Abstract: A motorboat water inlet foil grating comprises a frame and a pair of wing pieces. The frame is fastened to the water inlet located at the bottom of a motorboat hull. The wing pieces are mounted obliquely on the frame such that the lower segments of the wing pieces face forward and that the upper segments of the wing pieces face rearward. Each of the wing pieces has a concave upper surface and a convex lower surface. The concave upper surface faces upwards while the convex lower surface faces downwards. The frame is provided with a reinforcing portion for bracing the wing pieces which are capable of guiding water to flow evenly in the water channel of the motorboat so as to enable the propeller of the motorboat to compress the water current efficiently to enhance the forward power of the motorboat.

Abstract: A number of embodiments of jet propelled watercraft wherein the jet propulsion unit is positioned in a recess on the under side of the hull. A part of the water inlet opening of the jet propulsion unit is removable from above so as to permit clean-out of the jet propulsion unit water inlet and impeller when still mounted in the hull. Various locations and access openings are disclosed. In addition, embodiments of safety arrangements for disabling the prime mover when the removable part is removed for servicing are described.

Abstract: A jet drive for propelling a vessel has a rotatable impeller coupled to an engine. An impeller housing surrounds the impeller. A diffuser housing and a nozzle housing are attached to the impeller housing, which is supported by a transom. An intake duct is disposed in front of the impeller housing. The intake duct has an intake opening, the perimeter of which is defined by a forward edge portion substantially flush and a rear edge portion raised relative to the remainder of the edge, which is substantially parallel to the perimeter to the forward edge. A sloped surface connects the raised rear edge and the lowest point of the transom. The intake duct has a forward facing separator baffle depending from and substantially parallel to the wall and disposed interiorly thereof. The space defined between the separator baffle and the wall is in fluid communication through at least one discharge duct to either one of the transom and bottom.

Abstract: A jet propelled watercraft propelled using an internal combustion engine. The water providing the jet is drawn past a cooling device to cool the engine cooling liquid.

Abstract: An improved marine propulsion system that offers an attractive design with no external cables, gears, or the like and exceptional high speed performance is presented. It uses a unique new rotor concept that is supplied with water over the majority of a lower semicircle of its rotation and air over the top half of its rotation in the preferred embodiment. Since the rotor is pumping water over the lower half of its rotation the rotor sees greater average water inlet pressures than a standard full water flow waterjet. This results in improved efficiencies, especially at higher vehicle speeds. It is possible to vary the level of water flow into the rotor vanes by adjustment of an inlet flow regulating valve which results in adjustment in levels of power absorption. It is also possible, in most configurations, to run with the rotor filled with water which offers advantages at low vehicle speeds. Another feature is the aspiration of drive engine exhaust into the rotor which improves engine performance.

Abstract: A passive anti-clogging device for feeding water into marine jet pumps, which displaces the laminar flow around the trailing surfaces of the intake port, such that foreign debris and grass are precluded from clogging the intake to the jet pump. The primary component of the invention comprises an exclusion plate that is placed in, or immediately below the intake port, and affixed to the breadth of, or becoming a part of, the trailing edge of the intake port, leaving an opening, or slot, between the exclusion plate and ride plate, or bottom of the vessel, which, when at rest, allows the passage of water only from its anterior and lateral extents, thereby excluding the flow of water into the device from directly below or behind the plate. The edge of the exclusion plate angles or curves from a forward central point or apex to a back point at the trailing edge of the intake port, providing a fair surface to resist laminar attachment of debris, marine vegetation or other debris.

Abstract: A jet pump system for a water jet propelled boat is disclosed that provides for the adjustment of the area of the water intake opening or the water entry angle as a function of the speed of the boat. During low speed operation, the water inlet opening is adjusted to a maximum area, or the water entry angle is adjusted to a maximum angle to enable sufficient water to enter the water duct and permit efficient impeller operation. As the boat speed increases beyond a predetermined speed, the water inlet area is reduced, or the water inlet angle is reduced to prevent excess water from entering the water duct, thereby reducing the drag on the boat.

Abstract: An improved thruster system is provided for maneuvering and/or propulsion of a marine vessel, through the use of directionally oriented water jets discharged tangentially from a helical-conical flow chamber. The thruster system includes a high capacity pump for pumping water through a hull intake to the flow chamber with a substantial helical or swirling action. The water exits the flow chamber through one or more of a plurality of tangentially oriented discharge conduits having discharge nozzles for passage of high velocity water jets through the hull, resulting in reaction forces used to maneuver or propel the vessel. Each discharge conduit includes a valve member movable between open and closed positions for respectively permitting or preventing water flow to the associated nozzle.

Abstract: A jet propulsion for watercraft having a screen that extends across the water inlet opening of the jet propulsion unit for precluding foreign articles from entering the jet propulsion unit. The jet propulsion unit water inlet opening is supported for movement between a lowered driving position and an elevated service position. The screen is held in its closed position when the jet propulsion unit is in its driving position and may be pivoted to an open position when the jet propulsion unit is elevated.

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 water jet propelled watercraft having a hull defining a downwardly facing water inlet opening and a jet propulsion unit contained within the hull and having a water inlet opening portion through which water is drawn, an impeller portion containing an impeller for drawing the water and a discharge nozzle portion through which the water pumped by the impeller is discharged for powering the watercraft. The jet propulsion unit is supported for pivotal movement within the hull about a transversely extending horizontal axis. The water inlet opening of the jet propulsion unit water inlet portion and a corresponding portion of the hull water inlet opening are defined by mating flanges that lie in a plane that contains the horizontal pivotal axis to minimize sealing pressure variations on the seal therebetween.

Abstract: A ride plate according to this invention is adapted to be attached to the bottom of the hull of a personal watercraft. It has a forward and a rearward axial orientation along a nominal axis of forward action of the craft. The ride plate includes a channel portion having a central portion and a pair of laterally spaced apart wall members which slant away from the central portion and from each other, thereby to form an intake chamber into which the intake port opens. The channel member is open at both ends to permit debris and excess water to leave the chamber, thereby constituting a minimized source of drag. An intake grate is incorporated into the ride plate at its forward end, having a pair of generally parallel legs, each preferably having a foil cross-section, and leaving between them, and on outside of the pair, open regions through which water can flow to the chamber.

Abstract: A shaft shielding top loader (20) for use in the inlet water channel (12) of a water craft (10) is disclosed. Shaft shielding top loader (20) is configured to divide the incoming water into an upper portion and a lower portion, where the upper portion supplies the top of impeller (13). This is accomplished using an arcuate top loading plate (21) supported by a shaft shielding partition (22). Shaft shielding partition (22) is configured to have a trailing straight edge which is colinearly juxtapositioned with respect to impeller drive shaft (14) to shield impeller drive shaft (14) from the force of the incoming water. Shaft shielding top loader (20) is attached entirely within inlet water channel (12) using a suitable attachment device, such as a screw, at grate connecting adapter plate (24) and shoe plate (26). Shaft shielding top loader (20) insures a continuous water supply to impeller (13) regardless of the craft's orientation to the flow of incoming water.

Abstract: Several embodiments of jet propelled water vessels wherein the bull and jet propulsion unit cooperate to form an inlet opening so that the outer housing of the jet propulsion unit need not itself form the inlet. This facilitates servicing since the water inlet need not be removed along with the jet propulsion unit for servicing and minimizes the likelihood of damage to the inlet duct and support for the impeller shaft.

Abstract: The invention provides a crawler track belt assembly with flexible parallel belts interconnected by transverse grouser bars. The bars have guide portions spaced transversely apart and mutually aligned longitudinally with guide portions of other bars. A track bed of the vehicle has parallel, longitudinally extending, guide grooves which receive and guide the guide portions of the belt to maintain track alignment. To reduce belt tension, the lower track bed has a lateral profile which resembles a catenary. The vehicle body has spaced sponsons defining a hull tunnel therebetween, and in water is powered by a water jet having a primary intake adjacent the tunnel roof. If the primary intake becomes blocked, a secondary intake on the track bed is swept by the crawler track belt assembly to maintain the secondary nozzle free of obstruction. The water jet discharges through a rotatable nozzle which can be directed to assist in clearing the primary intake of blockage.

Abstract: A downward tubular extension constructed of shape retentive, but resilient, material is mounted from the lower end of the water inlet casing of a water jet pump of the outboard-type and the pump is mounted from the transom of an associated boat in elevated position thereon corresponding to the effective vertical extent of the extension. The extension is mounted from the lower end of the water inlet casing through the utilization of upwardly projecting mounting ears received in front and rear wall downwardly opening slots in the casing lower end in which the opposite ends of trash bars are conventionally mounted and the conventional trash bars are mounted in corresponding slots formed in the lower ends of the front and rear walls of the extension at the lower end thereof.

Abstract: A jet actuated boat propulsion device is provided for driving a boat in areas where hyacinths or other water vegetation exists, and which normally would foul up the operation of an outboard or inboard motor. A water pump positioned in a well in the bottom of the boat and communicating with the water in which the boat is floating is connected through conduits to discharge a jet of water through a nozzle extending into the body of water in which the boat is floating. The jettisoned water being discharged into the body of water exerts a jet action or thrust which drives the boat through the water.

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: An air aspiration prevention pan adapted to prevent aerated water from entering the intake of a water jet propulsion unit mounted in the hull of a water craft having low or zero dead rise characteristics or in a hull having sponsons or spaced apart skegs. The air aspiration prevention pan comprises sidewalls extending downwardly from the mounting means in a general V-configuration with the apex of the "V" toward the forward end of the hull. A lip extends outwardly from the bottom of the sidewalls and acts with them to confine and guide the aerated water under the hull so as to prevent a substantial portion of the aerated water from entering the intake of the water jet propulsion unit.

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 ride plate according to this invention is adapted to be attached to the bottom of the hull of a personal watercraft. It has a forward and a rearward axial orientation along a nominal axis of forward action of the craft. The ride plate includes a channel portion having a central portion and a pair of laterally spaced apart wall members which slant away from the central portion and from each other, thereby to form an intake chamber into which the intake port opens. The channel member is open at both ends to permit debris and excess water to leave the chamber, thereby constituting a minimized source of drag. An intake grate is incorporated into the ride plate at its forward end, having a pair of generally parallel legs, each preferably having a foil cross-section, and leaving between them, and on outside of the pair, open regions through which water can flow to the chamber.