic communication therebetween. A cutting mechanism is mounted within the channel for cutting debris upon the actuation thereof.

Abstract: A marine jet propulsion water inlet system having panels extending from the inlet opening at the bottom of a watercraft downstream, upward and rearwardly, in the water channel. The panels extend to the upper wall of the water channel or are integral with the upper wall. In this way, aquatic vegetation and debris will not have any surface to wrap around. This results in greatly reduced clogging of the water channel. The panels are also integral with downwardly extending fins which are beneath the bottom of the watercraft and which have edges that are also designed to direct vegetation and debris along the fin and pass the craft to reduce or eliminate the adhesion of vegetation and debris.

Abstract: The invention provides a water jet system with higher efficiency and better steering. The water jet system uses cantilever bars for an inlet grating, to prevent blockage. The water jet system also uses an elliptical impeller shaft housing to reduce turbulence and snagging of debris by the rotating impeller shaft. The water jet system uses impeller blades with a curved cross section that curves towards the direction of forward rotation. The water jet system uses U-shaped flanges mounted to the outlet of the water jet to provide steering.

Abstract: A water jet ski or boat that prevents weeds or grass from entering or clogging the intake grate area, is simple in construction and installation, operates automatically without operator intervention, and allows the craft to be beached and refloated without damaging the anticlogging elements or the craft. The craft includes one or more, preferably two or four, flexible rods mounted at the forward end of the intake grating and depending downward and preferably rearward. Growing or floating weeds or grass encountered during forward movement of the craft will be forced by the rods downward, rearward, and, in one alternate embodiment, outward. The rods do not interfere with the laminar water flow from any direction into the intake and are flexible enabling the craft to be stored, trailered, beached and pulled back from the beach as desired and without damage.

Abstract: A jet propulsion system for propelling a water craft through a body of water. The system includes a housing having a conduit formed therein for the passage of water, an inlet port and an outlet port. The inlet port has a lower edge which extends at least to the vertical plane defined by the upper edge such that the inlet port faces away from the bottom of the river or lake. An impeller is positioned in the housing between the inlet and outlet ports, and a stator structure is positioned between the impeller and the outlet port. The impeller is rotated by a drive assembly to draw water inwardly through the inlet port, drive the water past the impeller in an axial/rotational flow, and move the water through the outlet port.

Abstract: An inlet adapter for a personal watercraft jet propulsion system is hydrodynamically designed to achieve optimum performance at both low and high watercraft speeds. The inlet adapter provides an inlet opening having a fixed geometry. A plurality of tines extend from the inlet adapter rearward to cover an inlet opening through which water is pumped to a jet propulsion system. The aft portion of each tine has an exposed face that is blunt, preferably flat. The blunt face restricts water flow through the inlet opening at relatively high speeds, thereby improving high speed performance. The tines are also designed to facilitate laminar flow as the flow of water passes the tines en route to the jet propulsion system. In another aspect, the invention provides a hydrodynamic bulge downstream of the downstream edge of the inlet opening.

Abstract: A weedless system has been developed for personal watercraft which obtain their power by using jet propelled water pumps. The unique weedless system has a number of elements which help to reduce weed congestion in the jet pump. Firstly, a plurality of downwardly directed grates, which terminate at the head of the ride shoe, are used such that weeds striking such grates will tend to slide off the grates rather than become embroiled around them. In addition, between the venturi and the steering nozzle there is located a butterfly valve which can be manually closed or opened by the operator. Closure of the butterfly valve creates a rotating movement of the water within the jet pump to provoke shaking, cutting and dislodging of weeds that go through the great barrier. The weeds then pass out through the water inlet back through a weed outlet passage or become pulverized such that they will pass safely past the jet pump when the valve is reopened and the boat regains normal efficiency.

Abstract: An improved water jet propulsion system for a jet propelled watercraft is disclosed designed to operate more efficiently. The improved propulsion system includes an adjustable water inlet duct, a larger pump, and an adjustable discharge nozzle. The inlet duct includes a hydraulically efficient inlet tunnel with an adjustable entrance opening which adjust in size according to the velocity of the water-craft in the body of water and the flow of water through the system. Using the inlet tunnel and the adjustable grate structure, the total dynamic head of the incoming water may be recovered at the pump. The pump is larger than typical pumps used on jet propulsion systems so that a greater flow of water at low head pressure may be delivered to the adjustable discharge nozzle. The adjustable feature on the discharge nozzle enables the flow through the system to be adjusted so that the hydraulic conditions on the pump are maintained at all boat speeds and all shaft rpm.

Abstract: A device for clearing grilles covering water intake ports on watercraft whereby the grille may be easily cleared while remaining on or in the watercraft. The clearing device comprises at least one scraper that includes a base and a plurality of teeth extending outwardly from the base. A line is attached to the scraper and extends outwardly in opposing directions therefrom. By grasping one end of the line in each hand and looping the clearing device below the hull adjacent the grilles, the user moves the scraper back and forth across the grille so that the teeth grab the grasses and other materials pulling them free.

Abstract: A marine jet drive weed grate (50) has a plurality of cantilever tines (58-63) extending rearwardly along the water intake (32) and have suspended aft end tips (64-69) spaced from the aft end (36) of the water intake such that weeds and debris may slide rearwardly along and then off of the cantilever tines without clogging.